稻麦两熟条件下不同土壤耕作方式与秸秆还田效用分析

该文通过大田小区和网室水泥池微区的3年定位试验，比较研究了稻麦两熟条件下免耕秸秆覆盖、免耕高茬、翻耕秸秆还田(秸秆稻季翻埋麦季覆盖)、翻耕(对照，CK)4个处理对土壤理化性质和稻麦产量的影响，从土壤管理技术方面探讨了不同耕作方法与秸秆直接还田在稻麦两熟地区的应用效果。结果表明：免耕使土壤容重和穿透阻力增加，而秸秆还田可改善土壤结构，提高土壤养分含量，翻耕还田3年后土壤有机质、全氮、速效磷、速效钾含量比对照分别增加4.7%～13.0%、0%～10.6%、0.2%～10.6%、8.4%～15.5%。麦季秸秆还田的产量有增有减，实际产量免耕覆盖还田略低，对照的产量较高，秸秆还田平均减产1%左右；而水稻翻耕秸秆还田的产量最高，比对照平均增产3%左右。因此，在稻麦两熟条件下，从省工节本和提高地力角度可采用稻麦免耕秸秆覆盖与留高茬还田，从提高产量和地力角度宜采用稻季翻耕秸秆还田。

Effects of tillage and straw returning on soil fertility and grain yield in a wheat-rice double cropping system

Four treatments(no-tillage straw mulching,NTS;no-tillage high stubble remaining,NTH;(conventional) tillage straw incorporation, CTS and conventional tillage no straw returning,CT) were(designed) to investigate the effects of tillage and straw returning on soil fertility and grain yield in a wheat-rice double cropping system.The experiments were conducted under field condition and by means of micro-plots in isolated concrete ponds,respectively,and lasted for consecutive three years.Results showed that no tillage increased soil bulk density and penetration resistance,but straw returning significantly improved soil structure and increased soil nutrients content.After three years straw returning,soil organic matter,total N,available P and K in CTS treatment increased by 4.7%~13.0%,0%~10.6%,0.2%~10.6% and 8.4%~15.5%,respectively,compared with that in CT.Both positive and negative effects of straw returning on wheat yield were observed over three years,but NTS and NTH decreased wheat yield,compared with CT.On the average,wheat yield decreased approximately by 1% due to straw returning.However,rice yield was the highest in CTS and increased approximately by 3%,on the average,compared with that in CT.Therefore,no tillage combined with straw mulching or high stubble remaining was practical in saving labor and cost and maintaining soil fertility,while conventional tillage with straw incorporation was a beneficial option in sustaining soil fertility and increasing crop yield.