稻麦秸秆全量还田的产量与环境效应及其调控

秸秆还田是一项土壤培肥、实现农业可持续发展的重要措施,但稻秆还田经济效益低、增产效应不显著以及一些环境负效应,影响了该措施的推广。本文结合本课题组研究工作,综述了国内外近期的相关研究进展,就稻麦秸秆全量还田的产量效应、秸秆腐解特性与环境效应及其调控进行了分析。研究表明,秸秆还田能提高土壤肥力,增加稻麦产量,且增产效应随还田时间延长而增加;稻季麦秸/油菜秸的腐解率在50%~66%,其N、P、K养分释放率分别为42%~58%、55%~68%和92%~98%;秸秆还田能显著提高农田碳固定、减少径流损失,但也增加了稻田甲烷排放、氨挥发以及渗漏的养分损失。提高秸秆还田效益的调控措施有:增加稻麦前期氮肥施用比例,适当减少总的氮肥、磷肥用量,大幅减少钾肥用量;秸秆尽量在麦季还田、稻季采用湿润灌溉可减少甲烷排放。

Regulation and effect of 100% straw return on crop yield and environment

Incorporation of crop straw into the soil is an major soil management practice that improves soil fertility for sustainable agriculture. However, its application is severely hindered by low economic efficiency, low yield and negative environmental effects. This paper reviewed the effects of returning 100% of crop straw into the soil on crop yield, the mechanism and characteristics of straw decomposition, and environmental effects and regulation of straw return. For this purpose, the paper reviewed a huge number of published scientific research papers on the progresses of the effects of crop straw return into the soil. The results showed that 100% straw return improved soil fertility and increased yield of wheat and rice, which increased with increasing time of straw return. The decomposition rates of wheat and rape straws were 50%?66% during rice growing season, respectively releasing 42%?58%, 55%?68% and 92%?98% of total straw nitrogen (N), phosphorous (P) and potassium (K) into the soil. Straw return significantly increased soil organic carbon storage and reduced runoff loss. However, it enhanced CH4 emission, ammonia volatilization and nutrient loss through leaching. In order to mitigate the negative effects of straw return on economic growth and the environment, it was necessary to increase the proportion of N fertilization at the early stage of rice and wheat growth, properly reduce the N fertilization dose during whole growing season, and reduce P fertilization and especially K fertilization rates. In order to reduce CH₄ emission, it was recommended to apply straw return during dry periods and use intermittent flood/moist irrigation during rice growing season.