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Research ArticleEffects of Nitrogen Rates and Time of Application on Yield ofMaize Rainfall Variability Influenced Time of N Application

Zerihun Abebe and Hailu Feyisa

Bako Agricultural Research Center PO Box 03 West Shoa Ethiopia

Correspondence should be addressed to Zerihun Abebe baatireegmailcom

Received 14 February 2017 Revised 4 May 2017 Accepted 15 May 2017 Published 18 June 2017

Academic Editor Manuel Tejada

Copyright copy 2017 Zerihun Abebe and Hailu Feyisa This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Despite the fact that maize productivity is relatively better than other major cereal crops its current productivity is still far belowits potential productivity N rate and time of application are among the major abiotic factors limiting the productivity of the cropBecause of such gaps the experiment was conducted at Bako Agricultural Research Center in 2013 and 2014 cropping seasons todetermine optimum N rate and time of application Four levels of N rates (46 69 92 and 115N kg haminus1) and four levels (119879

1 1198792 1198793

and 1198794) of different time of N application were arranged in factorial combinations Moreover previously recommended N and the

control were arranged in a randomized complete block design with three replications In 2013 the highest significant biomass yield(212 thaminus1) was obtained at 115N kg haminus1 and119879

4followed by 69N kg haminus1 at119879

1and119879

2and 92N kg haminus1 at119879

2 In contrast the highest

grain yield in 2013 was obtained at 92N kg haminus1 at 1198792followed by 115N kg haminus1 at either 119879

2or 1198794and 69Nkg haminus1 at either 119879

1or

1198793application time Interestingly a significant yield increase by 37 was obtained when 92Nkg haminus1 at the time of 119879

2was applied

compared to previous recommended 110N kg haminus1 rate and time of application In 2014 however the highest yield was recordedwhen 92N kg haminus1 at 119879

1was used Application of 46N kg haminus1 at 119879

2showed statistically similar yield performance when compared

with previous N recommendation The lowest yield was recorded from the control plot in both years In 2013 the maximum netprofit and acceptable marginal rate of return (MMR) were obtained when 92Nkg haminus1 at 119879

2was used for maize production during

erratic and heavy rainfall distribution particularly at a time of N application However the maximum net benefit (30743 ETB haminus1)and acceptable MRR could be obtained when 92N kg haminus1 at 119879

1was used if the rainfall amount and distribution are relatively

uniform In conclusion application of 92N kg haminus1 at 1198791(10ndash15 DAP and 35ndash40 DAP) is the best N rate and time of application in

good rainy seasons and hence recommended for the end users However in the case of erratic and heavy rainy seasons applicationof 92N kg haminus1 at three times application regimes (13 N at 10ndash15 days after planting (DAP) 13 N at 35ndash40 DAP and 55ndash60 DAP)should be used to get maximum profit and acceptable MRR

1 Introduction

Maize (Zea mays) is one of the main and popular cereal cropsdue to its high value as stable food as well as its stover demandfor animal feed and fuel and even for construction purposes[1] Maize is also the most important stable crop in termsof calorie intake in Ethiopian rural families Approximately88 of maize produced in Ethiopia is used as food in bothgreen cobs and grain [2] Because of its multiple advantagesit ranks second in production area next to teff while it ranksfirst in its productivity among major cereal crops [3] and itis therefore one of the high priority crops to feed the ever-increasing Ethiopian population [2]

Despite the fact that its current productivity is higher thanother major cereal crops the yield productivity is below itspotential For instance the potential yield of late maturinghybrid maize varieties can produce up to 95ndash12 thaminus1 atresearch field and 6ndash85 t haminus1 at an on-farm field [4] whereasthe national average productivity is 32 thaminus1 [5] Even thoughmany biotic and abiotic factors can contribute to thesebig yield gaps soil fertility depletion and poor nutrientmanagement are among themajor factors contributing to lowproductivity [6]

Nitrogen (N) management in maize production systemis one of the main concerns since it is the most importantand primary nutrient for growth and development of the

HindawiInternational Journal of AgronomyVolume 2017 Article ID 1545280 10 pageshttpsdoiorg10115520171545280

2 International Journal of Agronomy

crop [7] Hence application of fertilizer N resulting in higherbiomass is commonly increased Optimum rate and time ofNapplication can enhance yield productivity and nutrient useefficiencieswhile reducing the environmental pollution [8 9]N application beyond the optimum requirement of maizecould not increase yield and may lead to an elevated level ofNO3in the soil and susceptibility to NO

3loss by leaching

[10] Another report also indicated that abundant N supplyfavors NH

3losses especially if the supply is in excess of

plant requirements [11] However the negative environmentalimpacts associated with maize production can be minimizedthrough efficient N management including appropriate rateand time of N recommendation [11]

Time of N application at appropriate crop growth stageis also another main focus to enhance N use efficiency andincrease maize productivity All applied N is not absorbed bythe crop since leaching is one of themain challenges forN lossin high rainfall areas Research reports had shown that about50 and evenmore than this figure at higher doses of appliedN remain unavailable to a crop due toN loss through leaching[12] This leaching loss may be determined by a quantity of Napplied inappropriate time of application soil permeabilityand quantity of rainfall drops in the area [11] However anoptimum and efficient time of N application can increase therecovery of applied N up to 58ndash70 and hence increase yieldand grain quality of the crop [12 13]

Previous N recommendation for maize production inWestern Ethiopia was 92ndash110 kgha half at the time of plant-ing and half at 30ndash35 days after planting [2] while applyingall at planting is the best alternative to large scale maizefarming where mechanization is available [14] Howevermany research findings verified that N application at the timeof maize planting is not efficiently recovered since nodal rootgrowth and development from emergence up to 1-2 leavesrsquodevelopment stage is a very young stage [9]The same authorshowed that seed emergence usually occurs in 6ndash8 days afterplanting while 12ndash15 and 15ndash20 days after planting are neededto form one and two developed leaves for hybrid maizerespectively [9 15] At these stages the seedlings depend onkernel food reserve since nodal root development is not yetstarted for nutrient absorption If N application however atmaize planting is done its loss through leaching and runoffcan be articulated since its absorption by the crop up to10ndash15 days after planting is rare Hence application of N atthe time of planting is easily lost through leaching or runoffin heavy rainfall areas and it not only is attributed to anenvironmental population but also results in nonprofit cost[11 13 16] and hence the disadvantages of N application atthe time of planting may outweigh its advantages Thereforethe objective of this studywas to investigate optimumrate andtime of N application to increase optimum and economicallyprofitable maize yield

2 Material and Methods

Theexperimentwas conducted at BakoAgricultural ResearchCenter for two consecutive years (2013 and 2014) and it islocated in a subhumid area of Western Ethiopia which liesat a latitude of 9E61015840N and longitude of 37E91015840E and at an

altitude of 1650m asl It has an annual mean minimum andmaximum air temperatures of 135 and 297∘C respectivelyThe area received an annual rainfall of 1431mm (2013) and1067mm (2014) with maximum precipitation being receivedin the months of MayndashAugust

The soil of Bako area is reddish-brown nitosol It is anacidic soil with a pH range of 45ndash56The surrounding area isamixed farming zone and is one of themost importantmaize(Zea mays L) growing belts in Ethiopia and cultivations ofteff (Eragrostis tef ) fingermillet (Eleusine coronata) commonbean (Phaseolus vulgaris L) sorghum (Sorghum bicolor L)noug (Guizotia abyssinica Lf) and soybean (Glycine maxL) are common The area is predominantly maize basedmonocropping with low soil fertility problem that directlyinfluences production and productivity of the cultivatedcrops

The treatments consisted of two factors namely fourlevels of N rates (46 69 92 and 115N kg haminus1) and fourdifferent application times (119879

