Effects Of Garlic Cotton And Wheat Cotton Relay Intercropping On Soil Microorganism And Related Enzyme Activities

The field experiment was conducetd in Jinxiang of Shandong Province in 2009-2010. Cotton soil microbial properties and soil enzyme activities and available nutrients under garlic cotton intercropping and wheat cotton intercropping were studied, with cotton single culture as the control. The aim was to clarify the relationship between garlic cotton intercropping, wheat cotton intercropping and soil microbial characteristics, soil enzyme activity, and to supply a theoretical basis for the soil management. The main results were as follows:1. Effects of garlic cotton and wheat cotton relay intercropping on cotton growth characters.Numbers of fruiting branches of cotton plant under garlic cotton intercropping were significantly higher than that of cotton single culture and wheat cotton intercropping. Wheat cotton intercropping got less fruiting branches of cotton plant compared with the control. The number of fruiting node of cotton under garlic cotton intercropping was significantly higher than that of cotton single culture. The difference between wheat cotton intercropping and the control was not significant. This showed garlic cotton intercropping could increase the number of fruit branches and fruit node of cotton plant.Bolls per cotton plant of garlic cotton intercropping had no significant difference with cotton single culture. The number of cotton bolls per plant under wheat cotton intercropping was lower than the cotton single culture, which was benefit to increase cotton bolls per plant of garlic cotton intercropping. During the flower and boll stage, boll opening stage garlic cotton intercropping and wheat cotton intercropping shedding rate were significantly lower than the cotton single culture, the flower and boll period with the highly significant difference. That intercropping helped reduce the shedding rate of cotton.2. Effects of garlic cotton and wheat cotton relay intercropping on soil microbial number and diversity.During the seedling and the flower and boll stages, garlic cotton intercropping could increase the number of soil bacteria in cotton field, indicating that garlic cotton intercropping can provide a benefits environment for the growth of bacteria. From the bud stage to boll opening stage, the number of fungi under garlic cotton and wheat cotton intercropping were significantly deceased compared with the control which indicated that garlic cotton and wheat cotton intercropping could not be conducive to fungal proliferation environment in the soil. The number of actinomycetes under garlic cotton intercropping in the whole growth period of cotton was significantly increased compared with the cotton single culture. That meant garlic cotton intercropping system was conducive to the proliferation of actinomycetes. Total microorganisms number of garlic cotton, wheat cotton intercropping from the seedling stage to flower and boll stage were higher than that of the cotton single culture. Excepting bud stage, the microbial diversity was also significantly higher than that of the cotton single culture, which showed garlic cotton and wheat cotton intercropping could improve micro-ecological environment in cotton filed which were conducive to the growth of cotton variety of microorganisms.3. Effects of garlic cotton and wheat cotton relay intercropping on soil microbial number and diversity.Compared with cotton single culture, whole growing period of the active soil microbial biomass, soil respiration rate, microbial activity were increased in garlic cotton and wheat cotton intercropping. In other words both intercropping were conducive to the transformation and absorption of the soil nutrient, garlic cotton intercropping effect much better.4. Effects of garlic cotton and wheat cotton relay intercropping on soil microbial number and diversity.The results showed that garlic cotton intercropping system could significantly improve soil microbial biomass carbon, nitrogen, phosphorus during all growth stages. Wheat cotton intercropping in the bud, flower and boll stage could significantly improve the cotton microbial biomass carbon, in the seedling and bud stage could significantly increase microbial biomass nitrogen in cotton field, in the seedling and boll opening stage could increase the amount of soil microbial biomass phosphorus of cotton fields. The result showed that garlic cotton and wheat cotton intercropping system were conducive to increasing the content of soil microbial biomass carbon, nitrogen, phosphorus.5. Effects of garlic cotton and wheat cotton relay intercropping on soil enzyme activities.Under garlic cotton intercropping urease activity and invertase activity of 0-20 cm soil layer were significantly higher than that of the cotton single culture in the whole growth period, alkaline phosphatase activity except in blooming period were also significantly higher than the control; during the Seedling and boll opening period catalase activity was significantly higher than that of single culture. Under wheat intercropping urease activity and invertase activity of 0-20 cm soil were also higher than that of single culture. in the seedling stage, flowering and boll stage. Alkaline phosphatase activity was significantly increased in the bud stage compared with the control; catalase activity was increased significantly in the seedling and boll opening stage.6. Effects of garlic cotton and wheat cotton relay intercropping on soil physical and chemical characters.Soil moisture content of garlic cotton intercropping was higher than cotton single culture in all growth stages of cotton, wheat cotton intercropping had different performance about soil moisture of the two soil layers, soil moisture of 0-20 cm soil was lower than that of cotton single culture except boll opening stage; that of 20-40 cm soil was higher than the cotton single culture except during the flowering and bolling stage. That meant that soil water retention of garlic cotton intercropping was better than that of the cotton single culture. Compared with cotton single culture, alkaline pH values of garlic cotton and wheat cotton intercropping were conducive to bacteria proliferation.This experiment showed that under garlic cotton intercropping available nitrogen in 0-20 cm soil layer in the bud, flower and boll stages was significantly higher than that of the cotton single culture; while available nitrogen content of wheat cotton intercropping in all growth stage was lower than single culture. Those meant cotton intercropping could improve available nitrogen of cotton filed. Except the flower and boll stage, under garlic cotton intercropping available phosphorus content in 0-20 cm soil were higher than that in cotton single culture; available phosphorus content in 0-20 cm soil of wheat cotton intercropping in the seedling and bud stage was also increased significantly compared with the control. Both garlic and wheat cotton intercropping could increase the available phosphorus content of cotton filed, garlic cotton intercropping had more effect. Form the seedling stage to flowering and bolling stage available potassium content in 0-20cm soil layer of garlic cotton intercropping was increased significantly; only in the bud stage that of wheat cotton intercropping was significantly increased compared with the cotton single culture. Available potassium content of 20-40 cm soil layer under both garlic cotton and wheat cotton intercropping in the bud, flower and boll stage was significantly higher than that of the cotton single culture. Those indicated garlic cotton and wheat cotton intercropping could increase the available potassium in cotton filed.