Abstract: To investigate the effects of different tillage and straw management on soil nutrients, enzyme activities and microbial community structure, a field experiment was conducted at two experimental stations in Lanxi and Jinhua in 2016.The experiment consisted of four treatments with three replicates arranged in a completely randomized design: shallow tillage (tillage depth 1012 cm) without straw, shallow tillage with straw incorporation,deep tillage (tillage depth 1820 cm) without straw and deep tillage with straw incorporation. Soil nutrients, enzyme activities, phospholipid fatty acid (PLFA) content and microbial community composition were determined. It was shown that addition of straw in topsoil increased the contents of soil alkali-nitrogen and Olsen phosphorus, but there were no significant differences in pH, available potassium and organic matter contents among treatments. Straw incorporation at the same tillage depth increased rice grain yield, but tillage depth with the same straw management had no significant effect on rice grain yield. Increasing tillage depth or addition of straw in topsoil increased the activities of soil acid phosphatase and β-glucosidase. There were no significant differences on Shannon index among treatments. Straw incorporation at the same tillage depth increased total PLFA, bacterial PLFA and fungal PLFA, but deep tillage with the same straw incorporation decreased fungal PLFA. Straw incorporation with proper tillage depth was an effective management measure to increase soil nutrients, soil enzyme activities, contents of soil microbes, and consequently grain yield.

Key words: straw-returning, tillage depth, soil enzyme, phospholipid fatty acid