1= 12 N at 10ndash15 days after

planting (DAP) and 12 N at 35ndash40 DAP 1198792= 13 N at 10ndash15

DAP 13 N at 35ndash40 DAP and 13 N at 55ndash60 DAP 1198793=

13 N at 35ndash40 DAP 13 N at 55ndash60 DAP and 75ndash80 DAPand 119879

4= 14 N at 10ndash15 DAP 14 N at 33ndash40 DAP 14 N

at 55ndash60 DAP and 14 at 75ndash80 DAP) that were arrangedin 4 times 4 factorial combinations Moreover previous rate andapplication time of N (referred as 119877) and the control plotreceiving no N fertilizer were included for the comparisonspurposes A total of 16 treatment combinations plus previousrecommended rate and time ofN application and control plotwithout N were laid out using a randomized complete blockdesign (RCBD) with three replications Application time of Nwas done within the stated time ranges but at the same dateas per treatment arrangements

The experimental plots were plowed three times at dif-ferent time intervals starting from mid-May and leveledmanually prior to field layout Plant population for allexperimental plots was 44444 plants haminus1 75 cm betweenrows and 30 cm between plants Recommended phosphorus(20 kg P haminus1) in the form of triple superphosphate (TSP) forall experimental plots including standard check and controlplot was equally and uniformly applied at the time of maizeplanting Nwas applied in the form ofUREA as per treatmentarrangements One hybrid long maturing variety (BH661)of maize was used for the execution of the treatments Itsyield potential varies between 95 and 12 thaminus1 at researchfield and 6 and 85 thaminus1 at farmersrsquo field under integratedagronomic managements The variety was released by BakoNational Maize Research Center in 2011 and it can be grownin a range of 1600ndash2200m above sea level and it requires anannual rainfall of 1000ndash1500 with uniform distribution in itsgrowing periods The trial was planted on May 30th in the2013 and June 1st in 2014 Other agronomic managementsrather than treatment variations were uniformly applied toall experimental plots

At the time of harvesting the maize was harvested byexcluding two border rows from each side A net plot sizefor each plot was 225m times 51m (11475m2) Stand countsper net plot were counted at the time of harvesting Finally

International Journal of Agronomy 3

Table 1 Analysis of variance for yield and yield components of maize as influenced by N rates time of application and the interaction effectsin 2013 and 2014 at Bako Western Ethiopia

Sources of variations Df 119865 probability (119875 = 005)Biomass Grain yield HI AE

Year (Yr) 1 lt001 lt001 lt001 lt001Nitrogen (N) 3 lt001 lt001 0012 lt001Time of application (TA) 3 0277 0083 081 0063Yr times N 3 0193 0001 0008 lt001Yr times TA 3 0093 0054 0126 0106N times TA 9 lt001 0047 0004 0164Yr times N times TA 9 lt001 0024 0062 0159Replication 2 0155 0116 0271 0121Residual 62 mdash mdash mdash mdashTotal 95SE 1893 0724 336 00113CV () 86 76 76 86HI harvest index AE agronomic efficiency

biomass yield grain yield harvest index and other impor-tant agronomic traits were collected Maize grain yield wasadjusted to standard moisture contents to 10 as describedas follows adjusted yield = actual yield times 100 minus 119872100 minus119863 where 119872 and 119863 are measured and standard moisturecontents respectively Agronomic efficiency was calculatedas yield obtained per N applied Costs that vary amongtreatments were also assessedThe cost of UREAa the cost oflabor required for the application and cost for shelling wereestimated by assessing the current local market prices Theprice of UREA (1600 ETB 100 kgminus1) and daily labors (35 ETBper one person day based on governmentrsquos current scale inthe study area) and the cost of maize shelling (100 ETB t haminus1)were considered to get the total cost that varied amongthe treatments Time elapsed during UREA application forsome plots of each treatment was recorded to calculate dailylabor required for one hectare One person per day wasestimated based on eight working hours per day Howeverother nonvaried costs were not included since all agronomicmanagements were equally and uniformly applied to eachexperimental plot Before calculating gross revenue maizeyields obtained from each experimental plot were adjusteddown by 10 Finally gross revenue was calculated as totalyield obtained multiplied by field price (3800 ETB 1 thaminus1)The net benefit and the marginal rate of return (MRR) werealso calculated as per standardmanual [17] Finally combinedanalyses of variance (ANOVA) across seasons were carriedout using Gen Stat 15th edition software and the Duncanmultiple range test at 119875 lt 005 was used for comparingtreatmentmeans Sigma plot version 10was used for graphingand error bar for each treatment mean was also plotted

3 Results

The result of combined analysis revealed that seasonal vari-ations highly (119875 lt 0001) affected biomass grain yieldharvest index and agronomic efficiency of the crop (Table 1)Even though main effects of time of N application did not

show significant variation to all parameters there were highlysignificant effects due to the various applications of N ratesMoreover the effect of N rate and time of application signif-icantly affected biomass yield and harvest index while thisinteraction due to seasonal variations significantly affectedboth maize biomass and grain yield (Table 1) Thereforeseparate analysis for each season was done since the seasonalrainfall variability considerably affected the response of treat-ments

As depicted in Figure 2(a) application of N significantlyaffected themean yield ofmaizeThehighest significantmeanyields (98 thaminus1) in 2013 were obtained when 92N kg haminus1followed by 115N kg haminus1 was applied but both are sta-tistically at par In addition statistically comparable yieldperformance was obtained when 69Nkg haminus1 was appliedcompared to 92 and 115N kg haminus1 applications Howevermore than 23 and 45 significant yield increases wererecorded when N at 92 kg haminus1 was applied compared to46N kg haminus1 and the control plot receiving no N applicationIn contrary the lowest significant yield except the controlwas recorded when 110N kg haminus1 was applied as compared tootherN rates In 2013 season the amount and the distributionof rainfall during the growing period of the crop were muchhigher than in 2014 The cumulative rainfall in the entiregrowing period particularly from mid-June to August wasconsiderably higher in the 2013 (Figure 3(a)) than in 2014Moreover the daily rainfall distribution particularly fromearly June to late august was erratic and sometimes heavyrain causing high runoff and even leading to leachingoccurred in 2013 (Figure 3(b)) compared to 2014

In 2014 however the response of maize yield to the maineffect of N application rate did not show significant variationsdue to the application of 466992 and 115N kg haminus1 thoughthe highest grain yield was obtained when 69Nkg haminus1 wasapplied (Figure 2(a))The lowest yieldwas however recordedfrom the control plot without N Even though the yieldresponses of maize to 110N kg haminus1 were significantly better


0510152025303540

2013

20142013 (max)2014 (max)2013 (min)

2014 (min)

050

100150200250300350400

Mon

thly

mea

n ra

infa

ll (m

m)

Tem

pera

ture

(∘C)

Jan

Feb

Mar

Ap

rM

ayJu

n Jul

Aug

Sept

O

ct

Nov

D

ec

Mea

n

Figure 1 Mean monthly rainfall and minimum and maximum temperature of Bako research site 2013-2014

0 46 69 92 110 115

20132014Mean

Nitrogen rate (kgha)

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

(a)

T1 T2 T3 T4 R

Time of nitrogen application

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

20132014Mean

(b)

Figure 2The effect of nitrogen rates (a) and application time (b) on the yield of maize in the 2013 and 2014 cropping seasons at BakoWesternEthiopia

in 2014 than in 2013 significantly lower yield except N controlplot was recorded as compared to other N rates This couldbe related to the annual or monthly amount (Figure 1) andcumulative and daily distribution of the rainfall in 2014For instance the monthly amount of rainfall from June toAugust in 2014 was significantly lower than during 2013 rainyseason

Application time of N was significantly varied acrossseasons (Figure 2(b)) The highest yield in 2013 was obtainedat 1198793followed by 119879

2and 119879

1 but all are statistically at

par However the lowest yield was attained at 119877 (previousrecommendation) followed by119879

4The highest yield however

was recorded at 1198791in 2014 though all treatment means

were statistically similarThese response variations across the

seasons might also relate to rainfall amount and distributions(Figures 1 and 3)

Nitrogen rates by time of application also showed sig-nificant effects on both biomass and grain yield of maizein each season (Figure 4) In 2013 the highest significantbiomass yield (212 thaminus1) was obtained at 115N kg haminus1 and1198794(four times split application of equal doses) followed by

