application of animal manure/compost in an irrigated ...manure/compost in an irrigated alfalfa...

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


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)


Total N Removed for the Entire Study Period

0

200

400

600

800

1000

1200


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


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


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


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


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


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


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


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


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


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)


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)


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


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


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


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?

application of animal manure/compost in an irrigated ...manure/compost in an irrigated alfalfa...

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