Effects of crop stubbles on cotton yield and soil environment in continuously cropped cotton field

The cotton field continuously cropped for eight years was investigated between 2007 and 2008 in order to find out the effects on soil nutrients, soil microflora and cotton yield with different crop stubbles and the optimum stubbles for cotton. The result revealed that the content of soil organic matter, soil available nutrients and cotton yield with different crop stubbles treatment were all higher than that with continuous cotton cropping treatment, among which processing tomato stubble had a significant increase in soil available phosphorus, while wheat and corn stubbles had a significant increase in soil available potassium. All crop stubbles had apparent increases in the mass of microorganism in soil compared to that in cotton. In general, there was a increase in the number of bacteria and actinomycets, while a decrease in eumyophyta. The volume of ammonibacteria and physiological groups of nitrifying bacteria had significant increases in both sweet clover and processing tomato stubbles. The ranking (high to low) by cotton yield with different crop stubbles is processing tomato, sweet clover, wheat, corn, cotton; and processing tomato, corn and wheat can serve as appropriate interplant stubbles in cotton field.