秸秆还田少免耕对冲积土微生物多样性及微生物碳氮的影响

Effects of Straw Mulching and Little-or Zero-tillage on Microbial Diversity and Biomass C and N of Alluvial Soil in Chengdu Plain,China

土壤微生物是耕地质量的重要指标,为阐明秸秆还田少免耕对土壤质量的影响及其机理,在成都平原(温江)冲积水稻土区,开展了水稻–小麦/油菜轮作秸秆还田培肥定位试验(2003～2008年),在小麦生长季节,系统研究了土壤耕层微生物数量和微生物生物量的变化特征.结果表明,秸秆还田翻耕与秸秆还田免耕的土壤耕层微生物总量分别增加了51.7%、12.8%,土壤微生物数量增加主要来自土壤细菌数量的增加;从小麦全生育期看,在小麦分蘖期的增加幅度高于小麦播种期和小麦收获后,有利于促进小麦养分吸收与生长发育.秸秆还田少免耕显著增加了微生物生物量,秸秆还田翻耕和秸秆还田免耕处理土壤微生物碳总量分别比对照提高74.1%、25.8%,土壤微生物氮分别提高60.2%和12.1%.秸秆还田循环利用显著增加了土壤微生物数量和生物量,有利于土壤养分循环与转化,有利于提高土壤有机质含量并改善有机质质量,是耕地质量建设的重要途径.

Soil microbes are considered one of the most important indexes of soil quality.Aiming to illustrate the mechanism and effect of straw mulching and little-or zero-tillage on soil quality,the changes in soil microbial composition,microbial biomass C and N,and soil fertility in paddy soils in the Chengdu Plain（Wenjiang County,Sichuan,China） were investigated through a fixed field experiment on rice and wheat/rape rotation（2003～2008）.The results indicated that because of the increase of soil bacteria after straw mulching,the total microorganisms of ST（straw mulching and tillage） soil and SNT（straw mulching and no-tillage） soil increased by 51.7% and 12.8%,respectively,than CK（no straw mulching and tillage）,which can improve rates of straw decomposition and nutrient release.Meanwhile,the total soil microorganisms changed at different growth stages of wheat,and the soil microorganisms at tillering stage were significantly more than those at seeding stage and maturity stage.The soil microbial biomass C of ST and SNT increased by 74.1% and 25.8%,respectively,and the soil microbial biomass N of ST and SNT increased by 60.2% and 12.1% as well,compared with the CK.Therefore,straw mulching can increase soil microbial composition and biomass remarkably,promote soil nutrient circulation and translation,increase soil organic matter content,and improve soil quality.