69N kg haminus1 at 1198791and 119879

2and 92N kg haminus1 at 119879

2 which are

statistically at par However application of 69 kg haminus1 at 1198794

and 46 kg haminus1 at 1198792or 1198794showed the lowest yield except

the control plot without N compared to other treatmentcombinations and even with previous recommendation Theresult revealed that more than 20 and 19 biomass yieldadvantages were obtained for 69N kg haminus1 at 119879

3and 119879

1or


2013

Dai

ly ra

infa

ll di

strib

utio

n (m

m)

2014

50 100 150 200 2500Growing periods (May 1ndashNov 31)

01020304050607080

01020304050607080

(a)

20132014

0

200

400

600

800

1000

1200

1400

1600

Cum

ulat

ive r

ainf

all (

mm

)

50 100 150 200 2500Days (May 1 to Nov 31)

(b)

Figure 3 Daily rainfall distribution (a) and cumulative rainfall (b) received in growing periods of 2013 and 2014 rainy seasons at BakoWestern Ethiopia

46 69 92 115 110 0

T1

T2

T3

T4

APR

Nitrogen rates (kgha)

2013

0

5

10

15

20

25

Biom

ass y

ield

(th

a)

(a)

46 69 92 115 110 0Nitrogen rates (kgha)

2014

0

5

10

15

20

25

30

35

Biom

ass y

ield

(th

a)

T1

T2

T3

T4

APR

(b)

Figure 4 The effect of N rate and time of application on biomass yield of maize in the 2013 and 2014 rainy seasons

92N kg haminus1 at1198793compared to 110N kgahaminus1 half of the total

at planting and the remaining at knee height This result maybe related to rainfall amount and distribution thatmay lead torunoff and leaching due to mismatch N application and timeof crop N demand The lowest and significant biomass yieldwas recorded from control plot

The overall means regardless of treatment variationsrevealed that significantly higher biomass yield (25 thaminus1)was obtained in the 2014 than in 2013 (17 thaminus1) Thisvariation might be related to the effect of rainfall amount anddistribution during the growing seasons (Figures 1 and 3)

In addition to higher monthly rainfall amount in pick rainyseasons regarding rainfall distribution (Figures 1 and 3) thecumulative rainfall in different proposed application timewasconsiderably higher in 2013 than 2014 (Figure 5) which mayfavor N losses through runoff and leaching Similar to theresult observed in 2013 the highest and significant biomassyield was obtained at a rate of 115N kg haminus1 and119879

4in the 2014

and more than 17 and 100 yield advantage were obtainedwhen compared with previously recommended rate and timeof N application and the control plot (Figure 5) respectivelyApplication of 69N kg haminus1 at 119879

1or 1198792and 92N kg haminus1 at


2013 2014

020406080

100120140

Cum

ulat

ive r

ainf

all (

mm

)

76 78 80 82 84 867475ndash85 DAP

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)

2 4 6 8 10 120From time of planting up to 10 DAP

16 18 20 22 24 261415ndash25 DAP

56 58 60 62 64 665455ndash65 DAP

36 38 40 42 44 463435ndash45 DAP

2013 2014

Figure 5 Cumulative rainfall distribution in different proposed N application times in 2013 and 2014 rainy seasons

1198792statistically showed the next highest biomass even though

these means are at parity with previous recommendation(110N kg haminus1 at 119877) The lowest yield except the control plotwas recorded when 115N kg haminus1 at 119879

4was practiced

Maize yield response to N rates and time of applicationwas also significantly varied across seasons (Figure 6) Thehighest grain yield in 2013 was obtained when 92N kg haminus1at 1198792followed by 115N kg haminus1 at either 119879

2or 1198794and

69Nkg haminus1 at either 1198791or 1198793applications time were prac-

ticed but all means are statistically at par The lowest yieldexcept the control plot was recorded when 46Nkg haminus1followed by 69N kg haminus1 at 119879

4was used Interestingly a

significant yield increase by 297 and 244 was obtainedwhen 69Nkg haminus1 at the time of 119879

1and 119879

3was applied

compared to the application of 110N kg haminus1 half at the timeof planting and the remaining at the knee height were appliedThe lowest however grain yield was recorded from controlplot receiving no N fertilizer (Figure 6)

Similar to biomass yield significantly higher grain yieldwas recorded in 2014 (99 thaminus1) than in 2013 (87 thaminus1) The

highest yields in 2014were also recordedwhen 92N kg haminus1 at1198791followed by 115N kg haminus1 at 119879

4and 69Nkg haminus1 at 119879

1was

used although all of these means are statistically similar (Fig-ure 6) The lower rate of N (46 kg haminus1) at 119879

2showed similar

yield performance compared to the highest three treatmentmeans Interestingly application of 46N kg haminus1 at119879

2showed

statistically similar yield performance though with 10 yieldadvantage when compared with the application of previouslyrecommended 110N kg haminus1 and when half of the total N atplanting and the remaining half at the stage of knee heightwere applied (Figure 6) Moreover more than 14 yieldincrease could be obtained when the application of either69N kg haminus1 or 92N kg haminus1 at 119879

1was practiced compared to

previous N rate and time of application (Figure 6)The lowestyield was however recorded from control plot receiving noN

Conversely the highest and significant harvest index (HI)was recorded from the control plot without N (Figure 7)in each cropping season Application of 46N kg haminus1 at 119879

2

and 115N kg haminus1 at 1198794showed the next significant HI in


2013

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)

Figure 6The effect of N rate and time of application on grain yield of maize in the 2013 and 2014 cropping seasons at BakoWestern Ethiopia

2013

0

10

20

30

40

50

60

70

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

0

10

20

30

40

50

60

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)

Figure 7 The effect of N rate and time of application on harvest index of maize in 2013 and 2014 cropping seasons

2013 whereas 46N kg haminus1 at 1198792and 92N kg haminus1 at 119879

4also

showed the next significant HI in 2014 compared to othertreatment means However previously recommended N andtime of application showed significantly lower HI comparedto different N rates and time of the applications (Figure 7)

Agronomic efficiency (AE) of the crop as affected byN rates indicated that the highest and significant AE wasrecorded at the lowest N rate and AE was linearly decreasedas the function of N rate increased (Figure 8(a)) However

the AE was not significantly varied due to the difference intime of application from 119879

1to 1198794(Figure 8(b)) Significantly

the lowest HI was however recorded from the previouslyrecommended time of application (119877)

Even though both biomass and grain yield of maize wereminimum at lower N rate (46N kg haminus1) the highest andsignificant agronomic efficiency (AE) was recorded at a lowerrate and therewere decreased trends as the function ofN ratesincreased from 46 to 115N kg haminus1 (Figure 8) However time


46 69 92 115 110Nitrogen rates (kgha)

0

50

100

150

200

250A

E (k

g of

mai

ze1

Nkg

)

(a)

T1 T2 T3 T4 R

Time of application

0

50

100

150

AE

(kg

of m

aize

1N

kg)

(b)

Figure 8 The effect of N rate (a) and time of application (b) on combined means of agronomic efficiency of maize

Table 2 Partial and marginal analysis as affected by N rates and time of application on maize in 2013 and 2014 cropping seasons

Trt TC 2013 2014N TA Yd Ayd GB NB DA MRR Yd Ayd GB NB DA MRRControl 2503 67 60 22880 20377 mdash mdash 79 71 27070 24568 mdash mdash46 119879

