influence of long term nitrogen and potassium fertilization on the biochemistry of tea soil
TRANSCRIPT
Influence of Long Term Nitrogen and Potassium Fertilization on the
Biochemistry of Tea Soil
Keywords Soil enzymes urease cellulase Tea Soil pH nitrogen and potassium fertilizers
ABSTRACT As the tea plantation in hilly tracts are located in slopes the management of
fertilizer regimes is somewhat challengeable due to leaching which in turn affect the quality of tea soil In light of this fact the present study was focused to determine the quality of tea soil in terms of the evaluation of certain physical and biological characteristics as influenced by various dosage of fertilizer applications The impact of long term nitrogen and potassium fertilization on biochemical characteristics and microbial activities in tea soil has been analyzed in the present study Different sources and rates of nitrogen (ammonium sulphate and urea) and potassium (muriate of potash) were tested at two soil depths (0-10 cm and 10-20 cm) and for two seasons (premonsoon and monsoon) The acidic tea soil was further acidified with nitrogen application and the extent of acidification varied with the fertilizer type and season Soil respiration rates were higher in 0-10 cm soils and were positively related to soil nitrogen and potassium concentrations Among the soil enzymes analyzed urease activity exhibited different trends in the two soil depths at different seasons Urease activity tended to increase with increasing potassium application rates whereas higher cellulase activity was associated with lower nitrogen application rates This study clearly indicates that the soil quality depends on the fertilizer application rates and season
124-135 | JRA | 2012 | Vol 1 | No 2
This article is governed by the Creative Commons Attribution License (httpcreativecommonsorg
licensesby20) which gives permission for unrestricted use non-commercial distribution and reproduction in all medium provided the original work is properly cited
wwwjagriinfo
Journal of Research in
Agriculture An International Scientific
Research Journal
Authors
Thenmozhi K1 Manian S2
and Paulsamy S1
Institution
1Department of Botany
Kongunadu Arts and Science
College Coimbatore
641 029 Tamil Nadu India
2 Department of Botany
Bharathiar University
Coimbatore 641 046 Tamil
Nadu India
Corresponding author
Thenmozhi K
Email thenmozhi_05yahoocoin
Phone No
+91- 9942474703
Web Address
httpwwwjagriinfo
documentsAG0029pdf
Dates Received 14 Sep 2012 Accepted 01 Oct 2012 Published 06 Oct 2012
Article Citation Thenmozhi K Manian S and Paulsamy S Influence of Long Term Nitrogen and Potassium Fertilization on the Biochemistry of Tea Soil Journal of Research in Agriculture (2012) 1(2) 124-135
Original Research
Journal of Research in Agriculture
Jou
rn
al of R
esearch
in
A
gricu
ltu
re
An International Scientific Research Journal
INTRODUCTION
Tea (Camellia sinensis (L) O Kuntz) a
perennial shrub cultivated in acid soil yields one of the
most popular non-alcoholic beverage tea which is
consumed world-wide for its taste aroma and health
effects South India contributes about 24 of Indiarsquos
total tea production Being a foliage crop nutrient
requirements for commercial tea production are
particularly high Nitrogen and potassium are the two
major nutrients of tea without which commercial
production levels are difficult to achieve (Verma 1993
Verma et al 2001) In south Indian tea gardens nitrogen
and potassium fertilizers are always applied in
combination There are three different sources of
nitrogen namely ammonium sulphate urea and calcium
ammonium nitrate However the choice of potassium is
confined to muriate of potash This soil management has
potential impact upon soil biological quality Nitrogen
fertilizers when used on a regular basis tend to acidify
soil Further long-term nitrogen fertilization has been
shown to affect the distribution and the amount of
organic carbon soil microbial biomass and soil enzyme
activities (Darusman et al 1991 Mc Andrew and
Malhi 1992) Thus fertilizers as nutrient sources may
have beneficial influence on plants however there may
be adverse effects especially on microorganisms as a
result of soil acidification
Enzymes catalyze all biochemical reactions and
are an integral part of nutrient cycling in soil
Investigations are often limited to few enzymes to show
that agricultural management practices affect enzyme
activity (Dick 1994) A wide range of enzymes have not
been systematically investigated for their potential to
reflect short and long-term soil management effects in
relation to soil quality
Although the effect of combined application of
nitrogen and potassium fertilizers on biochemical
characteristics of tea is well reported (Venkatesan and
Ganapathy 2004 Venkatesan et al 2005) its effect on
soil physico-chemical and biological characteristics are
scarce (Venkatesan et al 2004) Increasing evidence
indicates that soil biological parameters may hold
potential as early and sensitive indicators of soil health
Microbial characteristics of acid tea soils are reported to
be qualitatively different from normal acid soils
(Nioh et al 1993) The objective of the study was to
evaluate the long - term impact of fertilizer application
on physico-chemical and microbiological properties of
selected soil in an experimental tea field receiving
fertilizer treatment since 1994 The selection of
biological response variables was based upon their
relationship to soil function The soil microbial
community inhabits an environment responding to
physical chemical or biological perturbation Soil
biological properties were chosen to represent the soil
environment in which the organism must exist (soil
organic matter and moisture) the microbial community
itself (soil respiration) and biochemical activities of these
populations (soil cellulase and urease activity) These
biochemical activities were chosen to be a representative
of nutrients that influence plant production
MATERIALS AND METHODS
Experimental site and design
The experimental site was located at United
Planters Association of Southern India (UPASI) Tea
Research Foundation at Anamallais (10deg30rsquoN and
77deg0rsquoE at 1050 m asl) southern India The climatic
data collected from UPASI Tea Research
Institute - Meterological station Valparai for the past 20
years showed that the site is experiencing an average
annual rainfall of 1100 mm and the temperature range of
11-29degC The investigation was carried out in the long
term fertilizer trial plots (10m x 10m) established in 1994
using tea clone SA 6 with 100 bushes plot The duration
of the study period was one year from Nov 2010 to
Oct 2011
125 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Experimental setup
The experimental plots were setup to investigate
the impacts of nitrogen and potassium fertilization on
soil biochemistry and employed a randomized complete
block design with three replicate plots for the fifteen
treatments and unfertilized control plots The fifteen
treatments included different levels of nitrogen and
potassium (150 300 and 450 kg ha-1y -1) individually and
in various combinations
Fertilizers were broadcasted in four split doses in
order to avoid volatilization and leaching Nitrogen was
applied as 25 sulphate of ammonia (containing 20
nitrogen) and urea (containing 46 nitrogen) Potassium
was applied as muriate of potash (containing 63
potassium) Sulphate of ammonia was broadcasted at the
rate of 75 15 and 225 kg ha-1 between February and
November Urea at the rate of 1725 345 and
5175 kg ha-1 was broadcasted between May and August
Muriate of potash was applied at the rate of 2363 4725
and 7088 kg ha-1 along with sulphate of ammonia or
urea Other nutrients (Phosphorus Calcium Magnesium
Sulphur Zinc Manganese and Boron) were applied at
recommended rates and regular cultural practices were
carried out uniformly in all the plots (Verma and Palani
1997)
Sampling
Soil samples were collected during premonsoon
(March) and monsoon (June) in 2011 Ten soil cores
(5 cm in diameter) at the depths of 0-10 cm (L1 layer)
and 10-20 cm (L2 layer) were randomly taken from each
plot and bulked Field moist samples were passed
through a 2-mm sieve and divided into two equal parts
One part was used for the determination of soil moisture
pH electrical conductivity total nitrogen exchangeable
potassium and organic carbon The other part was stored
at 4degC prior to microbiological assays
Soil analysis
Soil moisture content was determined after
drying at 105degC to a constant weight Soil pH and
Journal of Research in Agriculture (2012) 1(2) 124-135 126
Thenmozhi et al2012
Treatm
en
t M
ois
ture (
)
pH
E
C (
dS
m-1
) S
1
S
2
S
1
S
2
S1
S 2
L
1
L2
L1
L2
L1
L2
L1
L2
L1
L2
L1
L2
N0 K
0
11
00 b
c 1
16
7 d
e 1
80
0 d
ef
19
00 d
e 3
76 f
3
36 h
4
69 b
4
33 d
0
21
6 i
0
24
8 h
0
38
8 e
0
33
2 e
N
0 K
15
0
66
7 e
-h
10
00 d
ef
19
67 b
-e
21
00 b
cd
38
6 d
3
65 c
4
79 a
4
66 a
0
27
7 g
0
30
9 d
e 0
29
4 h
0
30
4 f
N
0 K
300
80
0 d
e 1
20
0 c
d
19
00 b
-f
21
67 b
c 3
89 c
3
55 d
4
60 c
4
40 c
0
18
2 j
0
21
1 j
0
32
0 g
0
24
3 i
N
0 K
45
0
56
7 f
gh
9
67 e
fg
20
33 b
c 2
10
0 b
cd
43
2 a
3
82 b
4
59 c
4
47 b
0
17
8 j
0
32
0 d
0
23
9 i
0
21
4 k
N
15
0 K
0
10
00 c
d
11
33 d
e 2
03
3 b
c 2
26
7 b
3
55 h
3
43 f
4
25 d
4
38 c
0
32
4 e
0
24
9 h
0
33
5 f
0
25
6 h
N
15
0 K
15
0
13
00 a
b
14
00 b
c 2
00
0 b
cd
21
67 b
c 3
68 g
3
47 e
4
26 d
4
30 d
0
32
8 e
0
22
5 i
0
33
8 f
0
22
8 j
N
15
0 K
30
0
11
00 b
c 1
56
7 a
b
21
00 b
2
30
0 a
b
34
3 k
3
39 g
4
23 d
e 4
33 d
0
36
0 c
0
22
3 i
0
34
6 f
0
25
7 h
N
15
0 K
45
0
14
67 a
1
63
3 a
2
40
0 a
2
50
0 a
3
82 e
3
43 f
4
19 f
4
31 d
0
36
5 c
0
26
4 g
0
42
1 d
0
36
7 d
N
30
0 K
0
70
0 e
fg
10
00 d
ef
18
67 c
-f
19
67 c
de
35
4 h
3
28 i
4
20 e
f 4
25 e
0
24
5 h
0
26
9 g
0
28
7 h
0
29
9 f
N
30
0 K
15
0
80
0 d
e 1
20
0 c
d
17
67 e
f 1
90
0 d
e 3
50 i
3
28 i
4
14 g
4
32 d
0
38
9 b
0
31
6 d
e 0
34
5 f
0
32
6 e
N
30
0 K
30
0
50
0 g
h
70
0 h
i 1
83
3 c
-f
18
00 e
3
46 j
3
22 j
3
86 k
4
40 c
0
28
0 g
0
35
2 b
0
49
1 a
0
24
9 h
i N
30
0 K
45
0
46
7 h
6
00 i
1
90
0b-f
1
93
3 d
e 4
06 b
3
97 a
4
07 h
4
31 d
0
30
4 f
0
30
8 e
0
33
7 f
0
42
0 b
N
45
0 K
0
70
0 e
fg
76
7 g
hi
17
67 e
f 2
00
0 c
de
32
4 m
3
03 k
4
04 h
4
14 g
0
45
4 a
0
43
2 a
0
31
9 g
0
32
5 e
N
45
0 K
15
0
70
0ef
g
96
7 e
fg
18
00
def
1
80
0 e
3
43 k
3
36 h
3
98 i
4
20
f
02
14 i
0
26
6 g
0
34
3 f
0
28
8 g
N
45
0 K
30
0
76
7 e
f 9
00 f
gh
1
93
3 b
-e
19
67 c
de
32
9 l
3
21 j
3
89 j
4
23 e
f 0
34
3 d
0
33
9 c
0
47
3 b
0
38
2 c
N
45
0 K
45
0
73
3ef
9
00 f
gh
1
70
0 f
2
00
0 c
de
32
9 l
3
23 j
4
05 h
4
23 e
f 0
38
0 b
0
28
7 f
0
45
2 c
0
50
1 a
Tab
le 1
P
hy
sical
ch
aracte
rs
of
soil
for
0-1
0 c
m l
ay
er (
L1)
an
d 1
0-2
0 c
m l
ay
er (
L2)
du
rin
g p
rem
on
soon
(S
1)
an
d m
on
soon
(S
2)
sea
son
s a
s in
flu
en
ced
by
nit
rog
en
an
d p
ota
ssiu
m
ferti
lizati
on
Mea
ns
in a
colu
mn
for a
soil
la
yer
foll
ow
ed
by
sa
me
lett
er(s
) d
o n
ot
sig
nif
ica
ntl
y d
iffe
r (P
lt0
05
) accord
ing t
o D
un
ca
nrsquos
Mu
ltip
le R
an
ge
Test
electrical conductivity were measured using a digital pH
meter (Cyberscan 510 Singapore) and Conductivity
Bridge Meter (ORLAB 201 India) Total nitrogen was
measured using an autoanalyser (Skalar autoanalyser
Netherlands) after Kjeldahl digestion and distillation
Exchangeable potassium was extracted in ammonium
acetate solution (pH 7) and measured using a flame
photometer (GENWAY) Total organic carbon was
determined according to Nelson and Sommers (1982)
The titration method of Jaggi (1976) was used to
assess soil respiration Urease activity was determined
according to Kandeler and Gerber (1988) with urea (1M)
as a substrate and the values were expressed as
microg Ng -1dm2h -1 using the calibration curve Cellulase
activity was determined by incubation of soil samples
with water-soluble carboxymethylcellulose (Schinner
and Von Mersi 1990) for 24 h at 50degC pH 55 Low
molecular products and sugars resulting from the
enzymatic degradation of carboxymethylcellulose were
used for the quantitative reduction of potassium
hexacyanoferrate II to potassium hexacyanoferrate III
which reacts with Fe (III) ammonium sulfate to form a
complex known as ldquoPrussian Blueldquo which is determined
photometrically at 690 nm Cellulase activity is
expressed as microg GE g-1 dm 24 h -1
Statistical analysis
All data were subjected to analysis of variance
(ANOVA) (IRRISTAT version 393) and Duncanrsquos
Multiple Range Test (Plt005) was used to separate the
means when the differences were significant Pearsonrsquos
correlation analysis was used to assess the relationship
between soil and microbial variables The latter analysis
was carried out in SPSS 90
RESULTS
Soil properties
Soil in the experimental plots were clayey loam
and fertilizer application had a profound influence on
soil moisture As expected soil moisture was
127 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatm
en
t T
ota
l n
itrogen
(
) E
xch
an
gea
ble
pota
ssiu
m (
mg
kg
-1l)
Org
an
ic c
arb
on
(
) S
1
S2
S1
S2
S1
S 2
L1
L2
L1
L2
L1
L2
L1
L2
L1
L2
L1
L2
N0 K
0
03
7 h
i 0
29 e
f 0
27 f
g
02
4 b
1
552
1 h
1
018
3 i
1
626
5 i
1
074
3 k
4
83 h
3
26 h
3
99 h
3
55 f
N
0 K
15
0
03
6 i
0
31 d
e 0
29 e
fg
01
4 e
2
484
5 d
1
868
8 e
2
282
0 d
1
974
3 d
5
24 f
3
69 e
4
06 h
3
63 e
N
0 K
300
04
0 d
ef
03
4 a
bc
02
4 h
0
19 c
2
598
3 c
2
235
9 c
2
178
5 e
1
577
8 e
5
07 g
3
39 g
4
37 g
3
00 j
N
0 K
45
0
03
8 f
gh
0
27 g
0
27 g
0
19 c
3
237
0 b
2
467
2 b
2
812
2 b
2
597
7 b
4
79 h
3
82 d
4
91 e
4
10 c
N
15
0 K
0
03
8 g
hi
02
8 f
g
02
8 f
g
01
6 d
e 1
369
5 j
9
33
5 j
1
230
2 m
1
153
3 i
5
00 g
3
32 g
4
45 g
3
08 i
N
15
0 K
15
0
04
7 a
0
31 d
e 0
29 e
f 0
15 e
1
415
0 i
8
08
8 l
1
374
3 k
1
153
3 i
6
07 a
3
84 d
3
90 i
3
20 h
N
15
0 K
30
0
03
8 g
hi
02
8 f
g
02
7 g
0
31 a
1
598
3 g
1
191
8 g
1
972
0 f
1
433
6 f
5
34 e
3
33 g
h
52
7 c
3
39 g
N
15
0 K
45
0
04
2 b
cd
02
7 f
g
03
8 b
0
30 a
4
427
1 a
3
132
3 a
3
700
1 a
2
651
0 a
5
04 g
3
80 d
5
85 b
3
86 d
N
30
0 K
0
04
2 c
de
03
3 b
cd
03
7 b
0
25 b
7
68
0 n
6
08
6 n
6
72
8 p
8
85
3 m
5
46 d
4
00 c
4
00 h
4
02 c
N
30
0 K
15
0
04
2 c
d
02
9 e
fg
03
6 b
c 0
31 a
1
061
2 l
8
08
8 l
9
29
0 o
1
062
5 l
5
50 c
d
37
8 d
5
19 c
4
96 a
N
30
0 K
30
0
03
9 f
g
03
5 a
0
36 b
c 0
24 b
1
280
2 k
1
147
9 h
1
529
5 j
1
199
2 h
5
69 b
4
37 a
5
93 b
3
71 e
N
30
0 K
45
0
04
3 b
c 0
31 d
e 0
31 d
e 0
25 b
2
170
2 f
2
024
4 d
1
923
9 g
1
386
1 g
5
27 e
f 3
59 f
4
64 f
3
28 h
N
45
0 K
0
04
4 b
0
35 a
b
03
8 a
b
01
6 d
e 8
08
8 m
7
38
0 m
1
017
6 n
5
51
0 o
5
46 d
3
94 c
5
03 d
3
82 d
N
45
0 K
15
0
04
3 b
c 0
32 c
d
03
5 c
0
16 d
e 1
280
2 k
8
50
0 k
1
292
0 l
7
56
5 n
6
01 a
4
10 b
4
37 g
3
28 h
N
45
0 K
30
0
04
0 e
fg
03
3 a
bc
03
3 d
0
24 b
1
280
2 k
8
08
8 l
1
873
7 h
1
107
7 j
5
56 c
4
29 a
5
19 c
4
33 b
N
45
0 K
45
0
04
4 b
c 0
34 a
bc
04
0 a
0
17 c
d
22
35
9 e
1
808
8 f
2
700
1 c
2
017
6 c
6
08 a
4
35 a
6
08 a
4
29 b
M
ea
ns
in a
colu
mn
for a
soil
la
yer
foll
ow
ed
by s
am
e le
tter
(s)
do n
ot
sig
nif
ica
ntl
y d
iffe
r (P
lt0
05
) accord
ing t
o D
un
ca
nrsquos
Mu
ltip
le R
an
ge
Test
Ta
ble
2 C
hem
ical
chara
cter
s of
soil
for
0-1
0 c
m l
ayer
(L
1)
an
d 1
0-2
0 c
m l
ayer
(L
2)
du
rin
g p
rem
on
soon
(S
1)
an
d m
on
soon
(S
2)
sea
son
s as
infl
uen
ced
by n
itro
gen
an
d
po
tass
ium
fe
rti
liza
tion
significantly higher during monsoon and was affected by
fertilization Similarly the L2 layer was moister than the
L1 layer during both the seasons For premonsoon period
it ranged between 467-1467 (L1) and 600-1633
(L2) respectively On the other hand it registered
1700-2400 (L1) and 1800-2500 (L2) of mixture
for monsoon seasons (Table 1) Soil moisture was higher
in unfertilized soils during both seasons but
progressively decreased with fertilizer application rates
especially nitrogen (300 and 450 kg ha-1)
A significant difference in soil pH was evident
between layers seasons and most treatments Soils
fertilized with potassium had higher pH values the
exception being the 0-10 cm soils fertilized with 300 and
450 kg ha-1of potassium In contrast soils fertilized with
nitrogen had the lowest pH values and this drop in pH
was more evident in the top 0-10 cm soils than in 10-20
cm soils Soil pH correlated positively with soil moisture
levels (r = 0737 Plt001) (Table 1 3) Like pH soil
electrical conductivity also exhibited significant
differences between treatments seasons and layers
During premonsoon soils fertilized with nitrogen had
either almost similar or significantly higher electrical
conductivity values In contrast during monsoon soil in
nitrogen fertilized plots had decreased electrical
conductivity values compared to unfertilized plots
(Table 1)
Total soil nitrogen and exchangeable potassium
significantly differed between seasons layers and among
treatments (Tables 2 and 3) The percentage nitrogen
content of the tea soil was higher during premonsoon
period (S1) when compared to the monsoon season (S2)
Similarly the nitrogen content of L1 layer was higher
when compared to their respective L2 layer Further the
application of nitrogen fertilizer at different doses
enhanced the available nitrogen in L1 layer
concomitantly (Table 2) The exchangeable potassium
level was comparable between premonsoon (S1) and
monsoon (S2) seasons and it fluctuated between different
Journal of Research in Agriculture (2012) 1(2) 124-135 128
Thenmozhi et al2012
So
urce
of
va
ria
tion
df
Mois
ture (
)
pH
E
C (
dS
m-1
)
Soil
nu
trie
nts
Tota
l n
itrog
en
(
) E
xch
an
gea
ble
pota
ssiu
m (
mg
kg -1
l)
Org
an
ic c
arb
on
(
)
Tre
atm
ent
(T)
15
12
8
34
25
15
491
4
74
64
49
53
12998228394
7
23
06
Laye
r (L
) 1
12
8
10
09
2
58
38
4
92
83
3
30
78
56
16275748913
7
15
66
2
Sea
son
(S
) 1
12
8
33
067
2
84
72
17
8
15
98
55
2
385
60
9
118
003
5
64
56
T x
L
15
12
8
13
9
22
84
8
17
54
9
28
54
401064267
8
11
13
T x
S
15
12
8
71
6
37
90
4
27
52
1
37
60
501731007
1
21
50
L x
S
11
28
83
3
33
518
3
26
68
6
20
5
29
53
9621
6
14
09
8
T x
L x
S
51
28
12
4
74
64
19
66
5
29
49
148581688
7
16
02
Tab
le 3
F
- V
alu
es o
f vari
ou
s so
il p
hy
sico
ch
em
ical
ch
aracte
rs a
s in
flu
en
ced
by
nit
rogen
an
d p
ota
ssiu
m f
erti
liza
tio
n
an
d
s
ign
ific
an
t a
t P
lt0
01
an
d P
lt0
00
1 r
esp
ecti
vely
treatment plots in the range of 551 and 4427 mg kg dry
soil However the potassium content was comparably
higher in the L1 layer than the L2 layer The application
of increasing doses of muriate of potash in the different
experimental plots resulted in the enhanced amount of
potassium content in both L1 and L2 layers (Table 2)
Generally nitrogen content in the 0-10 cm soils was
higher when compared to their respective 10-20 cm soils
Exchangeable potassium was lower in nitrogen fertilized
soils than unfertilized soils Soil nitrogen was
significantly (Plt001) and negatively correlated to soil
moisture (r = -0627) and pH (r = -0518) In contrast
soil potassium and pH had a significant and positive
correlation (r = 0267 Plt005) Organic carbon was
higher in the 0-10 cm soils than in 10-20 cm soils and
significantly varied with fertilization and seasons
Generally organic carbon was higher during
premonsoon than monsoon season As organic carbon
was significantly and positively correlated to electrical
conductivity (r = 0315 Plt005) and nitrogen (r = 0752
Plt 001) it was significantly and negatively correlated to
soil moisture (r = -0334 Plt001) (Table 3)
Soil respiration
Soil respiration tended to be higher in 0-10 cm
soils and significantly varied between seasons and
among treatments (Fig 1) During premonsoon
maximum respiration rates were occurred in the 0-10 cm
soils and it was moderate (300 kg ha-1) and high
(450 kg ha-1) in potassium fertilized soils In contrast
maximum respiration rates in the 10-20 cm soils during
129 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
mg
CO
2g
-1 d
m2
4
Fig 1 Influence of nitrogen and potassium fertilization on soil respiration in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
Treatments (Fertilizer dose in kghay)
premonsoon occurred in soils fertilized with high
nitrogen (450 kg ha-1) During monsoon maximum
respiration rates were occurred in the 0-10 cm soils of
treatment involving moderate potassium and high
nitrogen levels (K300 and N450) The respiration rates in
10-20 cm soils during monsoon in fertilized plots were
generally lower compared to unfertilized soils Soil
respiration was significantly and positively correlated to
soil nitrogen (r=0325 Plt0001) and potassium
(r =0309 Plt005)
Enzyme activities
Application of nitrogen and potassium either
individually or in combinations significantly affected soil
urease activity (Fig 2) Urease activity exhibited different
trends in the two soil layers at different seasons High
urease activity occurred during premonsoon in 0-10 cm
soils and during monsoon in the 10-20 cm soils
However maximum urease activity occurred in soils
fertilized with higher doses of nitrogen and potassium
(N450 and K450) during both the seasons and layers except
in 0-10 cm soils where maximum urease activity was
detected in soils fertilized with low nitrogen and
moderate potassium (N150 and K300) Soil urease activity
was significantly and positively correlated to organic
carbon (r=0265 Plt005) and negatively to soil
respiration (r =-0347 Plt 001)
Journal of Research in Agriculture (2012) 1(2) 124-135 130
Thenmozhi et al2012
Fig 2 Influence of nitrogen and potassium fertilization on soil urease activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
μg
Ng
-1d
m2
h-1
L1
n p
L1
L2
Treatments (Fertilizer dose in kghay)
Cellulase activity in the soil differed
significantly among treatments and between seasons and
soil layers (Fig 3) Cellulase activity was higher in 0-10
cm soils during premonsoon season There was a greater
cellulase activity in both soil layers during both the
seasons at low nitrogen application rates (N150)
However increasing concentration of nitrogen
fertilization affected cellulase activity to a greater extent
in the 0-10 cm soils than in 10-20 cm soils A significant
(Plt005) positive correlation existed between soil
cellulase activity and total soil nitrogen (r = 0283)
DISCUSSION
Regular nitrogen fertilization of the acid
soil further acidified the soils The acidification was
more in sulphate of ammonia application during
premonsoon than in urea application during monsoon
These are in accordance with the fact that regular
nitrogen fertilization tend to acidify soils (Khonje et al
1989 Darusman et al 1991) Biederbeck et al (1996)
indicated that application of anhydrous ammonia
lowered soil pH more than urea which clearly indicates
varied levels of soil acidification by different nitrogen
sources Furthermore soil total nitrogen levels were
lower in plots during urea application than sulphate of
131 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatments (Fertilizer dose in kghay)
μg
GE
g-1
dm
24 h
-1
Fig 3 Influence of nitrogen and potassium fertilization on soil cellulase activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
ammonia Most of the broadcasted urea might have
leached out in heavy monsoon showers as considerable
loss (10-25) of nitrogen has been reported to occur due
to leaching or volatilization if urea was not incorporated
into soil soon after its application (Yang 1991 Byrnes
and Freney 1995)
The physico-chemical complexity of soil
contributes significantly to underlying variability in
K+ levels with soil pH moisture and chemical
composition all having marked effects (eg Maathuis
and Sanders 1996) In particular acidic pH leads to
desorption of K+ from anionic binding sites in the soil
and accounts for the tendency towards higher K+ levels
in acidic soils (Gassmann et al 1993) The
exchangeable potassium increased with increasing
potassium application rates It has been thought for a
long time that exchangeable potassium do not built up in
the tea soils of south India because of the dominance of
Kaolinite clay mineral (Verma 1997 Venkatesan et al
2003) However the presence of other minerals other
than Kaolinitic might contribute to the build up of
potassium in the soil (Venkatesan et al 2004) In this
study exchangeable potassium was not related to pH
moisture or chemical composition of the soil However
application of nitrogen significantly reduced soil
potassium which ranged from 18-55 in the 0-10cm
soils and 0-38 in 10-20 cm soils Application of
nitrogen is known to enhance the growth of tea plants
An increased plant growth resulting from nitrogen
fertilization tends to increase potassium uptake from the
