Koli Ann Tanksley and Edward C. Martin
Agricultural & Biosystems EngineeringThe University of Arizona
Application of Animal Manure/Compost in an Irrigated
Alfalfa Production System
The ProblemThe Problem
The recently enacted ruling (The recently enacted ruling (Unified National Unified National Animal Feeding Operation StrategyAnimal Feeding Operation Strategy ) set ) set restrictions on the application of animal waste on restrictions on the application of animal waste on agricultural lands by agricultural lands by CAFOsCAFOs..
The ruling calls for a balance between the The ruling calls for a balance between the amount of nutrients added by the manure and the amount of nutrients added by the manure and the amount used by the plants and held by the soil.amount used by the plants and held by the soil.
The ProblemThe Problem
In essence, a CAFO owner cannot apply animal In essence, a CAFO owner cannot apply animal waste in excess of the expected plant uptake and waste in excess of the expected plant uptake and the soil’s ability to hold the nutrients in the the soil’s ability to hold the nutrients in the animal waste applied.animal waste applied.
The nutrients chosen for limiting animal waste The nutrients chosen for limiting animal waste applications were nitrogen and phosphorus applications were nitrogen and phosphorus ––each state could determine which nutrient would each state could determine which nutrient would be the limiting nutrient.be the limiting nutrient.
The ObjectiveThe Objective
In Arizona, nitrogen was considered to be In Arizona, nitrogen was considered to be the limiting nutrient since surface water is the limiting nutrient since surface water is not prevalent.not prevalent.
The objective was to use manure/compost The objective was to use manure/compost in an alfalfa production system and assess in an alfalfa production system and assess whether there was nitrogen buildwhether there was nitrogen build--up in the up in the soil.soil.
N
Irrigation DitchIrrigation Ditch
Plot Plot 11CC
Plot Plot 22NN
Plot Plot 33MM
Plot Plot 44MM
Plot Plot 55CC
Plot Plot 66NN
Plot Plot 77NN
Plot Plot 88MM
Plot Plot 99CC
Plot Plot 1010CC
Plot Plot 1111NN
Plot Plot 1212MM
Repetition 1Repetition 1Repetition 2Repetition 2Repetition 3Repetition 3Repetition 4Repetition 4
L L L
Irrigation Irrigation -- AZSCHEDAZSCHED
AZSCHEDAZSCHED
ProceduresProcedures
Alfalfa was harvestedAlfalfa was harvestedYield was determinedYield was determinedHarvest was analyzed for Harvest was analyzed for nitrogen removednitrogen removedManure and compost were Manure and compost were analyzed for nitrogenanalyzed for nitrogenManure and compost were Manure and compost were added in an amount equal to added in an amount equal to the nitrogen removed by the the nitrogen removed by the cuttingcutting
DigestionDigestion
Total nitrogen in the alfalfa was Total nitrogen in the alfalfa was determined from a Kjeldahl determined from a Kjeldahl digestion that converted the organic digestion that converted the organic nitrogen to ammonium.nitrogen to ammonium.
Addition of Manure and CompostAddition of Manure and Compost
Manure and compost were added, using Manure and compost were added, using a spreader, in the amount determined to a spreader, in the amount determined to be removed in the harvest.be removed in the harvest.
Nitrogen concentration was determined by Nitrogen concentration was determined by Kjeldahl digestion and Kjeldahl digestion and KClKCl extract.extract.
Nitrogen AnalysisNitrogen Analysis
Ammonium Ammonium –– KClKCl extractextractNitrate Nitrate –– KClKCl extractextractOrganic Nitrogen Organic Nitrogen –– TKN minus TKN minus ammoniumammoniumTotal Nitrogen Total Nitrogen –– TKN plus nitrateTKN plus nitrate
ProceduresProcedures
Drainage was analyzed Drainage was analyzed for nitrogen and for nitrogen and phosphorous.phosphorous.
Soil samples were Soil samples were analyzed for nitrogen, analyzed for nitrogen, phosphorous, and phosphorous, and electrical conductivity.electrical conductivity.
RESULTSRESULTS
Alfalfa Yield and Nitrogen Alfalfa Yield and Nitrogen CompositionComposition
Total yield did not vary between Total yield did not vary between treatments.treatments.