14829 80 72 27360 22531 mdash 926 94 84 32031 27201 mdash 113

46 1198792

5318 82 74 27876 22558 mdash 553 103 93 35262 29944 mdash 56146 119879

35488 82 74 27930 22441 D mdash 98 88 33486 27998 D mdash

69 1198791

5695 93 84 31895 26200 mdash 967 93 84 31895 26200 D mdash46 119879

45760 69 62 23683 17923 D mdash 99 89 33775 28015 D mdash

69 1198792

6076 84 76 28760 22684 D 84 76 28760 22684 D mdash69 119879

36332 97 88 33276 26944 mdash 117 107 96 36581 30250 mdash 302

92 1198791

6448 91 82 31195 24747 D mdash 109 98 37191 30743 mdash 42369 119879

46548 76 68 25903 19355 D mdash 100 90 34276 27728 D mdash

110 119877 6659 73 66 24898 18239 D mdash 94 84 32060 25401 D mdash92 119879

26904 103 92 35129 28225 mdash 224 99 89 33858 26954 D mdash

92 1198793

7059 91 82 31155 24097 D mdash 102 91 34714 27655 D mdash115 119879

17193 94 85 32150 24957 D mdash 101 92 34647 27454 D mdash

92 1198794

7375 98 88 33477 26102 D mdash 95 85 32309 24933 D mdash115 119879

27630 95 85 32362 24732 D mdash 99 89 33764 26134 D mdash

115 1198793

7821 100 90 34079 26258 D mdash 94 85 32099 24278 D mdash115 119879

48143 86 78 29478 21335 D mdash 108 98 37071 28928 D mdash

Trt = treatment combinations N = nitrogen rate (kgha) TA = time of N application TC = total cost that varied among treatments (ETB haminus1) Yd = yield ofmaize (tha) Ayd = adjusted yield of maize (tha) GB = gross benefit (ETB haminus1) NB = net benefit (ETB haminus1) DA = dominance analysis MRR = marginalrate of return () D = dominated 119877 = previously recommended time of N application and 1 USD = 2250 ETB

of application except the recommended one (119877) did not showany significant variation among the treatment means

Partial and marginal analysis for means of treatmentcombinations against the previous recommendation and thecontrol were carried out (Table 2) The result indicated thatboth partial andmarginal analysis showed differences in eachcropping season since the yield responses to the treatmentswere different across the seasons In 2013 season the highestnet benefit (28225 ETBhaminus1) was obtainedwhen 92N kg haminus1

at 1198792was carried out although the use of 69N kg haminus1 at

1198793followed by 69Nkg haminus1 at 119879

1gave the next maximum

net benefit However the maximum net profit and accept-able marginal rate of return (MMR) were obtained when92N kg haminus1 at 119879


erratic and heavy rainfall distribution In 2014 cropping sea-son however the maximum net benefit was 30743 ETBhaminus1followed by 30250 ETBhaminus1 and 29944 ETBhaminus1 which wereachieved when 92N kg haminus1 at 119879

1 69N kg haminus1 at 119879

3 and


46Nkg haminus1 at 1198792were respectively applied However the

analysis ofMRR showed that application of 92N kg haminus1 at1198791

is the best practice that could give the maximum net benefitand the marginal rate of return in a less rainy season

4 Discussion

Erratic rainfall distribution and the amount can considerablyinfluence the response of maize to N application as it maycause runoff and leaching of appliedN Some research findingalso confirmed that the yield of maize with high rainfallregimes is generally low due to poor nutrient use efficiency[18] N use efficiency by the crop can be reduced underheavy rainfall particularly at the time of application sincethe nutrient can be lost throughNO

3losses and even through

soil erosion [19] If the rainfall amount and distributionare relatively adequate like in 2014 cropping season Nuptake by the crop could be enhanced since runoff and evenleaching effect can be reduced and hence yield productionand productivity are increased [11 20] However the Nuse efficiency can be improved through the further splitapplication of N at different growth stage absorbed by thecrop since leaching is one of the main challenges for N loss inhigh rainfall areas [11 20] Jamal et al [12] also indicated thatabout 50 at higher doses of applied N remains unavailableto a crop due to N loss through leaching in areas receivingheavy rainfall amount and uneven distribution

In 2013 higher doses of N (115 kg haminus1) could give similaryield performance as compared to the lower (69N kg haminus1)This might be due to low absorption of nitrogen by thecrop since N losses through leaching and runoff may behigh as compared to adequate and even distribution ofthe rainfall [21] However this result in line with otherresearch reports revealed that grain yield of maize due tothe application of N in a heavy and uneven distribution ofrainfall areas significantly increased compared to the controlplot [22 23] Application of recommended N half at the timeof maize planting significantly reduced the yield of maizewhen compared with different N rates at a different time ofapplication but not at the time of planting This result isdirectly related to N losses through leaching since the cropcould not be utilized at the early emergence stage until its rootdevelopment [15 24] Similar findings were also reported byother authors [11 13 16]

The response of maize at the higher rates of N wasobserved in 2014 This might be related to rainfall amountand distribution of rainfall particularly at the time of Napplication that may reduce the loss [24ndash26] Delayed time ofapplication after root development significantly enhanced theyield of maize compared to before or at the time of planting[25]This is in agreement with this result that application ofNafter 10ndash15 days after planting onwards significantly increasedyield compared with farmersrsquo practices N use efficiency evenunder low rates of N at two to three times applicationsconsiderably enhancesN absorption in good rainy seasons [627] Moreover time of application significantly enhances Nabsorption particularly at the time of critical N requirementfor the crop [11 13] Other reports also confirmed that

split application of N after the good establishment of thecrop markedly reduces N losses [16] The lowest yield washowever recorded from control plot receiving no N [6]

In line with the agreement of this result both agronomicefficiency and HI were not significantly increased as thefunction of N rate increased and other reports were alsosimilar [11 13] However delayed application of N aftercrop establishment significantly increased HI compared to Napplication at the time of planting [24] The highest AE andHI were recorded from the control plot [11 28]

5 Conclusion

Despite the fact that maize productivity is relatively betterthan other major cereal crops its current productivity isstill far below its potential productivity N rate and time ofapplication are among the major abiotic factors limiting theproduction and productivity of the crop Amount and distri-bution of rainfall across the seasons considerably influencedthe responses of maize to rate and time of N applicationIn a heavy and uneven distribution of rainfall similar to2013 cropping season application of 92N kg haminus1 at 119879

2(10ndash15

days after planting (DAP) 35ndash40 DAP and 55ndash60 DAP)gave comparable optimum grain yield compared to othertreatmentmeans Even though the application of 92N kg haminus1gave optimum grain yield in 2014 season two times appli-cation (10ndash15 DAP and 35ndash40 DAP) was an optimum timeIn conclusion application of 92N kg haminus1 at 1198791 is the best Nrate and time of application to get the maximum net benefitand acceptable MRR in good rainy seasons and hence isrecommended for the end users However in case of erraticand heavy rainy seasons that may lead to N losses throughrunoff and leaching during time of N application applicationof 92N kg haminus1 at three times application (13 N at 10ndash15 DAP13 N at 35ndash40 DAP and 55ndash60 DAP) should be used to getmaximum profit and acceptable MRR

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

The authors greatly acknowledge Oromia Agricultural Re-search Institute for financial supportThey sincerely acknowl-edge Bako Agricultural Research Center for all the technicaland managerial support provided during the experimentalperiod Great thanks also go to the research staffs of cerealresearch teamswhowere directly or indirectly involved in theexecution of the experiment

References

[1] Z Abebe C Dabala and T Birhanu ldquoSystem Productivity asInfluenced by Varieties and Temporal Arrangement of Bean inMaize-climbing Bean Intercroppingrdquo Journal of Agronomy vol16 no 1 pp 1ndash11 2016


[2] N Mandefro D Tanner and S Twumasi-Afriyie ldquoEnhancingthe contribution of maize to food security in Ethiopia inrdquo inProceedings of the Second National MaizeWorkshop o f Ethiopiapp 12ndash16 Addis Ababa Ethiopia 2001

[3] T Abate B Shiferaw AMenkir et al ldquoFactors that transformedmaize productivity in Ethiopiardquo Food Security vol 7 no 5 pp965ndash981 2015

[4] Variety Registration Crop Variety Registration in CVR (CropAddis Ababa 2012

[5] C C S Authority Agricultural Sample Survey for 201314 CropSeasonReport on Area and Production of Crops for Private andPeasant Holdings in Central Statistical Authority EthiopiaAddis Ababa 2013

[6] S K Mourice S D Tumbo A Nyambilila and C L Rweye-mamu ldquoModeling potential rain-fed maize productivity andyield gaps in the Wami River sub-basin Tanzaniardquo Acta Agri-culturae Scandinavica Section B Soil and Plant Science vol 65no 2 pp 132ndash140 2015