soil Studies by The Chinese Tea Research Institute
showed that tea leaves contain 12-25 potassium (TRI
1997) So a large amount of potassium is being mined
from the soil system by the tea plants as a result of
increased growth response to nitrogen fertilization
(Tchienkoua and Zech 2004)
The existence of a significant positive correlation
between soil organic carbon and soil nitrogen indicates
an increasing soil organic carbon content with increasing
nitrogen application rates This is in accordance with
Venkatesan et al (2004) who has also reported higher
organic carbon in soils fertilized with nitrogen Further
Venkatesan et al (2004) indicated that natural organic
carbon reserves of tea soil would be lost due to no or
inadequate supply of nitrogen because tea plants tended
to mineralize and absorb nutrients from organic matter in
the soil under nutrient stress conditions In addition
other studies indicate an increase in soil organic carbon
with increasing soil acidity (Willett et al 2004 Kemmitt
et al 2006) Results from this study tended to indicate
that soil pH and organic carbon were negatively
correlated to each other but this relation is not
statistically significant However when the correlation
analysis was staggered between layers a significant
negative correlation existed between soil pH and organic
carbon in 0-10 cm soils (r = -0667 Plt0000) but not in
10-20 cm soils (r = -0193 Pgt005) This varied relation
between soil organic carbon and pH between layers
could be attributed to soil nitrogen which tended to
strongly influence soil pH than soil potassium
Correlation coefficient values for soil pH and nitrogen in
0-10 cm soils were higher (r= -0773) compared to
10-20 cm soils (r = -0734) These observations are in
line with results of Mc Andrew and Malhi (1992) who
reported an increase in soil organic matter with
increasing soil nitrogen
Soil respiration rates were within normal ranges
reported for natural soils (Srivastava and Singh 1991
Maxwell and Coleman 1995) Results from this study
tended to show that nitrogen and potassium fertilization
affected soil respiration in 0-10 cm soils more than in the
10-20 cm soils Results of Chen et al (2002) also
indicate that nitrogen fertilization reduced soil
respiration in 0-10 cm soils The low respiration rate
with fertilizer application might be attributable to lower
availability of carbon with decreasing soil pH induced by
the nitrogen application (Thirukkumaran and Parkinson
2000)
Journal of Research in Agriculture (2012) 1(2) 124-135 132
Thenmozhi et al2012
Soil urease activity has been reported to follow
changes in soil factors (Cookson and Lepiece 1996) In
the present study fertilizer application generally
increased soil urease activity This is in agreement with
Venkatesan and Senthurpandian (2006) who also
reported an increased urease activity in fertilized tea
soils However these observations contrasts the studies of
Dick et al (1988) and Bandick and Dick (1999) where
soil urease activity was reported to decrease with
increasing application of ammonia based nitrogen
fertilizers Since urease is a substrate inducible enzyme
the application of fertilizers especially urea could have
resulted in higher urease activity Further the binding of
the urease to organic matter insulating itself from
denaturation and biological degradation by soil humic
polymers (Beri et al 1978 Baligar and Wright 1991)
could also attribute to increased level of urease as this
urease could be released from these protected sites by
acid sensitive ammonia oxidizers in response to
fertilization (Martikainen 1985)
Cellulase activity was higher in the surface layer
(0-10 cm soils) than in the subsoils (10-20 cm soils) and
was positively correlated to soil organic matter
Fertilization increased soil cellulase activity which are
in accordance with studies of Aescht and Foissner
(1992)
CONCLUSION
Results from the present study revealed that long
term application of nitrogen and potassium fertilizers
affected soil nutrients and pH Further these fertilizers
can interact with soil microbial communities in a variety
of ways and consequently disturb their normal
functioning The use of nitrogenous fertilizers is
inevitable and an essential part of agricultural practices
In the present study we determined that longndashterm
application of higher doses of urea or ammonium
sulphate fertilizers had an inverse effect on pH moisture
soil respiration and enzyme activities Therefore the
maintenance of low rates of nitrogen and potassium
(ie lt 300 kg-1ha-1y-1) are vital for preserving the soil
quality as higher doses of nitrogen and potassium
(ie gt 300 kg-1ha-1y-1) adversely affects the soil quality
However the actual mechanisms behind these changes
are difficult to infer and needs further investigation
ACKNOWLEDGEMENTS
I express my sincere thanks to
Dr N Muraleedharan Director UPASI Tea Research
Institute Valparai Coimbatore District Tamil Nadu
India for kind permission to use their experimental plots
which formed vital foundation for this work I
acknowledge the invaluable help and support rendered
by Dr S Premkumar Samuel Asir Dr UI Baby and
Dr S Venkatesan Dr R Selvasundaram UPASI Tea
Research Institute Valparai Coimbatore District Tamil
Nadu India during the course of this study
REFERENCES
Aescht E and Foissner W 1992 Effects of mineral and
organic fertilizers on the micro fauna in a high-altitude
reafforestation trial Biology and Fertility of Soils
1317-24
Baligar VC and Wright RJ 1991 Enzyme activities in
Appalachian soils I Aryl-sulfatase Communications in
Soil Science and Plant Analysis 22305-314
Bandick AK and Dick RP 1999 Field management
effects on soil enzyme activities Soil Biology and
Biochemistry 311471-1479
Beri V Goswami KP Brar SS 1978 Urease activity
and its Michaelis constant for soil systems Plant and
Soil 49105-115
Biederbeck VO Campbell CA Ukrainetz H Curtin
D Bouman OT 1996 Soil microbial and biochemical
properties after ten years of fertilization with urea and
anhydrous ammonia Canadian Journal of Soil Science
133 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
76 7-14
Byrnes BH and Freney JR 1995 Recent developments
on the use of urease inhibitors in the tropics Fertilizer
Research 42251-259
Chen CR Xu ZH Hughes JM 2002 Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland Australia Biology
and Fertility of Soils 36276-283
Cookson P and Lepiece AG 1996 Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman Journal of Arid Environment 32225-238
Darusman Stone LR Whitney DA Janssen KA
Long JH 1991 Soil properties after twenty years of
fertilization with different nitrogen sources Soil Science
Society of America Journal 551097-1100
Dick RP 1994 Soil enzyme activities as indicators of
soil quality In Doran JW Coleman DC Bezdicek DF
Stewart BA (Eds) Defining soil quality for a
sustainable environment Special publication no35
SSSA MadisonWI 107-124
Dick RP Rasmussen PE Kerle EA 1988 Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system Biology and Fertility of Soils 6159-164
Gassmann W Ward JM Schroeder JI 1993
Physiological roles of inward rectifying K+ channels
Plant Cell 51491-1493
Jaggi W 1976 Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat Schw Landw
Forsch 15371-380
Kandeler E and Gerber H 1988 Short ndash term assay of
soil urease activity using colorimetric determination of
ammonium Biology and Fertility of Soils 668-72
Kemmitt SJ Wright D Goulding KWT Jones DL
2006 pH regulation of carbon and nitrogen dynamics in
two agricultural soils Soil Biology and Biochemistry
38898-911
Khonje DJ Varsa EC Klubek B 1989 The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil
Communications in Soil Science and Plant Analysis
201377-1395
Maathuis FJM and Sanders D 1996 Mechanism of
Potassium absorption by higher plant roots Physiology
Plantarum 96158-168
Martikainen PJ 1985 Nitrification in forest soil of
different pH as affected by urea ammonium sulphate and
potassium sulphate Soil Biology and Biochemistry
17363-367
Maxwell RA and Coleman DC 1995 Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians Soil
Biology and Biochemistry 2779-84
Mc Andrew DW and Malhi SS 1992 Long-term N
fertilization of a Solonetzic soil Effects on chemical and
biological properties Soil Biology and Biochemistry
24619-623
Nelson DW and Sommers LE 1982 Total carbon
organic carbon and organic matter In Page AL Miller
RH Keeney DR (Eds) Methods of soil analysis Part -
2 Chemical and microbiological properties ASA
monograph number 9 MadisonWI 539-579
Nioh I Isobe T Osada M 1993 Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil Soil Science and Plant Nutrition 39617-625
Schinner F and Von Mersi W 1990 Xylanase- CM-
cellulase- and invertase activity in soil an improved
Journal of Research in Agriculture (2012) 1(2) 124-135 134
Thenmozhi et al2012
method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
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INTRODUCTION
Tea (Camellia sinensis (L) O Kuntz) a
perennial shrub cultivated in acid soil yields one of the
most popular non-alcoholic beverage tea which is
consumed world-wide for its taste aroma and health
effects South India contributes about 24 of Indiarsquos
total tea production Being a foliage crop nutrient
requirements for commercial tea production are
particularly high Nitrogen and potassium are the two
major nutrients of tea without which commercial
production levels are difficult to achieve (Verma 1993
Verma et al 2001) In south Indian tea gardens nitrogen
and potassium fertilizers are always applied in
combination There are three different sources of
nitrogen namely ammonium sulphate urea and calcium
ammonium nitrate However the choice of potassium is
confined to muriate of potash This soil management has
potential impact upon soil biological quality Nitrogen
fertilizers when used on a regular basis tend to acidify
soil Further long-term nitrogen fertilization has been
shown to affect the distribution and the amount of
organic carbon soil microbial biomass and soil enzyme
activities (Darusman et al 1991 Mc Andrew and
Malhi 1992) Thus fertilizers as nutrient sources may
have beneficial influence on plants however there may
be adverse effects especially on microorganisms as a
result of soil acidification
Enzymes catalyze all biochemical reactions and
are an integral part of nutrient cycling in soil
Investigations are often limited to few enzymes to show
that agricultural management practices affect enzyme
activity (Dick 1994) A wide range of enzymes have not
been systematically investigated for their potential to
reflect short and long-term soil management effects in
relation to soil quality
Although the effect of combined application of
nitrogen and potassium fertilizers on biochemical
characteristics of tea is well reported (Venkatesan and
Ganapathy 2004 Venkatesan et al 2005) its effect on
soil physico-chemical and biological characteristics are
scarce (Venkatesan et al 2004) Increasing evidence
indicates that soil biological parameters may hold
potential as early and sensitive indicators of soil health
Microbial characteristics of acid tea soils are reported to
be qualitatively different from normal acid soils
(Nioh et al 1993) The objective of the study was to
evaluate the long - term impact of fertilizer application
on physico-chemical and microbiological properties of
selected soil in an experimental tea field receiving
fertilizer treatment since 1994 The selection of
biological response variables was based upon their
relationship to soil function The soil microbial
community inhabits an environment responding to
physical chemical or biological perturbation Soil
biological properties were chosen to represent the soil
environment in which the organism must exist (soil
organic matter and moisture) the microbial community
itself (soil respiration) and biochemical activities of these
populations (soil cellulase and urease activity) These
biochemical activities were chosen to be a representative
of nutrients that influence plant production
MATERIALS AND METHODS
Experimental site and design
The experimental site was located at United
Planters Association of Southern India (UPASI) Tea
Research Foundation at Anamallais (10deg30rsquoN and
77deg0rsquoE at 1050 m asl) southern India The climatic
data collected from UPASI Tea Research
Institute - Meterological station Valparai for the past 20
years showed that the site is experiencing an average
annual rainfall of 1100 mm and the temperature range of
11-29degC The investigation was carried out in the long
term fertilizer trial plots (10m x 10m) established in 1994
using tea clone SA 6 with 100 bushes plot The duration
of the study period was one year from Nov 2010 to
Oct 2011
125 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Experimental setup
The experimental plots were setup to investigate
the impacts of nitrogen and potassium fertilization on
soil biochemistry and employed a randomized complete
block design with three replicate plots for the fifteen
treatments and unfertilized control plots The fifteen
treatments included different levels of nitrogen and
potassium (150 300 and 450 kg ha-1y -1) individually and
in various combinations
Fertilizers were broadcasted in four split doses in
order to avoid volatilization and leaching Nitrogen was
applied as 25 sulphate of ammonia (containing 20
nitrogen) and urea (containing 46 nitrogen) Potassium
was applied as muriate of potash (containing 63
potassium) Sulphate of ammonia was broadcasted at the
rate of 75 15 and 225 kg ha-1 between February and
November Urea at the rate of 1725 345 and
5175 kg ha-1 was broadcasted between May and August
Muriate of potash was applied at the rate of 2363 4725
and 7088 kg ha-1 along with sulphate of ammonia or
urea Other nutrients (Phosphorus Calcium Magnesium
Sulphur Zinc Manganese and Boron) were applied at
recommended rates and regular cultural practices were
carried out uniformly in all the plots (Verma and Palani
1997)
Sampling
Soil samples were collected during premonsoon
(March) and monsoon (June) in 2011 Ten soil cores
(5 cm in diameter) at the depths of 0-10 cm (L1 layer)
and 10-20 cm (L2 layer) were randomly taken from each
plot and bulked Field moist samples were passed
through a 2-mm sieve and divided into two equal parts
One part was used for the determination of soil moisture
pH electrical conductivity total nitrogen exchangeable
potassium and organic carbon The other part was stored
at 4degC prior to microbiological assays
Soil analysis
Soil moisture content was determined after
drying at 105degC to a constant weight Soil pH and
Journal of Research in Agriculture (2012) 1(2) 124-135 126
Thenmozhi et al2012
Treatm
en
t M
ois
ture (
)
pH
E
C (
dS
m-1
) S
1
S
2
S
1
S
2
S1
S 2
L
1
L2
L1
L2
L1
L2
L1
L2
L1
L2
L1
L2
N0 K
0
11
00 b
c 1
16
7 d
e 1
80
0 d
ef
19
00 d
e 3
76 f
3
36 h
4
69 b
4
33 d
0
21
6 i
0
24
8 h
0
38
8 e
0
33
2 e
N
0 K
15
0
66
7 e
-h
10
00 d
ef
19
67 b
-e
21
00 b
cd
38
6 d
3
65 c
4
79 a
4
66 a
0
27
7 g
0
30
9 d
e 0
29
4 h
0
30
4 f
N
0 K
300
80
0 d
e 1
20
0 c
d
19
00 b
-f
21
67 b
c 3
89 c
3
55 d
4
60 c
4
40 c
0
18
2 j
0
21
1 j
0
32
0 g
0
24
3 i
N
0 K
45
0
56
7 f
gh
9
67 e
fg
20
33 b
c 2
10
0 b
cd
43
2 a
3
82 b
4
59 c
4
47 b
0
17
8 j
0
32
0 d
0
23
9 i
0
21
4 k
N
15
0 K
0
10
00 c
d
11
33 d
e 2
03
3 b
c 2
26
7 b
3
55 h
3
43 f
4
25 d
4
38 c
0
32
4 e
0
24
9 h
0
33
5 f
0
25
6 h
N
15
0 K
15
0
13
00 a
b
14
00 b
c 2
00
0 b
cd
21
67 b
c 3
68 g
3
47 e
4
26 d
4
30 d
0
32
8 e
0
22
5 i
0
33
8 f
0
22
8 j
N
15
0 K
30
0
11
00 b
c 1
56
7 a
b
21
00 b
2
30
0 a
b
34
3 k
3
39 g
4
23 d
e 4
33 d
0
36
0 c
0
22
3 i
0
34
6 f
0
25
7 h
N
15
0 K
45
0
14
67 a
1
63
3 a
2
40
0 a
2
50
0 a
3
82 e
3
43 f
4
19 f
4
31 d
0
36
5 c
0
26
4 g
0
42
1 d
0
36
7 d
N
30
0 K
0
70
0 e
fg
10
00 d
ef
18
67 c
-f
19
67 c
de
35
4 h
3
28 i
4
20 e
f 4
25 e
0
24
5 h
0
26
9 g
0
28
7 h
0
29
9 f
N
30
0 K
15
0
80
0 d
e 1
20
0 c
d
17
67 e
f 1
90
0 d
e 3
50 i
3
28 i
4
14 g
4
32 d
0
38
9 b
0
31
6 d
e 0
34
5 f
0
32
6 e
N
30
0 K
30
0
50
0 g
h
70
0 h
i 1
83
3 c
-f
18
00 e
3
46 j
3
22 j
3
86 k
4
40 c
0
28
0 g
0
35
2 b
0
49
1 a
0
24
9 h
i N
30
0 K
45
0
46
7 h
6
00 i
1
90
0b-f
1
93
3 d
e 4
06 b
3
97 a
4
07 h
4
31 d
0
30
4 f
0
30
8 e
0
33
7 f
0
42
0 b
N
45
0 K
0
70
0 e
fg
76
7 g
hi
17
67 e
f 2
00
0 c
de
32
4 m
3
03 k
4
04 h
4
14 g
0
45
4 a
0
43
2 a
0
31
9 g
0
32
5 e
N
45
0 K
15
0
70
0ef
g
96
7 e
fg
18
00
def
1
80
0 e
3
43 k
3
36 h
3
98 i
4
20
f
02
14 i
0
26
6 g
0
34
3 f
0
28
8 g
N
45
0 K
30
0
76
7 e
f 9
00 f
gh
1
93
3 b
-e
19
67 c
de
32
9 l
3
21 j
3
89 j
4
23 e
f 0
34
3 d
0
33
9 c
0
47
3 b
0
38
2 c
N
45
0 K
45
0
73
3ef
9
00 f
gh
1
70
0 f
2
00
0 c
de
32
9 l
3
23 j
4
05 h
4
23 e
f 0
38
0 b
0
28
7 f
0
45
2 c
0
50
1 a
Tab
le 1
P
hy
sical
ch
aracte
rs
of
soil
for
0-1
0 c
m l
ay
er (
L1)
an
d 1
0-2
0 c
m l
ay
er (
L2)
du
rin
g p
rem
on
soon
(S
1)
an
d m
on
soon
(S
2)
sea
son
s a
s in
flu
en
ced
by
nit
rog
en
an
d p
ota
ssiu
m
ferti
lizati
on
Mea
ns
in a
colu
mn
for a
soil
la
yer
foll
ow
ed
by
sa
me
lett
er(s
) d
o n
ot
sig
nif
ica
ntl
y d
iffe
r (P
lt0
05
) accord
ing t
o D
un
ca
nrsquos
Mu
ltip
le R
an
ge
Test
electrical conductivity were measured using a digital pH
meter (Cyberscan 510 Singapore) and Conductivity
Bridge Meter (ORLAB 201 India) Total nitrogen was
measured using an autoanalyser (Skalar autoanalyser
Netherlands) after Kjeldahl digestion and distillation
Exchangeable potassium was extracted in ammonium
acetate solution (pH 7) and measured using a flame
photometer (GENWAY) Total organic carbon was
determined according to Nelson and Sommers (1982)
The titration method of Jaggi (1976) was used to
assess soil respiration Urease activity was determined
according to Kandeler and Gerber (1988) with urea (1M)
as a substrate and the values were expressed as
microg Ng -1dm2h -1 using the calibration curve Cellulase
activity was determined by incubation of soil samples
with water-soluble carboxymethylcellulose (Schinner
and Von Mersi 1990) for 24 h at 50degC pH 55 Low
molecular products and sugars resulting from the
enzymatic degradation of carboxymethylcellulose were
used for the quantitative reduction of potassium
hexacyanoferrate II to potassium hexacyanoferrate III
which reacts with Fe (III) ammonium sulfate to form a
complex known as ldquoPrussian Blueldquo which is determined
photometrically at 690 nm Cellulase activity is
expressed as microg GE g-1 dm 24 h -1
Statistical analysis
All data were subjected to analysis of variance
(ANOVA) (IRRISTAT version 393) and Duncanrsquos
Multiple Range Test (Plt005) was used to separate the
means when the differences were significant Pearsonrsquos
correlation analysis was used to assess the relationship
between soil and microbial variables The latter analysis
was carried out in SPSS 90
RESULTS
Soil properties
Soil in the experimental plots were clayey loam
and fertilizer application had a profound influence on
soil moisture As expected soil moisture was
127 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatm
en
t T
ota
l n
itrogen
(
) E
xch
an
gea
ble
pota
ssiu
m (
mg
kg
-1l)
Org
an
ic c
arb
on
(
) S
1
S2
S1
S2
S1
S 2
L1
L2
L1
L2
L1
L2
L1
L2
L1
L2
L1
L2
N0 K
0
03
7 h
i 0
29 e
f 0
27 f
g
02
4 b
1
552
1 h
1
018
3 i
1
626
5 i
1
074
3 k
4
83 h
3
26 h
3
99 h
3
55 f
N
0 K
15
0
03
6 i
0
31 d
e 0
29 e
fg
01
4 e
2
484
5 d
1
868
8 e
2
282
0 d
1
974
3 d
5
24 f
3
69 e
4
06 h
3
63 e
N
0 K
300
04
0 d
ef
03
4 a
bc
02
4 h
0
19 c
2
598
3 c
2
235
9 c
2
178
5 e
1
577
8 e
5
07 g
3
39 g
4
37 g
3
00 j
N
0 K
45
0
03
8 f
gh
0
27 g
0
27 g
0
19 c
3
237
0 b
2
467
2 b
2
812
2 b
2
597
7 b
4
79 h
3
82 d
4
91 e
4
10 c
N
15
0 K
0
03
8 g
hi
02
8 f
g
02
8 f
g
01
6 d
e 1
369
5 j
9
33
5 j
1
230
2 m
1
153
3 i
5
00 g
3
32 g
4
45 g
3
08 i
N
15
0 K
15
0
04
7 a
0
31 d
e 0
29 e
f 0
15 e
1
415
0 i
8
08
8 l
1
374
3 k
1
153
3 i
6
07 a
3
84 d
3
90 i
3
20 h
N
15
0 K
30
0
03
8 g
hi
02
8 f
g
02
7 g
0
31 a
1
598
3 g
1
191
8 g
1
972
0 f
1
433
6 f
5
34 e
3
33 g
h
52
7 c
3
39 g
N
15
0 K
45
0
04
2 b
cd
02
7 f
g
03
8 b
0
30 a
4
427
1 a
3
132
3 a
3
700
1 a
2
651
0 a
5
04 g
3
80 d
5
85 b
3
86 d
N
30
0 K
0
04
2 c
de
03
3 b
cd
03
7 b
0
25 b
7
68
0 n
6
08
6 n
6
72
8 p
8
85
3 m
5
46 d
4
00 c
4
00 h
4
02 c
N
30
0 K
15
0
04
2 c
d
02
9 e
fg
03
6 b
c 0
31 a
1
061
2 l
8
08
8 l
9
29
0 o
1
062
5 l
5
50 c
d
37
8 d
5
19 c
4
96 a
N
30
0 K
30
0
03
9 f
g
03
5 a
0
36 b
c 0
24 b
1
280
2 k
1
147
9 h
1
529
5 j
1
199
2 h
5
69 b
4
37 a
5
93 b
3
71 e
N
30
0 K
45
0
04
3 b
c 0
31 d
e 0
31 d
e 0
25 b
2
170
2 f
2
024
4 d
1
923
9 g
1
386
1 g
5
27 e
f 3
59 f
4
64 f
3
28 h
N
45
0 K
0
04
4 b
0
35 a
b
03
8 a
b
01
6 d
e 8
08
8 m
7
38
0 m
1
017
6 n
5
51
0 o
5
46 d
3
94 c
5
03 d
3
82 d
N
45
0 K
15
0
04
3 b
c 0
32 c
d
03
5 c
0
16 d
e 1
280
2 k
8
50
0 k
1
292
0 l
7
56
5 n
6
01 a
4
10 b
4
37 g
3
28 h
N
45
0 K
30
0
04
0 e
fg
03
3 a
bc
03
3 d
0
24 b
1
280
2 k
8
08
8 l
1
873
7 h
1
107
7 j
5
56 c
4
29 a
5
19 c
4
33 b
N
45
0 K
45
0
04
4 b
c 0
34 a
bc
04
0 a
0
17 c
d
22
35
9 e
1
808
8 f
2
700
1 c
2
017
6 c
6
08 a
4
35 a
6
08 a
4
29 b
M
ea
ns
in a
colu
mn
for a
soil
la
yer
foll
ow
ed
by s
am
e le
tter
(s)
do n
ot
sig
nif
ica
ntl
y d
iffe
r (P
lt0
05
) accord
ing t
o D
un
ca
nrsquos
Mu
ltip
le R
an
ge
Test
Ta
ble
2 C
hem
ical
chara
cter
s of
soil
for
0-1
0 c
m l
ayer
(L
1)
an
d 1
0-2
0 c
m l
ayer
(L
2)
du
rin
g p
rem
on
soon
(S
1)
an
d m
on
soon
(S
2)
sea
son
s as
infl
uen
ced
by n
itro
gen
an
d
po
tass
ium
fe
rti
liza
tion
significantly higher during monsoon and was affected by
fertilization Similarly the L2 layer was moister than the
L1 layer during both the seasons For premonsoon period
it ranged between 467-1467 (L1) and 600-1633
(L2) respectively On the other hand it registered
1700-2400 (L1) and 1800-2500 (L2) of mixture
for monsoon seasons (Table 1) Soil moisture was higher
in unfertilized soils during both seasons but
progressively decreased with fertilizer application rates
especially nitrogen (300 and 450 kg ha-1)
A significant difference in soil pH was evident
between layers seasons and most treatments Soils
fertilized with potassium had higher pH values the
exception being the 0-10 cm soils fertilized with 300 and
450 kg ha-1of potassium In contrast soils fertilized with
nitrogen had the lowest pH values and this drop in pH
was more evident in the top 0-10 cm soils than in 10-20
cm soils Soil pH correlated positively with soil moisture
levels (r = 0737 Plt001) (Table 1 3) Like pH soil
electrical conductivity also exhibited significant
differences between treatments seasons and layers
During premonsoon soils fertilized with nitrogen had
either almost similar or significantly higher electrical
conductivity values In contrast during monsoon soil in
nitrogen fertilized plots had decreased electrical
conductivity values compared to unfertilized plots
(Table 1)
Total soil nitrogen and exchangeable potassium
significantly differed between seasons layers and among
treatments (Tables 2 and 3) The percentage nitrogen
content of the tea soil was higher during premonsoon
period (S1) when compared to the monsoon season (S2)
Similarly the nitrogen content of L1 layer was higher
when compared to their respective L2 layer Further the
application of nitrogen fertilizer at different doses
enhanced the available nitrogen in L1 layer
concomitantly (Table 2) The exchangeable potassium
level was comparable between premonsoon (S1) and
monsoon (S2) seasons and it fluctuated between different
Journal of Research in Agriculture (2012) 1(2) 124-135 128
Thenmozhi et al2012
So
urce
of
va
ria
tion
df
Mois
ture (
)
pH
E
C (
dS
m-1
)
Soil
nu
trie
nts
Tota
l n
itrog
en
(
) E
xch
an
gea
ble
pota
ssiu
m (
mg
kg -1
l)
Org
an
ic c
arb
on
(
)
Tre
atm
ent
(T)
15
12
8
34
25
15
491
4
74
64
49
53
12998228394
7
23
06
Laye
r (L
) 1
12
8
10
09
2
58
38
4
92
83
3
30
78
56
16275748913
7
15
66
2
Sea
son
(S
) 1
12
8
33
067
2
84
72
17
8
15
98
55
2
385
60
9
118
003
5
64
56
T x
L
15
12
8
13
9
22
84
8
17
54
9
28
54
401064267
8
11
13
T x
S
15
12
8
71
6
37
90
4
27
52
1
37
60
501731007
1
21
50
L x
S
11
28
83
3
33
518
3
26
68
6
20
5
29
53
9621
6
14
09
8
T x
L x
S
51
28
12
4
74
64
19
66
5
29
49
148581688
7
16
02
Tab
le 3
F
- V
alu
es o
f vari
ou
s so
il p
hy
sico
ch
em
ical
ch
aracte
rs a
s in
flu
en
ced
by
nit
rogen
an
d p
ota
ssiu
m f
erti
liza
tio
n
an
d
s
ign
ific
an
t a
t P
lt0
01
an
d P
lt0
00
1 r
esp
ecti
vely
treatment plots in the range of 551 and 4427 mg kg dry
soil However the potassium content was comparably
higher in the L1 layer than the L2 layer The application
of increasing doses of muriate of potash in the different
