Effects Of Water Stress On The Soil Microbial And Enzyme Activities In Intercropping Cotton Field

The jujube tree（Zizyphus jujuba Mill.）/cotton（Gossypium hirsutum L.）agroforestry system is beneficial to improve the comprehensive economic benefits of young orchards.Reasonable planting distance and irrigation can improve the soil nutrient status,so that the crops are in a good growth and development environment to achieve the purpose of increasing yield;therefore,screening out scientific planting distance and reasonable irrigation amount can more accurately guide the management of intercropping cotton in jujube,and also provide a basis for the standardized development of jujube intercropping.The experiment was conducted in the jujube of the Tarim University and the high-yield cultivation laboratory of the Tarim University from 2017 to 2019.The two-factor splitting experiment design was adopted.The distance between jujube and cotton intercropping was the main area,and the irrigation amount was the cracking area.The soil microbial diversity,soil enzyme activity and soil chemistry in the three-dimensional cropping system of jujube-cotton intercropping were studied under different planting distances.The nature of the effect,combined with intercropping crop yields,leads to the following main conclusions:1.Planting distance and water treatment can change the soil microbial quantity and improve the soil bacterial flora richness.Proteobacteria is the dominant species in the bacterial population,accounting for42.56%of the microbial population and 4 500 m³·hm^-22 treatment.The richness of the flora was higher;the soil bacteria and fungi showed a downward trend with the promotion of the growth period;the number of soil actinomycetes showed a trend of decreasing first and then increasing during the growth period of cotton;under the same water conditions,the planting distance The number of bacteria and fungi showed M2>M1,and the highest in the same planting distance was 4 500 m³·hm^-22 under water treatment;the number of actinomycetes was the highest under 3 450 m³·hm^-22 water treatment,and in soil The actinomycetes in the bacterial community structure are also dominant populations.2.The soil enzyme activity of the jujube-cotton intercropping system showed that different intercropping distances and irrigation amount would make the soil enzyme activities have certain differences,and they showed different degrees in different growth stages.As the growth period progressed,the invertase and polyphenol oxidase showed a trend of increasing first and then decreasing,and the alkaline phosphatase showed a gradual decline.The catalase and protease showed a gradual increase trend,and urease appeared first.After the decline,the growth trend of the other enzymes except the protease showed M2>M1,and reached the highest enzyme activity under the irrigation of 4 500 m³·hm^-2,and the protein active enzyme showed M1>M2,the enzyme activity was highest under 6 000 m³·hm^-22 irrigation treatment.3.With the promotion of cotton growth period,soil alkaline nitrogen,total nitrogen,available phosphorus and organic matter showed a trend of increasing first and then decreasing,and soil available potassium showed a trend of decreasing first and then increasing;under the same water treatment,soil The nutrient content was M2>M1.Under the same planting distance,the soil nutrient content was higher at4 500 m³·hm^-2;the soil total salt content was M1>M2 under the same water treatment,and the soil was treated with 4 500 m³·hm^-22 at the same planting distance.The salt content is low.4.M2 planting distance is 13%higher than M1 planting distance,red jujube yield is 7%higher;two crop yields are highest under 5 250 m³·hm^-22 water treatment,under 3 750 m³·hm^-22 treatment The lowest yield.5.There is a positive correlation between available potassium,catalase,available phosphorus,polyphenol oxidase,urease and protease;positive correlation between protease,invertase,total nitrogen and organic matter;19 bacterial to soil enzymes activity has a significant effect,and 16 bacterial species have a significant effect on soil nutrients.The above results indicated that different intercropping distance and irrigation amount affected the soil microbial diversity,chemical properties and soil enzyme activity in the jujube-cotton intercropping system to a certain extent,which also affected crop yield to some extent.The scientific planting and irrigation management of related intercropping systems provide theoretical references.