Effects of Different Tillage, Straw Returning and Transplanting Methods on Paddy Soil Fertility in Middle Subtropical Region
To evaluate the effects of light cultural techniques on soil fertility,a field experiment was conducted in the northeast of Jiangxi from 2008,which including deep and shallow tillage,with or without straw returning and direct seeding (DS),throwing seeding (TS) and transplantation (TP).The results showed that straw returning could increase grain yield of early and late rice by 1.6% to 7.6% compared without straw returning.The shallow tillage and straw returning could improve soil organic matter and available nutrient contents significantly.Compared with deep tillage,soil organic matter,alkali-hydrolysable nitrogen,available phosphorus and potassium of shallow tillage were increased by 5.1%-11.5%,2.2%-10.4%,5.5%-29.2% and 7.8%-22.1%,respectively.Compared with the treatments without straw returning,soil organic matter,alkali-hydrolysable nitrogen,available phosphorus and available potassium were increased by 2.7%-6.6%,3.4%-5.5%,2.2%-5.0% and 16.3%-49.3% respectively in the treatments with straw returning.This indicates that shallow tillage and straw returning could improve paddy soil fertility and grain yield in the middle subtropical region.