experimental plots resulted in the enhanced amount of
potassium content in both L1 and L2 layers (Table 2)
Generally nitrogen content in the 0-10 cm soils was
higher when compared to their respective 10-20 cm soils
Exchangeable potassium was lower in nitrogen fertilized
soils than unfertilized soils Soil nitrogen was
significantly (Plt001) and negatively correlated to soil
moisture (r = -0627) and pH (r = -0518) In contrast
soil potassium and pH had a significant and positive
correlation (r = 0267 Plt005) Organic carbon was
higher in the 0-10 cm soils than in 10-20 cm soils and
significantly varied with fertilization and seasons
Generally organic carbon was higher during
premonsoon than monsoon season As organic carbon
was significantly and positively correlated to electrical
conductivity (r = 0315 Plt005) and nitrogen (r = 0752
Plt 001) it was significantly and negatively correlated to
soil moisture (r = -0334 Plt001) (Table 3)
Soil respiration
Soil respiration tended to be higher in 0-10 cm
soils and significantly varied between seasons and
among treatments (Fig 1) During premonsoon
maximum respiration rates were occurred in the 0-10 cm
soils and it was moderate (300 kg ha-1) and high
(450 kg ha-1) in potassium fertilized soils In contrast
maximum respiration rates in the 10-20 cm soils during
129 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
mg
CO
2g
-1 d
m2
4
Fig 1 Influence of nitrogen and potassium fertilization on soil respiration in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
Treatments (Fertilizer dose in kghay)
premonsoon occurred in soils fertilized with high
nitrogen (450 kg ha-1) During monsoon maximum
respiration rates were occurred in the 0-10 cm soils of
treatment involving moderate potassium and high
nitrogen levels (K300 and N450) The respiration rates in
10-20 cm soils during monsoon in fertilized plots were
generally lower compared to unfertilized soils Soil
respiration was significantly and positively correlated to
soil nitrogen (r=0325 Plt0001) and potassium
(r =0309 Plt005)
Enzyme activities
Application of nitrogen and potassium either
individually or in combinations significantly affected soil
urease activity (Fig 2) Urease activity exhibited different
trends in the two soil layers at different seasons High
urease activity occurred during premonsoon in 0-10 cm
soils and during monsoon in the 10-20 cm soils
However maximum urease activity occurred in soils
fertilized with higher doses of nitrogen and potassium
(N450 and K450) during both the seasons and layers except
in 0-10 cm soils where maximum urease activity was
detected in soils fertilized with low nitrogen and
moderate potassium (N150 and K300) Soil urease activity
was significantly and positively correlated to organic
carbon (r=0265 Plt005) and negatively to soil
respiration (r =-0347 Plt 001)
Journal of Research in Agriculture (2012) 1(2) 124-135 130
Thenmozhi et al2012
Fig 2 Influence of nitrogen and potassium fertilization on soil urease activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
μg
Ng
-1d
m2
h-1
L1
n p
L1
L2
Treatments (Fertilizer dose in kghay)
Cellulase activity in the soil differed
significantly among treatments and between seasons and
soil layers (Fig 3) Cellulase activity was higher in 0-10
cm soils during premonsoon season There was a greater
cellulase activity in both soil layers during both the
seasons at low nitrogen application rates (N150)
However increasing concentration of nitrogen
fertilization affected cellulase activity to a greater extent
in the 0-10 cm soils than in 10-20 cm soils A significant
(Plt005) positive correlation existed between soil
cellulase activity and total soil nitrogen (r = 0283)
DISCUSSION
Regular nitrogen fertilization of the acid
soil further acidified the soils The acidification was
more in sulphate of ammonia application during
premonsoon than in urea application during monsoon
These are in accordance with the fact that regular
nitrogen fertilization tend to acidify soils (Khonje et al
1989 Darusman et al 1991) Biederbeck et al (1996)
indicated that application of anhydrous ammonia
lowered soil pH more than urea which clearly indicates
varied levels of soil acidification by different nitrogen
sources Furthermore soil total nitrogen levels were
lower in plots during urea application than sulphate of
131 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatments (Fertilizer dose in kghay)
μg
GE
g-1
dm
24 h
-1
Fig 3 Influence of nitrogen and potassium fertilization on soil cellulase activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
ammonia Most of the broadcasted urea might have
leached out in heavy monsoon showers as considerable
loss (10-25) of nitrogen has been reported to occur due
to leaching or volatilization if urea was not incorporated
into soil soon after its application (Yang 1991 Byrnes
and Freney 1995)
The physico-chemical complexity of soil
contributes significantly to underlying variability in
K+ levels with soil pH moisture and chemical
composition all having marked effects (eg Maathuis
and Sanders 1996) In particular acidic pH leads to
desorption of K+ from anionic binding sites in the soil
and accounts for the tendency towards higher K+ levels
in acidic soils (Gassmann et al 1993) The
exchangeable potassium increased with increasing
potassium application rates It has been thought for a
long time that exchangeable potassium do not built up in
the tea soils of south India because of the dominance of
Kaolinite clay mineral (Verma 1997 Venkatesan et al
2003) However the presence of other minerals other
than Kaolinitic might contribute to the build up of
potassium in the soil (Venkatesan et al 2004) In this
study exchangeable potassium was not related to pH
moisture or chemical composition of the soil However
application of nitrogen significantly reduced soil
potassium which ranged from 18-55 in the 0-10cm
soils and 0-38 in 10-20 cm soils Application of
nitrogen is known to enhance the growth of tea plants
An increased plant growth resulting from nitrogen
fertilization tends to increase potassium uptake from the
soil Studies by The Chinese Tea Research Institute
showed that tea leaves contain 12-25 potassium (TRI
1997) So a large amount of potassium is being mined
from the soil system by the tea plants as a result of
increased growth response to nitrogen fertilization
(Tchienkoua and Zech 2004)
The existence of a significant positive correlation
between soil organic carbon and soil nitrogen indicates
an increasing soil organic carbon content with increasing
nitrogen application rates This is in accordance with
Venkatesan et al (2004) who has also reported higher
organic carbon in soils fertilized with nitrogen Further
Venkatesan et al (2004) indicated that natural organic
carbon reserves of tea soil would be lost due to no or
inadequate supply of nitrogen because tea plants tended
to mineralize and absorb nutrients from organic matter in
the soil under nutrient stress conditions In addition
other studies indicate an increase in soil organic carbon
with increasing soil acidity (Willett et al 2004 Kemmitt
et al 2006) Results from this study tended to indicate
that soil pH and organic carbon were negatively
correlated to each other but this relation is not
statistically significant However when the correlation
analysis was staggered between layers a significant
negative correlation existed between soil pH and organic
carbon in 0-10 cm soils (r = -0667 Plt0000) but not in
10-20 cm soils (r = -0193 Pgt005) This varied relation
between soil organic carbon and pH between layers
could be attributed to soil nitrogen which tended to
strongly influence soil pH than soil potassium
Correlation coefficient values for soil pH and nitrogen in
0-10 cm soils were higher (r= -0773) compared to
10-20 cm soils (r = -0734) These observations are in
line with results of Mc Andrew and Malhi (1992) who
reported an increase in soil organic matter with
increasing soil nitrogen
Soil respiration rates were within normal ranges
reported for natural soils (Srivastava and Singh 1991
Maxwell and Coleman 1995) Results from this study
tended to show that nitrogen and potassium fertilization
affected soil respiration in 0-10 cm soils more than in the
10-20 cm soils Results of Chen et al (2002) also
indicate that nitrogen fertilization reduced soil
respiration in 0-10 cm soils The low respiration rate
with fertilizer application might be attributable to lower
availability of carbon with decreasing soil pH induced by
the nitrogen application (Thirukkumaran and Parkinson
2000)
Journal of Research in Agriculture (2012) 1(2) 124-135 132
Thenmozhi et al2012
Soil urease activity has been reported to follow
changes in soil factors (Cookson and Lepiece 1996) In
the present study fertilizer application generally
increased soil urease activity This is in agreement with
Venkatesan and Senthurpandian (2006) who also
reported an increased urease activity in fertilized tea
soils However these observations contrasts the studies of
Dick et al (1988) and Bandick and Dick (1999) where
soil urease activity was reported to decrease with
increasing application of ammonia based nitrogen
fertilizers Since urease is a substrate inducible enzyme
the application of fertilizers especially urea could have
resulted in higher urease activity Further the binding of
the urease to organic matter insulating itself from
denaturation and biological degradation by soil humic
polymers (Beri et al 1978 Baligar and Wright 1991)
could also attribute to increased level of urease as this
urease could be released from these protected sites by
acid sensitive ammonia oxidizers in response to
fertilization (Martikainen 1985)
Cellulase activity was higher in the surface layer
(0-10 cm soils) than in the subsoils (10-20 cm soils) and
was positively correlated to soil organic matter
Fertilization increased soil cellulase activity which are
in accordance with studies of Aescht and Foissner
(1992)
CONCLUSION
Results from the present study revealed that long
term application of nitrogen and potassium fertilizers
affected soil nutrients and pH Further these fertilizers
can interact with soil microbial communities in a variety
of ways and consequently disturb their normal
functioning The use of nitrogenous fertilizers is
inevitable and an essential part of agricultural practices
In the present study we determined that longndashterm
application of higher doses of urea or ammonium
sulphate fertilizers had an inverse effect on pH moisture
soil respiration and enzyme activities Therefore the
maintenance of low rates of nitrogen and potassium
(ie lt 300 kg-1ha-1y-1) are vital for preserving the soil
quality as higher doses of nitrogen and potassium
(ie gt 300 kg-1ha-1y-1) adversely affects the soil quality
However the actual mechanisms behind these changes
are difficult to infer and needs further investigation
ACKNOWLEDGEMENTS
I express my sincere thanks to
Dr N Muraleedharan Director UPASI Tea Research
Institute Valparai Coimbatore District Tamil Nadu
India for kind permission to use their experimental plots
which formed vital foundation for this work I
acknowledge the invaluable help and support rendered
by Dr S Premkumar Samuel Asir Dr UI Baby and
Dr S Venkatesan Dr R Selvasundaram UPASI Tea
Research Institute Valparai Coimbatore District Tamil
Nadu India during the course of this study
REFERENCES
Aescht E and Foissner W 1992 Effects of mineral and
organic fertilizers on the micro fauna in a high-altitude
reafforestation trial Biology and Fertility of Soils
1317-24
Baligar VC and Wright RJ 1991 Enzyme activities in
Appalachian soils I Aryl-sulfatase Communications in
Soil Science and Plant Analysis 22305-314
Bandick AK and Dick RP 1999 Field management
effects on soil enzyme activities Soil Biology and
Biochemistry 311471-1479
Beri V Goswami KP Brar SS 1978 Urease activity
and its Michaelis constant for soil systems Plant and
Soil 49105-115
Biederbeck VO Campbell CA Ukrainetz H Curtin
D Bouman OT 1996 Soil microbial and biochemical
properties after ten years of fertilization with urea and
anhydrous ammonia Canadian Journal of Soil Science
133 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
76 7-14
Byrnes BH and Freney JR 1995 Recent developments
on the use of urease inhibitors in the tropics Fertilizer
Research 42251-259
Chen CR Xu ZH Hughes JM 2002 Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland Australia Biology
and Fertility of Soils 36276-283
Cookson P and Lepiece AG 1996 Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman Journal of Arid Environment 32225-238
Darusman Stone LR Whitney DA Janssen KA
Long JH 1991 Soil properties after twenty years of
fertilization with different nitrogen sources Soil Science
Society of America Journal 551097-1100
Dick RP 1994 Soil enzyme activities as indicators of
soil quality In Doran JW Coleman DC Bezdicek DF
Stewart BA (Eds) Defining soil quality for a
sustainable environment Special publication no35
SSSA MadisonWI 107-124
Dick RP Rasmussen PE Kerle EA 1988 Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system Biology and Fertility of Soils 6159-164
Gassmann W Ward JM Schroeder JI 1993
Physiological roles of inward rectifying K+ channels
Plant Cell 51491-1493
Jaggi W 1976 Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat Schw Landw
Forsch 15371-380
Kandeler E and Gerber H 1988 Short ndash term assay of
soil urease activity using colorimetric determination of
ammonium Biology and Fertility of Soils 668-72
Kemmitt SJ Wright D Goulding KWT Jones DL
2006 pH regulation of carbon and nitrogen dynamics in
two agricultural soils Soil Biology and Biochemistry
38898-911
Khonje DJ Varsa EC Klubek B 1989 The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil
Communications in Soil Science and Plant Analysis
201377-1395
Maathuis FJM and Sanders D 1996 Mechanism of
Potassium absorption by higher plant roots Physiology
Plantarum 96158-168
Martikainen PJ 1985 Nitrification in forest soil of
different pH as affected by urea ammonium sulphate and
potassium sulphate Soil Biology and Biochemistry
17363-367
Maxwell RA and Coleman DC 1995 Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians Soil
Biology and Biochemistry 2779-84
Mc Andrew DW and Malhi SS 1992 Long-term N
fertilization of a Solonetzic soil Effects on chemical and
biological properties Soil Biology and Biochemistry
24619-623
Nelson DW and Sommers LE 1982 Total carbon
organic carbon and organic matter In Page AL Miller
RH Keeney DR (Eds) Methods of soil analysis Part -
2 Chemical and microbiological properties ASA
monograph number 9 MadisonWI 539-579
Nioh I Isobe T Osada M 1993 Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil Soil Science and Plant Nutrition 39617-625
Schinner F and Von Mersi W 1990 Xylanase- CM-
cellulase- and invertase activity in soil an improved
Journal of Research in Agriculture (2012) 1(2) 124-135 134
Thenmozhi et al2012
method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
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Experimental setup
The experimental plots were setup to investigate
the impacts of nitrogen and potassium fertilization on
soil biochemistry and employed a randomized complete
block design with three replicate plots for the fifteen
treatments and unfertilized control plots The fifteen
treatments included different levels of nitrogen and
potassium (150 300 and 450 kg ha-1y -1) individually and
in various combinations
Fertilizers were broadcasted in four split doses in
order to avoid volatilization and leaching Nitrogen was
applied as 25 sulphate of ammonia (containing 20
nitrogen) and urea (containing 46 nitrogen) Potassium
was applied as muriate of potash (containing 63
potassium) Sulphate of ammonia was broadcasted at the
rate of 75 15 and 225 kg ha-1 between February and
November Urea at the rate of 1725 345 and
5175 kg ha-1 was broadcasted between May and August
Muriate of potash was applied at the rate of 2363 4725
and 7088 kg ha-1 along with sulphate of ammonia or
urea Other nutrients (Phosphorus Calcium Magnesium
Sulphur Zinc Manganese and Boron) were applied at
recommended rates and regular cultural practices were
carried out uniformly in all the plots (Verma and Palani
1997)
Sampling
Soil samples were collected during premonsoon
(March) and monsoon (June) in 2011 Ten soil cores
(5 cm in diameter) at the depths of 0-10 cm (L1 layer)
and 10-20 cm (L2 layer) were randomly taken from each
plot and bulked Field moist samples were passed
through a 2-mm sieve and divided into two equal parts
One part was used for the determination of soil moisture
pH electrical conductivity total nitrogen exchangeable
potassium and organic carbon The other part was stored
at 4degC prior to microbiological assays
Soil analysis
Soil moisture content was determined after
drying at 105degC to a constant weight Soil pH and
Journal of Research in Agriculture (2012) 1(2) 124-135 126
Thenmozhi et al2012
Treatm
en
t M
ois
ture (
)
pH
E
C (
dS
m-1
) S
1
S
2
S
1
S
2
S1
S 2
L
1
L2
L1
L2
L1
L2
L1
L2
L1
L2
L1
L2
N0 K
0
11
00 b
c 1
16
7 d
e 1
80
0 d
ef
19
00 d
e 3
76 f
3
36 h
4
69 b
4
33 d
0
21
6 i
0
24
8 h
0
38
8 e
0
33
2 e
N
0 K
15
0
66
7 e
-h
10
00 d
ef
19
67 b
-e
21
00 b
cd
38
6 d
3
65 c
4
79 a
4
66 a
0
27
7 g
0
30
9 d
e 0
29
4 h
0
30
4 f
N
0 K
300
80
0 d
e 1
20
0 c
d
19
00 b
-f
21
67 b
c 3
89 c
3
55 d
4
60 c
4
40 c
0
18
2 j
0
21
1 j
0
32
0 g
0
24
3 i
N
0 K
45
0
56
7 f
gh
9
67 e
fg
20
33 b
c 2
10
0 b
cd
43
2 a
3
82 b
4
59 c
4
47 b
0
17
8 j
0
32
0 d
0
23
9 i
0
21
4 k
N
15
0 K
0
10
00 c
d
11
33 d
e 2
03
3 b
c 2
26
7 b
3
55 h
3
43 f
4
25 d
4
38 c
0
32
4 e
0
24
9 h
0
33
5 f
0
25
6 h
N
15
0 K
15
0
13
00 a
b
14
00 b
c 2
00
0 b
cd
21
67 b
c 3
68 g
3
47 e
4
26 d
4
30 d
0
32
8 e
0
22
5 i
0
33
8 f
0
22
8 j
N
15
0 K
30
0
11
00 b
c 1
56
7 a
b
21
00 b
2
30
0 a
b
34
3 k
3
39 g
4
23 d
e 4
33 d
0
36
0 c
0
22
3 i
0
34
6 f
0
25
7 h
N
15
0 K
45
0
14
67 a
1
63
3 a
2
40
0 a
2
50
0 a
3
82 e
3
43 f
4
19 f
4
31 d
0
36
5 c
0
26
4 g
0
42
1 d
0
36
7 d
N
30
0 K
0
70
0 e
fg
10
00 d
ef
18
67 c
-f
19
67 c
de
35
4 h
3
28 i
4
20 e
f 4
25 e
0
24
5 h
0
26
9 g
0
28
7 h
0
29
9 f
N
30
0 K
15
0
80
0 d
e 1
20
0 c
d
17
67 e
f 1
90
0 d
e 3
50 i
3
28 i
4
14 g
4
32 d
0
38
9 b
0
31
6 d
e 0
34
5 f
0
32
6 e
N
30
0 K
30
0
50
0 g
h
70
0 h
i 1
83
3 c
-f
18
00 e
3
46 j
3
22 j
3
86 k
4
40 c
0
28
0 g
0
35
2 b
0
49
1 a
0
24
9 h
i N
30
0 K
45
0
46
7 h
6
00 i
1
90
0b-f
1
93
3 d
e 4
06 b
3
97 a
4
07 h
4
31 d
0
30
4 f
0
30
8 e
0
33
7 f
0
42
0 b
N
45
0 K
0
70
0 e
fg
76
7 g
hi
17
67 e
f 2
00
0 c
de
32
4 m
3
03 k
4
04 h
4
14 g
0
45
4 a
0
43
2 a
0
31
9 g
0
32
5 e
N
45
0 K
15
0
70
0ef
g
96
7 e
fg
18
00
def
1
80
0 e
3
43 k
3
36 h
3
98 i
4
20
f
02
14 i
0
26
6 g
0
34
3 f
0
28
8 g
N
45
0 K
30
0
76
7 e
f 9
00 f
gh
1
93
3 b
-e
19
67 c
de
32
9 l
3
21 j
3
89 j
4
23 e
f 0
34
3 d
0
33
9 c
0
47
3 b
0
38
2 c
N
45
0 K
45
0
73
3ef
9
00 f
gh
1
70
0 f
2
00
0 c
de
32
9 l
3
23 j
4
05 h
4
23 e
f 0
38
0 b
0
28
7 f
0
45
2 c
0
50
1 a
Tab
le 1
P
hy
sical
ch
aracte
rs
of
soil
for
0-1
0 c
m l
ay
er (
L1)
an
d 1
0-2
0 c
m l
ay
er (
L2)
du
rin
g p
rem
on
soon
(S
1)
an
d m
on
soon
(S
2)
sea
son
s a
s in
flu
en
ced
by
nit
rog
en
an
d p
ota
ssiu
m
ferti
lizati
on
Mea
ns
in a
colu
mn
for a
soil
la
yer
foll
ow
ed
by
sa
me
lett
er(s
) d
o n
ot
sig
nif
ica
ntl
y d
iffe
r (P
lt0
05
) accord
ing t
o D
un
ca
nrsquos
Mu
ltip
le R
an
ge
Test
electrical conductivity were measured using a digital pH
meter (Cyberscan 510 Singapore) and Conductivity
Bridge Meter (ORLAB 201 India) Total nitrogen was
measured using an autoanalyser (Skalar autoanalyser
Netherlands) after Kjeldahl digestion and distillation
Exchangeable potassium was extracted in ammonium
acetate solution (pH 7) and measured using a flame
photometer (GENWAY) Total organic carbon was
determined according to Nelson and Sommers (1982)
The titration method of Jaggi (1976) was used to
assess soil respiration Urease activity was determined
according to Kandeler and Gerber (1988) with urea (1M)
as a substrate and the values were expressed as
microg Ng -1dm2h -1 using the calibration curve Cellulase
activity was determined by incubation of soil samples
with water-soluble carboxymethylcellulose (Schinner
and Von Mersi 1990) for 24 h at 50degC pH 55 Low
molecular products and sugars resulting from the
enzymatic degradation of carboxymethylcellulose were
used for the quantitative reduction of potassium
hexacyanoferrate II to potassium hexacyanoferrate III
which reacts with Fe (III) ammonium sulfate to form a
complex known as ldquoPrussian Blueldquo which is determined
photometrically at 690 nm Cellulase activity is
expressed as microg GE g-1 dm 24 h -1
Statistical analysis
All data were subjected to analysis of variance
(ANOVA) (IRRISTAT version 393) and Duncanrsquos
Multiple Range Test (Plt005) was used to separate the
means when the differences were significant Pearsonrsquos
correlation analysis was used to assess the relationship
between soil and microbial variables The latter analysis
was carried out in SPSS 90
RESULTS
Soil properties
Soil in the experimental plots were clayey loam
and fertilizer application had a profound influence on
soil moisture As expected soil moisture was
127 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatm
en
t T
ota
l n
itrogen
(
) E
xch
an
gea
ble
pota
ssiu
m (
mg
kg
-1l)
Org
an
ic c
arb
on
(
) S
1
S2
S1
S2
S1
S 2
L1
L2
L1
L2
L1
L2
L1
L2
L1
L2
L1
L2
N0 K
0
03
7 h
i 0
29 e
f 0
27 f
g
02
4 b
1
552
1 h
1
018
3 i
1
626
5 i
1
074
3 k
4
83 h
3
26 h
3
99 h
3
55 f
N
0 K
15
0
03
6 i
0
31 d
e 0
29 e
fg
01
4 e
2
484
5 d
1
868
8 e
2
282
0 d
1
974
3 d
5
24 f
3
69 e
4
06 h
3
63 e
N
0 K
300
04
0 d
ef
03
4 a
bc
02
4 h
0
19 c
2
598
3 c
2
235
9 c
2
178
5 e
1
577
8 e
5
07 g
3
39 g
4
37 g
3
00 j
N
0 K
45
0
03
8 f
gh
0
27 g
0
27 g
0
19 c
3
237
0 b
2
467
2 b
2
812
2 b
2
597
7 b
4
79 h
3
82 d
4
91 e
4
10 c
N
15
0 K
0
03
8 g
hi
02
8 f
g
02
8 f
g
01
6 d
e 1
369
5 j
9
33
5 j
1
230
2 m
1
153
3 i
5
00 g
3
32 g
4
45 g
3
08 i
N
15
0 K
15
0
04
7 a
0
31 d
e 0
29 e
f 0
15 e
1
415
0 i
8
08
8 l
1
374
3 k
1
153
3 i
6
07 a
3
84 d
3
90 i
3
20 h
N
15
0 K
30
0
03
8 g
hi
02
8 f
g
02
7 g
0
31 a
1
598
3 g
1
191
8 g
1
972
0 f
1
433
6 f
5
34 e
3
33 g
h
52
7 c
3
39 g
N
15
0 K
45
0
04
2 b
cd
02
7 f
g
03
8 b
0
30 a
4
427
1 a
3
132
3 a
3
700
1 a
2
651
0 a
5
04 g
3
80 d
5
85 b
3
86 d
N
30
0 K
0
04
2 c
de
03
3 b
cd
03
7 b
0
25 b
7
68
0 n
6
08
6 n
6
72
8 p
8
85
3 m
5
46 d
4
00 c
4
00 h
4
02 c
N
30
0 K
15
0
04
2 c
d
02
9 e
fg
03
6 b
c 0
31 a
1
061
2 l
8
08
8 l
9
29
0 o
1
062
5 l
5
50 c
d
37
8 d
5
19 c
4
96 a
N
30
0 K
30
0
03
9 f
g
03
5 a
0
36 b
c 0
24 b
1
280
2 k
1
147
9 h
1
529
5 j
1
199
2 h
5
69 b
4
37 a
5
93 b
3
71 e
N
30
0 K
45
0
04
3 b
c 0
31 d
e 0
31 d
e 0
25 b
2
170
2 f
2
024
4 d
1
923
9 g
1
386
1 g
5
27 e
f 3
59 f
4
64 f
3
28 h
N
45
0 K
0
04
4 b
0
35 a
b
03
8 a
b
01
6 d
e 8
08
8 m
7
38
0 m
1
017
6 n
5
51
0 o
5
46 d
3
94 c
5
03 d
3
82 d
N
45
0 K
15
0
04
3 b
c 0
32 c
d
03
5 c
0
16 d
e 1
280
2 k
8
50
0 k
1
292
0 l
7
56
5 n
6
01 a
4
10 b
4
37 g
3
28 h
N
45
0 K
30
0
04
0 e
fg
03
3 a
bc
03
3 d
0
24 b
1
280
2 k
8
08
8 l
1
873
7 h
1
107
7 j
5
56 c
4
29 a
5
19 c
4
33 b
N
45
0 K
45
0
04
4 b
c 0
34 a
bc
04
0 a
0
17 c
d
22
35
9 e
1
808
8 f
2
700
1 c
2
017
6 c
6
08 a
4
35 a
6
08 a
4
29 b
M
ea
ns
in a
colu
mn
for a
soil
la
yer
foll
ow
ed
by s
am
e le
tter
(s)
do n
ot
sig
nif
ica
ntl
y d
iffe
r (P
lt0
05
) accord
ing t
o D
un
ca
nrsquos
Mu
ltip
le R
an
ge
Test
Ta
ble
2 C
hem
ical
chara
cter
s of
soil
for
0-1
0 c
m l
ayer
(L
1)
an
d 1
0-2
0 c
m l
ayer
(L
2)
du
rin
g p
rem
on
soon
(S
1)
an
d m
on
soon
(S
2)
sea
son
s as
infl
uen
ced
by n
itro
gen
an
d
po
tass
ium
fe
rti
liza
tion
significantly higher during monsoon and was affected by
fertilization Similarly the L2 layer was moister than the
L1 layer during both the seasons For premonsoon period
it ranged between 467-1467 (L1) and 600-1633
(L2) respectively On the other hand it registered
1700-2400 (L1) and 1800-2500 (L2) of mixture
for monsoon seasons (Table 1) Soil moisture was higher
in unfertilized soils during both seasons but
progressively decreased with fertilizer application rates
especially nitrogen (300 and 450 kg ha-1)
A significant difference in soil pH was evident
between layers seasons and most treatments Soils
fertilized with potassium had higher pH values the
exception being the 0-10 cm soils fertilized with 300 and
450 kg ha-1of potassium In contrast soils fertilized with
nitrogen had the lowest pH values and this drop in pH
was more evident in the top 0-10 cm soils than in 10-20
