Quantification of Greenhouse Gas Emissions from Soil Applied Swine Effluent by Different Methods

Abstract

Greenhouse gas (CO2, CH4, and N2O) emissions were measured from a field experiment in which pre-plant swine effluent application methods were evaluated for no-till corn grain production. The treatments included a control, an inorganic fertilizer treatment that received 179 kg N/ha as urea ammonium nitrate (UAN), and three methods of swine effluent application at a rate of 200 kg N/ha through surface application with no incorporation, direct injection, and application in combination with soil aeration. Gas emission measurements were initiated directly after application and were collected throughout the growing season (141 d) using a vented chamber technique. There were no significant differences in CO2 losses, which averaged 738 g CO2/m2. Methane emissions from the effluent injection and aeration treatments were 0.26 and 0.21 g CH4/m2. A significantly lower loss of 0.12 g CH4/m2 was measured from the surface applied effluent, which was elevated compared to control and fertilizer treatments that lost 0.06 and 0.08 g CH4/m2. Nitrous oxide emissions were similar for the fertilizer, surface effluent application, and aeration effluent application treatments; emitting 0.74, 0.73, and 0.69 g N2O/m2, respectively. The effluent injection treatment emitted 0.47 g N2O/m2, which was not significantly different from the control treatment that emitted 0.24 g N2O/m2. Therefore, liquid manure application method needs to be considered when evaluating the impacts of liquid manure management on atmospheric greenhouse gas concentrations.