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 CO2 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 CO2 efflux and temperature, with Q10 values in a range of 2.6–3. CO2 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 CO2 efflux in the cropland of North China Plain.

中文翻译：

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生物炭改良和秸秆还田对土壤异养呼吸和土壤有机碳解吸的影响

虽然生物炭改良剂和秸秆掺入土壤由于具有固碳和改善土壤理化性质的潜力而受到广泛关注，但关于它们在季节周期内对土壤异养呼吸的影响的研究有限。在此，我们进行了田间试验，评估生物炭改良和秸秆掺入对华北平原土壤异养呼吸和土壤有机碳（SOC）解吸的时间变化的影响。我们在现场测量了一年内的二氧化碳流出量，以及水可提取有机碳 (WEOC) 和土壤微生物生物量碳 (SMBC)。我们的研究表明，CO2 流出量与温度之间存在显着的指数关系（P < 0.001），Q10 值在 2.6-3 范围内。夏季，秸秆掺入（5.66 μmol m−2 s−1）下的二氧化碳流出量显着高于生物炭改良（3.54–3.92 μmol m−2 s−1）和无改良（3.76 μmol m−2 s−1）下。我们发现，与秸秆掺入和无改良相比，生物炭改良后的 WEOC:SOC 比率和 SMBC:SOC 比率显着降低。我们的研究表明，生物炭改良剂在减少华北平原农田的SOC解吸和CO2外排方面具有更大的潜力。