Nitrogen removed in alfalfa harvest did Nitrogen removed in alfalfa harvest did not vary between treatments.not vary between treatments.
Average Yield
0
1000
2000
3000
4000
5000
6000
Apr 01 May 01 Jun 01 Jul 01 Aug 01 Sep 01 Nov 01 Feb 02 Apr 02 May 02 Jun 02 Jul 02 Aug 02
Month/Yr
Ave
rage
Yie
ld (k
g/ha
)
No Nitrogen Compost Manure
Alfalfa Yield
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
No Nitrogen Compost Manure
Tota
l Yie
ld (k
g/ha
)
Nitrogen Removed
0
20
40
60
80
100
120
140
160
180
Apr 01 May 01 Jun 01 Jul 01 Aug 01 Sep 01 Nov 01 Feb 02 Apr 02 May 02 Jun 02 Jul 02 Aug 02
Month/Yr
Aver
age
N R
emov
ed in
Har
vest
(kg/
ha)
No Nitrogen Compost Manure
Total N Removed for the Entire Study Period
0
200
400
600
800
1000
1200
No Nitrogen Compost Manure
Tota
l N R
emov
ed (k
g/ha
)
Manure and Compost Manure and Compost CompositionComposition
More ammonium was applied to the More ammonium was applied to the manure plots.manure plots.
More nitrate was applied to the compost More nitrate was applied to the compost plots.plots.
About equal amounts of total nitrogen About equal amounts of total nitrogen was applied to all treatment plots.was applied to all treatment plots.
Manure and Compost Manure and Compost CompositionComposition
More phosphorous was applied to More phosphorous was applied to manure plots.manure plots.
More total dissolved solids were applied More total dissolved solids were applied to manure plots.to manure plots.
Manure/Compost NO3-N Content
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
Nov 00 Apr 01 May 01 Jun 01 Jul 01 Aug 01 Sep 01 Nov 01 Feb 02 Apr 02 May 02 Jun 02 Jul 02
Ave
rage
NO
3-N
App
lied
(kg/
ha)
Manure Compost
Month/Yr
Manure/Compost NH4-N Content
0
2
4
6
8
10
12
14
16
Nov 00 Apr 01 May 01 Jun 01 Jul 01 Aug 01 Sep 01 Nov 01 Feb 02 Apr 02 May 02 Jun 02 Jul 02
Month/Yr
Ave
rage
NH
4-N
App
lied
(kg/
ha)
Manure Compost
Nitrogen Applied
050
100150200250300350400450500
Nov 00 Apr 01 Ma y 01 J un 01 J ul 01 Aug 01 S e p 01 Nov 01 Fe b 02 Apr 02 Ma y 02 J un 02 J ul 02
Month/Yr
Tota
l N A
pplie
d (k
g/ha
)
Manure Compost
Manure/Compost EC Values
0
10
20
30
40
50
60
70
80
90
100
Nov 00 May 01 Aug 01 Oct 01 Jul 02
Month/Yr
Ave
rage
Ele
ctric
al C
ondu
ctiv
ity (d
S/m
)
Manure Compost
Manure/Compost Phosphorus Concentration
0
200
400
600
800
1000
1200
1400
1600
1800
Nov 00 May 01 Aug 01 Oct 01 Jul 02
Month/Yr
Ave
rage
PO
4-P
Con
cent
ratio
n (m
g/kg
)
Manure Compost
Soil CompositionSoil Composition
Compost plots were higher in total Compost plots were higher in total nitrogen.nitrogen.
All plots were similar in ammonium.All plots were similar in ammonium.
Manure and compost plots were higher Manure and compost plots were higher in nitrate.in nitrate.
Soil CompositionSoil Composition
Manure and compost plots were higher Manure and compost plots were higher in phosphorus.in phosphorus.
All plots were similar in electrical All plots were similar in electrical conductivity.conductivity.
