生物质炭施加对水-旱轮作农田土壤CO_2排放及碳库的影响

Effects of Biochar on Soil CO_2 Emissions and Carbon Pool in Rice-Wheat Rotation Croplands

选择典型亚热带稻-麦轮作农田,比较不同施加量的玉米芯生物质炭对作物产量、土壤理化性质和CO_2排放的影响,并结合同位素分析研究了生物质炭的分解程度及其在水作影响下的田间存留量。结果显示,施加生物质炭显著增加了土壤阳离子交换量和总有机碳含量,降低了土壤CO_2排放速率。δ^(13)C数据表明,生物质炭在施加初期被快速分解,对土壤CO_2排放的短期贡献率可达35.95%,但一个生长季后分解微弱;生物质炭在水田中流失明显,一个轮作周期后的田间存留率为17.33%~36.50%。结果表明,生物质炭可提升亚热带水-旱轮作农田土壤碳库并降低土壤CO_2排放速率。

This study analyzed the effects of corncob-made biochar applied at different rates on crop yield, soil physicochemical properties and CO2 fluxes in typical rice-wheat rotation croplands in tropical China. The degradation of biochar and the retainment of biochar in soil under irrigation were also investigated by isotopic analysis. The results indicated that biochar addition significantly increased soil cation exchange capacity and total organic carbon content, but significantly decreased soil CO2 emission rates. Isotopic data （δ^13C） indicated that biochar was rapidly decomposed at the early stages after application, with a short-term contribution of 35.95% to total CO2 emission; however, the decomposition of bioehar became negligible after one growing season. There was evident loss of biochar in these irrigated paddy rice croplands, with only 17.33% -36.50% of applied biochar retained in soil after one rice-wheat rotation cycle. Overall, this study revealed that biochar can increase soil carbon stocks and decrease soil CO2 emission in tropical rice-wheat rotation croplands.