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

Abstract

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.