[7] J Blumenthal D Baltensperger K G Cassman S Mason andA Pavlista Importance and effect of nitrogen on crop qualityand health Nitrogen in the Environment Sources Problems andManagement Elsevier Oxford 2nd edition 2008

[8] F G Fernszligndez E D Nafziger S A Ebelhar and R G HoeftldquoManaging nitrogen in Illinois agronomy handbook UnivIllinois Coop Ext ServrdquoUrbana-Champaign pp 113ndash132 2009

[9] R B Nielsen Root Development in Young Corn in PurdueUniversity Department of Agronomy 2013

[10] R J Gehl J P Schmidt L DMaddux andW B Gordon ldquoCornyield response to nitrogen rate and timing in sandy irrigatedsoilsrdquo Agronomy Journal vol 97 no 4 pp 1230ndash1238 2005

[11] N K Fageria and V C Baligar ldquoEnhancing Nitrogen UseEfficiency in Crop Plantsrdquo Advances in Agronomy vol 88 pp97ndash185 2005

[12] Z Jamal M Hamayun N Ahmad and M F ChaudharyldquoEffects of soil and foliar application of different concentrationsof NPK and foliar application of (NH4)2 SO4 on different yieldparameters in wheatrdquo Journal of Agronomy vol 5 no 2 pp 251ndash256 2006

[13] D Haile D Nigussie and A Ayana ldquoNitrogen use efficiencyof bread wheat effects of nitrogen rate and time of applicationrdquoJournal of Soil Science and Plant Nutrition vol 12 no 3 pp 389ndash409 2012

[14] T Debele G Gedano and M Leul ldquoResponse of Maize to SplitApplication of Nitrogen Fertilizer at Bakordquo in Proceedings of thein 6 Annual Conference of the Crop Science Society of Ethiopiap 3 1994

[15] H Darby and J Lauer ldquoPlant physiologymdashcritical stages in thelife of a corn plant Field Cornrdquo Tech Rep 2004 httpwwwmn nrcs USDA govtechnicalECSpestplanning aids

[16] J E Sawyer ldquoNitrogen application timing forms and addi-tivesrdquoAmerican Society of Agricultural and Biological Engineers2008

[17] CIMMYT From agronomic data to farmer recommendations aneconomics training manual 1988

[18] S Sitthaphanit V Limpinuntana B Toomsan S PanchabanandRWBell ldquoGrowth and yield responses inmaize to split anddelayed fertilizer applications on sandy soils under high rainfallregimesrdquo Kasetsart Journal (Natural Science) vol 44 pp 991ndash1003 2010

[19] J M Sogbedji H M Van Es C L Yang L D Geohring andF R Magdoff ldquoNitrate leaching and nitrogen budget as affected

by maize nitrogen rate and soil typerdquo Journal of EnvironmentalQuality vol 29 no 6 pp 1813ndash1820 2000

[20] R Chikowo P Mapfumo P Nyamugafata and K E GillerldquoMineral N dynamics leaching and nitrous oxide losses undermaize following two-year improved fallows on a sandy loam soilin ZimbabwerdquoPlant and Soil vol 259 no 1-2 pp 315ndash330 2004

[21] P Scharf J Lory and J Grundler ldquoBest management practicesfor nitrogen fertilizer in Missourirdquo 2006

[22] E RThomandB RWatkin ldquoEffect of rate and time of fertilisernitrogen application on total plant shoot and root yields ofmaize (zea mays l)rdquo New Zealand Journal of ExperimentalAgriculture vol 6 no 1 pp 29ndash38 1978

[23] G L Wang Y L Ye X P Chen and Z L Cui ldquoDeterminingthe optimal nitrogen rate for summer maize in China byintegrating agronomic economic and environmental aspectsrdquoBiogeosciences vol 11 no 11 pp 3031ndash3041 2014

[24] A Niaz M Yaseen M Arshad and R Ahmad ldquoResponseof maize yield quality and nitrogen use efficiency indices todifferent rates and application timingsrdquo Journal of Animal andPlant Sciences vol 25 no 4 pp 1022ndash1031 2015

[25] L Sangoi P R Ernani and P R F Da Silva ldquoMaize responseto nitrogen fertilization timing in two tillage systems in a soilwith high organic matter contentrdquo Revista Brasileira de Cienciado Solo vol 31 no 3 pp 507ndash517 2007

[26] O S Walsh Effect of delayed nitrogen fertilization on corn grainyields Oklahoma State University 2006

[27] A Limon-Ortega N A Ruiz-Torres G Vazquez-Carrillo andA Baez-Perez ldquoEnvironment and nitrogen influence on rainfedmaize yield and qualityrdquo Crop Science vol 56 no 3 pp 1257ndash1264 2016

[28] SDhital andWR Raun ldquoVariability in optimumnitrogen ratesfor maizerdquo Agronomy Journal vol 108 no 6 pp 2165ndash21732016

Submit your manuscripts athttpswwwhindawicom

Nutrition and Metabolism

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Food ScienceInternational Journal of

Agronomy


International Journal of



Microbiology

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

AgricultureAdvances in


PsycheHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BiodiversityInternational Journal of


ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

GenomicsInternational Journal of


Plant GenomicsInternational Journal of


Biotechnology Research International


Forestry ResearchInternational Journal of


Journal of BotanyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EcologyInternational Journal of


Veterinary Medicine International


Cell BiologyInternational Journal of


Evolutionary BiologyInternational Journal of



crop [7] Hence application of fertilizer N resulting in higherbiomass is commonly increased Optimum rate and time ofNapplication can enhance yield productivity and nutrient useefficiencieswhile reducing the environmental pollution [8 9]N application beyond the optimum requirement of maizecould not increase yield and may lead to an elevated level ofNO3in the soil and susceptibility to NO

3loss by leaching

[10] Another report also indicated that abundant N supplyfavors NH

3losses especially if the supply is in excess of

plant requirements [11] However the negative environmentalimpacts associated with maize production can be minimizedthrough efficient N management including appropriate rateand time of N recommendation [11]

Time of N application at appropriate crop growth stageis also another main focus to enhance N use efficiency andincrease maize productivity All applied N is not absorbed bythe crop since leaching is one of themain challenges forN lossin high rainfall areas Research reports had shown that about50 and evenmore than this figure at higher doses of appliedN remain unavailable to a crop due toN loss through leaching[12] This leaching loss may be determined by a quantity of Napplied inappropriate time of application soil permeabilityand quantity of rainfall drops in the area [11] However anoptimum and efficient time of N application can increase therecovery of applied N up to 58ndash70 and hence increase yieldand grain quality of the crop [12 13]

Previous N recommendation for maize production inWestern Ethiopia was 92ndash110 kgha half at the time of plant-ing and half at 30ndash35 days after planting [2] while applyingall at planting is the best alternative to large scale maizefarming where mechanization is available [14] Howevermany research findings verified that N application at the timeof maize planting is not efficiently recovered since nodal rootgrowth and development from emergence up to 1-2 leavesrsquodevelopment stage is a very young stage [9]The same authorshowed that seed emergence usually occurs in 6ndash8 days afterplanting while 12ndash15 and 15ndash20 days after planting are neededto form one and two developed leaves for hybrid maizerespectively [9 15] At these stages the seedlings depend onkernel food reserve since nodal root development is not yetstarted for nutrient absorption If N application however atmaize planting is done its loss through leaching and runoffcan be articulated since its absorption by the crop up to10ndash15 days after planting is rare Hence application of N atthe time of planting is easily lost through leaching or runoffin heavy rainfall areas and it not only is attributed to anenvironmental population but also results in nonprofit cost[11 13 16] and hence the disadvantages of N application atthe time of planting may outweigh its advantages Thereforethe objective of this studywas to investigate optimumrate andtime of N application to increase optimum and economicallyprofitable maize yield

2 Material and Methods

Theexperimentwas conducted at BakoAgricultural ResearchCenter for two consecutive years (2013 and 2014) and it islocated in a subhumid area of Western Ethiopia which liesat a latitude of 9E61015840N and longitude of 37E91015840E and at an

altitude of 1650m asl It has an annual mean minimum andmaximum air temperatures of 135 and 297∘C respectivelyThe area received an annual rainfall of 1431mm (2013) and1067mm (2014) with maximum precipitation being receivedin the months of MayndashAugust

