Agricultural BMPs to Reduce N Emissions

Jessica G. DavisColorado State University

Types of BMPs• Livestock Producers

– Nutrition– Production site– Manure storage and treatment– Land application of manure

• Crop Producers– Fertilizer management practices

BMPs: Nutrition—Basic Principles

• Don’t overfeed protein• Analyze feeds regularly• Phase feeding

– By growth stage– By sex– By productivity

• PRECISION FEEDING

0

2

4

6

8

10

12

14

16

C L LMTT

Am

mo

nia

em

itte

d (

g)

Day 3Day 2Day 1

12.5%

55.4%

BMPs: Nutrition--swine

Wendy Powers, Iowa State University

BMPs: Nutrition--Feedlot Cattle•Cole et al. (2005) found that increasing crude protein in feeder diets from 11.5 to 13.0% resulted in increases in NH3 loss from 60-200%

BMPs: Nutrition—Dairy (NH3 loss from slurry applied to soil)

Feeding trial

type Trial

components

Slurry type

Fresh Stored

% applied N lost as ammonia

13.6% 31b 12b Crude Protein level

19.4% 68a 29a

Misselbrook et al., 2005 (lab study)

BMPs: Nutrition--layers

•Diet acidification minimizes volatilization of ammonia by acidifying excreta

050

100150200250300350400450500

Daily NH3emissions, g

per bird

Control

Acidified

Wendy Powers, Iowa State University

42%

BMPs: Livestock Production Site• Dust control

– Frequent manure harvesting– Pen moisture management

• Stocking density• Watering

– Reduce surface pH

Manure harvested within previous 3 days, < 1” deep

Wind

Manure not yet harvested, > 2” deep

Manure Harvesting

Pen Moisture

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Moisture Content (%wb)

Du

st/O

do

r P

ote

nti

al

Dust Odor

Dust and odor events are driven principally by the effect of short-term weather patterns on the moisture content of the manure pack on the corral surface.

Fee

d ap

ron

1 2 3 4

Moisture Dynamics Vary Within Corrals

Water trough

High activity;High moisture

Low activity;Low moisture

BMPs: Livestock Production Site

•Feedlot Surface–Application of a urease inhibitor onto the feedlot surface every 8 days reduced NH3 loss from 49-69%–Lab study by Parker et al. (2005)

Washing Wall• 33-50% reduction in NH3 loss

Biofilter• Reduces NH3 loss 50-60%

Alum in Broiler Litter

Ammonia loss

0

2

4

6

8

10

12

14

16

Control 100 g/kg alum 200 g/kg alum

Treatment

Lo

ss

(g

/kg

)

Annual loss of ammonia nitrogen100 heifers using different beddings

0

200

400

600

800

1000

1200

Chopped corn stalks

Composted manure solids

Chopped newspaper

Chopped straw

Pine shavings

Sand

N lo

ss (

lbs)

Misselbrook and Powell (2005)

Bedding types--Dairy

BMPs: Manure Storage and Treatment

• Minimize storage time• Cover piles and lagoons• Divert rainfall and runoff from

stockpiles• Aerobic lagoons reduce

gaseous N loss and conserve N• Constructed wetlands increase

N2O loss (denitrification)• Aerobic/anaerobic alternating

lagoons increase N2O loss • Anaerobic digestors conserve N

Dairy Lagoons•A self-forming crust on dairy lagoons reduced NH3 loss by ~50% (Misselbrook et al., 2005)

•Composting•Composting feedlot manure with different beddings

–Straw bedding -- 42% N lost–Wood chip bedding—12% N lost

–There was little difference in N2O loss; apparently, the difference was mainly in NH3 loss.

–(Hao et al., 2004)

BMPs: Land Application of Manure• Incorporate immediately after

application• Injection of slurries• Drop nozzles for sprinkler

irrigation

BMPs: Fertilizer Management• Fertilizer Selection

– In general, dry fertilizers have less NH3 loss.

– In calcareous soils, ammonium nitrate has the lowest amounts of NH3 loss.

• Ammonium sulfate has the highest loss.• Urea is moderate.

• Application Method– Band N fertilizers to reduce NH3

loss.– Broadcasting increases N loss.

• Fertilizer Application Rate– Higher rates result in higher N loss.– Use agronomic rates.

BMPs: Fertilizer Management• Timing

– Synchronize application with crop demand.

– Use slow-release fertilizers.

• Soil Properties– NH3 loss is greatest in

• Sandy, low organic matter soils• High temperatures• Moist soil conditions—Don’t over-

irrigate!

• Tillage Practices– No-till increases N loss due to

reduction in both soil evaporation and infiltration of fertilizers.

Impact of improved management on reductions in ammonia emission from dairy farms

Together these management practices can reduce ammonia N loss by 65-70%.

Mark Powell, USDA-ARS, Madison, WI

Management practice Mechanism for decrease ammonia loss

Decrease in ammonia loss (%)

Remove excess and/or feed balanced dietary protein

Decrease N output in urine

10 to 15

Cover manure storage Decrease ammonia escape

20 to 30

Incorporate or inject manure

Reduce ammonia production and loss

30 to 50

Future Needs

•Thorough literature review–Cost of BMPs–Effectiveness of BMPs

•BMP adoption rates•Decision tree to help agricultural producers choose appropriate BMPs