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MANAGING CLOVER AND POULTRY LITTER FOR PECAN PRODUCTION
Lenny WellsUGA Horticulture
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Poultry Litter & Clover as a Fertilizer Source for Pecan
• Ponder Farm—Tifton/ Solid Set Irrigation• ~25 year old ‘Desirable’ trees• 4 treatments/ 6 replications/ RCB• Single Tree Plots/Border Trees between treatments
1. ‘Dixie’ Crimson Clover 30 lbs/Acre planted in November ‘07
2. Poultry Litter1 ton/Acre
3. Clover+Poultry Litter4. Ammonium Nitrate (75 lbs N/A)
5. Untreated Control (2009)
All Litter & Fertilizer Application Made in April
In 2009, untreated control added (3 reps)
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• Poultry Litter Analysis Year 1:
75 lbs N; 30 lbs K; 16 lbs P; 0.44 lbs Zn
Year 2:
60 lbs N; 62 lbs P; 68 lbs K; 0.58 lbs Zn
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Effect of Poultry Litter and Clover on Leaf Elemental Analysis of ‘Desirable’ Pecan
Year 1 (2008)
Treatment N P K Mg Ca S B Zn Mn Fe Cu
Poultry Litter
2.52a 0.15a 1.38a 0.54a 1.56a 0.23a
39a 98a 193a
83a 8.5a
Crimson Clover
2.41a 0.15a 1.20b
0.46b 1.49a 0.22a
32b 98a 325a
106a 8.8a
Litter + Clover
2.44a 0.15a 1.46a 0.46b 1.45a 0.23a
36ab
91a 143a
117a 8.8a
Ammonium Nitrate (75 lbs N/acre)
2.57a 0.16a 1.45a 0.43b 1.39a 0.23a
35b 75a 161a
198a 8.2a
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Effect of Poultry Litter and Clover on Leaf Elemental Analysis of ‘Desirable’ Pecan --Year 2 (2009)
Treatment N P K Mg Ca S B Zn Mn Fe Cu
Poultry Litter
2.63a 0.147ab
1.34a 0.49a 1.54ab
0.22b 37a 73ab
265b
111b 9.3a
Crimson Clover
2.67a 0.145b 1.28a 0.46b 1.69a 0.22b 36a 92a 637a
97b 9.5a
Litter + Clover
2.96a 0.153a 1.28a 0.5a 1.68ab
0.24a
38a 83ab
372b
156a 9.5a
Ammonium Nitrate (75 lbs N/acre)
2.66a 0.145b 1.26a 0.47ab
1.52b 0.21b 33a 64b 226b
95b 8.1b
Untreated 2.67a 0.15ab 1.27a 0.44b 1.58ab
0.22b 33a 63b 184b
111b 7.8b
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Clover Tissue Analysis
Treatment % N % P % K Zn ppm
Crimson Clover
1.98a 0.25a 1.25a 59.35a
Litter + Clover
2.63b 0.26a 2.80b 62.09a
Treatment % N % P % K Zn ppm
Crimson Clover
1.98a 0.10a 1.63a 64.2b
Litter + Clover
2.63b 0.13b 1.74b 52a
May 2008
May 2009
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Mycorrhizae– Fungi colonizing the
roots of plants
• Mycorrhizal associations enable trees to compete for limited resources
• Pecan seedlings inoculated with mycorrhizae have >uptake of N,P, K, Ca, Mg, Cu, and Mn (Sharpe and Marx, 1986)
• Conditions favorable for mycorrhizal development:
– High organic matter– High light intensity—related to
carbohydrate production– Adequate soil moisture
N, P, K, Ca, etc.
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Effects of Clover/Litter on Soil MIP
0
10
20
30
40
50
MIP
(%
Co
lon
iza
tio
n)
2008 2009
Clover Litter Litter+cloverFertilizer Untreated
MIP=Mycorrhizae Inoculum Potential Bioassay using sweet corn as host plant
a
abab
ba
b abbb
MIP determines suitability of soil for mycorrhizal colonization of roots
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Soil Respiration
0
0.2
0.4
0.6
0.8
1
Soil CO2 (mg/g)
2008 2009
Clover Litter Litter+CloverFertilizer Untreated
a aab
bcc
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Phosphorous Availability
0
2
4
6
8
10
12
Ph
os
ph
ota
se
(mM
ol/g
so
il/ h
r)
Clover Litter Litter+CloverFertilizer Untreated
abc ab abc
c
a ab
b b
Clover roots produce phosphotase
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Effect of Poultry Litter and Clover on ‘Desirable’ Pecan
Treatment N Cost/A
Percent Kernel(2008)
Percent Kernel(2009)
Yield/tree(2008)
Yield/tree(2009)
2 Year Avg Yield/tree
Poultry Litter $35 54a 51.7a 92.7a 122ab 107.4a
Crimson Clover $40* 53.4a 50.8a 94.7a 86ab 90.4ab
Litter + Clover $75* 52a 50.3a 87a 84b 85.5b
Ammonium Nitrate (75 lbs N/acre)
$75 52.4a 52.1a 62a 129a 95.5ab
Untreated $0 --- 52.6a --- 130a ---
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Conclusions
• A single application of 1 ton poultry litter/acre appears to provide adequate N for pecans
• Clover alone may provide enough N for pecans in the second year after establishment
• Clover can remove significant P, K, and Zn from orchard soils• Clover can bring otherwise unavailable P into the feeder root
zone• Microbial activity in pecan orchard soil is higher where clover
is grown or litter is applied than where ammonium nitrate is used
• No Salmonella spp. recovered from poultry litter or orchard soil in any treatment from application through harvest
Fertilizer studies on pecan require multiple (4-6) years to get accurate interpretation of results
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2009 Soil Mineralization Tubes
2” PVC8” longRemove at 0, 30, 60, 120, 240, and 330 days after treatmentTest Soil Core NO3, NH4
When is N from clover and poultry litter available to pecan trees?
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• Plots established for 1 full year before tubes are set
• Tubes placed in orchard immediately after application of fertilizer/manure
(April 2009: clover blooming but not yet at peak bloom)
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-80-60-40-20
020406080
0 days 30 days 60 days 120days
240days
Ch
an
ge
in S
oil
NO
3+
So
il N
H4
(lb
s/a
)
Clover Litter/Clover LitterAmm Nitrate UT
Nitrogen Availability
This change related to loss of NH4
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-40
-20
0
20
40
60
80
0 days 30 days 60 days 120days
240days
Ch
an
ge
in S
oil
NO
3
(lb
s/a
cre
)
Clover Litter/Clover LitterAmm Nitrate UT
Nitrogen Availability
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Management Conclusions• Most N from synthetic N is utilized or lost within 1st
60 days after application• Poultry Litter provides adequate season long N for
pecan• Use synthetic N for early spring N needs and clover
for late season• Clover can provide adequate N for pecans; Best used
as a N supplement; • The longer clover is in the orchard, the more it can
be relied upon• Monitor P, K, and Zn where clover is planted