The Responses Of Micro-ecological Environment To Different Tillages Form Of Cotton In Hunan

In this test, with the study of1year,5years,10years,15years of continuous cropping cotton field soil microorganisms, enzymes and physical and chemical properties, as well as cotton, rice, wheat, corn, peas, rapeseed rotation, we can tell the effect of continuous cropping and rotation cotton field soil microorganisms, enzymes and Physical and Chemical Properties, reveal the status and trends of cotton cropping and rotation, proposed counter measures. And all these work are to select alternative crops suitable for cotton planting area of Hunan cotton field crop rotation, provide theoretical basis for cotton planting area to establish a rational system of land use dependent, promote Hunan cotton planting structure optimization, and ensure the sustainable development of the cotton industry in Hunan. The test results are as follows.1. In the whole growth period of cotton, cotton field soil microbial of different cropping duration varies with the variation of growth period, where bacteria and actinomycetes substantially the same overall trend. In one-year cotton fields, the number of bacteria and actinomycetes in different growth period show the greater variation than fungi, while in fifteen-year cotton fields the number of fungi increases sharply, showing great variation in different growth period.2. By studying the variation of the activity of urease, phosphatase, catalase, cellulose and saccharase in continuous cropping cotton soil between different years and growth periods we can find that, the activity of urease and phosphatase continue to go higher with the time going on. The activity of catalase will become lower and lower in first10years of the whole period of continuous cropping, while the activity of catalase has a tendency of becoming higher when the enzyme exists in continuous cropping cotton soil more than15years. These five enzymes exhibit different variation tendencies in the whole growth period of the cotton, and changes of the activity of cellulose and saccharase emerge more noticeable.3. The contents of total nitrogen total phosphorus and organic matters in continuous cropping soil show a decreasing trend after the first increase, and the maximum emerges in the10th year.While the content of available nitrogen shows a tendency of becoming increase, and the pH of the soil exhibits a tendency of becoming higher and higher, So a conclusion can be made that continuous cropping has different effects on different components.4. Soil fertility in cotton field was improved in various degrees when rotated with other crops. The content of organic matters in pea treatment groups was9.50%higher than the control groups, while the available nitrogen54.65%higher.The content of available phosphorus in rape treatment groups was12.81%higher than control groups as well as the available potassium was15.60%higher than control groups. Almost every index in many other treatment groups was higher than in control groups. This fully indicates that different cropping strategies could effectively improve the content of available nutrients in continuous cropping of cotton fields, what’s more, different cropping strategies could availably make the physical and chemical properties of the soil in continuous cropping of cotton fields better.5. By the results of the experiment we knew the indexes of volume weight and soil porosity were better in rice/wheat/corn/pea/rape treatment groups than in control groups, it indicates that the result of each treatment group is better than control group, especially in the cotton-rice rotation. This indicates that different cropping strategies have profound effects on the physical and chemical properties of the soil in continuous cropping of cotton fields, and they have a significant function in promoting the soil constitution become well.6. Through the study we found that the number of bacteria flora is larger than fungus and ray fungi in different cropping strategies. The number of bacteria flora and ray fungi in pea treatment groups is higher while the number of fungus is lower in these six treatment groups modes, it’s good for continuous cropping with cotton because that helps to reduce diseases and insect pests and increase the cotton production. By making comparisons of the activity of different enzymes in soil between different cropping strategies we can find that the activity of soil enzymes in rice treatment groups is higher, that indicates land/water rotation can effectively make the earth better, keeping all kinds of metabolic processes functioning well.