Effect of tillage on conversion of soil organic carbon in paddy soil.

In order to elucidate the effect of conversion process of the soil organic carbon on carbon fixation,four tillage patterns including no-tillage with straw incorporated(NTS),conventional tillage with straw incorporated(CTS),no-tillage without straw incorporated(NT) and conventional tillage without straw incorporated(CT) were designed.Soil samples were collected in soil layers(0-5,5-12 and 12-20 cm) during rice growth period.The result showed that in 0-5 cm layer,the content of organic carbon,active carbon,hot water-extractable carbohydrate,total phenol and humic were continuous increasing with the rice growth and were significantly improved under no-tillage(NTS and NT) in the whole rice growth period,but in 5-12 and 12-20 cm layers were lesser but had no significant difference between no-tillage and conventional tillage(CT and CTS).Correlation analysis revealed that there were significant positive correlation among differents carbon forms.These results indicated that no-tillage and straw incorporated were benefit for the organic conversion and humification in 0-5 cm layer and improved stable carbon by elevating humification,which was much better for improvement of soil fertility and inhibition of soil greenhouse gas emissions.