See more from this Session: Virtual Posters
Sunday, October 31, 2010
Long Beach Convention Center, Outside Room 204, Second Floor, Virtual Posters
Hog manure is a valuable nutrient source in crop production but significant gaseous emissions of methane (CH4) and carbon dioxide (CO2) may occur at land-application. In a field trial study on a winter wheat crop (cv. Alchemy) at UCD Lyons Farm, gaseous emissions of CH4 and CO2 post land-application of hog manure were investigated. Two manures types were tested containing either a high (HN) or low (LN) nitrogen content. Grower-finisher pigs were assigned to one of two diets; a high crude protein (CP) diet (230g/kg) and a low CP diet (160g/kg) to generate the manures. In a 2 x 3 factorial experimental design the manure products were applied to a winter wheat crop at three timings; growth stage (G.S) 25 (T1), G.S 30-31 (T2) and G.S 37-39 (T3), at a rate of 30 m3/ha using a 6 meter band spread applicator to plots 30m x 24m. Gaseous fluxes were measured using the static chamber technique at 1-3 day intervals for 4 weeks post manure application. Significantly higher CH4 emissions were measured from the HN manure treatments (19.41 vs. 11.88 gCH4-C/ha/day) while CO2 emissions were unaffected by manure type. Greatest CH4 and CO2 emissions were measured immediately post-manure application with loss rates returning to background levels within 24 hours. Highest CH4 emissions were measured at T1 (range 3.81-28.92 gCH4-C/ha/day) while peak CO2 emissions were recorded at T3. Thus, it was concluded that CH4 was formed during storage and a longer storage period prior to application at T1 (7 weeks) - led to higher emissions than those measured at T2 (3 weeks) and T3 (2 weeks) while higher CO2 emissions were due to increased plant respiration rates at more advanced G.S. Therefore, dietary manipulation is a useful technique for CH4 emission reduction while CO2 emissions tended to increase with advancing growth stage.