The soil of Bako area is reddish-brown nitosol It is anacidic soil with a pH range of 45ndash56The surrounding area isamixed farming zone and is one of themost importantmaize(Zea mays L) growing belts in Ethiopia and cultivations ofteff (Eragrostis tef ) fingermillet (Eleusine coronata) commonbean (Phaseolus vulgaris L) sorghum (Sorghum bicolor L)noug (Guizotia abyssinica Lf) and soybean (Glycine maxL) are common The area is predominantly maize basedmonocropping with low soil fertility problem that directlyinfluences production and productivity of the cultivatedcrops

The treatments consisted of two factors namely fourlevels of N rates (46 69 92 and 115N kg haminus1) and fourdifferent application times (119879

1= 12 N at 10ndash15 days after

planting (DAP) and 12 N at 35ndash40 DAP 1198792= 13 N at 10ndash15

DAP 13 N at 35ndash40 DAP and 13 N at 55ndash60 DAP 1198793=

13 N at 35ndash40 DAP 13 N at 55ndash60 DAP and 75ndash80 DAPand 119879

4= 14 N at 10ndash15 DAP 14 N at 33ndash40 DAP 14 N

at 55ndash60 DAP and 14 at 75ndash80 DAP) that were arrangedin 4 times 4 factorial combinations Moreover previous rate andapplication time of N (referred as 119877) and the control plotreceiving no N fertilizer were included for the comparisonspurposes A total of 16 treatment combinations plus previousrecommended rate and time ofN application and control plotwithout N were laid out using a randomized complete blockdesign (RCBD) with three replications Application time of Nwas done within the stated time ranges but at the same dateas per treatment arrangements

The experimental plots were plowed three times at dif-ferent time intervals starting from mid-May and leveledmanually prior to field layout Plant population for allexperimental plots was 44444 plants haminus1 75 cm betweenrows and 30 cm between plants Recommended phosphorus(20 kg P haminus1) in the form of triple superphosphate (TSP) forall experimental plots including standard check and controlplot was equally and uniformly applied at the time of maizeplanting Nwas applied in the form ofUREA as per treatmentarrangements One hybrid long maturing variety (BH661)of maize was used for the execution of the treatments Itsyield potential varies between 95 and 12 thaminus1 at researchfield and 6 and 85 thaminus1 at farmersrsquo field under integratedagronomic managements The variety was released by BakoNational Maize Research Center in 2011 and it can be grownin a range of 1600ndash2200m above sea level and it requires anannual rainfall of 1000ndash1500 with uniform distribution in itsgrowing periods The trial was planted on May 30th in the2013 and June 1st in 2014 Other agronomic managementsrather than treatment variations were uniformly applied toall experimental plots

At the time of harvesting the maize was harvested byexcluding two border rows from each side A net plot sizefor each plot was 225m times 51m (11475m2) Stand countsper net plot were counted at the time of harvesting Finally






3 Results






0510152025303540

2013

20142013 (max)2014 (max)2013 (min)

2014 (min)

050

100150200250300350400

Mon

thly

mea

n ra

infa

ll (m

m)

Tem

pera

ture

(∘C)

Jan

Feb

Mar

Ap

rM

ayJu

n Jul

Aug

Sept

O

ct

Nov

D

ec

Mea

n


0 46 69 92 110 115

20132014Mean


00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

(a)

T1 T2 T3 T4 R


00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

20132014Mean

(b)




2and 119879










2 which are




3and 119879

1or


2013

Dai

ly ra

infa

ll di

strib

utio

n (m

m)

2014


01020304050607080

01020304050607080

(a)

20132014

0

200

400

600

800

1000

1200

1400

1600

Cum

ulat

ive r

ainf

all (

mm

)

50 100 150 200 2500Days (May 1 to Nov 31)

(b)


46 69 92 115 110 0

T1

T2

T3

T4

APR


2013

0

5

10

15

20

25

Biom

ass y

ield

(th

a)

(a)


2014

0

5

10

15

20

25

30

35

Biom

ass y

ield

(th

a)

T1

T2

T3

T4

APR

(b)






4in the 2014




2013 2014

020406080

100120140

Cum

ulat

ive r

ainf

all (

mm

)

76 78 80 82 84 867475ndash85 DAP

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)


16 18 20 22 24 261415ndash25 DAP

56 58 60 62 64 665455ndash65 DAP

36 38 40 42 44 463435ndash45 DAP

2013 2014




4was practiced


2or 1198794and





1and 119879

3was applied





1was


2showed similar


2showed





2



2013

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)


2013

0

10

20

30

40

50

60

70

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

0

10

20

30

40

50

60

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)



4also









0

50

100

150

200

250A

E (k

g of

mai

ze1

Nkg

)

(a)

T1 T2 T3 T4 R

Time of application

0

50

100

150

AE

(kg

of m

aize

1N

kg)

(b)




14829 80 72 27360 22531 mdash 926 94 84 32031 27201 mdash 113

46 1198792

5318 82 74 27876 22558 mdash 553 103 93 35262 29944 mdash 56146 119879

35488 82 74 27930 22441 D mdash 98 88 33486 27998 D mdash

69 1198791

5695 93 84 31895 26200 mdash 967 93 84 31895 26200 D mdash46 119879

45760 69 62 23683 17923 D mdash 99 89 33775 28015 D mdash

69 1198792

6076 84 76 28760 22684 D 84 76 28760 22684 D mdash69 119879

36332 97 88 33276 26944 mdash 117 107 96 36581 30250 mdash 302

92 1198791

6448 91 82 31195 24747 D mdash 109 98 37191 30743 mdash 42369 119879

46548 76 68 25903 19355 D mdash 100 90 34276 27728 D mdash

110 119877 6659 73 66 24898 18239 D mdash 94 84 32060 25401 D mdash92 119879

26904 103 92 35129 28225 mdash 224 99 89 33858 26954 D mdash

92 1198793

7059 91 82 31155 24097 D mdash 102 91 34714 27655 D mdash115 119879

17193 94 85 32150 24957 D mdash 101 92 34647 27454 D mdash

92 1198794

7375 98 88 33477 26102 D mdash 95 85 32309 24933 D mdash115 119879

27630 95 85 32362 24732 D mdash 99 89 33764 26134 D mdash

115 1198793

7821 100 90 34079 26258 D mdash 94 85 32099 24278 D mdash115 119879

48143 86 78 29478 21335 D mdash 108 98 37071 28928 D mdash











3 and





4 Discussion








5 Conclusion


2(10ndash15




Acknowledgments


References

































Journal of




Agronomy





Microbiology






























3 Results






0510152025303540

2013

20142013 (max)2014 (max)2013 (min)

2014 (min)

050

100150200250300350400

Mon

thly

mea

n ra

infa

ll (m

m)

Tem

pera

ture

(∘C)

Jan

Feb

Mar

Ap

rM

ayJu

n Jul

Aug

Sept

O

ct

Nov

D

ec

Mea

n


0 46 69 92 110 115

20132014Mean


00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

(a)

T1 T2 T3 T4 R


00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

20132014Mean

(b)




2and 119879










2 which are




3and 119879

1or


2013

Dai

ly ra

infa

ll di

strib

utio

n (m

m)

2014


01020304050607080

01020304050607080

(a)

20132014

0

200

400

600

800

1000

1200

1400

1600

Cum

ulat

ive r

ainf

all (

mm

)

50 100 150 200 2500Days (May 1 to Nov 31)

(b)


46 69 92 115 110 0

T1

T2

T3

T4

APR


2013

0

5

10

15

20

25

Biom

ass y

ield

(th

a)

(a)


2014

0

5

10

15

20

25

30

35

Biom

ass y

ield

(th

a)

T1

T2

T3

T4

APR

(b)






4in the 2014




2013 2014

020406080

100120140

Cum

ulat

ive r

ainf

all (

mm

)

76 78 80 82 84 867475ndash85 DAP

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)