cm soils Soil pH correlated positively with soil moisture
levels (r = 0737 Plt001) (Table 1 3) Like pH soil
electrical conductivity also exhibited significant
differences between treatments seasons and layers
During premonsoon soils fertilized with nitrogen had
either almost similar or significantly higher electrical
conductivity values In contrast during monsoon soil in
nitrogen fertilized plots had decreased electrical
conductivity values compared to unfertilized plots
(Table 1)
Total soil nitrogen and exchangeable potassium
significantly differed between seasons layers and among
treatments (Tables 2 and 3) The percentage nitrogen
content of the tea soil was higher during premonsoon
period (S1) when compared to the monsoon season (S2)
Similarly the nitrogen content of L1 layer was higher
when compared to their respective L2 layer Further the
application of nitrogen fertilizer at different doses
enhanced the available nitrogen in L1 layer
concomitantly (Table 2) The exchangeable potassium
level was comparable between premonsoon (S1) and
monsoon (S2) seasons and it fluctuated between different
Journal of Research in Agriculture (2012) 1(2) 124-135 128
Thenmozhi et al2012
So
urce
of
va
ria
tion
df
Mois
ture (
)
pH
E
C (
dS
m-1
)
Soil
nu
trie
nts
Tota
l n
itrog
en
(
) E
xch
an
gea
ble
pota
ssiu
m (
mg
kg -1
l)
Org
an
ic c
arb
on
(
)
Tre
atm
ent
(T)
15
12
8
34
25
15
491
4
74
64
49
53
12998228394
7
23
06
Laye
r (L
) 1
12
8
10
09
2
58
38
4
92
83
3
30
78
56
16275748913
7
15
66
2
Sea
son
(S
) 1
12
8
33
067
2
84
72
17
8
15
98
55
2
385
60
9
118
003
5
64
56
T x
L
15
12
8
13
9
22
84
8
17
54
9
28
54
401064267
8
11
13
T x
S
15
12
8
71
6
37
90
4
27
52
1
37
60
501731007
1
21
50
L x
S
11
28
83
3
33
518
3
26
68
6
20
5
29
53
9621
6
14
09
8
T x
L x
S
51
28
12
4
74
64
19
66
5
29
49
148581688
7
16
02
Tab
le 3
F
- V
alu
es o
f vari
ou
s so
il p
hy
sico
ch
em
ical
ch
aracte
rs a
s in
flu
en
ced
by
nit
rogen
an
d p
ota
ssiu
m f
erti
liza
tio
n
an
d
s
ign
ific
an
t a
t P
lt0
01
an
d P
lt0
00
1 r
esp
ecti
vely
treatment plots in the range of 551 and 4427 mg kg dry
soil However the potassium content was comparably
higher in the L1 layer than the L2 layer The application
of increasing doses of muriate of potash in the different
experimental plots resulted in the enhanced amount of
potassium content in both L1 and L2 layers (Table 2)
Generally nitrogen content in the 0-10 cm soils was
higher when compared to their respective 10-20 cm soils
Exchangeable potassium was lower in nitrogen fertilized
soils than unfertilized soils Soil nitrogen was
significantly (Plt001) and negatively correlated to soil
moisture (r = -0627) and pH (r = -0518) In contrast
soil potassium and pH had a significant and positive
correlation (r = 0267 Plt005) Organic carbon was
higher in the 0-10 cm soils than in 10-20 cm soils and
significantly varied with fertilization and seasons
Generally organic carbon was higher during
premonsoon than monsoon season As organic carbon
was significantly and positively correlated to electrical
conductivity (r = 0315 Plt005) and nitrogen (r = 0752
Plt 001) it was significantly and negatively correlated to
soil moisture (r = -0334 Plt001) (Table 3)
Soil respiration
Soil respiration tended to be higher in 0-10 cm
soils and significantly varied between seasons and
among treatments (Fig 1) During premonsoon
maximum respiration rates were occurred in the 0-10 cm
soils and it was moderate (300 kg ha-1) and high
(450 kg ha-1) in potassium fertilized soils In contrast
maximum respiration rates in the 10-20 cm soils during
129 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
mg
CO
2g
-1 d
m2
4
Fig 1 Influence of nitrogen and potassium fertilization on soil respiration in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
Treatments (Fertilizer dose in kghay)
premonsoon occurred in soils fertilized with high
nitrogen (450 kg ha-1) During monsoon maximum
respiration rates were occurred in the 0-10 cm soils of
treatment involving moderate potassium and high
nitrogen levels (K300 and N450) The respiration rates in
10-20 cm soils during monsoon in fertilized plots were
generally lower compared to unfertilized soils Soil
respiration was significantly and positively correlated to
soil nitrogen (r=0325 Plt0001) and potassium
(r =0309 Plt005)
Enzyme activities
Application of nitrogen and potassium either
individually or in combinations significantly affected soil
urease activity (Fig 2) Urease activity exhibited different
trends in the two soil layers at different seasons High
urease activity occurred during premonsoon in 0-10 cm
soils and during monsoon in the 10-20 cm soils
However maximum urease activity occurred in soils
fertilized with higher doses of nitrogen and potassium
(N450 and K450) during both the seasons and layers except
in 0-10 cm soils where maximum urease activity was
detected in soils fertilized with low nitrogen and
moderate potassium (N150 and K300) Soil urease activity
was significantly and positively correlated to organic
carbon (r=0265 Plt005) and negatively to soil
respiration (r =-0347 Plt 001)
Journal of Research in Agriculture (2012) 1(2) 124-135 130
Thenmozhi et al2012
Fig 2 Influence of nitrogen and potassium fertilization on soil urease activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
μg
Ng
-1d
m2
h-1
L1
n p
L1
L2
Treatments (Fertilizer dose in kghay)
Cellulase activity in the soil differed
significantly among treatments and between seasons and
soil layers (Fig 3) Cellulase activity was higher in 0-10
cm soils during premonsoon season There was a greater
cellulase activity in both soil layers during both the
seasons at low nitrogen application rates (N150)
However increasing concentration of nitrogen
fertilization affected cellulase activity to a greater extent
in the 0-10 cm soils than in 10-20 cm soils A significant
(Plt005) positive correlation existed between soil
cellulase activity and total soil nitrogen (r = 0283)
DISCUSSION
Regular nitrogen fertilization of the acid
soil further acidified the soils The acidification was
more in sulphate of ammonia application during
premonsoon than in urea application during monsoon
These are in accordance with the fact that regular
nitrogen fertilization tend to acidify soils (Khonje et al
1989 Darusman et al 1991) Biederbeck et al (1996)
indicated that application of anhydrous ammonia
lowered soil pH more than urea which clearly indicates
varied levels of soil acidification by different nitrogen
sources Furthermore soil total nitrogen levels were
lower in plots during urea application than sulphate of
131 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatments (Fertilizer dose in kghay)
μg
GE
g-1
dm
24 h
-1
Fig 3 Influence of nitrogen and potassium fertilization on soil cellulase activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
ammonia Most of the broadcasted urea might have
leached out in heavy monsoon showers as considerable
loss (10-25) of nitrogen has been reported to occur due
to leaching or volatilization if urea was not incorporated
into soil soon after its application (Yang 1991 Byrnes
and Freney 1995)
The physico-chemical complexity of soil
contributes significantly to underlying variability in
K+ levels with soil pH moisture and chemical
composition all having marked effects (eg Maathuis
and Sanders 1996) In particular acidic pH leads to
desorption of K+ from anionic binding sites in the soil
and accounts for the tendency towards higher K+ levels
in acidic soils (Gassmann et al 1993) The
exchangeable potassium increased with increasing
potassium application rates It has been thought for a
long time that exchangeable potassium do not built up in
the tea soils of south India because of the dominance of
Kaolinite clay mineral (Verma 1997 Venkatesan et al
2003) However the presence of other minerals other
than Kaolinitic might contribute to the build up of
potassium in the soil (Venkatesan et al 2004) In this
study exchangeable potassium was not related to pH
moisture or chemical composition of the soil However
application of nitrogen significantly reduced soil
potassium which ranged from 18-55 in the 0-10cm
soils and 0-38 in 10-20 cm soils Application of
nitrogen is known to enhance the growth of tea plants
An increased plant growth resulting from nitrogen
fertilization tends to increase potassium uptake from the
soil Studies by The Chinese Tea Research Institute
showed that tea leaves contain 12-25 potassium (TRI
1997) So a large amount of potassium is being mined
from the soil system by the tea plants as a result of
increased growth response to nitrogen fertilization
(Tchienkoua and Zech 2004)
The existence of a significant positive correlation
between soil organic carbon and soil nitrogen indicates
an increasing soil organic carbon content with increasing
nitrogen application rates This is in accordance with
Venkatesan et al (2004) who has also reported higher
organic carbon in soils fertilized with nitrogen Further
Venkatesan et al (2004) indicated that natural organic
carbon reserves of tea soil would be lost due to no or
inadequate supply of nitrogen because tea plants tended
to mineralize and absorb nutrients from organic matter in
the soil under nutrient stress conditions In addition
other studies indicate an increase in soil organic carbon
with increasing soil acidity (Willett et al 2004 Kemmitt
et al 2006) Results from this study tended to indicate
that soil pH and organic carbon were negatively
correlated to each other but this relation is not
statistically significant However when the correlation
analysis was staggered between layers a significant
negative correlation existed between soil pH and organic
carbon in 0-10 cm soils (r = -0667 Plt0000) but not in
10-20 cm soils (r = -0193 Pgt005) This varied relation
between soil organic carbon and pH between layers
could be attributed to soil nitrogen which tended to
strongly influence soil pH than soil potassium
Correlation coefficient values for soil pH and nitrogen in
0-10 cm soils were higher (r= -0773) compared to
10-20 cm soils (r = -0734) These observations are in
line with results of Mc Andrew and Malhi (1992) who
reported an increase in soil organic matter with
increasing soil nitrogen
Soil respiration rates were within normal ranges
reported for natural soils (Srivastava and Singh 1991
Maxwell and Coleman 1995) Results from this study
tended to show that nitrogen and potassium fertilization
affected soil respiration in 0-10 cm soils more than in the
10-20 cm soils Results of Chen et al (2002) also
indicate that nitrogen fertilization reduced soil
respiration in 0-10 cm soils The low respiration rate
with fertilizer application might be attributable to lower
availability of carbon with decreasing soil pH induced by
the nitrogen application (Thirukkumaran and Parkinson
2000)
Journal of Research in Agriculture (2012) 1(2) 124-135 132
Thenmozhi et al2012
Soil urease activity has been reported to follow
changes in soil factors (Cookson and Lepiece 1996) In
the present study fertilizer application generally
increased soil urease activity This is in agreement with
Venkatesan and Senthurpandian (2006) who also
reported an increased urease activity in fertilized tea
soils However these observations contrasts the studies of
Dick et al (1988) and Bandick and Dick (1999) where
soil urease activity was reported to decrease with
increasing application of ammonia based nitrogen
fertilizers Since urease is a substrate inducible enzyme
the application of fertilizers especially urea could have
resulted in higher urease activity Further the binding of
the urease to organic matter insulating itself from
denaturation and biological degradation by soil humic
polymers (Beri et al 1978 Baligar and Wright 1991)
could also attribute to increased level of urease as this
urease could be released from these protected sites by
acid sensitive ammonia oxidizers in response to
fertilization (Martikainen 1985)
Cellulase activity was higher in the surface layer
(0-10 cm soils) than in the subsoils (10-20 cm soils) and
was positively correlated to soil organic matter
Fertilization increased soil cellulase activity which are
in accordance with studies of Aescht and Foissner
(1992)
CONCLUSION
Results from the present study revealed that long
term application of nitrogen and potassium fertilizers
affected soil nutrients and pH Further these fertilizers
can interact with soil microbial communities in a variety
of ways and consequently disturb their normal
functioning The use of nitrogenous fertilizers is
inevitable and an essential part of agricultural practices
In the present study we determined that longndashterm
application of higher doses of urea or ammonium
sulphate fertilizers had an inverse effect on pH moisture
soil respiration and enzyme activities Therefore the
maintenance of low rates of nitrogen and potassium
(ie lt 300 kg-1ha-1y-1) are vital for preserving the soil
quality as higher doses of nitrogen and potassium
(ie gt 300 kg-1ha-1y-1) adversely affects the soil quality
However the actual mechanisms behind these changes
are difficult to infer and needs further investigation
ACKNOWLEDGEMENTS
I express my sincere thanks to
Dr N Muraleedharan Director UPASI Tea Research
Institute Valparai Coimbatore District Tamil Nadu
India for kind permission to use their experimental plots
which formed vital foundation for this work I
acknowledge the invaluable help and support rendered
by Dr S Premkumar Samuel Asir Dr UI Baby and
Dr S Venkatesan Dr R Selvasundaram UPASI Tea
Research Institute Valparai Coimbatore District Tamil
Nadu India during the course of this study
REFERENCES
Aescht E and Foissner W 1992 Effects of mineral and
organic fertilizers on the micro fauna in a high-altitude
reafforestation trial Biology and Fertility of Soils
1317-24
Baligar VC and Wright RJ 1991 Enzyme activities in
Appalachian soils I Aryl-sulfatase Communications in
Soil Science and Plant Analysis 22305-314
Bandick AK and Dick RP 1999 Field management
effects on soil enzyme activities Soil Biology and
Biochemistry 311471-1479
Beri V Goswami KP Brar SS 1978 Urease activity
and its Michaelis constant for soil systems Plant and
Soil 49105-115
Biederbeck VO Campbell CA Ukrainetz H Curtin
D Bouman OT 1996 Soil microbial and biochemical
properties after ten years of fertilization with urea and
anhydrous ammonia Canadian Journal of Soil Science
133 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
76 7-14
Byrnes BH and Freney JR 1995 Recent developments
on the use of urease inhibitors in the tropics Fertilizer
Research 42251-259
Chen CR Xu ZH Hughes JM 2002 Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland Australia Biology
and Fertility of Soils 36276-283
Cookson P and Lepiece AG 1996 Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman Journal of Arid Environment 32225-238
Darusman Stone LR Whitney DA Janssen KA
Long JH 1991 Soil properties after twenty years of
fertilization with different nitrogen sources Soil Science
Society of America Journal 551097-1100
Dick RP 1994 Soil enzyme activities as indicators of
soil quality In Doran JW Coleman DC Bezdicek DF
Stewart BA (Eds) Defining soil quality for a
sustainable environment Special publication no35
SSSA MadisonWI 107-124
Dick RP Rasmussen PE Kerle EA 1988 Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system Biology and Fertility of Soils 6159-164
Gassmann W Ward JM Schroeder JI 1993
Physiological roles of inward rectifying K+ channels
Plant Cell 51491-1493
Jaggi W 1976 Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat Schw Landw
Forsch 15371-380
Kandeler E and Gerber H 1988 Short ndash term assay of
soil urease activity using colorimetric determination of
ammonium Biology and Fertility of Soils 668-72
Kemmitt SJ Wright D Goulding KWT Jones DL
2006 pH regulation of carbon and nitrogen dynamics in
two agricultural soils Soil Biology and Biochemistry
38898-911
Khonje DJ Varsa EC Klubek B 1989 The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil
Communications in Soil Science and Plant Analysis
201377-1395
Maathuis FJM and Sanders D 1996 Mechanism of
Potassium absorption by higher plant roots Physiology
Plantarum 96158-168
Martikainen PJ 1985 Nitrification in forest soil of
different pH as affected by urea ammonium sulphate and
potassium sulphate Soil Biology and Biochemistry
17363-367
Maxwell RA and Coleman DC 1995 Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians Soil
Biology and Biochemistry 2779-84
Mc Andrew DW and Malhi SS 1992 Long-term N
fertilization of a Solonetzic soil Effects on chemical and
biological properties Soil Biology and Biochemistry
24619-623
Nelson DW and Sommers LE 1982 Total carbon
organic carbon and organic matter In Page AL Miller
RH Keeney DR (Eds) Methods of soil analysis Part -
2 Chemical and microbiological properties ASA
monograph number 9 MadisonWI 539-579
Nioh I Isobe T Osada M 1993 Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil Soil Science and Plant Nutrition 39617-625
Schinner F and Von Mersi W 1990 Xylanase- CM-
cellulase- and invertase activity in soil an improved
Journal of Research in Agriculture (2012) 1(2) 124-135 134
Thenmozhi et al2012
method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
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electrical conductivity were measured using a digital pH
meter (Cyberscan 510 Singapore) and Conductivity
Bridge Meter (ORLAB 201 India) Total nitrogen was
measured using an autoanalyser (Skalar autoanalyser
Netherlands) after Kjeldahl digestion and distillation
Exchangeable potassium was extracted in ammonium
acetate solution (pH 7) and measured using a flame
photometer (GENWAY) Total organic carbon was
determined according to Nelson and Sommers (1982)
The titration method of Jaggi (1976) was used to
assess soil respiration Urease activity was determined
according to Kandeler and Gerber (1988) with urea (1M)
as a substrate and the values were expressed as
microg Ng -1dm2h -1 using the calibration curve Cellulase
activity was determined by incubation of soil samples
with water-soluble carboxymethylcellulose (Schinner
and Von Mersi 1990) for 24 h at 50degC pH 55 Low
molecular products and sugars resulting from the
enzymatic degradation of carboxymethylcellulose were
used for the quantitative reduction of potassium
hexacyanoferrate II to potassium hexacyanoferrate III
which reacts with Fe (III) ammonium sulfate to form a
complex known as ldquoPrussian Blueldquo which is determined
photometrically at 690 nm Cellulase activity is
expressed as microg GE g-1 dm 24 h -1
Statistical analysis
All data were subjected to analysis of variance
(ANOVA) (IRRISTAT version 393) and Duncanrsquos
Multiple Range Test (Plt005) was used to separate the
means when the differences were significant Pearsonrsquos
correlation analysis was used to assess the relationship
between soil and microbial variables The latter analysis
was carried out in SPSS 90
RESULTS
Soil properties
Soil in the experimental plots were clayey loam
and fertilizer application had a profound influence on
soil moisture As expected soil moisture was
127 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatm
en
t T
ota
l n
itrogen
(
) E
xch
an
gea
ble
pota
ssiu
m (
mg
kg
-1l)
Org
an
ic c
arb
on
(
) S
1
S2
S1
S2
S1
S 2
L1
L2
L1
L2
L1
L2
L1
L2
L1
L2
L1
L2
N0 K
0
03
7 h
i 0
29 e
f 0
27 f
g
02
4 b
1
552
1 h
1
018
3 i
1
626
5 i
1
074
3 k
4
83 h
3
26 h
3
99 h
3
55 f
N
0 K
15
0
03
6 i
0
31 d
e 0
29 e
fg
01
4 e
2
484
5 d
1
868
8 e
2
282
0 d
1
974
3 d
5
24 f
3
69 e
4
06 h
3
63 e
N
0 K
300
04
0 d
ef
03
4 a
bc
02
4 h
0
19 c
2
598
3 c
2
235
9 c
2
178
5 e
1
577
8 e
5
07 g
3
39 g
4
37 g
3
00 j
N
0 K
45
0
03
8 f
gh
0
27 g
0
27 g
0
19 c
3
237
0 b
2
467
2 b
2
812
2 b
2
597
7 b
4
79 h
3
82 d
4
91 e
4
10 c
N
15
0 K
0
03
8 g
hi
02
8 f
g
02
8 f
g
01
6 d
e 1
369
5 j
9
33
5 j
1
230
2 m
1
153
3 i
5
00 g
3
32 g
4
45 g
3
08 i
N
15
0 K
15
0
04
7 a
0
31 d
e 0
29 e
f 0
15 e
1
415
0 i
8
08
8 l
1
374
3 k
1
153
3 i
6
07 a
3
84 d
3
90 i
3
20 h
N
15
0 K
30
0
03
8 g
hi
02
8 f
g
02
7 g
0
31 a
1
598
3 g
1
191
8 g
1
972
0 f
1
433
6 f
5
34 e
3
33 g
h
52
7 c
3
39 g
N
15
0 K
45
0
04
2 b
cd
02
7 f
g
03
8 b
0
30 a
4
427
1 a
3
132
3 a
3
700
1 a
2
651
0 a
5
04 g
3
80 d
5
85 b
3
86 d
N
30
0 K
0
04
2 c
de
03
3 b
cd
03
7 b
0
25 b
7
68
0 n
6
08
6 n
6
72
8 p
8
85
3 m
5
46 d
4
00 c
4
00 h
4
02 c
N
30
0 K
15
0
04
2 c
d
02
9 e
fg
03
6 b
c 0
31 a
1
061
2 l
8
08
8 l
9
29
0 o
1
062
5 l
5
50 c
d
37
8 d
5
19 c
4
96 a
N
30
0 K
30
0
03
9 f
g
03
5 a
0
36 b
c 0
24 b
1
280
2 k
1
147
9 h
1
529
5 j
1
199
2 h
5
69 b
4
37 a
5
93 b
3
71 e
N
30
0 K
45
0
04
3 b
c 0
31 d
e 0
31 d
e 0
25 b
2
170
2 f
2
024
4 d
1
923
9 g
1
386
1 g
5
27 e
f 3
59 f
4
64 f
3
28 h
N
45
0 K
0
04
4 b
0
35 a
b
03
8 a
b
01
6 d
e 8
08
8 m
7
38
0 m
1
017
6 n
5
51
0 o
5
46 d
3
94 c
5
03 d
3
82 d
N
45
0 K
15
0
04
3 b
c 0
32 c
d
03
5 c
0
16 d
e 1
280
2 k
8
50
0 k
1
292
0 l
7
56
5 n
6
01 a
4
10 b
4
37 g
3
28 h
N
45
0 K
30
0
04
0 e
fg
03
3 a
bc
03
3 d
0
24 b
1
280
2 k
8
08
8 l
1
873
7 h
1
107
7 j
5
56 c
4
29 a
5
19 c
4
33 b
N
45
0 K
45
0
04
4 b
c 0
34 a
bc
04
0 a
0
17 c
d
22
35
9 e
1
808
8 f
2
700
1 c
2
017
6 c
6
08 a
4
35 a
6
08 a
4
29 b
M
ea
ns
in a
colu
mn
for a
soil
la
yer
foll
ow
ed
by s
am
e le
tter
(s)
do n
ot
sig
nif
ica
ntl
y d
iffe
r (P
lt0
05
) accord
ing t
o D
un
ca
nrsquos
Mu
ltip
le R
an
ge
Test
Ta
ble
2 C
hem
ical
chara
cter
s of
soil
for
0-1
0 c
m l
ayer
(L
1)
an
d 1
0-2
0 c
m l
ayer
(L
2)
du
rin
g p
rem
on
soon
(S
1)
an
d m
on
soon
(S
2)
sea
son
s as
infl
uen
ced
by n
itro
gen
an
d
po
tass
ium
fe
rti
liza
tion
significantly higher during monsoon and was affected by
fertilization Similarly the L2 layer was moister than the
L1 layer during both the seasons For premonsoon period
it ranged between 467-1467 (L1) and 600-1633
(L2) respectively On the other hand it registered
1700-2400 (L1) and 1800-2500 (L2) of mixture
for monsoon seasons (Table 1) Soil moisture was higher
in unfertilized soils during both seasons but
progressively decreased with fertilizer application rates
especially nitrogen (300 and 450 kg ha-1)
A significant difference in soil pH was evident
between layers seasons and most treatments Soils
fertilized with potassium had higher pH values the
exception being the 0-10 cm soils fertilized with 300 and
450 kg ha-1of potassium In contrast soils fertilized with
nitrogen had the lowest pH values and this drop in pH
was more evident in the top 0-10 cm soils than in 10-20
cm soils Soil pH correlated positively with soil moisture
levels (r = 0737 Plt001) (Table 1 3) Like pH soil
electrical conductivity also exhibited significant
differences between treatments seasons and layers
During premonsoon soils fertilized with nitrogen had
either almost similar or significantly higher electrical
conductivity values In contrast during monsoon soil in
nitrogen fertilized plots had decreased electrical
conductivity values compared to unfertilized plots
(Table 1)
Total soil nitrogen and exchangeable potassium
significantly differed between seasons layers and among
treatments (Tables 2 and 3) The percentage nitrogen
content of the tea soil was higher during premonsoon
period (S1) when compared to the monsoon season (S2)
Similarly the nitrogen content of L1 layer was higher
when compared to their respective L2 layer Further the
application of nitrogen fertilizer at different doses
enhanced the available nitrogen in L1 layer
concomitantly (Table 2) The exchangeable potassium
level was comparable between premonsoon (S1) and
monsoon (S2) seasons and it fluctuated between different
Journal of Research in Agriculture (2012) 1(2) 124-135 128
Thenmozhi et al2012
So
urce
of
va
ria
tion
df
Mois
ture (
)
pH
E
C (
dS
m-1
)
Soil
nu
trie
nts
Tota
l n
itrog
en
(
) E
xch
an
gea
ble
pota
ssiu
m (
mg
kg -1
l)
Org
an
ic c
arb
on
(
)
Tre
atm
ent
(T)
15
12
8
34
25
15
491
4
74
64
49
53
12998228394
7
23
06
Laye
r (L
) 1
12
8
10
09
2
58
38
4
92
83
3
30
78
56
16275748913
7
15
66
2
Sea
son
(S
) 1
12
8
33
067
2
84
72
17
8
15
98
55
2
385
60
9
118
003
5
64
56
T x
L
15
12
8
13
9
22
84
8
17
54
9
28
54
401064267
8
11
13
T x
S
15
12
8
71
6
37
90
4
27
52
1
37
60
501731007
1
21
50
L x
S
11
28
83
3
33
518
3
26
68
6
20
5
29
53
9621
6
14
09
8
T x
L x
S
51
28
12
4
74
64
19
66
5
29
49
148581688
7
16
02
Tab
le 3
F
- V
alu
es o
f vari
ou
s so
il p
hy
sico
ch
em
ical
ch
aracte
rs a
s in
flu
en
ced
by
nit
rogen
an
d p
ota
ssiu
m f
erti
liza
tio
n
an
d
s
ign
ific
an
t a
t P
lt0
01
an
d P
lt0
00
1 r
esp
ecti
vely
treatment plots in the range of 551 and 4427 mg kg dry
