Greenhouse Gas Emissions and Ryegrass Yield after Application of Solid-Liquid Pig Slurry and Biochar to an Agricultural Soil

Background The application of animal slurry to the soil improves its quality, as manure contains many nutrients for plants. However, this could negatively impact the environment. Objective This field study investigated the effects of the addition of biochar after the mechanical separation of Whole pig Slurry (WS) into Solid (SF) and Liquid Fractions (LF) on Greenhouse Gases (GHG) emissions (N 2 O, CO 2, and CH 4 ) and ryegrass ( Lolium multiflorum Lam. cv magnum) yield. Methods Biochar (1.0 kg m -2 ) was applied in plots alone or together with each of the three slurries (80 kg N ha -1 ) in a total of eight treatments with three replications, including just soil with and without biochar as controls. Soil properties, Greenhouse Gas (GHG) fluxes, and yield were measured during theautumn/winter growing season. Results The results showed that the addition of biochar to these three slurries significantly increased the soil pH and showed no impact on the other physicochemical properties. The GHG emissions were not significantly different between treatments with and without biochar. The N use efficiency increased significantly in SF > WS > LF, whereas no differences were observed among these three slurries with and without biochar. Conclusion It can be concluded that the addition of biochar combined with WS or SF/LF to sandy-loam soil appears to have no impact on GHG emissions and ryegrass yield during the autumn/winter season. Overall, this finding suggests that amounts higher than 1.0 kg m -2 of biochar combined with SF may need to be applied to soil to reduce GHG emissions and nitrate leaching and increase N use efficiency and crop yield.