1. Curtis Dell USDA-ARS-PSWMRU University Park, PA
Nitrous Oxide Emissions from Soils Receiving a Combination of Dairy Manure and Mineral Nitrogen Fertilizer
Curtis Dell
USDA-ARS-PSWMRU
University Park, PA

2. Nitrous Oxide (N2O)
Approximately 300 times more effective than CO2 as a greenhouse gas
Agriculture is a significant contributor
By-product of both nitrification (aerobic) and denitrification (anaerobic)
Denitrification generally believed to be largest N2O source in soils, but rates vary greatly depending on soil aeration

3. Manure Management In NE US
Large number of dairy, poultry, and swine facilities
Limited land base for manure application
Water quality problems resulting from excess P accumulations in soil
Nutrient management planning required in several NE/Chesapeake Bay states

4. Nutrient Management In NE US
Manure application in excess of plant P requirement discouraged/prohibited in many locations
A larger land base for spreading or costly waste treatment required
Combinations of manure and mineral N fertilizers used more frequently

5. Manure Applications and N2O Emissions
Greater potential for N2O production when manure is fertilizer source because of addition of organic C
Energy source for denitrifying bacteria
Stimulates activity by general microbial population, depleting O2 supply
Combinations of organic and mineral N fertilizers may have even greater potential for emissions
Organic C from manure and readily available N from mineral fertilizer

6. Objectives
Determine if N2O emissions from a corn field differ when N fertilizer is applied as NH4NO3, dairy manure,or a combination of the two.

7. Methods

8. N Source Treatments

9. N Source Treatments All mineral fertilizer
75 kg ha-1 N as NH4NO3: preplant-incorporated
75 kg ha-1 N as NH4NO3: side dress, surface
60 kg ha-1 mineral P: preplant, incorporated

10. N Source Treatments All mineral fertilizer
75 kg ha-1 N as NH4NO3: preplant-incorporated
75 kg ha-1 N as NH4NO3: side dress, surface
60 kg ha-1 mineral P: preplant, incorporated
P-based manure (31 Mg ha-1)
~75 kg ha-1 N as manure: preplant, incorporated
75 kg ha-1 N as NH4NO3: side dress, surface
~60 kg ha-1 P as manure: preplant, incorporated

11. N Source Treatments ~150 kg ha-1 N as manure: preplant, incorporated
All mineral fertilizer
75 kg ha-1 N as NH4NO3: preplant-incorporated
75 kg ha-1 N as NH4NO3: side dress, surface
60 kg ha-1 mineral P: preplant, incorporated
P-based manure (31 Mg ha-1)
~75 kg ha-1 N as manure: preplant, incorporated
~60 kg ha-1 P as manure: preplant, incorporated
N-based manure (62 Mg ha-1)
~150 kg ha-1 N as manure: preplant, incorporated
~120 kg ha-1 P as manure: preplant, incorporated

12. Vented chambers

13. Sampling and Analysis

14. Additional Measurements
Gravimetric soil water content
Soil inorganic N (2004 only)

15. Results

16. Rainfall
Source: Penn State Univ. Dept. of Meteorology

17. Soil Water Content

18. Soil Nitrate: 2004

19. N2O Emissions: 2003

20. N2O Emissions: 2004

21. Estimated Seasonal N2O Emissions

22. Conclusions
N2O emissions are potentially greater when all or part of the N was supplied by manure
Application of only manure or a combination of manure and mineral N resulted in similar emissions

23. Implications
Utilization of manures as a fertilizer source must be a accounted for in the estimation of N2O emissions from cropping systems.
Application of manure to a larger land base, even at lower rates, has the potential to increase overall annual N2O emissions.

24. Acknowledgements
Bill Priddy, MaryKay Krasinski, Dianna Sturrock, and Jessica Agnew for all their efforts in the field and lab