1. Agricultural BMPs to Reduce N Emissions Jessica G. Davis Colorado State University

2. Types of BMPs Livestock Producers –Nutrition –Production site –Manure storage and treatment –Land application of manure Crop Producers –Fertilizer management practices

3. BMPs: Nutrition—Basic Principles Don’t overfeed protein Analyze feeds regularly Phase feeding –By growth stage –By sex –By productivity PRECISION FEEDING

4. 12.5% 55.4% BMPs: Nutrition--swine Wendy Powers, Iowa State University

5. 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 NH 3 loss from 60-200%

6. BMPs: Nutrition—Dairy (NH 3 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)

7. BMPs: Nutrition--layers Diet acidification minimizes volatilization of ammonia by acidifying excreta Wendy Powers, Iowa State University 42%

8. BMPs: Livestock Production Site Dust control –Frequent manure harvesting –Pen moisture management Stocking density Watering –Reduce surface pH

9. Manure harvested within previous 3 days, < 1” deep Wind Manure not yet harvested, > 2” deep Manure Harvesting

10. Pen Moisture 0 10 20 30 40 50 60 70 80 90 100 0102030405060708090100 Moisture Content (%wb) Dust/Odor Potential DustOdor 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.

11. Feed apron 1234 Moisture Dynamics Vary Within Corrals Water trough High activity; High moisture Low activity; Low moisture

14. BMPs: Livestock Production Site Feedlot Surface –Application of a urease inhibitor onto the feedlot surface every 8 days reduced NH 3 loss from 49-69% –Lab study by Parker et al. (2005)

15. Washing Wall 33-50% reduction in NH 3 loss

16. Biofilter Reduces NH 3 loss 50-60%

17. Alum in Broiler Litter

18. Annual loss of ammonia nitrogen 100 heifers using different beddings Chopped corn stalks Composted manure solids Chopped newspaper Chopped straw Pine shavings Sand N loss (lbs) Misselbrook and Powell (2005) Bedding types--Dairy

19. 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 N 2 O loss (denitrification) Aerobic/anaerobic alternating lagoons increase N 2 O loss Anaerobic digestors conserve N

21. Dairy Lagoons A self-forming crust on dairy lagoons reduced NH 3 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 N 2 O loss; apparently, the difference was mainly in NH 3 loss. –(Hao et al., 2004)

22. BMPs: Land Application of Manure Incorporate immediately after application Injection of slurries Drop nozzles for sprinkler irrigation

24. BMPs: Fertilizer Management Fertilizer Selection –In general, dry fertilizers have less NH 3 loss. –In calcareous soils, ammonium nitrate has the lowest amounts of NH 3 loss. Ammonium sulfate has the highest loss. Urea is moderate. Application Method –Band N fertilizers to reduce NH 3 loss. –Broadcasting increases N loss. Fertilizer Application Rate –Higher rates result in higher N loss. –Use agronomic rates.

25. BMPs: Fertilizer Management Timing –Synchronize application with crop demand. –Use slow-release fertilizers. Soil Properties –NH 3 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.

26. 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

27. Future Needs Thorough literature review –Cost of BMPs –Effectiveness of BMPs BMP adoption rates Decision tree to help agricultural producers choose appropriate BMPs