soil However the potassium content was comparably
higher in the L1 layer than the L2 layer The application
of increasing doses of muriate of potash in the different
experimental plots resulted in the enhanced amount of
potassium content in both L1 and L2 layers (Table 2)
Generally nitrogen content in the 0-10 cm soils was
higher when compared to their respective 10-20 cm soils
Exchangeable potassium was lower in nitrogen fertilized
soils than unfertilized soils Soil nitrogen was
significantly (Plt001) and negatively correlated to soil
moisture (r = -0627) and pH (r = -0518) In contrast
soil potassium and pH had a significant and positive
correlation (r = 0267 Plt005) Organic carbon was
higher in the 0-10 cm soils than in 10-20 cm soils and
significantly varied with fertilization and seasons
Generally organic carbon was higher during
premonsoon than monsoon season As organic carbon
was significantly and positively correlated to electrical
conductivity (r = 0315 Plt005) and nitrogen (r = 0752
Plt 001) it was significantly and negatively correlated to
soil moisture (r = -0334 Plt001) (Table 3)
Soil respiration
Soil respiration tended to be higher in 0-10 cm
soils and significantly varied between seasons and
among treatments (Fig 1) During premonsoon
maximum respiration rates were occurred in the 0-10 cm
soils and it was moderate (300 kg ha-1) and high
(450 kg ha-1) in potassium fertilized soils In contrast
maximum respiration rates in the 10-20 cm soils during
129 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
mg
CO
2g
-1 d
m2
4
Fig 1 Influence of nitrogen and potassium fertilization on soil respiration in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
Treatments (Fertilizer dose in kghay)
premonsoon occurred in soils fertilized with high
nitrogen (450 kg ha-1) During monsoon maximum
respiration rates were occurred in the 0-10 cm soils of
treatment involving moderate potassium and high
nitrogen levels (K300 and N450) The respiration rates in
10-20 cm soils during monsoon in fertilized plots were
generally lower compared to unfertilized soils Soil
respiration was significantly and positively correlated to
soil nitrogen (r=0325 Plt0001) and potassium
(r =0309 Plt005)
Enzyme activities
Application of nitrogen and potassium either
individually or in combinations significantly affected soil
urease activity (Fig 2) Urease activity exhibited different
trends in the two soil layers at different seasons High
urease activity occurred during premonsoon in 0-10 cm
soils and during monsoon in the 10-20 cm soils
However maximum urease activity occurred in soils
fertilized with higher doses of nitrogen and potassium
(N450 and K450) during both the seasons and layers except
in 0-10 cm soils where maximum urease activity was
detected in soils fertilized with low nitrogen and
moderate potassium (N150 and K300) Soil urease activity
was significantly and positively correlated to organic
carbon (r=0265 Plt005) and negatively to soil
respiration (r =-0347 Plt 001)
Journal of Research in Agriculture (2012) 1(2) 124-135 130
Thenmozhi et al2012
Fig 2 Influence of nitrogen and potassium fertilization on soil urease activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
μg
Ng
-1d
m2
h-1
L1
n p
L1
L2
Treatments (Fertilizer dose in kghay)
Cellulase activity in the soil differed
significantly among treatments and between seasons and
soil layers (Fig 3) Cellulase activity was higher in 0-10
cm soils during premonsoon season There was a greater
cellulase activity in both soil layers during both the
seasons at low nitrogen application rates (N150)
However increasing concentration of nitrogen
fertilization affected cellulase activity to a greater extent
in the 0-10 cm soils than in 10-20 cm soils A significant
(Plt005) positive correlation existed between soil
cellulase activity and total soil nitrogen (r = 0283)
DISCUSSION
Regular nitrogen fertilization of the acid
soil further acidified the soils The acidification was
more in sulphate of ammonia application during
premonsoon than in urea application during monsoon
These are in accordance with the fact that regular
nitrogen fertilization tend to acidify soils (Khonje et al
1989 Darusman et al 1991) Biederbeck et al (1996)
indicated that application of anhydrous ammonia
lowered soil pH more than urea which clearly indicates
varied levels of soil acidification by different nitrogen
sources Furthermore soil total nitrogen levels were
lower in plots during urea application than sulphate of
131 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatments (Fertilizer dose in kghay)
μg
GE
g-1
dm
24 h
-1
Fig 3 Influence of nitrogen and potassium fertilization on soil cellulase activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
ammonia Most of the broadcasted urea might have
leached out in heavy monsoon showers as considerable
loss (10-25) of nitrogen has been reported to occur due
to leaching or volatilization if urea was not incorporated
into soil soon after its application (Yang 1991 Byrnes
and Freney 1995)
The physico-chemical complexity of soil
contributes significantly to underlying variability in
K+ levels with soil pH moisture and chemical
composition all having marked effects (eg Maathuis
and Sanders 1996) In particular acidic pH leads to
desorption of K+ from anionic binding sites in the soil
and accounts for the tendency towards higher K+ levels
in acidic soils (Gassmann et al 1993) The
exchangeable potassium increased with increasing
potassium application rates It has been thought for a
long time that exchangeable potassium do not built up in
the tea soils of south India because of the dominance of
Kaolinite clay mineral (Verma 1997 Venkatesan et al
2003) However the presence of other minerals other
than Kaolinitic might contribute to the build up of
potassium in the soil (Venkatesan et al 2004) In this
study exchangeable potassium was not related to pH
moisture or chemical composition of the soil However
application of nitrogen significantly reduced soil
potassium which ranged from 18-55 in the 0-10cm
soils and 0-38 in 10-20 cm soils Application of
nitrogen is known to enhance the growth of tea plants
An increased plant growth resulting from nitrogen
fertilization tends to increase potassium uptake from the
soil Studies by The Chinese Tea Research Institute
showed that tea leaves contain 12-25 potassium (TRI
1997) So a large amount of potassium is being mined
from the soil system by the tea plants as a result of
increased growth response to nitrogen fertilization
(Tchienkoua and Zech 2004)
The existence of a significant positive correlation
between soil organic carbon and soil nitrogen indicates
an increasing soil organic carbon content with increasing
nitrogen application rates This is in accordance with
Venkatesan et al (2004) who has also reported higher
organic carbon in soils fertilized with nitrogen Further
Venkatesan et al (2004) indicated that natural organic
carbon reserves of tea soil would be lost due to no or
inadequate supply of nitrogen because tea plants tended
to mineralize and absorb nutrients from organic matter in
the soil under nutrient stress conditions In addition
other studies indicate an increase in soil organic carbon
with increasing soil acidity (Willett et al 2004 Kemmitt
et al 2006) Results from this study tended to indicate
that soil pH and organic carbon were negatively
correlated to each other but this relation is not
statistically significant However when the correlation
analysis was staggered between layers a significant
negative correlation existed between soil pH and organic
carbon in 0-10 cm soils (r = -0667 Plt0000) but not in
10-20 cm soils (r = -0193 Pgt005) This varied relation
between soil organic carbon and pH between layers
could be attributed to soil nitrogen which tended to
strongly influence soil pH than soil potassium
Correlation coefficient values for soil pH and nitrogen in
0-10 cm soils were higher (r= -0773) compared to
10-20 cm soils (r = -0734) These observations are in
line with results of Mc Andrew and Malhi (1992) who
reported an increase in soil organic matter with
increasing soil nitrogen
Soil respiration rates were within normal ranges
reported for natural soils (Srivastava and Singh 1991
Maxwell and Coleman 1995) Results from this study
tended to show that nitrogen and potassium fertilization
affected soil respiration in 0-10 cm soils more than in the
10-20 cm soils Results of Chen et al (2002) also
indicate that nitrogen fertilization reduced soil
respiration in 0-10 cm soils The low respiration rate
with fertilizer application might be attributable to lower
availability of carbon with decreasing soil pH induced by
the nitrogen application (Thirukkumaran and Parkinson
2000)
Journal of Research in Agriculture (2012) 1(2) 124-135 132
Thenmozhi et al2012
Soil urease activity has been reported to follow
changes in soil factors (Cookson and Lepiece 1996) In
the present study fertilizer application generally
increased soil urease activity This is in agreement with
Venkatesan and Senthurpandian (2006) who also
reported an increased urease activity in fertilized tea
soils However these observations contrasts the studies of
Dick et al (1988) and Bandick and Dick (1999) where
soil urease activity was reported to decrease with
increasing application of ammonia based nitrogen
fertilizers Since urease is a substrate inducible enzyme
the application of fertilizers especially urea could have
resulted in higher urease activity Further the binding of
the urease to organic matter insulating itself from
denaturation and biological degradation by soil humic
polymers (Beri et al 1978 Baligar and Wright 1991)
could also attribute to increased level of urease as this
urease could be released from these protected sites by
acid sensitive ammonia oxidizers in response to
fertilization (Martikainen 1985)
Cellulase activity was higher in the surface layer
(0-10 cm soils) than in the subsoils (10-20 cm soils) and
was positively correlated to soil organic matter
Fertilization increased soil cellulase activity which are
in accordance with studies of Aescht and Foissner
(1992)
CONCLUSION
Results from the present study revealed that long
term application of nitrogen and potassium fertilizers
affected soil nutrients and pH Further these fertilizers
can interact with soil microbial communities in a variety
of ways and consequently disturb their normal
functioning The use of nitrogenous fertilizers is
inevitable and an essential part of agricultural practices
In the present study we determined that longndashterm
application of higher doses of urea or ammonium
sulphate fertilizers had an inverse effect on pH moisture
soil respiration and enzyme activities Therefore the
maintenance of low rates of nitrogen and potassium
(ie lt 300 kg-1ha-1y-1) are vital for preserving the soil
quality as higher doses of nitrogen and potassium
(ie gt 300 kg-1ha-1y-1) adversely affects the soil quality
However the actual mechanisms behind these changes
are difficult to infer and needs further investigation
ACKNOWLEDGEMENTS
I express my sincere thanks to
Dr N Muraleedharan Director UPASI Tea Research
Institute Valparai Coimbatore District Tamil Nadu
India for kind permission to use their experimental plots
which formed vital foundation for this work I
acknowledge the invaluable help and support rendered
by Dr S Premkumar Samuel Asir Dr UI Baby and
Dr S Venkatesan Dr R Selvasundaram UPASI Tea
Research Institute Valparai Coimbatore District Tamil
Nadu India during the course of this study
REFERENCES
Aescht E and Foissner W 1992 Effects of mineral and
organic fertilizers on the micro fauna in a high-altitude
reafforestation trial Biology and Fertility of Soils
1317-24
Baligar VC and Wright RJ 1991 Enzyme activities in
Appalachian soils I Aryl-sulfatase Communications in
Soil Science and Plant Analysis 22305-314
Bandick AK and Dick RP 1999 Field management
effects on soil enzyme activities Soil Biology and
Biochemistry 311471-1479
Beri V Goswami KP Brar SS 1978 Urease activity
and its Michaelis constant for soil systems Plant and
Soil 49105-115
Biederbeck VO Campbell CA Ukrainetz H Curtin
D Bouman OT 1996 Soil microbial and biochemical
properties after ten years of fertilization with urea and
anhydrous ammonia Canadian Journal of Soil Science
133 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
76 7-14
Byrnes BH and Freney JR 1995 Recent developments
on the use of urease inhibitors in the tropics Fertilizer
Research 42251-259
Chen CR Xu ZH Hughes JM 2002 Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland Australia Biology
and Fertility of Soils 36276-283
Cookson P and Lepiece AG 1996 Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman Journal of Arid Environment 32225-238
Darusman Stone LR Whitney DA Janssen KA
Long JH 1991 Soil properties after twenty years of
fertilization with different nitrogen sources Soil Science
Society of America Journal 551097-1100
Dick RP 1994 Soil enzyme activities as indicators of
soil quality In Doran JW Coleman DC Bezdicek DF
Stewart BA (Eds) Defining soil quality for a
sustainable environment Special publication no35
SSSA MadisonWI 107-124
Dick RP Rasmussen PE Kerle EA 1988 Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system Biology and Fertility of Soils 6159-164
Gassmann W Ward JM Schroeder JI 1993
Physiological roles of inward rectifying K+ channels
Plant Cell 51491-1493
Jaggi W 1976 Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat Schw Landw
Forsch 15371-380
Kandeler E and Gerber H 1988 Short ndash term assay of
soil urease activity using colorimetric determination of
ammonium Biology and Fertility of Soils 668-72
Kemmitt SJ Wright D Goulding KWT Jones DL
2006 pH regulation of carbon and nitrogen dynamics in
two agricultural soils Soil Biology and Biochemistry
38898-911
Khonje DJ Varsa EC Klubek B 1989 The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil
Communications in Soil Science and Plant Analysis
201377-1395
Maathuis FJM and Sanders D 1996 Mechanism of
Potassium absorption by higher plant roots Physiology
Plantarum 96158-168
Martikainen PJ 1985 Nitrification in forest soil of
different pH as affected by urea ammonium sulphate and
potassium sulphate Soil Biology and Biochemistry
17363-367
Maxwell RA and Coleman DC 1995 Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians Soil
Biology and Biochemistry 2779-84
Mc Andrew DW and Malhi SS 1992 Long-term N
fertilization of a Solonetzic soil Effects on chemical and
biological properties Soil Biology and Biochemistry
24619-623
Nelson DW and Sommers LE 1982 Total carbon
organic carbon and organic matter In Page AL Miller
RH Keeney DR (Eds) Methods of soil analysis Part -
2 Chemical and microbiological properties ASA
monograph number 9 MadisonWI 539-579
Nioh I Isobe T Osada M 1993 Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil Soil Science and Plant Nutrition 39617-625
Schinner F and Von Mersi W 1990 Xylanase- CM-
cellulase- and invertase activity in soil an improved
Journal of Research in Agriculture (2012) 1(2) 124-135 134
Thenmozhi et al2012
method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
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significantly higher during monsoon and was affected by
fertilization Similarly the L2 layer was moister than the
L1 layer during both the seasons For premonsoon period
it ranged between 467-1467 (L1) and 600-1633
(L2) respectively On the other hand it registered
1700-2400 (L1) and 1800-2500 (L2) of mixture
for monsoon seasons (Table 1) Soil moisture was higher
in unfertilized soils during both seasons but
progressively decreased with fertilizer application rates
especially nitrogen (300 and 450 kg ha-1)
A significant difference in soil pH was evident
between layers seasons and most treatments Soils
fertilized with potassium had higher pH values the
exception being the 0-10 cm soils fertilized with 300 and
450 kg ha-1of potassium In contrast soils fertilized with
nitrogen had the lowest pH values and this drop in pH
was more evident in the top 0-10 cm soils than in 10-20
cm soils Soil pH correlated positively with soil moisture
levels (r = 0737 Plt001) (Table 1 3) Like pH soil
electrical conductivity also exhibited significant
differences between treatments seasons and layers
During premonsoon soils fertilized with nitrogen had
either almost similar or significantly higher electrical
conductivity values In contrast during monsoon soil in
nitrogen fertilized plots had decreased electrical
conductivity values compared to unfertilized plots
(Table 1)
Total soil nitrogen and exchangeable potassium
significantly differed between seasons layers and among
treatments (Tables 2 and 3) The percentage nitrogen
content of the tea soil was higher during premonsoon
period (S1) when compared to the monsoon season (S2)
Similarly the nitrogen content of L1 layer was higher
when compared to their respective L2 layer Further the
application of nitrogen fertilizer at different doses
enhanced the available nitrogen in L1 layer
concomitantly (Table 2) The exchangeable potassium
level was comparable between premonsoon (S1) and
monsoon (S2) seasons and it fluctuated between different
Journal of Research in Agriculture (2012) 1(2) 124-135 128
Thenmozhi et al2012
So
urce
of
va
ria
tion
df
Mois
ture (
)
pH
E
C (
dS
m-1
)
Soil
nu
trie
nts
Tota
l n
itrog
en
(
) E
xch
an
gea
ble
pota
ssiu
m (
mg
kg -1
l)
Org
an
ic c
arb
on
(
)
Tre
atm
ent
(T)
15
12
8
34
25
15
491
4
74
64
49
53
12998228394
7
23
06
Laye
r (L
) 1
12
8
10
09
2
58
38
4
92
83
3
30
78
56
16275748913
7
15
66
2
Sea
son
(S
) 1
12
8
33
067
2
84
72
17
8
15
98
55
2
385
60
9
118
003
5
64
56
T x
L
15
12
8
13
9
22
84
8
17
54
9
28
54
401064267
8
11
13
T x
S
15
12
8
71
6
37
90
4
27
52
1
37
60
501731007
1
21
50
L x
S
11
28
83
3
33
518
3
26
68
6
20
5
29
53
9621
6
14
09
8
T x
L x
S
51
28
12
4
74
64
19
66
5
29
49
148581688
7
16
02
Tab
le 3
F
- V
alu
es o
f vari
ou
s so
il p
hy
sico
ch
em
ical
ch
aracte
rs a
s in
flu
en
ced
by
nit
rogen
an
d p
ota
ssiu
m f
erti
liza
tio
n
an
d
s
ign
ific
an
t a
t P
lt0
01
an
d P
lt0
00
1 r
esp
ecti
vely
treatment plots in the range of 551 and 4427 mg kg dry
soil However the potassium content was comparably
higher in the L1 layer than the L2 layer The application
of increasing doses of muriate of potash in the different
experimental plots resulted in the enhanced amount of
potassium content in both L1 and L2 layers (Table 2)
Generally nitrogen content in the 0-10 cm soils was
higher when compared to their respective 10-20 cm soils
Exchangeable potassium was lower in nitrogen fertilized
soils than unfertilized soils Soil nitrogen was
significantly (Plt001) and negatively correlated to soil
moisture (r = -0627) and pH (r = -0518) In contrast
soil potassium and pH had a significant and positive
correlation (r = 0267 Plt005) Organic carbon was
higher in the 0-10 cm soils than in 10-20 cm soils and
significantly varied with fertilization and seasons
Generally organic carbon was higher during
premonsoon than monsoon season As organic carbon
was significantly and positively correlated to electrical
conductivity (r = 0315 Plt005) and nitrogen (r = 0752
Plt 001) it was significantly and negatively correlated to
soil moisture (r = -0334 Plt001) (Table 3)
Soil respiration
Soil respiration tended to be higher in 0-10 cm
soils and significantly varied between seasons and
among treatments (Fig 1) During premonsoon
maximum respiration rates were occurred in the 0-10 cm
soils and it was moderate (300 kg ha-1) and high
(450 kg ha-1) in potassium fertilized soils In contrast
maximum respiration rates in the 10-20 cm soils during
129 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
mg
CO
2g
-1 d
m2
4
Fig 1 Influence of nitrogen and potassium fertilization on soil respiration in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
Treatments (Fertilizer dose in kghay)
premonsoon occurred in soils fertilized with high
nitrogen (450 kg ha-1) During monsoon maximum
respiration rates were occurred in the 0-10 cm soils of
treatment involving moderate potassium and high
nitrogen levels (K300 and N450) The respiration rates in
10-20 cm soils during monsoon in fertilized plots were
generally lower compared to unfertilized soils Soil
respiration was significantly and positively correlated to
soil nitrogen (r=0325 Plt0001) and potassium
(r =0309 Plt005)
Enzyme activities
Application of nitrogen and potassium either
individually or in combinations significantly affected soil
urease activity (Fig 2) Urease activity exhibited different
trends in the two soil layers at different seasons High
urease activity occurred during premonsoon in 0-10 cm
soils and during monsoon in the 10-20 cm soils
However maximum urease activity occurred in soils
fertilized with higher doses of nitrogen and potassium
(N450 and K450) during both the seasons and layers except
in 0-10 cm soils where maximum urease activity was
detected in soils fertilized with low nitrogen and
moderate potassium (N150 and K300) Soil urease activity
was significantly and positively correlated to organic
carbon (r=0265 Plt005) and negatively to soil
respiration (r =-0347 Plt 001)
Journal of Research in Agriculture (2012) 1(2) 124-135 130
Thenmozhi et al2012
Fig 2 Influence of nitrogen and potassium fertilization on soil urease activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
μg
Ng
-1d
m2
h-1
L1
n p
L1
L2
Treatments (Fertilizer dose in kghay)
Cellulase activity in the soil differed
significantly among treatments and between seasons and
soil layers (Fig 3) Cellulase activity was higher in 0-10
cm soils during premonsoon season There was a greater
cellulase activity in both soil layers during both the
seasons at low nitrogen application rates (N150)
However increasing concentration of nitrogen
fertilization affected cellulase activity to a greater extent
in the 0-10 cm soils than in 10-20 cm soils A significant
(Plt005) positive correlation existed between soil
cellulase activity and total soil nitrogen (r = 0283)
DISCUSSION
Regular nitrogen fertilization of the acid
soil further acidified the soils The acidification was
more in sulphate of ammonia application during
premonsoon than in urea application during monsoon
These are in accordance with the fact that regular
nitrogen fertilization tend to acidify soils (Khonje et al
1989 Darusman et al 1991) Biederbeck et al (1996)
indicated that application of anhydrous ammonia
lowered soil pH more than urea which clearly indicates
varied levels of soil acidification by different nitrogen
sources Furthermore soil total nitrogen levels were
lower in plots during urea application than sulphate of
131 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatments (Fertilizer dose in kghay)
μg
GE
g-1
dm
24 h
-1
Fig 3 Influence of nitrogen and potassium fertilization on soil cellulase activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
ammonia Most of the broadcasted urea might have
leached out in heavy monsoon showers as considerable
loss (10-25) of nitrogen has been reported to occur due
to leaching or volatilization if urea was not incorporated
into soil soon after its application (Yang 1991 Byrnes
and Freney 1995)
The physico-chemical complexity of soil
contributes significantly to underlying variability in
K+ levels with soil pH moisture and chemical
composition all having marked effects (eg Maathuis
and Sanders 1996) In particular acidic pH leads to
desorption of K+ from anionic binding sites in the soil
and accounts for the tendency towards higher K+ levels
in acidic soils (Gassmann et al 1993) The
exchangeable potassium increased with increasing
potassium application rates It has been thought for a
long time that exchangeable potassium do not built up in
the tea soils of south India because of the dominance of
Kaolinite clay mineral (Verma 1997 Venkatesan et al
2003) However the presence of other minerals other
than Kaolinitic might contribute to the build up of
potassium in the soil (Venkatesan et al 2004) In this
study exchangeable potassium was not related to pH
moisture or chemical composition of the soil However
application of nitrogen significantly reduced soil
potassium which ranged from 18-55 in the 0-10cm
soils and 0-38 in 10-20 cm soils Application of
nitrogen is known to enhance the growth of tea plants
An increased plant growth resulting from nitrogen
fertilization tends to increase potassium uptake from the
soil Studies by The Chinese Tea Research Institute
