Combined Application of Acidic Phosphate Fertilizers Improves Drip-Irrigated Soybean Yield and Phosphorus Utilization Efficiency in Liming Soil

Phosphorus (P) characteristics significantly affect crop yield and P use efficiency (PUE). It is unclear whether different types of acidic phosphate fertilizers can enhance the availability of phosphorus in liming soil and soybean yields. In this field experiment in 2022 and 2023 in Xinjiang, China, four phosphate fertilization treatments, including no phosphate fertilization (CK), application of monoammonium phosphate (MAP), application of urea phosphate (UP), and application of a mixture of monoammonium phosphate and urea phosphate (8:2, M8U2), were designed. Then, the impacts of the four phosphate treatments on the PUE, growth, and yield of the high-oil soybean variety Kennong 23 under drip irrigation were explored. The results showed that the application of phosphate fertilizers significantly increased the soil inorganic P, available P, and total P content compared with CK, promoting the growth and yield formation of soybeans. The soil Ca2-P content of the UP treatment was higher than that of the MAP treatment. The soil Ca8-P content of the M8U2 treatment was higher than that of the MAP treatment, but the soil phosphorus fixation was lower. The soil available P content, soybean plant P accumulation, leaf photosynthetic capacity, and dry matter accumulation all reached the maximum in the M8U2 treatment. The soybean yield, net revenue, and PUE of the M8U2 treatment were 6.04%, 9.37%, and 14.16% higher than those of the MAP treatment, and 7.64%, 16.59%, and 23.50% higher than those of the UP treatment, respectively. Therefore, the combined application of acidic phosphate fertilizers (MAP and UP) can increase soil available P content and plant P absorption in liming soil and stimulate photosynthesis, enhancing soybean yield and PUE. This study will provide a technical reference for the P reduction and soybean yield enhancement in arid areas.