Effects Of Returning Of Winter Green Manure And Straw On Soil Physical And Chemical Properties And Enzyme Activity

In order to explore the effect of winter green manure and crop stalk return on the soil ecological environment of continuous cropping cotton fields,this study carried out a 3 year field experiment with the soil of the continuous cropping cotton field for 15 years,it reveals the effect of the cooperative utilization of green manure and straw on soil physical and chemical properties and enzyme activities at the three soil depths of0-20 cm,20-40 cm and 40-60 cm.Three treatments were set up in the experiment:winter fallow + straw not returned to the field(CK),winter fallow + cotton straw crushed and returned to the field(T1),and winter rape + cotton straw crushed and returned to the field(T2),each treatment applied equal quantitative fertilizer.The results show:(1)Compared with the control group,the two returning treatments did not have a significant effect on the soil bulk density of the 0-20 cm soil layer,but significantly reduced the soil bulk density of the 20-40 cm soil layer;the two return methods both increased The soil porosity of the soil layer,and the surface layer is larger than the deep layer;T1 and T2 treatments can significantly increase by 20-40 cm Soil moisture content of the soil layer.After correlation analysis,it is found that soil bulk density has a significant negative correlation with porosity,and a significant positive correlation with soil water content.(2)T1 and T2 treatments can lower the soil pH at the three soil layer depths,but as the soil layer depth increases,the degree of influence decreases;the contents of soil organic matter,available N,available P and available K of the three soil layers treated with T1 and T2 were all higher than those of the control group.Among them,the content of organic matter and available N in the three soil layers treated with T1 was the highest.Increased by 19%,23%,69% and 15%,23%,61%;and T2 treatment has the highest available P and available K content,which are increased by 110%,69%,37% and respectively in the three soil layers.69%,21%,22%,and the two treatment modes of returning to the field all showed a time cumulative effect on the soil nutrient content.After correlation analysis,it was found that the soil pH value and the soil nutrient content are significantly negatively correlated;soil;There was a significant positive correlation between the nutrient contents.(3)T1 and T2 treatments promoted the activities of soil catalase,alkaline phosphatase,urease and invertase.Among them,catalase showed an inverted "saddle" shape in the soil layer,and the other three The soil enzyme activities all decrease with the increase of soil depth.After correlation analysis,it was found that there was a significant positive correlation among soil alkaline phosphatase,invertase and urease activities.(4)Soil alkaline phosphatase,urease and invertase activities have a very significant correlation with soil physical and chemical properties(P<0.01),while soil catalase activity is only significantly correlated with soil available phosphorus content(P<0.05).Principal component analysis showed that in the first principal component,soil alkaline phosphatase,urease and invertase have higher weights,which can be used to evaluate cotton field soil fertility.Sort the principal component scores of different treatments,from highest to lowest: T2>T1>CK.In summary,winter planting of green manure and straw returning to the field can provide scientific basis and technical support for fertilizing continuous cropping cotton fields and building a healthy soil ecosystem.At the same time,on the other hand,it also provides a new perspective for the comprehensive utilization of agricultural resources in the context of carbon peak and carbon neutrality.