Impacts of biochar amendment and straw incorporation on soil heterotrophic respiration and desorption of soil organic carbon

Abstract While biochar amendment and straw incorporation in soil have received great attention due to the potential of carbon sequestration and improvements in soil physicochemical properties, there were limited studies addressing their impacts on soil heterotrophic respiration over a seasonal cycle. Here, we conducted a field experiment to evaluate the effects of biochar amendment and straw incorporation on the temporal variations of soil heterotrophic respiration and desorption of soil organic carbon (SOC) in the North China Plain. We measured CO 2 efflux over 1-year period in the field, together with water extractable organic carbon (WEOC) and soil microbial biomass carbon (SMBC). Our study showed a significant exponential relationship ( P < 0.001) between CO 2 efflux and temperature, with Q 10 values in a range of 2.6–3. CO 2 efflux was significantly higher in summer under straw incorporation (5.66 μmol m −2 s −1 ) than under biochar amendments (3.54–3.92 μmol m −2 s −1 ) and without amendment (3.76 μmol m −2 s −1 ). We found significantly lower WEOC:SOC ratio and SMBC:SOC ratio under biochar amendments than with straw incorporation and without amendment. Our study indicated that biochar amendment had a greater potential for reducing SOC desorption and CO 2 efflux in the cropland of North China Plain.