showed that tea leaves contain 12-25 potassium (TRI
1997) So a large amount of potassium is being mined
from the soil system by the tea plants as a result of
increased growth response to nitrogen fertilization
(Tchienkoua and Zech 2004)
The existence of a significant positive correlation
between soil organic carbon and soil nitrogen indicates
an increasing soil organic carbon content with increasing
nitrogen application rates This is in accordance with
Venkatesan et al (2004) who has also reported higher
organic carbon in soils fertilized with nitrogen Further
Venkatesan et al (2004) indicated that natural organic
carbon reserves of tea soil would be lost due to no or
inadequate supply of nitrogen because tea plants tended
to mineralize and absorb nutrients from organic matter in
the soil under nutrient stress conditions In addition
other studies indicate an increase in soil organic carbon
with increasing soil acidity (Willett et al 2004 Kemmitt
et al 2006) Results from this study tended to indicate
that soil pH and organic carbon were negatively
correlated to each other but this relation is not
statistically significant However when the correlation
analysis was staggered between layers a significant
negative correlation existed between soil pH and organic
carbon in 0-10 cm soils (r = -0667 Plt0000) but not in
10-20 cm soils (r = -0193 Pgt005) This varied relation
between soil organic carbon and pH between layers
could be attributed to soil nitrogen which tended to
strongly influence soil pH than soil potassium
Correlation coefficient values for soil pH and nitrogen in
0-10 cm soils were higher (r= -0773) compared to
10-20 cm soils (r = -0734) These observations are in
line with results of Mc Andrew and Malhi (1992) who
reported an increase in soil organic matter with
increasing soil nitrogen
Soil respiration rates were within normal ranges
reported for natural soils (Srivastava and Singh 1991
Maxwell and Coleman 1995) Results from this study
tended to show that nitrogen and potassium fertilization
affected soil respiration in 0-10 cm soils more than in the
10-20 cm soils Results of Chen et al (2002) also
indicate that nitrogen fertilization reduced soil
respiration in 0-10 cm soils The low respiration rate
with fertilizer application might be attributable to lower
availability of carbon with decreasing soil pH induced by
the nitrogen application (Thirukkumaran and Parkinson
2000)
Journal of Research in Agriculture (2012) 1(2) 124-135 132
Thenmozhi et al2012
Soil urease activity has been reported to follow
changes in soil factors (Cookson and Lepiece 1996) In
the present study fertilizer application generally
increased soil urease activity This is in agreement with
Venkatesan and Senthurpandian (2006) who also
reported an increased urease activity in fertilized tea
soils However these observations contrasts the studies of
Dick et al (1988) and Bandick and Dick (1999) where
soil urease activity was reported to decrease with
increasing application of ammonia based nitrogen
fertilizers Since urease is a substrate inducible enzyme
the application of fertilizers especially urea could have
resulted in higher urease activity Further the binding of
the urease to organic matter insulating itself from
denaturation and biological degradation by soil humic
polymers (Beri et al 1978 Baligar and Wright 1991)
could also attribute to increased level of urease as this
urease could be released from these protected sites by
acid sensitive ammonia oxidizers in response to
fertilization (Martikainen 1985)
Cellulase activity was higher in the surface layer
(0-10 cm soils) than in the subsoils (10-20 cm soils) and
was positively correlated to soil organic matter
Fertilization increased soil cellulase activity which are
in accordance with studies of Aescht and Foissner
(1992)
CONCLUSION
Results from the present study revealed that long
term application of nitrogen and potassium fertilizers
affected soil nutrients and pH Further these fertilizers
can interact with soil microbial communities in a variety
of ways and consequently disturb their normal
functioning The use of nitrogenous fertilizers is
inevitable and an essential part of agricultural practices
In the present study we determined that longndashterm
application of higher doses of urea or ammonium
sulphate fertilizers had an inverse effect on pH moisture
soil respiration and enzyme activities Therefore the
maintenance of low rates of nitrogen and potassium
(ie lt 300 kg-1ha-1y-1) are vital for preserving the soil
quality as higher doses of nitrogen and potassium
(ie gt 300 kg-1ha-1y-1) adversely affects the soil quality
However the actual mechanisms behind these changes
are difficult to infer and needs further investigation
ACKNOWLEDGEMENTS
I express my sincere thanks to
Dr N Muraleedharan Director UPASI Tea Research
Institute Valparai Coimbatore District Tamil Nadu
India for kind permission to use their experimental plots
which formed vital foundation for this work I
acknowledge the invaluable help and support rendered
by Dr S Premkumar Samuel Asir Dr UI Baby and
Dr S Venkatesan Dr R Selvasundaram UPASI Tea
Research Institute Valparai Coimbatore District Tamil
Nadu India during the course of this study
REFERENCES
Aescht E and Foissner W 1992 Effects of mineral and
organic fertilizers on the micro fauna in a high-altitude
reafforestation trial Biology and Fertility of Soils
1317-24
Baligar VC and Wright RJ 1991 Enzyme activities in
Appalachian soils I Aryl-sulfatase Communications in
Soil Science and Plant Analysis 22305-314
Bandick AK and Dick RP 1999 Field management
effects on soil enzyme activities Soil Biology and
Biochemistry 311471-1479
Beri V Goswami KP Brar SS 1978 Urease activity
and its Michaelis constant for soil systems Plant and
Soil 49105-115
Biederbeck VO Campbell CA Ukrainetz H Curtin
D Bouman OT 1996 Soil microbial and biochemical
properties after ten years of fertilization with urea and
anhydrous ammonia Canadian Journal of Soil Science
133 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
76 7-14
Byrnes BH and Freney JR 1995 Recent developments
on the use of urease inhibitors in the tropics Fertilizer
Research 42251-259
Chen CR Xu ZH Hughes JM 2002 Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland Australia Biology
and Fertility of Soils 36276-283
Cookson P and Lepiece AG 1996 Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman Journal of Arid Environment 32225-238
Darusman Stone LR Whitney DA Janssen KA
Long JH 1991 Soil properties after twenty years of
fertilization with different nitrogen sources Soil Science
Society of America Journal 551097-1100
Dick RP 1994 Soil enzyme activities as indicators of
soil quality In Doran JW Coleman DC Bezdicek DF
Stewart BA (Eds) Defining soil quality for a
sustainable environment Special publication no35
SSSA MadisonWI 107-124
Dick RP Rasmussen PE Kerle EA 1988 Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system Biology and Fertility of Soils 6159-164
Gassmann W Ward JM Schroeder JI 1993
Physiological roles of inward rectifying K+ channels
Plant Cell 51491-1493
Jaggi W 1976 Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat Schw Landw
Forsch 15371-380
Kandeler E and Gerber H 1988 Short ndash term assay of
soil urease activity using colorimetric determination of
ammonium Biology and Fertility of Soils 668-72
Kemmitt SJ Wright D Goulding KWT Jones DL
2006 pH regulation of carbon and nitrogen dynamics in
two agricultural soils Soil Biology and Biochemistry
38898-911
Khonje DJ Varsa EC Klubek B 1989 The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil
Communications in Soil Science and Plant Analysis
201377-1395
Maathuis FJM and Sanders D 1996 Mechanism of
Potassium absorption by higher plant roots Physiology
Plantarum 96158-168
Martikainen PJ 1985 Nitrification in forest soil of
different pH as affected by urea ammonium sulphate and
potassium sulphate Soil Biology and Biochemistry
17363-367
Maxwell RA and Coleman DC 1995 Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians Soil
Biology and Biochemistry 2779-84
Mc Andrew DW and Malhi SS 1992 Long-term N
fertilization of a Solonetzic soil Effects on chemical and
biological properties Soil Biology and Biochemistry
24619-623
Nelson DW and Sommers LE 1982 Total carbon
organic carbon and organic matter In Page AL Miller
RH Keeney DR (Eds) Methods of soil analysis Part -
2 Chemical and microbiological properties ASA
monograph number 9 MadisonWI 539-579
Nioh I Isobe T Osada M 1993 Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil Soil Science and Plant Nutrition 39617-625
Schinner F and Von Mersi W 1990 Xylanase- CM-
cellulase- and invertase activity in soil an improved
Journal of Research in Agriculture (2012) 1(2) 124-135 134
Thenmozhi et al2012
method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
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treatment plots in the range of 551 and 4427 mg kg dry
soil However the potassium content was comparably
higher in the L1 layer than the L2 layer The application
of increasing doses of muriate of potash in the different
experimental plots resulted in the enhanced amount of
potassium content in both L1 and L2 layers (Table 2)
Generally nitrogen content in the 0-10 cm soils was
higher when compared to their respective 10-20 cm soils
Exchangeable potassium was lower in nitrogen fertilized
soils than unfertilized soils Soil nitrogen was
significantly (Plt001) and negatively correlated to soil
moisture (r = -0627) and pH (r = -0518) In contrast
soil potassium and pH had a significant and positive
correlation (r = 0267 Plt005) Organic carbon was
higher in the 0-10 cm soils than in 10-20 cm soils and
significantly varied with fertilization and seasons
Generally organic carbon was higher during
premonsoon than monsoon season As organic carbon
was significantly and positively correlated to electrical
conductivity (r = 0315 Plt005) and nitrogen (r = 0752
Plt 001) it was significantly and negatively correlated to
soil moisture (r = -0334 Plt001) (Table 3)
Soil respiration
Soil respiration tended to be higher in 0-10 cm
soils and significantly varied between seasons and
among treatments (Fig 1) During premonsoon
maximum respiration rates were occurred in the 0-10 cm
soils and it was moderate (300 kg ha-1) and high
(450 kg ha-1) in potassium fertilized soils In contrast
maximum respiration rates in the 10-20 cm soils during
129 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
mg
CO
2g
-1 d
m2
4
Fig 1 Influence of nitrogen and potassium fertilization on soil respiration in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
Treatments (Fertilizer dose in kghay)
premonsoon occurred in soils fertilized with high
nitrogen (450 kg ha-1) During monsoon maximum
respiration rates were occurred in the 0-10 cm soils of
treatment involving moderate potassium and high
nitrogen levels (K300 and N450) The respiration rates in
10-20 cm soils during monsoon in fertilized plots were
generally lower compared to unfertilized soils Soil
respiration was significantly and positively correlated to
soil nitrogen (r=0325 Plt0001) and potassium
(r =0309 Plt005)
Enzyme activities
Application of nitrogen and potassium either
individually or in combinations significantly affected soil
urease activity (Fig 2) Urease activity exhibited different
trends in the two soil layers at different seasons High
urease activity occurred during premonsoon in 0-10 cm
soils and during monsoon in the 10-20 cm soils
However maximum urease activity occurred in soils
fertilized with higher doses of nitrogen and potassium
(N450 and K450) during both the seasons and layers except
in 0-10 cm soils where maximum urease activity was
detected in soils fertilized with low nitrogen and
moderate potassium (N150 and K300) Soil urease activity
was significantly and positively correlated to organic
carbon (r=0265 Plt005) and negatively to soil
respiration (r =-0347 Plt 001)
Journal of Research in Agriculture (2012) 1(2) 124-135 130
Thenmozhi et al2012
Fig 2 Influence of nitrogen and potassium fertilization on soil urease activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
μg
Ng
-1d
m2
h-1
L1
n p
L1
L2
Treatments (Fertilizer dose in kghay)
Cellulase activity in the soil differed
significantly among treatments and between seasons and
soil layers (Fig 3) Cellulase activity was higher in 0-10
cm soils during premonsoon season There was a greater
cellulase activity in both soil layers during both the
seasons at low nitrogen application rates (N150)
However increasing concentration of nitrogen
fertilization affected cellulase activity to a greater extent
in the 0-10 cm soils than in 10-20 cm soils A significant
(Plt005) positive correlation existed between soil
cellulase activity and total soil nitrogen (r = 0283)
DISCUSSION
Regular nitrogen fertilization of the acid
soil further acidified the soils The acidification was
more in sulphate of ammonia application during
premonsoon than in urea application during monsoon
These are in accordance with the fact that regular
nitrogen fertilization tend to acidify soils (Khonje et al
1989 Darusman et al 1991) Biederbeck et al (1996)
indicated that application of anhydrous ammonia
lowered soil pH more than urea which clearly indicates
varied levels of soil acidification by different nitrogen
sources Furthermore soil total nitrogen levels were
lower in plots during urea application than sulphate of
131 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatments (Fertilizer dose in kghay)
μg
GE
g-1
dm
24 h
-1
Fig 3 Influence of nitrogen and potassium fertilization on soil cellulase activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
ammonia Most of the broadcasted urea might have
leached out in heavy monsoon showers as considerable
loss (10-25) of nitrogen has been reported to occur due
to leaching or volatilization if urea was not incorporated
into soil soon after its application (Yang 1991 Byrnes
and Freney 1995)
The physico-chemical complexity of soil
contributes significantly to underlying variability in
K+ levels with soil pH moisture and chemical
composition all having marked effects (eg Maathuis
and Sanders 1996) In particular acidic pH leads to
desorption of K+ from anionic binding sites in the soil
and accounts for the tendency towards higher K+ levels
in acidic soils (Gassmann et al 1993) The
exchangeable potassium increased with increasing
potassium application rates It has been thought for a
long time that exchangeable potassium do not built up in
the tea soils of south India because of the dominance of
Kaolinite clay mineral (Verma 1997 Venkatesan et al
2003) However the presence of other minerals other
than Kaolinitic might contribute to the build up of
potassium in the soil (Venkatesan et al 2004) In this
study exchangeable potassium was not related to pH
moisture or chemical composition of the soil However
application of nitrogen significantly reduced soil
potassium which ranged from 18-55 in the 0-10cm
soils and 0-38 in 10-20 cm soils Application of
nitrogen is known to enhance the growth of tea plants
An increased plant growth resulting from nitrogen
fertilization tends to increase potassium uptake from the
soil Studies by The Chinese Tea Research Institute
showed that tea leaves contain 12-25 potassium (TRI
1997) So a large amount of potassium is being mined
from the soil system by the tea plants as a result of
increased growth response to nitrogen fertilization
(Tchienkoua and Zech 2004)
The existence of a significant positive correlation
between soil organic carbon and soil nitrogen indicates
an increasing soil organic carbon content with increasing
nitrogen application rates This is in accordance with
Venkatesan et al (2004) who has also reported higher
organic carbon in soils fertilized with nitrogen Further
Venkatesan et al (2004) indicated that natural organic
carbon reserves of tea soil would be lost due to no or
inadequate supply of nitrogen because tea plants tended
to mineralize and absorb nutrients from organic matter in
the soil under nutrient stress conditions In addition
other studies indicate an increase in soil organic carbon
with increasing soil acidity (Willett et al 2004 Kemmitt
et al 2006) Results from this study tended to indicate
that soil pH and organic carbon were negatively
correlated to each other but this relation is not
statistically significant However when the correlation
analysis was staggered between layers a significant
negative correlation existed between soil pH and organic
carbon in 0-10 cm soils (r = -0667 Plt0000) but not in
10-20 cm soils (r = -0193 Pgt005) This varied relation
between soil organic carbon and pH between layers
could be attributed to soil nitrogen which tended to
strongly influence soil pH than soil potassium
Correlation coefficient values for soil pH and nitrogen in
0-10 cm soils were higher (r= -0773) compared to
10-20 cm soils (r = -0734) These observations are in
line with results of Mc Andrew and Malhi (1992) who
reported an increase in soil organic matter with
increasing soil nitrogen
Soil respiration rates were within normal ranges
reported for natural soils (Srivastava and Singh 1991
Maxwell and Coleman 1995) Results from this study
tended to show that nitrogen and potassium fertilization
affected soil respiration in 0-10 cm soils more than in the
10-20 cm soils Results of Chen et al (2002) also
indicate that nitrogen fertilization reduced soil
respiration in 0-10 cm soils The low respiration rate
with fertilizer application might be attributable to lower
availability of carbon with decreasing soil pH induced by
the nitrogen application (Thirukkumaran and Parkinson
2000)
Journal of Research in Agriculture (2012) 1(2) 124-135 132
Thenmozhi et al2012
Soil urease activity has been reported to follow
changes in soil factors (Cookson and Lepiece 1996) In
the present study fertilizer application generally
increased soil urease activity This is in agreement with
Venkatesan and Senthurpandian (2006) who also
reported an increased urease activity in fertilized tea
soils However these observations contrasts the studies of
Dick et al (1988) and Bandick and Dick (1999) where
soil urease activity was reported to decrease with
increasing application of ammonia based nitrogen
fertilizers Since urease is a substrate inducible enzyme
the application of fertilizers especially urea could have
resulted in higher urease activity Further the binding of
the urease to organic matter insulating itself from
denaturation and biological degradation by soil humic
polymers (Beri et al 1978 Baligar and Wright 1991)
could also attribute to increased level of urease as this
urease could be released from these protected sites by
acid sensitive ammonia oxidizers in response to
fertilization (Martikainen 1985)
Cellulase activity was higher in the surface layer
(0-10 cm soils) than in the subsoils (10-20 cm soils) and
was positively correlated to soil organic matter
Fertilization increased soil cellulase activity which are
in accordance with studies of Aescht and Foissner
(1992)
CONCLUSION
Results from the present study revealed that long
term application of nitrogen and potassium fertilizers
affected soil nutrients and pH Further these fertilizers
can interact with soil microbial communities in a variety
of ways and consequently disturb their normal
functioning The use of nitrogenous fertilizers is
inevitable and an essential part of agricultural practices
In the present study we determined that longndashterm
application of higher doses of urea or ammonium
sulphate fertilizers had an inverse effect on pH moisture
soil respiration and enzyme activities Therefore the
maintenance of low rates of nitrogen and potassium
(ie lt 300 kg-1ha-1y-1) are vital for preserving the soil
quality as higher doses of nitrogen and potassium
(ie gt 300 kg-1ha-1y-1) adversely affects the soil quality
However the actual mechanisms behind these changes
are difficult to infer and needs further investigation
ACKNOWLEDGEMENTS
I express my sincere thanks to
Dr N Muraleedharan Director UPASI Tea Research
Institute Valparai Coimbatore District Tamil Nadu
India for kind permission to use their experimental plots
which formed vital foundation for this work I
acknowledge the invaluable help and support rendered
by Dr S Premkumar Samuel Asir Dr UI Baby and
Dr S Venkatesan Dr R Selvasundaram UPASI Tea
Research Institute Valparai Coimbatore District Tamil
Nadu India during the course of this study
REFERENCES
Aescht E and Foissner W 1992 Effects of mineral and
organic fertilizers on the micro fauna in a high-altitude
reafforestation trial Biology and Fertility of Soils
1317-24
Baligar VC and Wright RJ 1991 Enzyme activities in
Appalachian soils I Aryl-sulfatase Communications in
Soil Science and Plant Analysis 22305-314
Bandick AK and Dick RP 1999 Field management
effects on soil enzyme activities Soil Biology and
Biochemistry 311471-1479
Beri V Goswami KP Brar SS 1978 Urease activity
and its Michaelis constant for soil systems Plant and
Soil 49105-115
Biederbeck VO Campbell CA Ukrainetz H Curtin
D Bouman OT 1996 Soil microbial and biochemical
properties after ten years of fertilization with urea and
anhydrous ammonia Canadian Journal of Soil Science
133 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
76 7-14
Byrnes BH and Freney JR 1995 Recent developments
on the use of urease inhibitors in the tropics Fertilizer
Research 42251-259
Chen CR Xu ZH Hughes JM 2002 Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland Australia Biology
and Fertility of Soils 36276-283
Cookson P and Lepiece AG 1996 Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman Journal of Arid Environment 32225-238
Darusman Stone LR Whitney DA Janssen KA
Long JH 1991 Soil properties after twenty years of
fertilization with different nitrogen sources Soil Science
Society of America Journal 551097-1100
Dick RP 1994 Soil enzyme activities as indicators of
soil quality In Doran JW Coleman DC Bezdicek DF
Stewart BA (Eds) Defining soil quality for a
sustainable environment Special publication no35
SSSA MadisonWI 107-124
Dick RP Rasmussen PE Kerle EA 1988 Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system Biology and Fertility of Soils 6159-164
Gassmann W Ward JM Schroeder JI 1993
Physiological roles of inward rectifying K+ channels
Plant Cell 51491-1493
Jaggi W 1976 Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat Schw Landw
Forsch 15371-380
Kandeler E and Gerber H 1988 Short ndash term assay of
soil urease activity using colorimetric determination of
ammonium Biology and Fertility of Soils 668-72
Kemmitt SJ Wright D Goulding KWT Jones DL
2006 pH regulation of carbon and nitrogen dynamics in
two agricultural soils Soil Biology and Biochemistry
38898-911
Khonje DJ Varsa EC Klubek B 1989 The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil
Communications in Soil Science and Plant Analysis
201377-1395
Maathuis FJM and Sanders D 1996 Mechanism of
Potassium absorption by higher plant roots Physiology
Plantarum 96158-168
Martikainen PJ 1985 Nitrification in forest soil of
different pH as affected by urea ammonium sulphate and
potassium sulphate Soil Biology and Biochemistry
17363-367
Maxwell RA and Coleman DC 1995 Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians Soil
Biology and Biochemistry 2779-84
Mc Andrew DW and Malhi SS 1992 Long-term N
fertilization of a Solonetzic soil Effects on chemical and
biological properties Soil Biology and Biochemistry
24619-623
Nelson DW and Sommers LE 1982 Total carbon
organic carbon and organic matter In Page AL Miller
RH Keeney DR (Eds) Methods of soil analysis Part -
2 Chemical and microbiological properties ASA
monograph number 9 MadisonWI 539-579
Nioh I Isobe T Osada M 1993 Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil Soil Science and Plant Nutrition 39617-625
Schinner F and Von Mersi W 1990 Xylanase- CM-
cellulase- and invertase activity in soil an improved
Journal of Research in Agriculture (2012) 1(2) 124-135 134
Thenmozhi et al2012
method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Submit your articles online at wwwjagriinfo
Advantages
Easy online submission Complete Peer review Affordable Charges Quick processing Extensive indexing You retain your copyright
submitjagriinfo
wwwjagriinfoSumitphp
premonsoon occurred in soils fertilized with high
nitrogen (450 kg ha-1) During monsoon maximum
respiration rates were occurred in the 0-10 cm soils of
