Short-term effects of biochar amendment on greenhouse gas emissions from rainfed agricultural soils of the semi–arid loess plateau region

Abstract

In rainfed agricultural ecosystems in northwest China, improving soil fertility and reducing greenhouse gas (GHG) emissions are key factors for developing sustainable agriculture. This study determined the short-term effects of different biochar amendment rates on diurnal and seasonal variations of GHG emissions in the Loess Plateau to produce a background dataset that may be used to inform nutrient management guidelines for semiarid environments. Biochar produced by pyrolysis at 300–500 ◦C from maize straw was applied at rates of 0, 10, 20, 30, 40, and 50 t ha−1 (T0, T1, T2, T3, T4, T5), respectively. The results indicated that in the first year after the application, T3, T4, and T5 treatments increased soil organic carbon (0–10 cm) by 54.7%, 56.3%, and 56.9% compared to the other treatments. In the first, year, biochar amendment decreased diurnal CH4 and N2O flux by an average of 17–119% compared to T0, among which T3 had the lowest mean value. T3 and T4 also had similar mean CO2 flux, which was 33% lower than T0. Application of 30 t ha−1 biochar produced the lowest cumulative CO2 and N2O emissions of 2300 and 4.07 kg h−1, respectively. Biochar amendment showed no effect on grain yiel but reduced the global warming potential and GHG emission intensity by an average of 23% and 25%, respectively. The biochar application rate of 30 t ha−1 under the conditions of this study may be an appropriate rate for improving soil C sequestration and mitigation of GHG emissions in the first year after its application to soils on semi–arid Loess Plateau.