16 18 20 22 24 261415ndash25 DAP

56 58 60 62 64 665455ndash65 DAP

36 38 40 42 44 463435ndash45 DAP

2013 2014




4was practiced


2or 1198794and





1and 119879

3was applied





1was


2showed similar


2showed





2



2013

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)


2013

0

10

20

30

40

50

60

70

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

0

10

20

30

40

50

60

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)



4also









0

50

100

150

200

250A

E (k

g of

mai

ze1

Nkg

)

(a)

T1 T2 T3 T4 R

Time of application

0

50

100

150

AE

(kg

of m

aize

1N

kg)

(b)




14829 80 72 27360 22531 mdash 926 94 84 32031 27201 mdash 113

46 1198792

5318 82 74 27876 22558 mdash 553 103 93 35262 29944 mdash 56146 119879

35488 82 74 27930 22441 D mdash 98 88 33486 27998 D mdash

69 1198791

5695 93 84 31895 26200 mdash 967 93 84 31895 26200 D mdash46 119879

45760 69 62 23683 17923 D mdash 99 89 33775 28015 D mdash

69 1198792

6076 84 76 28760 22684 D 84 76 28760 22684 D mdash69 119879

36332 97 88 33276 26944 mdash 117 107 96 36581 30250 mdash 302

92 1198791

6448 91 82 31195 24747 D mdash 109 98 37191 30743 mdash 42369 119879

46548 76 68 25903 19355 D mdash 100 90 34276 27728 D mdash

110 119877 6659 73 66 24898 18239 D mdash 94 84 32060 25401 D mdash92 119879

26904 103 92 35129 28225 mdash 224 99 89 33858 26954 D mdash

92 1198793

7059 91 82 31155 24097 D mdash 102 91 34714 27655 D mdash115 119879

17193 94 85 32150 24957 D mdash 101 92 34647 27454 D mdash

92 1198794

7375 98 88 33477 26102 D mdash 95 85 32309 24933 D mdash115 119879

27630 95 85 32362 24732 D mdash 99 89 33764 26134 D mdash

115 1198793

7821 100 90 34079 26258 D mdash 94 85 32099 24278 D mdash115 119879

48143 86 78 29478 21335 D mdash 108 98 37071 28928 D mdash











3 and





4 Discussion








5 Conclusion


2(10ndash15




Acknowledgments


References

































Journal of




Agronomy





Microbiology


























0510152025303540

2013

20142013 (max)2014 (max)2013 (min)

2014 (min)

050

100150200250300350400

Mon

thly

mea

n ra

infa

ll (m

m)

Tem

pera

ture

(∘C)

Jan

Feb

Mar

Ap

rM

ayJu

n Jul

Aug

Sept

O

ct

Nov

D

ec

Mea

n


0 46 69 92 110 115

20132014Mean


00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

(a)

T1 T2 T3 T4 R


00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

20132014Mean

(b)




2and 119879










2 which are




3and 119879

1or


2013

Dai

ly ra

infa

ll di

strib

utio

n (m

m)

2014


01020304050607080

01020304050607080

(a)

20132014

0

200

400

600

800

1000

1200

1400

1600

Cum

ulat

ive r

ainf

all (

mm

)

50 100 150 200 2500Days (May 1 to Nov 31)

(b)


46 69 92 115 110 0

T1

T2

T3

T4

APR


2013

0

5

10

15

20

25

Biom

ass y

ield

(th

a)

(a)


2014

0

5

10

15

20

25

30

35

Biom

ass y

ield

(th

a)

T1

T2

T3

T4

APR

(b)






4in the 2014




2013 2014

020406080

100120140

Cum

ulat

ive r

ainf

all (

mm

)

76 78 80 82 84 867475ndash85 DAP

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)


16 18 20 22 24 261415ndash25 DAP

56 58 60 62 64 665455ndash65 DAP

36 38 40 42 44 463435ndash45 DAP

2013 2014




4was practiced


2or 1198794and





1and 119879

3was applied





1was


2showed similar


2showed





2



2013

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)


2013

0

10

20

30

40

50

60

70

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

0

10

20

30

40

50

60

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)



4also









0

50

100

150

200

250A

E (k

g of

mai

ze1

Nkg

)

(a)

T1 T2 T3 T4 R

Time of application

0

50

100

150

AE

(kg

of m

aize

1N

kg)

(b)




14829 80 72 27360 22531 mdash 926 94 84 32031 27201 mdash 113

46 1198792

5318 82 74 27876 22558 mdash 553 103 93 35262 29944 mdash 56146 119879

35488 82 74 27930 22441 D mdash 98 88 33486 27998 D mdash

69 1198791

5695 93 84 31895 26200 mdash 967 93 84 31895 26200 D mdash46 119879

45760 69 62 23683 17923 D mdash 99 89 33775 28015 D mdash

69 1198792

6076 84 76 28760 22684 D 84 76 28760 22684 D mdash69 119879

36332 97 88 33276 26944 mdash 117 107 96 36581 30250 mdash 302

92 1198791

6448 91 82 31195 24747 D mdash 109 98 37191 30743 mdash 42369 119879

46548 76 68 25903 19355 D mdash 100 90 34276 27728 D mdash

110 119877 6659 73 66 24898 18239 D mdash 94 84 32060 25401 D mdash92 119879

26904 103 92 35129 28225 mdash 224 99 89 33858 26954 D mdash

92 1198793

7059 91 82 31155 24097 D mdash 102 91 34714 27655 D mdash115 119879

17193 94 85 32150 24957 D mdash 101 92 34647 27454 D mdash

92 1198794

7375 98 88 33477 26102 D mdash 95 85 32309 24933 D mdash115 119879

27630 95 85 32362 24732 D mdash 99 89 33764 26134 D mdash

115 1198793

7821 100 90 34079 26258 D mdash 94 85 32099 24278 D mdash115 119879

48143 86 78 29478 21335 D mdash 108 98 37071 28928 D mdash











3 and





4 Discussion








5 Conclusion


2(10ndash15




Acknowledgments


References

































Journal of




Agronomy





Microbiology


























2013

Dai

ly ra

infa

ll di

strib

utio

n (m

m)

2014


01020304050607080

01020304050607080

(a)

20132014

0

200

400

600

800

1000

1200

1400

1600

Cum

ulat

ive r

ainf

all (

mm

)

50 100 150 200 2500Days (May 1 to Nov 31)

(b)


46 69 92 115 110 0

T1

T2

T3

T4

APR


2013

0

5

10

15

20

25

Biom

ass y

ield

(th

a)

(a)


2014

0

5

10

15

20

25

30

35

Biom

ass y

ield

(th

a)

T1

T2

T3

T4

APR

(b)






4in the 2014




2013 2014

020406080

100120140

Cum

ulat

ive r

ainf

all (

mm

)

76 78 80 82 84 867475ndash85 DAP

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)


16 18 20 22 24 261415ndash25 DAP

56 58 60 62 64 665455ndash65 DAP

36 38 40 42 44 463435ndash45 DAP

2013 2014




4was practiced


2or 1198794and





1and 119879

3was applied





1was


2showed similar


2showed





2



2013

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)


2013

0

10

20

30

40

50

60

70

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

0

10

20

30

40

50

60

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)



4also









0

50

100

150

200

250A

E (k

g of

mai

ze1

Nkg

)

(a)

T1 T2 T3 T4 R

Time of application

0

50

100

150

AE

(kg

of m

aize

1N

kg)

(b)