treatment involving moderate potassium and high
nitrogen levels (K300 and N450) The respiration rates in
10-20 cm soils during monsoon in fertilized plots were
generally lower compared to unfertilized soils Soil
respiration was significantly and positively correlated to
soil nitrogen (r=0325 Plt0001) and potassium
(r =0309 Plt005)
Enzyme activities
Application of nitrogen and potassium either
individually or in combinations significantly affected soil
urease activity (Fig 2) Urease activity exhibited different
trends in the two soil layers at different seasons High
urease activity occurred during premonsoon in 0-10 cm
soils and during monsoon in the 10-20 cm soils
However maximum urease activity occurred in soils
fertilized with higher doses of nitrogen and potassium
(N450 and K450) during both the seasons and layers except
in 0-10 cm soils where maximum urease activity was
detected in soils fertilized with low nitrogen and
moderate potassium (N150 and K300) Soil urease activity
was significantly and positively correlated to organic
carbon (r=0265 Plt005) and negatively to soil
respiration (r =-0347 Plt 001)
Journal of Research in Agriculture (2012) 1(2) 124-135 130
Thenmozhi et al2012
Fig 2 Influence of nitrogen and potassium fertilization on soil urease activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
μg
Ng
-1d
m2
h-1
L1
n p
L1
L2
Treatments (Fertilizer dose in kghay)
Cellulase activity in the soil differed
significantly among treatments and between seasons and
soil layers (Fig 3) Cellulase activity was higher in 0-10
cm soils during premonsoon season There was a greater
cellulase activity in both soil layers during both the
seasons at low nitrogen application rates (N150)
However increasing concentration of nitrogen
fertilization affected cellulase activity to a greater extent
in the 0-10 cm soils than in 10-20 cm soils A significant
(Plt005) positive correlation existed between soil
cellulase activity and total soil nitrogen (r = 0283)
DISCUSSION
Regular nitrogen fertilization of the acid
soil further acidified the soils The acidification was
more in sulphate of ammonia application during
premonsoon than in urea application during monsoon
These are in accordance with the fact that regular
nitrogen fertilization tend to acidify soils (Khonje et al
1989 Darusman et al 1991) Biederbeck et al (1996)
indicated that application of anhydrous ammonia
lowered soil pH more than urea which clearly indicates
varied levels of soil acidification by different nitrogen
sources Furthermore soil total nitrogen levels were
lower in plots during urea application than sulphate of
131 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatments (Fertilizer dose in kghay)
μg
GE
g-1
dm
24 h
-1
Fig 3 Influence of nitrogen and potassium fertilization on soil cellulase activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
ammonia Most of the broadcasted urea might have
leached out in heavy monsoon showers as considerable
loss (10-25) of nitrogen has been reported to occur due
to leaching or volatilization if urea was not incorporated
into soil soon after its application (Yang 1991 Byrnes
and Freney 1995)
The physico-chemical complexity of soil
contributes significantly to underlying variability in
K+ levels with soil pH moisture and chemical
composition all having marked effects (eg Maathuis
and Sanders 1996) In particular acidic pH leads to
desorption of K+ from anionic binding sites in the soil
and accounts for the tendency towards higher K+ levels
in acidic soils (Gassmann et al 1993) The
exchangeable potassium increased with increasing
potassium application rates It has been thought for a
long time that exchangeable potassium do not built up in
the tea soils of south India because of the dominance of
Kaolinite clay mineral (Verma 1997 Venkatesan et al
2003) However the presence of other minerals other
than Kaolinitic might contribute to the build up of
potassium in the soil (Venkatesan et al 2004) In this
study exchangeable potassium was not related to pH
moisture or chemical composition of the soil However
application of nitrogen significantly reduced soil
potassium which ranged from 18-55 in the 0-10cm
soils and 0-38 in 10-20 cm soils Application of
nitrogen is known to enhance the growth of tea plants
An increased plant growth resulting from nitrogen
fertilization tends to increase potassium uptake from the
soil Studies by The Chinese Tea Research Institute
showed that tea leaves contain 12-25 potassium (TRI
1997) So a large amount of potassium is being mined
from the soil system by the tea plants as a result of
increased growth response to nitrogen fertilization
(Tchienkoua and Zech 2004)
The existence of a significant positive correlation
between soil organic carbon and soil nitrogen indicates
an increasing soil organic carbon content with increasing
nitrogen application rates This is in accordance with
Venkatesan et al (2004) who has also reported higher
organic carbon in soils fertilized with nitrogen Further
Venkatesan et al (2004) indicated that natural organic
carbon reserves of tea soil would be lost due to no or
inadequate supply of nitrogen because tea plants tended
to mineralize and absorb nutrients from organic matter in
the soil under nutrient stress conditions In addition
other studies indicate an increase in soil organic carbon
with increasing soil acidity (Willett et al 2004 Kemmitt
et al 2006) Results from this study tended to indicate
that soil pH and organic carbon were negatively
correlated to each other but this relation is not
statistically significant However when the correlation
analysis was staggered between layers a significant
negative correlation existed between soil pH and organic
carbon in 0-10 cm soils (r = -0667 Plt0000) but not in
10-20 cm soils (r = -0193 Pgt005) This varied relation
between soil organic carbon and pH between layers
could be attributed to soil nitrogen which tended to
strongly influence soil pH than soil potassium
Correlation coefficient values for soil pH and nitrogen in
0-10 cm soils were higher (r= -0773) compared to
10-20 cm soils (r = -0734) These observations are in
line with results of Mc Andrew and Malhi (1992) who
reported an increase in soil organic matter with
increasing soil nitrogen
Soil respiration rates were within normal ranges
reported for natural soils (Srivastava and Singh 1991
Maxwell and Coleman 1995) Results from this study
tended to show that nitrogen and potassium fertilization
affected soil respiration in 0-10 cm soils more than in the
10-20 cm soils Results of Chen et al (2002) also
indicate that nitrogen fertilization reduced soil
respiration in 0-10 cm soils The low respiration rate
with fertilizer application might be attributable to lower
availability of carbon with decreasing soil pH induced by
the nitrogen application (Thirukkumaran and Parkinson
2000)
Journal of Research in Agriculture (2012) 1(2) 124-135 132
Thenmozhi et al2012
Soil urease activity has been reported to follow
changes in soil factors (Cookson and Lepiece 1996) In
the present study fertilizer application generally
increased soil urease activity This is in agreement with
Venkatesan and Senthurpandian (2006) who also
reported an increased urease activity in fertilized tea
soils However these observations contrasts the studies of
Dick et al (1988) and Bandick and Dick (1999) where
soil urease activity was reported to decrease with
increasing application of ammonia based nitrogen
fertilizers Since urease is a substrate inducible enzyme
the application of fertilizers especially urea could have
resulted in higher urease activity Further the binding of
the urease to organic matter insulating itself from
denaturation and biological degradation by soil humic
polymers (Beri et al 1978 Baligar and Wright 1991)
could also attribute to increased level of urease as this
urease could be released from these protected sites by
acid sensitive ammonia oxidizers in response to
fertilization (Martikainen 1985)
Cellulase activity was higher in the surface layer
(0-10 cm soils) than in the subsoils (10-20 cm soils) and
was positively correlated to soil organic matter
Fertilization increased soil cellulase activity which are
in accordance with studies of Aescht and Foissner
(1992)
CONCLUSION
Results from the present study revealed that long
term application of nitrogen and potassium fertilizers
affected soil nutrients and pH Further these fertilizers
can interact with soil microbial communities in a variety
of ways and consequently disturb their normal
functioning The use of nitrogenous fertilizers is
inevitable and an essential part of agricultural practices
In the present study we determined that longndashterm
application of higher doses of urea or ammonium
sulphate fertilizers had an inverse effect on pH moisture
soil respiration and enzyme activities Therefore the
maintenance of low rates of nitrogen and potassium
(ie lt 300 kg-1ha-1y-1) are vital for preserving the soil
quality as higher doses of nitrogen and potassium
(ie gt 300 kg-1ha-1y-1) adversely affects the soil quality
However the actual mechanisms behind these changes
are difficult to infer and needs further investigation
ACKNOWLEDGEMENTS
I express my sincere thanks to
Dr N Muraleedharan Director UPASI Tea Research
Institute Valparai Coimbatore District Tamil Nadu
India for kind permission to use their experimental plots
which formed vital foundation for this work I
acknowledge the invaluable help and support rendered
by Dr S Premkumar Samuel Asir Dr UI Baby and
Dr S Venkatesan Dr R Selvasundaram UPASI Tea
Research Institute Valparai Coimbatore District Tamil
Nadu India during the course of this study
REFERENCES
Aescht E and Foissner W 1992 Effects of mineral and
organic fertilizers on the micro fauna in a high-altitude
reafforestation trial Biology and Fertility of Soils
1317-24
Baligar VC and Wright RJ 1991 Enzyme activities in
Appalachian soils I Aryl-sulfatase Communications in
Soil Science and Plant Analysis 22305-314
Bandick AK and Dick RP 1999 Field management
effects on soil enzyme activities Soil Biology and
Biochemistry 311471-1479
Beri V Goswami KP Brar SS 1978 Urease activity
and its Michaelis constant for soil systems Plant and
Soil 49105-115
Biederbeck VO Campbell CA Ukrainetz H Curtin
D Bouman OT 1996 Soil microbial and biochemical
properties after ten years of fertilization with urea and
anhydrous ammonia Canadian Journal of Soil Science
133 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
76 7-14
Byrnes BH and Freney JR 1995 Recent developments
on the use of urease inhibitors in the tropics Fertilizer
Research 42251-259
Chen CR Xu ZH Hughes JM 2002 Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland Australia Biology
and Fertility of Soils 36276-283
Cookson P and Lepiece AG 1996 Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman Journal of Arid Environment 32225-238
Darusman Stone LR Whitney DA Janssen KA
Long JH 1991 Soil properties after twenty years of
fertilization with different nitrogen sources Soil Science
Society of America Journal 551097-1100
Dick RP 1994 Soil enzyme activities as indicators of
soil quality In Doran JW Coleman DC Bezdicek DF
Stewart BA (Eds) Defining soil quality for a
sustainable environment Special publication no35
SSSA MadisonWI 107-124
Dick RP Rasmussen PE Kerle EA 1988 Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system Biology and Fertility of Soils 6159-164
Gassmann W Ward JM Schroeder JI 1993
Physiological roles of inward rectifying K+ channels
Plant Cell 51491-1493
Jaggi W 1976 Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat Schw Landw
Forsch 15371-380
Kandeler E and Gerber H 1988 Short ndash term assay of
soil urease activity using colorimetric determination of
ammonium Biology and Fertility of Soils 668-72
Kemmitt SJ Wright D Goulding KWT Jones DL
2006 pH regulation of carbon and nitrogen dynamics in
two agricultural soils Soil Biology and Biochemistry
38898-911
Khonje DJ Varsa EC Klubek B 1989 The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil
Communications in Soil Science and Plant Analysis
201377-1395
Maathuis FJM and Sanders D 1996 Mechanism of
Potassium absorption by higher plant roots Physiology
Plantarum 96158-168
Martikainen PJ 1985 Nitrification in forest soil of
different pH as affected by urea ammonium sulphate and
potassium sulphate Soil Biology and Biochemistry
17363-367
Maxwell RA and Coleman DC 1995 Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians Soil
Biology and Biochemistry 2779-84
Mc Andrew DW and Malhi SS 1992 Long-term N
fertilization of a Solonetzic soil Effects on chemical and
biological properties Soil Biology and Biochemistry
24619-623
Nelson DW and Sommers LE 1982 Total carbon
organic carbon and organic matter In Page AL Miller
RH Keeney DR (Eds) Methods of soil analysis Part -
2 Chemical and microbiological properties ASA
monograph number 9 MadisonWI 539-579
Nioh I Isobe T Osada M 1993 Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil Soil Science and Plant Nutrition 39617-625
Schinner F and Von Mersi W 1990 Xylanase- CM-
cellulase- and invertase activity in soil an improved
Journal of Research in Agriculture (2012) 1(2) 124-135 134
Thenmozhi et al2012
method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Submit your articles online at wwwjagriinfo
Advantages
Easy online submission Complete Peer review Affordable Charges Quick processing Extensive indexing You retain your copyright
submitjagriinfo
wwwjagriinfoSumitphp
Cellulase activity in the soil differed
significantly among treatments and between seasons and
soil layers (Fig 3) Cellulase activity was higher in 0-10
cm soils during premonsoon season There was a greater
cellulase activity in both soil layers during both the
seasons at low nitrogen application rates (N150)
However increasing concentration of nitrogen
fertilization affected cellulase activity to a greater extent
in the 0-10 cm soils than in 10-20 cm soils A significant
(Plt005) positive correlation existed between soil
cellulase activity and total soil nitrogen (r = 0283)
DISCUSSION
Regular nitrogen fertilization of the acid
soil further acidified the soils The acidification was
more in sulphate of ammonia application during
premonsoon than in urea application during monsoon
These are in accordance with the fact that regular
nitrogen fertilization tend to acidify soils (Khonje et al
1989 Darusman et al 1991) Biederbeck et al (1996)
indicated that application of anhydrous ammonia
lowered soil pH more than urea which clearly indicates
varied levels of soil acidification by different nitrogen
sources Furthermore soil total nitrogen levels were
lower in plots during urea application than sulphate of
131 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Treatments (Fertilizer dose in kghay)
μg
GE
g-1
dm
24 h
-1
Fig 3 Influence of nitrogen and potassium fertilization on soil cellulase activity in the two soil layers (L1 L2)
during premonsoon (S1) and monsoon (S2) seasons Points bearing same letter(s) for a season do not
significantly differ (Plt005) according to Duncanrsquos Multiple Range Test
L1
L2
ammonia Most of the broadcasted urea might have
leached out in heavy monsoon showers as considerable
loss (10-25) of nitrogen has been reported to occur due
to leaching or volatilization if urea was not incorporated
into soil soon after its application (Yang 1991 Byrnes
and Freney 1995)
The physico-chemical complexity of soil
contributes significantly to underlying variability in
K+ levels with soil pH moisture and chemical
composition all having marked effects (eg Maathuis
and Sanders 1996) In particular acidic pH leads to
desorption of K+ from anionic binding sites in the soil
and accounts for the tendency towards higher K+ levels
in acidic soils (Gassmann et al 1993) The
exchangeable potassium increased with increasing
potassium application rates It has been thought for a
long time that exchangeable potassium do not built up in
the tea soils of south India because of the dominance of
Kaolinite clay mineral (Verma 1997 Venkatesan et al
2003) However the presence of other minerals other
than Kaolinitic might contribute to the build up of
potassium in the soil (Venkatesan et al 2004) In this
study exchangeable potassium was not related to pH
moisture or chemical composition of the soil However
application of nitrogen significantly reduced soil
potassium which ranged from 18-55 in the 0-10cm
soils and 0-38 in 10-20 cm soils Application of
nitrogen is known to enhance the growth of tea plants
An increased plant growth resulting from nitrogen
fertilization tends to increase potassium uptake from the
soil Studies by The Chinese Tea Research Institute
showed that tea leaves contain 12-25 potassium (TRI
1997) So a large amount of potassium is being mined
from the soil system by the tea plants as a result of
increased growth response to nitrogen fertilization
(Tchienkoua and Zech 2004)
The existence of a significant positive correlation
between soil organic carbon and soil nitrogen indicates
an increasing soil organic carbon content with increasing
nitrogen application rates This is in accordance with
Venkatesan et al (2004) who has also reported higher
organic carbon in soils fertilized with nitrogen Further
Venkatesan et al (2004) indicated that natural organic
carbon reserves of tea soil would be lost due to no or
inadequate supply of nitrogen because tea plants tended
to mineralize and absorb nutrients from organic matter in
the soil under nutrient stress conditions In addition
other studies indicate an increase in soil organic carbon
with increasing soil acidity (Willett et al 2004 Kemmitt
et al 2006) Results from this study tended to indicate
that soil pH and organic carbon were negatively
correlated to each other but this relation is not
statistically significant However when the correlation
analysis was staggered between layers a significant
negative correlation existed between soil pH and organic
carbon in 0-10 cm soils (r = -0667 Plt0000) but not in
10-20 cm soils (r = -0193 Pgt005) This varied relation
between soil organic carbon and pH between layers
could be attributed to soil nitrogen which tended to
strongly influence soil pH than soil potassium
Correlation coefficient values for soil pH and nitrogen in
0-10 cm soils were higher (r= -0773) compared to
10-20 cm soils (r = -0734) These observations are in
line with results of Mc Andrew and Malhi (1992) who
reported an increase in soil organic matter with
increasing soil nitrogen
Soil respiration rates were within normal ranges
reported for natural soils (Srivastava and Singh 1991
Maxwell and Coleman 1995) Results from this study
tended to show that nitrogen and potassium fertilization
affected soil respiration in 0-10 cm soils more than in the
10-20 cm soils Results of Chen et al (2002) also
indicate that nitrogen fertilization reduced soil
respiration in 0-10 cm soils The low respiration rate
with fertilizer application might be attributable to lower
availability of carbon with decreasing soil pH induced by
the nitrogen application (Thirukkumaran and Parkinson
2000)
Journal of Research in Agriculture (2012) 1(2) 124-135 132
Thenmozhi et al2012
Soil urease activity has been reported to follow
changes in soil factors (Cookson and Lepiece 1996) In
the present study fertilizer application generally
increased soil urease activity This is in agreement with
Venkatesan and Senthurpandian (2006) who also
reported an increased urease activity in fertilized tea
soils However these observations contrasts the studies of
Dick et al (1988) and Bandick and Dick (1999) where
soil urease activity was reported to decrease with
increasing application of ammonia based nitrogen
fertilizers Since urease is a substrate inducible enzyme
the application of fertilizers especially urea could have
resulted in higher urease activity Further the binding of
the urease to organic matter insulating itself from
denaturation and biological degradation by soil humic
polymers (Beri et al 1978 Baligar and Wright 1991)
could also attribute to increased level of urease as this
urease could be released from these protected sites by
acid sensitive ammonia oxidizers in response to
fertilization (Martikainen 1985)
Cellulase activity was higher in the surface layer
(0-10 cm soils) than in the subsoils (10-20 cm soils) and
was positively correlated to soil organic matter
Fertilization increased soil cellulase activity which are
in accordance with studies of Aescht and Foissner
(1992)
CONCLUSION
Results from the present study revealed that long
term application of nitrogen and potassium fertilizers
affected soil nutrients and pH Further these fertilizers
can interact with soil microbial communities in a variety
of ways and consequently disturb their normal
functioning The use of nitrogenous fertilizers is
inevitable and an essential part of agricultural practices
In the present study we determined that longndashterm
application of higher doses of urea or ammonium
sulphate fertilizers had an inverse effect on pH moisture
soil respiration and enzyme activities Therefore the
maintenance of low rates of nitrogen and potassium
(ie lt 300 kg-1ha-1y-1) are vital for preserving the soil
quality as higher doses of nitrogen and potassium
(ie gt 300 kg-1ha-1y-1) adversely affects the soil quality
However the actual mechanisms behind these changes
are difficult to infer and needs further investigation
ACKNOWLEDGEMENTS
I express my sincere thanks to
Dr N Muraleedharan Director UPASI Tea Research
Institute Valparai Coimbatore District Tamil Nadu
India for kind permission to use their experimental plots
which formed vital foundation for this work I
acknowledge the invaluable help and support rendered
by Dr S Premkumar Samuel Asir Dr UI Baby and
Dr S Venkatesan Dr R Selvasundaram UPASI Tea
Research Institute Valparai Coimbatore District Tamil
Nadu India during the course of this study
REFERENCES
Aescht E and Foissner W 1992 Effects of mineral and
organic fertilizers on the micro fauna in a high-altitude
reafforestation trial Biology and Fertility of Soils
1317-24
Baligar VC and Wright RJ 1991 Enzyme activities in
Appalachian soils I Aryl-sulfatase Communications in
Soil Science and Plant Analysis 22305-314
Bandick AK and Dick RP 1999 Field management
effects on soil enzyme activities Soil Biology and
Biochemistry 311471-1479
Beri V Goswami KP Brar SS 1978 Urease activity
and its Michaelis constant for soil systems Plant and
Soil 49105-115
Biederbeck VO Campbell CA Ukrainetz H Curtin
D Bouman OT 1996 Soil microbial and biochemical
properties after ten years of fertilization with urea and
anhydrous ammonia Canadian Journal of Soil Science
133 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
76 7-14
Byrnes BH and Freney JR 1995 Recent developments
on the use of urease inhibitors in the tropics Fertilizer
Research 42251-259
Chen CR Xu ZH Hughes JM 2002 Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland Australia Biology
and Fertility of Soils 36276-283
Cookson P and Lepiece AG 1996 Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman Journal of Arid Environment 32225-238
Darusman Stone LR Whitney DA Janssen KA
Long JH 1991 Soil properties after twenty years of
fertilization with different nitrogen sources Soil Science
Society of America Journal 551097-1100
Dick RP 1994 Soil enzyme activities as indicators of
soil quality In Doran JW Coleman DC Bezdicek DF
Stewart BA (Eds) Defining soil quality for a
sustainable environment Special publication no35
SSSA MadisonWI 107-124
Dick RP Rasmussen PE Kerle EA 1988 Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system Biology and Fertility of Soils 6159-164
Gassmann W Ward JM Schroeder JI 1993
Physiological roles of inward rectifying K+ channels
Plant Cell 51491-1493
Jaggi W 1976 Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat Schw Landw
Forsch 15371-380
Kandeler E and Gerber H 1988 Short ndash term assay of
soil urease activity using colorimetric determination of
ammonium Biology and Fertility of Soils 668-72
Kemmitt SJ Wright D Goulding KWT Jones DL
2006 pH regulation of carbon and nitrogen dynamics in
two agricultural soils Soil Biology and Biochemistry
38898-911
Khonje DJ Varsa EC Klubek B 1989 The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil
Communications in Soil Science and Plant Analysis
201377-1395
Maathuis FJM and Sanders D 1996 Mechanism of
Potassium absorption by higher plant roots Physiology
Plantarum 96158-168
