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
Top Related