Surface wind speeds and simulated rainfall on GHG emission from stockpiled dairy manure: a laboratory study

Abstract.

In a common dairy farming system in China, solid manure is typically stored on the farm from days to months before land application, making it an important source of greenhouse gases (CO2, CH4 and N2O) and ammonia (NH3) emissions, and the emissions may be directly affected by the environment, air temperature, wind speed and rainfall in particular. A laboratory experiment was conducted to explore the influences of surface wind speeds (0.5, 0.8, 1.2 and 1.6 m•s-1) and simulated rainfall on GHG and NH3 emissions from stockpile of dairy manure. Results indicated that wind speeds had different influences on CO2, N2O and CH4 emissions. NH3 emission was significantly smaller under lower wind speed (<0.5 m•s-1), and it was kept relatively stable at higher wind speeds (0.8, 1.2 and 1.6 m•s-1). The emissions of CO2 and CH4 from simulated manure storages decreased instantly after rainfall operation and rebounded consequently, where CO2 emission took longer time for returning to previous level. The simulated rainfall resulted in a sharp increasing of N2O emission and then the emission decreased to previous level for 6-10 h. No significant influence was found of rainfall operation on NH3 emission.