Total Soil NitrogenOctober 2000
0
500
1000
1500
2000
2500
3000
No Nitrogen Compost Manure
Ave
rag
e To
tal N
itro
gen
(kg
/ha)
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Total Soil NitrogenAugust 2002
0
500
1000
1500
2000
2500
3000
No Nitrogen Compost Manure
Ave
rage
Tot
al N
itrog
en (k
g/ha
)
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Soil AmmoniumOctober 2000
0
2
4
6
8
10
12
No Nitrogen Compost Manure
Ave
rage
NH
4-N
(kg/
ha)
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Soil AmmoniumAugust 2002
0
2
4
6
8
10
12
No Nitrogen Compost Manure
Ave
rage
NH
4-N
(kg/
ha)
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Soil NitrateOctober 2000
0
10
20
30
40
50
60
No Nitrogen Compost Manure
Ave
rage
NO
3-N
(kg/
ha)
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Soil NitrateAugust 2002
0
10
20
30
40
50
60
No Nitrogen Compost Manure
Ave
rage
NO 3
-N (k
g/ha
)
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Soil PhosphorusOctober 2000
0
20
40
60
80
100
120
140
No Nitrogen Compost Manure
Ave
rage
PO
4-P
(kg/
ha)
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Soil PhosphorusAugust 2002
0
20
40
60
80
100
120
140
No Nitrogen Compost Manure
Ave
rage
PO
4-P
(kg/
ha)
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Soil ECOctober 2000
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Ele
ctric
al C
ondu
ctiv
ity (d
S m
-1)
No Nitrogen Compost Manure
Soil ECAugust 2002
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Ele
ctric
al C
ondu
ctiv
ity (d
S m
-1)
No Nitrogen Compost Manure
Lysimeter ResultsLysimeter Results
Little drainage was obtained during the Little drainage was obtained during the study.study.
No detectable nitrate or phosphate was No detectable nitrate or phosphate was found in the drainage water.found in the drainage water.
ConclusionsConclusions
All treatments had the same yield and N All treatments had the same yield and N concentrations concentrations –– Thus the addition of the Thus the addition of the manure/compost had no effect.manure/compost had no effect.
Although not statistically significant Although not statistically significant –– the the no nitrogen treatment had a slightly higher no nitrogen treatment had a slightly higher yield, probably due to less surface traffic.yield, probably due to less surface traffic.
ConclusionsConclusions
Nitrogen mass balance showed that a Nitrogen mass balance showed that a substantial amount of nitrogen in the substantial amount of nitrogen in the manure plots were unaccounted for.manure plots were unaccounted for.
Even the phosphorus readings were low Even the phosphorus readings were low for the manure treatment.for the manure treatment.
Total Soil NitrogenAugust 2002
0
500
1000
1500
2000
2500
3000
No Nitrogen Compost Manure
Ave
rage
Tot
al N
itrog
en (k
g/ha
)
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Soil PhosphorusAugust 2002
0
20
40
60
80
100
120
140
No Nitrogen Compost Manure
Ave
rage
PO
4-P
(kg/
ha)
15 cm 30 cm 45 cm 60 cm 90 cm 120 cm 150 cm
Manure/Compost Phosphorus Concentration
0
200
400
600
800
1000
1200
1400
1600
1800
Nov 00 May 01 Aug 01 Oct 01 Jul 02
Month/Yr
Ave
rage
PO
4-P
Con
c. (m
g/kg
)
Manure Compost
Manure DiscrepanciesManure Discrepancies
The low values for nitrogen and The low values for nitrogen and phosphorus in the soil manure plots phosphorus in the soil manure plots suggests that manure was lost somehow.suggests that manure was lost somehow.
Reports from the farm manager indicated Reports from the farm manager indicated that the hay was “dirty” and “not salable” that the hay was “dirty” and “not salable” because of the manure chunks in the bales. because of the manure chunks in the bales.
Manure DiscrepanciesManure Discrepancies
One theory was that the manure was One theory was that the manure was physically removed from the plots, thus physically removed from the plots, thus causing lower than expected values.causing lower than expected values.
The other is that the manure is still there The other is that the manure is still there and sitting on the surface.and sitting on the surface.
LongLong--term Projectionsterm Projections
Nitrogen increases in the treated plots may Nitrogen increases in the treated plots may threaten groundwater qualitythreaten groundwater quality
Phosphorous increase may threaten Phosphorous increase may threaten environmental qualityenvironmental quality
Questions?Questions?