Martikainen PJ 1985 Nitrification in forest soil of
different pH as affected by urea ammonium sulphate and
potassium sulphate Soil Biology and Biochemistry
17363-367
Maxwell RA and Coleman DC 1995 Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians Soil
Biology and Biochemistry 2779-84
Mc Andrew DW and Malhi SS 1992 Long-term N
fertilization of a Solonetzic soil Effects on chemical and
biological properties Soil Biology and Biochemistry
24619-623
Nelson DW and Sommers LE 1982 Total carbon
organic carbon and organic matter In Page AL Miller
RH Keeney DR (Eds) Methods of soil analysis Part -
2 Chemical and microbiological properties ASA
monograph number 9 MadisonWI 539-579
Nioh I Isobe T Osada M 1993 Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil Soil Science and Plant Nutrition 39617-625
Schinner F and Von Mersi W 1990 Xylanase- CM-
cellulase- and invertase activity in soil an improved
Journal of Research in Agriculture (2012) 1(2) 124-135 134
Thenmozhi et al2012
method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Submit your articles online at wwwjagriinfo
Advantages
Easy online submission Complete Peer review Affordable Charges Quick processing Extensive indexing You retain your copyright
submitjagriinfo
wwwjagriinfoSumitphp
ammonia Most of the broadcasted urea might have
leached out in heavy monsoon showers as considerable
loss (10-25) of nitrogen has been reported to occur due
to leaching or volatilization if urea was not incorporated
into soil soon after its application (Yang 1991 Byrnes
and Freney 1995)
The physico-chemical complexity of soil
contributes significantly to underlying variability in
K+ levels with soil pH moisture and chemical
composition all having marked effects (eg Maathuis
and Sanders 1996) In particular acidic pH leads to
desorption of K+ from anionic binding sites in the soil
and accounts for the tendency towards higher K+ levels
in acidic soils (Gassmann et al 1993) The
exchangeable potassium increased with increasing
potassium application rates It has been thought for a
long time that exchangeable potassium do not built up in
the tea soils of south India because of the dominance of
Kaolinite clay mineral (Verma 1997 Venkatesan et al
2003) However the presence of other minerals other
than Kaolinitic might contribute to the build up of
potassium in the soil (Venkatesan et al 2004) In this
study exchangeable potassium was not related to pH
moisture or chemical composition of the soil However
application of nitrogen significantly reduced soil
potassium which ranged from 18-55 in the 0-10cm
soils and 0-38 in 10-20 cm soils Application of
nitrogen is known to enhance the growth of tea plants
An increased plant growth resulting from nitrogen
fertilization tends to increase potassium uptake from the
soil Studies by The Chinese Tea Research Institute
showed that tea leaves contain 12-25 potassium (TRI
1997) So a large amount of potassium is being mined
from the soil system by the tea plants as a result of
increased growth response to nitrogen fertilization
(Tchienkoua and Zech 2004)
The existence of a significant positive correlation
between soil organic carbon and soil nitrogen indicates
an increasing soil organic carbon content with increasing
nitrogen application rates This is in accordance with
Venkatesan et al (2004) who has also reported higher
organic carbon in soils fertilized with nitrogen Further
Venkatesan et al (2004) indicated that natural organic
carbon reserves of tea soil would be lost due to no or
inadequate supply of nitrogen because tea plants tended
to mineralize and absorb nutrients from organic matter in
the soil under nutrient stress conditions In addition
other studies indicate an increase in soil organic carbon
with increasing soil acidity (Willett et al 2004 Kemmitt
et al 2006) Results from this study tended to indicate
that soil pH and organic carbon were negatively
correlated to each other but this relation is not
statistically significant However when the correlation
analysis was staggered between layers a significant
negative correlation existed between soil pH and organic
carbon in 0-10 cm soils (r = -0667 Plt0000) but not in
10-20 cm soils (r = -0193 Pgt005) This varied relation
between soil organic carbon and pH between layers
could be attributed to soil nitrogen which tended to
strongly influence soil pH than soil potassium
Correlation coefficient values for soil pH and nitrogen in
0-10 cm soils were higher (r= -0773) compared to
10-20 cm soils (r = -0734) These observations are in
line with results of Mc Andrew and Malhi (1992) who
reported an increase in soil organic matter with
increasing soil nitrogen
Soil respiration rates were within normal ranges
reported for natural soils (Srivastava and Singh 1991
Maxwell and Coleman 1995) Results from this study
tended to show that nitrogen and potassium fertilization
affected soil respiration in 0-10 cm soils more than in the
10-20 cm soils Results of Chen et al (2002) also
indicate that nitrogen fertilization reduced soil
respiration in 0-10 cm soils The low respiration rate
with fertilizer application might be attributable to lower
availability of carbon with decreasing soil pH induced by
the nitrogen application (Thirukkumaran and Parkinson
2000)
Journal of Research in Agriculture (2012) 1(2) 124-135 132
Thenmozhi et al2012
Soil urease activity has been reported to follow
changes in soil factors (Cookson and Lepiece 1996) In
the present study fertilizer application generally
increased soil urease activity This is in agreement with
Venkatesan and Senthurpandian (2006) who also
reported an increased urease activity in fertilized tea
soils However these observations contrasts the studies of
Dick et al (1988) and Bandick and Dick (1999) where
soil urease activity was reported to decrease with
increasing application of ammonia based nitrogen
fertilizers Since urease is a substrate inducible enzyme
the application of fertilizers especially urea could have
resulted in higher urease activity Further the binding of
the urease to organic matter insulating itself from
denaturation and biological degradation by soil humic
polymers (Beri et al 1978 Baligar and Wright 1991)
could also attribute to increased level of urease as this
urease could be released from these protected sites by
acid sensitive ammonia oxidizers in response to
fertilization (Martikainen 1985)
Cellulase activity was higher in the surface layer
(0-10 cm soils) than in the subsoils (10-20 cm soils) and
was positively correlated to soil organic matter
Fertilization increased soil cellulase activity which are
in accordance with studies of Aescht and Foissner
(1992)
CONCLUSION
Results from the present study revealed that long
term application of nitrogen and potassium fertilizers
affected soil nutrients and pH Further these fertilizers
can interact with soil microbial communities in a variety
of ways and consequently disturb their normal
functioning The use of nitrogenous fertilizers is
inevitable and an essential part of agricultural practices
In the present study we determined that longndashterm
application of higher doses of urea or ammonium
sulphate fertilizers had an inverse effect on pH moisture
soil respiration and enzyme activities Therefore the
maintenance of low rates of nitrogen and potassium
(ie lt 300 kg-1ha-1y-1) are vital for preserving the soil
quality as higher doses of nitrogen and potassium
(ie gt 300 kg-1ha-1y-1) adversely affects the soil quality
However the actual mechanisms behind these changes
are difficult to infer and needs further investigation
ACKNOWLEDGEMENTS
I express my sincere thanks to
Dr N Muraleedharan Director UPASI Tea Research
Institute Valparai Coimbatore District Tamil Nadu
India for kind permission to use their experimental plots
which formed vital foundation for this work I
acknowledge the invaluable help and support rendered
by Dr S Premkumar Samuel Asir Dr UI Baby and
Dr S Venkatesan Dr R Selvasundaram UPASI Tea
Research Institute Valparai Coimbatore District Tamil
Nadu India during the course of this study
REFERENCES
Aescht E and Foissner W 1992 Effects of mineral and
organic fertilizers on the micro fauna in a high-altitude
reafforestation trial Biology and Fertility of Soils
1317-24
Baligar VC and Wright RJ 1991 Enzyme activities in
Appalachian soils I Aryl-sulfatase Communications in
Soil Science and Plant Analysis 22305-314
Bandick AK and Dick RP 1999 Field management
effects on soil enzyme activities Soil Biology and
Biochemistry 311471-1479
Beri V Goswami KP Brar SS 1978 Urease activity
and its Michaelis constant for soil systems Plant and
Soil 49105-115
Biederbeck VO Campbell CA Ukrainetz H Curtin
D Bouman OT 1996 Soil microbial and biochemical
properties after ten years of fertilization with urea and
anhydrous ammonia Canadian Journal of Soil Science
133 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
76 7-14
Byrnes BH and Freney JR 1995 Recent developments
on the use of urease inhibitors in the tropics Fertilizer
Research 42251-259
Chen CR Xu ZH Hughes JM 2002 Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland Australia Biology
and Fertility of Soils 36276-283
Cookson P and Lepiece AG 1996 Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman Journal of Arid Environment 32225-238
Darusman Stone LR Whitney DA Janssen KA
Long JH 1991 Soil properties after twenty years of
fertilization with different nitrogen sources Soil Science
Society of America Journal 551097-1100
Dick RP 1994 Soil enzyme activities as indicators of
soil quality In Doran JW Coleman DC Bezdicek DF
Stewart BA (Eds) Defining soil quality for a
sustainable environment Special publication no35
SSSA MadisonWI 107-124
Dick RP Rasmussen PE Kerle EA 1988 Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system Biology and Fertility of Soils 6159-164
Gassmann W Ward JM Schroeder JI 1993
Physiological roles of inward rectifying K+ channels
Plant Cell 51491-1493
Jaggi W 1976 Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat Schw Landw
Forsch 15371-380
Kandeler E and Gerber H 1988 Short ndash term assay of
soil urease activity using colorimetric determination of
ammonium Biology and Fertility of Soils 668-72
Kemmitt SJ Wright D Goulding KWT Jones DL
2006 pH regulation of carbon and nitrogen dynamics in
two agricultural soils Soil Biology and Biochemistry
38898-911
Khonje DJ Varsa EC Klubek B 1989 The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil
Communications in Soil Science and Plant Analysis
201377-1395
Maathuis FJM and Sanders D 1996 Mechanism of
Potassium absorption by higher plant roots Physiology
Plantarum 96158-168
Martikainen PJ 1985 Nitrification in forest soil of
different pH as affected by urea ammonium sulphate and
potassium sulphate Soil Biology and Biochemistry
17363-367
Maxwell RA and Coleman DC 1995 Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians Soil
Biology and Biochemistry 2779-84
Mc Andrew DW and Malhi SS 1992 Long-term N
fertilization of a Solonetzic soil Effects on chemical and
biological properties Soil Biology and Biochemistry
24619-623
Nelson DW and Sommers LE 1982 Total carbon
organic carbon and organic matter In Page AL Miller
RH Keeney DR (Eds) Methods of soil analysis Part -
2 Chemical and microbiological properties ASA
monograph number 9 MadisonWI 539-579
Nioh I Isobe T Osada M 1993 Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil Soil Science and Plant Nutrition 39617-625
Schinner F and Von Mersi W 1990 Xylanase- CM-
cellulase- and invertase activity in soil an improved
Journal of Research in Agriculture (2012) 1(2) 124-135 134
Thenmozhi et al2012
method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Submit your articles online at wwwjagriinfo
Advantages
Easy online submission Complete Peer review Affordable Charges Quick processing Extensive indexing You retain your copyright
submitjagriinfo
wwwjagriinfoSumitphp
Soil urease activity has been reported to follow
changes in soil factors (Cookson and Lepiece 1996) In
the present study fertilizer application generally
increased soil urease activity This is in agreement with
Venkatesan and Senthurpandian (2006) who also
reported an increased urease activity in fertilized tea
soils However these observations contrasts the studies of
Dick et al (1988) and Bandick and Dick (1999) where
soil urease activity was reported to decrease with
increasing application of ammonia based nitrogen
fertilizers Since urease is a substrate inducible enzyme
the application of fertilizers especially urea could have
resulted in higher urease activity Further the binding of
the urease to organic matter insulating itself from
denaturation and biological degradation by soil humic
polymers (Beri et al 1978 Baligar and Wright 1991)
could also attribute to increased level of urease as this
urease could be released from these protected sites by
acid sensitive ammonia oxidizers in response to
fertilization (Martikainen 1985)
Cellulase activity was higher in the surface layer
(0-10 cm soils) than in the subsoils (10-20 cm soils) and
was positively correlated to soil organic matter
Fertilization increased soil cellulase activity which are
in accordance with studies of Aescht and Foissner
(1992)
CONCLUSION
Results from the present study revealed that long
term application of nitrogen and potassium fertilizers
affected soil nutrients and pH Further these fertilizers
can interact with soil microbial communities in a variety
of ways and consequently disturb their normal
functioning The use of nitrogenous fertilizers is
inevitable and an essential part of agricultural practices
In the present study we determined that longndashterm
application of higher doses of urea or ammonium
sulphate fertilizers had an inverse effect on pH moisture
soil respiration and enzyme activities Therefore the
maintenance of low rates of nitrogen and potassium
(ie lt 300 kg-1ha-1y-1) are vital for preserving the soil
quality as higher doses of nitrogen and potassium
(ie gt 300 kg-1ha-1y-1) adversely affects the soil quality
However the actual mechanisms behind these changes
are difficult to infer and needs further investigation
ACKNOWLEDGEMENTS
I express my sincere thanks to
Dr N Muraleedharan Director UPASI Tea Research
Institute Valparai Coimbatore District Tamil Nadu
India for kind permission to use their experimental plots
which formed vital foundation for this work I
acknowledge the invaluable help and support rendered
by Dr S Premkumar Samuel Asir Dr UI Baby and
Dr S Venkatesan Dr R Selvasundaram UPASI Tea
Research Institute Valparai Coimbatore District Tamil
Nadu India during the course of this study
REFERENCES
Aescht E and Foissner W 1992 Effects of mineral and
organic fertilizers on the micro fauna in a high-altitude
reafforestation trial Biology and Fertility of Soils
1317-24
Baligar VC and Wright RJ 1991 Enzyme activities in
Appalachian soils I Aryl-sulfatase Communications in
Soil Science and Plant Analysis 22305-314
Bandick AK and Dick RP 1999 Field management
effects on soil enzyme activities Soil Biology and
Biochemistry 311471-1479
Beri V Goswami KP Brar SS 1978 Urease activity
and its Michaelis constant for soil systems Plant and
Soil 49105-115
Biederbeck VO Campbell CA Ukrainetz H Curtin
D Bouman OT 1996 Soil microbial and biochemical
properties after ten years of fertilization with urea and
anhydrous ammonia Canadian Journal of Soil Science
133 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
76 7-14
Byrnes BH and Freney JR 1995 Recent developments
on the use of urease inhibitors in the tropics Fertilizer
Research 42251-259
Chen CR Xu ZH Hughes JM 2002 Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland Australia Biology
and Fertility of Soils 36276-283
Cookson P and Lepiece AG 1996 Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman Journal of Arid Environment 32225-238
Darusman Stone LR Whitney DA Janssen KA
Long JH 1991 Soil properties after twenty years of
fertilization with different nitrogen sources Soil Science
Society of America Journal 551097-1100
Dick RP 1994 Soil enzyme activities as indicators of
soil quality In Doran JW Coleman DC Bezdicek DF
Stewart BA (Eds) Defining soil quality for a
sustainable environment Special publication no35
SSSA MadisonWI 107-124
Dick RP Rasmussen PE Kerle EA 1988 Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system Biology and Fertility of Soils 6159-164
Gassmann W Ward JM Schroeder JI 1993
Physiological roles of inward rectifying K+ channels
Plant Cell 51491-1493
Jaggi W 1976 Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat Schw Landw
Forsch 15371-380
Kandeler E and Gerber H 1988 Short ndash term assay of
soil urease activity using colorimetric determination of
ammonium Biology and Fertility of Soils 668-72
Kemmitt SJ Wright D Goulding KWT Jones DL
2006 pH regulation of carbon and nitrogen dynamics in
two agricultural soils Soil Biology and Biochemistry
38898-911
Khonje DJ Varsa EC Klubek B 1989 The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil
Communications in Soil Science and Plant Analysis
201377-1395
Maathuis FJM and Sanders D 1996 Mechanism of
Potassium absorption by higher plant roots Physiology
Plantarum 96158-168
Martikainen PJ 1985 Nitrification in forest soil of
different pH as affected by urea ammonium sulphate and
potassium sulphate Soil Biology and Biochemistry
17363-367
Maxwell RA and Coleman DC 1995 Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians Soil
Biology and Biochemistry 2779-84
Mc Andrew DW and Malhi SS 1992 Long-term N
fertilization of a Solonetzic soil Effects on chemical and
biological properties Soil Biology and Biochemistry
24619-623
Nelson DW and Sommers LE 1982 Total carbon
organic carbon and organic matter In Page AL Miller
RH Keeney DR (Eds) Methods of soil analysis Part -
2 Chemical and microbiological properties ASA
monograph number 9 MadisonWI 539-579
Nioh I Isobe T Osada M 1993 Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil Soil Science and Plant Nutrition 39617-625
Schinner F and Von Mersi W 1990 Xylanase- CM-
cellulase- and invertase activity in soil an improved
Journal of Research in Agriculture (2012) 1(2) 124-135 134
Thenmozhi et al2012
method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
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76 7-14
Byrnes BH and Freney JR 1995 Recent developments
on the use of urease inhibitors in the tropics Fertilizer
Research 42251-259
Chen CR Xu ZH Hughes JM 2002 Effects of
nitrogen fertilization on soil nitrogen pools and microbial
properties in a hoop pine (Araucaria cunninghamii)
plantation in southeast Queensland Australia Biology
and Fertility of Soils 36276-283
Cookson P and Lepiece AG 1996 Urease enzyme
activities in soils of the Batinah region of the Sultanate
of Oman Journal of Arid Environment 32225-238
Darusman Stone LR Whitney DA Janssen KA
Long JH 1991 Soil properties after twenty years of
fertilization with different nitrogen sources Soil Science
Society of America Journal 551097-1100
Dick RP 1994 Soil enzyme activities as indicators of
soil quality In Doran JW Coleman DC Bezdicek DF
Stewart BA (Eds) Defining soil quality for a
sustainable environment Special publication no35
SSSA MadisonWI 107-124
Dick RP Rasmussen PE Kerle EA 1988 Influence of
long-term residue management on soil enzyme activities
in relation to soil chemical properties of a wheat-fallow
system Biology and Fertility of Soils 6159-164
Gassmann W Ward JM Schroeder JI 1993
Physiological roles of inward rectifying K+ channels
Plant Cell 51491-1493
Jaggi W 1976 Die Bestimmung der CO2 - Bildung als
Mass der bodenbiologischen Aktivitat Schw Landw
Forsch 15371-380
Kandeler E and Gerber H 1988 Short ndash term assay of
soil urease activity using colorimetric determination of
ammonium Biology and Fertility of Soils 668-72
Kemmitt SJ Wright D Goulding KWT Jones DL
2006 pH regulation of carbon and nitrogen dynamics in
two agricultural soils Soil Biology and Biochemistry
38898-911
Khonje DJ Varsa EC Klubek B 1989 The
acidulation effects of nitrogenous fertilizers on selected
chemical and microbiological properties of soil
Communications in Soil Science and Plant Analysis
201377-1395
Maathuis FJM and Sanders D 1996 Mechanism of
Potassium absorption by higher plant roots Physiology
Plantarum 96158-168
Martikainen PJ 1985 Nitrification in forest soil of
different pH as affected by urea ammonium sulphate and
potassium sulphate Soil Biology and Biochemistry
17363-367
Maxwell RA and Coleman DC 1995 Seasonal
dynamics of nematode and microbial biomass in soils of
riparian-zone forests of the southern Appalachians Soil
Biology and Biochemistry 2779-84
Mc Andrew DW and Malhi SS 1992 Long-term N
fertilization of a Solonetzic soil Effects on chemical and
biological properties Soil Biology and Biochemistry
24619-623
Nelson DW and Sommers LE 1982 Total carbon
organic carbon and organic matter In Page AL Miller
RH Keeney DR (Eds) Methods of soil analysis Part -
2 Chemical and microbiological properties ASA
monograph number 9 MadisonWI 539-579
Nioh I Isobe T Osada M 1993 Microbial biomass and
some biochemical characteristics of a strongly acid tea
field soil Soil Science and Plant Nutrition 39617-625
Schinner F and Von Mersi W 1990 Xylanase- CM-
cellulase- and invertase activity in soil an improved
Journal of Research in Agriculture (2012) 1(2) 124-135 134
Thenmozhi et al2012
method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Submit your articles online at wwwjagriinfo
Advantages
Easy online submission Complete Peer review Affordable Charges Quick processing Extensive indexing You retain your copyright
submitjagriinfo
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method Soil Biology and Biochemistry 22511-515
Srivastava SC Singh JS 1991 Microbial C N and P in
dry tropical forest soils effects of alternative land-uses
and nutrient flux Soil Biology and Biochemistry 23117-
124
Tchienkoua M and Zech W 2004 Organic carbon and
plant nutrient dynamics under three land uses in the
highlands of West Cameroon Agriculture Ecosystem
and Environment 104673-679
Thirukkumaran CM and Parkinson D 2000
Microbial respiration biomass metabolic quotient and
litter decomposition in a lodgepole pine forest floor
amended with nitrogen and phosphorous fertilizers Soil
Biology and Biochemistry 3259-66
TRI 1997 Potassium and Magnesium for better tea
production TRI-IPI
Venkatesan S Ganapathy MNK 2004 Impact of
nitrogen and potassium fertilizer application on quality
of CTC teas Food Chemistry 84325-328
Venkatesan S Murugesan S Ganapathy MNK
Verma DP 2004 Longndashterm impact of nitrogen and
potassium fertilizers on yield soil nutrients and
biochemical parameters of tea Journal of the Science of
Food and Agriculture 841939-1944
Venkatesan S Murugesan S Senthur Pandian VK
Ganapathy MNK 2005 Impact of sources and doses of
potassium on biochemical and green leaf parameters of
tea Food Chemistry 90535-539
Venkatesan S Senthurpandian VK 2006 Comparison
of enzyme activity with depth under tea plantations and
forested sites in south India Geoderma 137212-216
Venkatesan S Verma DP Navaneetha Krishna
Ganapathy M 2003 Targeted yield equations of
nitrogen for clonal teas under south Indian conditions
Journal of the Indian Society of Soil Science
51178- 183
Verma DP 1993 Nutrient Management of Tea in South
India In Tea Culture Processing and Marketing Mulky
MJ and Sharma VS (Eds) Oxford and IBH Publishing
Co Pvt Ltd New Delhi India 55-69
Verma DP 1997 Potassium nutrition of tea Journal of
Potassium Research 1393-100
Verma DP Palani N Balasubramaniam K
Kumaraguru R Venkatesan S and Ganapathy MNK
2001 Nutritional management of tea for sustainable
productivity in South India The Planters Chronicle
215-227
Verma DP and Palani N 1997 Manuring of tea in
south India (revised recommendations)In Hand Book of
Tea Culture (section 11) Valparai Tamil Nadu India
UPASI Tea Research Institute 33
Willett VB Reynolds BA Stevens PA Ormerod SJ
Jones DL 2004 Dissolved organic nitrogen regulation
in freshwaters Journal of Environmental Quality
33201-209
Yang ZM 1991 Situation and improving measures of
N fertilizer use efficiency in tea fields of red soil in
China China Tea 310-12
135 Journal of Research in Agriculture (2012) 1(2) 124-135
Thenmozhi et al2012
Submit your articles online at wwwjagriinfo
Advantages
Easy online submission Complete Peer review Affordable Charges Quick processing Extensive indexing You retain your copyright
submitjagriinfo
wwwjagriinfoSumitphp