少免耕对小麦/玉米农田玉米还田秸秆腐解的影响

Effect of less tillage and no-tillage patterns on decomposition of returned maize straw in wheat/maize system

为了研究高产灌溉条件下土壤耕作模式对还田玉米秸秆腐解的影响,在山东龙口采用4种土壤耕作模式(常规耕作秸秆还田、旋耕秸秆还田、耙耕秸秆还田、免耕秸秆覆盖)进行了一年两季田间试验,测定了秸秆腐解率、秸秆腐解速率和秸秆的纤维素含量。结果表明:秸秆腐解速率与土壤温度具有显著的相关性。旋耕秸秆还田和耙耕秸秆还田两种少耕模式和常规耕作秸秆还田模式的秸秆腐解率、平均秸秆腐解速率无显著差异,说明少耕模式并不因减少耕作程序而降低作物秸秆在田间的腐解。免耕模式的秸秆腐解率和腐解速度显著低于以上3种耕作模式,经过小麦和玉米两个生长季节后仍有37.78%的玉米秸秆剩余,而且秸秆中纤维素质量分数为20.69%,腐解质量差,会对下年作物的出苗产生影响。

In order to research the effects of soil tillage pattems on decomposition of returning crops straw in wheat/maize farmlands of the irrigated high-yield farmland, four tillage patterns were adopted in Longkou city, Shandong Province, China for a whole year including winter wheat and maize growth seasons. Four tillage patterns were as follows： conventional tillage with straw returned （CS）, rotary tillage with straw returned （RS）, disk harrow tillage with straw returned （HS）, no-tillage with straw covered （NC）. Decomposition rate, decomposition speed and cellulose content of the returned straw were investigated. Results showed that the decomposition speed of the returned straw and soil temperature had a significant correlation; there was no significant difference between the decomposition rate of returned straw of RS, HS and CS, and it was the same case with decomposition speed of returned straw. Those phenomena showed that the two minimum tillage patterns （RS and HS） had not reduced straw decomposition because of reduced tillage compared with conventional tillage （CS）. While decomposition rate and decomposition speed of returned straw of NC were significantly lower than those of CS, RS and HS. After the wheat growth season and maize growth season, 37.78% of the returned straw whose cellulose content was 20.69% was still remained, which may affect the emergence of wheat in the next year.