14829 80 72 27360 22531 mdash 926 94 84 32031 27201 mdash 113

46 1198792

5318 82 74 27876 22558 mdash 553 103 93 35262 29944 mdash 56146 119879

35488 82 74 27930 22441 D mdash 98 88 33486 27998 D mdash

69 1198791

5695 93 84 31895 26200 mdash 967 93 84 31895 26200 D mdash46 119879

45760 69 62 23683 17923 D mdash 99 89 33775 28015 D mdash

69 1198792

6076 84 76 28760 22684 D 84 76 28760 22684 D mdash69 119879

36332 97 88 33276 26944 mdash 117 107 96 36581 30250 mdash 302

92 1198791

6448 91 82 31195 24747 D mdash 109 98 37191 30743 mdash 42369 119879

46548 76 68 25903 19355 D mdash 100 90 34276 27728 D mdash

110 119877 6659 73 66 24898 18239 D mdash 94 84 32060 25401 D mdash92 119879

26904 103 92 35129 28225 mdash 224 99 89 33858 26954 D mdash

92 1198793

7059 91 82 31155 24097 D mdash 102 91 34714 27655 D mdash115 119879

17193 94 85 32150 24957 D mdash 101 92 34647 27454 D mdash

92 1198794

7375 98 88 33477 26102 D mdash 95 85 32309 24933 D mdash115 119879

27630 95 85 32362 24732 D mdash 99 89 33764 26134 D mdash

115 1198793

7821 100 90 34079 26258 D mdash 94 85 32099 24278 D mdash115 119879

48143 86 78 29478 21335 D mdash 108 98 37071 28928 D mdash











3 and





4 Discussion








5 Conclusion


2(10ndash15




Acknowledgments


References

































Journal of




Agronomy





Microbiology


























2013 2014

020406080

100120140

Cum

ulat

ive r

ainf

all (

mm

)

76 78 80 82 84 867475ndash85 DAP

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)

020406080

100120140160

Cum

ulat

ive r

ainf

all (

mm

)


16 18 20 22 24 261415ndash25 DAP

56 58 60 62 64 665455ndash65 DAP

36 38 40 42 44 463435ndash45 DAP

2013 2014




4was practiced


2or 1198794and





1and 119879

3was applied





1was


2showed similar


2showed





2



2013

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)


2013

0

10

20

30

40

50

60

70

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

0

10

20

30

40

50

60

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)



4also









0

50

100

150

200

250A

E (k

g of

mai

ze1

Nkg

)

(a)

T1 T2 T3 T4 R

Time of application

0

50

100

150

AE

(kg

of m

aize

1N

kg)

(b)




14829 80 72 27360 22531 mdash 926 94 84 32031 27201 mdash 113

46 1198792

5318 82 74 27876 22558 mdash 553 103 93 35262 29944 mdash 56146 119879

35488 82 74 27930 22441 D mdash 98 88 33486 27998 D mdash

69 1198791

5695 93 84 31895 26200 mdash 967 93 84 31895 26200 D mdash46 119879

45760 69 62 23683 17923 D mdash 99 89 33775 28015 D mdash

69 1198792

6076 84 76 28760 22684 D 84 76 28760 22684 D mdash69 119879

36332 97 88 33276 26944 mdash 117 107 96 36581 30250 mdash 302

92 1198791

6448 91 82 31195 24747 D mdash 109 98 37191 30743 mdash 42369 119879

46548 76 68 25903 19355 D mdash 100 90 34276 27728 D mdash

110 119877 6659 73 66 24898 18239 D mdash 94 84 32060 25401 D mdash92 119879

26904 103 92 35129 28225 mdash 224 99 89 33858 26954 D mdash

92 1198793

7059 91 82 31155 24097 D mdash 102 91 34714 27655 D mdash115 119879

17193 94 85 32150 24957 D mdash 101 92 34647 27454 D mdash

92 1198794

7375 98 88 33477 26102 D mdash 95 85 32309 24933 D mdash115 119879

27630 95 85 32362 24732 D mdash 99 89 33764 26134 D mdash

115 1198793

7821 100 90 34079 26258 D mdash 94 85 32099 24278 D mdash115 119879

48143 86 78 29478 21335 D mdash 108 98 37071 28928 D mdash











3 and





4 Discussion








5 Conclusion


2(10ndash15




Acknowledgments


References

































Journal of




Agronomy





Microbiology


























2013

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

00

20

40

60

80

100

120

Gra

in y

ield

(th

a)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)


2013

0

10

20

30

40

50

60

70

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(a)

2014

0

10

20

30

40

50

60

Har

vest

inde

x (

)

46 69 92 115 110 0

T1

T2

T3

T4

APR


(b)



4also









0

50

100

150

200

250A

E (k

g of

mai

ze1

Nkg

)

(a)

T1 T2 T3 T4 R

Time of application

0

50

100

150

AE

(kg

of m

aize

1N

kg)

(b)




14829 80 72 27360 22531 mdash 926 94 84 32031 27201 mdash 113

46 1198792

5318 82 74 27876 22558 mdash 553 103 93 35262 29944 mdash 56146 119879

35488 82 74 27930 22441 D mdash 98 88 33486 27998 D mdash

69 1198791

5695 93 84 31895 26200 mdash 967 93 84 31895 26200 D mdash46 119879

45760 69 62 23683 17923 D mdash 99 89 33775 28015 D mdash

69 1198792

6076 84 76 28760 22684 D 84 76 28760 22684 D mdash69 119879

36332 97 88 33276 26944 mdash 117 107 96 36581 30250 mdash 302

92 1198791

6448 91 82 31195 24747 D mdash 109 98 37191 30743 mdash 42369 119879

46548 76 68 25903 19355 D mdash 100 90 34276 27728 D mdash

110 119877 6659 73 66 24898 18239 D mdash 94 84 32060 25401 D mdash92 119879

26904 103 92 35129 28225 mdash 224 99 89 33858 26954 D mdash

92 1198793

7059 91 82 31155 24097 D mdash 102 91 34714 27655 D mdash115 119879

17193 94 85 32150 24957 D mdash 101 92 34647 27454 D mdash

92 1198794

7375 98 88 33477 26102 D mdash 95 85 32309 24933 D mdash115 119879

27630 95 85 32362 24732 D mdash 99 89 33764 26134 D mdash

115 1198793

7821 100 90 34079 26258 D mdash 94 85 32099 24278 D mdash115 119879

48143 86 78 29478 21335 D mdash 108 98 37071 28928 D mdash











3 and





4 Discussion








5 Conclusion


2(10ndash15




Acknowledgments


References

































Journal of




Agronomy





Microbiology



























0

50

100

150

200

250A

E (k

g of

mai

ze1

Nkg

)

(a)

T1 T2 T3 T4 R

Time of application

0

50

100

150

AE

(kg

of m

aize

1N

kg)

(b)




14829 80 72 27360 22531 mdash 926 94 84 32031 27201 mdash 113

46 1198792

5318 82 74 27876 22558 mdash 553 103 93 35262 29944 mdash 56146 119879

35488 82 74 27930 22441 D mdash 98 88 33486 27998 D mdash

69 1198791

5695 93 84 31895 26200 mdash 967 93 84 31895 26200 D mdash46 119879

45760 69 62 23683 17923 D mdash 99 89 33775 28015 D mdash

69 1198792

6076 84 76 28760 22684 D 84 76 28760 22684 D mdash69 119879

36332 97 88 33276 26944 mdash 117 107 96 36581 30250 mdash 302

92 1198791

6448 91 82 31195 24747 D mdash 109 98 37191 30743 mdash 42369 119879

46548 76 68 25903 19355 D mdash 100 90 34276 27728 D mdash

110 119877 6659 73 66 24898 18239 D mdash 94 84 32060 25401 D mdash92 119879

26904 103 92 35129 28225 mdash 224 99 89 33858 26954 D mdash

92 1198793

7059 91 82 31155 24097 D mdash 102 91 34714 27655 D mdash115 119879

17193 94 85 32150 24957 D mdash 101 92 34647 27454 D mdash

92 1198794

7375 98 88 33477 26102 D mdash 95 85 32309 24933 D mdash115 119879

27630 95 85 32362 24732 D mdash 99 89 33764 26134 D mdash

115 1198793

7821 100 90 34079 26258 D mdash 94 85 32099 24278 D mdash115 119879

48143 86 78 29478 21335 D mdash 108 98 37071 28928 D mdash











3 and





4 Discussion








5 Conclusion


2(10ndash15




Acknowledgments


References

































Journal of




Agronomy





Microbiology





























4 Discussion








5 Conclusion


2(10ndash15




Acknowledgments


References

































Journal of




Agronomy





Microbiology
























































Journal of




Agronomy





Microbiology

























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