【Conclusion】 Rice straw incorporation in situ and ex situ increased SOC and MBC compared with single application of chemical fertilizer,and the effect was more significant for straw incorporation ex situ in only few years.

Yield effect of rice straw return depended on N fertilizer quantity,straw quantity and sorts of crop.

Field studies were conducted to investigate effects of rice straw incorporation and nitrogen application models on process of nitrogen uptake by rice paddy ecosystem and fertilizer-N use efficiency in the double rice cropping system.

To investigate the effects of rice straw incorporation and nitrogen application models on nitrogen supplying capacity of soils,nitrogen using efficiency and rice productivity in the double rice cropping systems,field experiments were conducted on a farmer s field in Taojiang County in April of 2003,using split-plot design with two main treatments,three subplot treatments and eight replications.

A two-year field experiment was conducted to investigate effects of application of N fertilizer and incorporation of rice straw on nitrogen supplying capacity of the soil and rice yield under a double rice cropping system.

Effects of long-term rice straw returning on the fertility and productivity of purplish paddy soil;

In Yongzhou of Hunan, with fixed position plot trials, ways of straw returned to field and sorts of mulching had been compared for series three years.

The experiment was conducted to study effects of chicken manure and straw returned to field on carbon and nitrogen metabolism, chemical components and economic properties of K326, the major flue-cured tobacco variety in Fujian.

In yongzhou of hunan,with fixed position plot trials,the effect of straw returned to field,straw mulching,film mulching,no mulching and no returning had been compared for series three years.