Effects of Irrigation Rate on Soil Bacterial Diversity and Lint Yield in a Jujube/Cotton Intercropping System

Jujube/cotton intercropping is a typical ecological ecosystem, and water is the dominant factor limiting the system productivity. However, it is not clear if and how irrigation rate affects soil bacterial diversity and lint yield in a jujube/cotton intercropping system. To explore the effects of irrigation rate on soil bacterial diversity and enzymatic activities in a jujube/cotton intercropping system, four water stress treatments were applied in 2017 and 2018 in Xinjiang, Northwest China: (1) W1, 3750 m³/ha; (2) W2, 4500 m³/ha; (3) W3, 5250 m³/ha; (4) W4, 6000 m³/ha. In the intercropping field, cotton yield in W2 and W3 treatment was higher than that in W1 and W4 treatments, and significant increases were also observed in soil available phosphorus and potassium, as well as soil alkaline phosphatase and urease activities. The richness and diversity of soil bacterial communities in W2 and W3 treatments were higher than in other treatments, and the abundance of Pseudomonas bacteria was highest under W2 and W3 treatments. Overall, soil nutrient levels and soil enzymatic activities influenced soil bacterial community structure in intercropping system, indicating that soil environment was effectively improved and the best farmland income was obtained when the irrigation rate was controlled at 4500 to 5250 m³/ha.