Abstract:In order to explore the salinization area controlled release nitrogen fertilizer coupling effect and optimum combination plan, improve the utilization efficiency of water and nitrogen, nitrate nitrogen loss reduction, a test of controlled release fertilizer application fields with different water and nitrogen ratios was conducted in 2019 and 2020 in Hetao Irrigation District, and the salinization of sunflower water yield and nitrogen use efficiency of controlled release fertilizer and traditional fertilizer were investigated. The effects of different water and nitrogen ratios of controlled release fertilizer on sunflower yield and water and nitrogen use efficiency were explored, and the mathematical regression model of interaction between economic benefit and water and nitrogen was established, and the water and nitrogen combination scheme was optimized. The results showed as follows: compared with traditional fertilizer, yield, nitrogen agronomic efficiency, partial nitrogen productivity and irrigation water efficiency of controlled release fertilizer were increased by 13.89%, 46.42%, 13.61% and 13.62% on average (P<0.05), but there was no significant difference in harvest index (P>0.05). Under controlled release fertilizer application, the interaction of different water and nitrogen treatments was obvious, and controlled irrigation limited nitrogen use efficiency. Sunflower yield, nitrogen fertilizer agricultural utilization efficiency and nitrogen fertilizer partial productivity were increased by 21.87%, 80.89% and 21.53%, respectively. Low N also reduced water use efficiency. From low N to medium N, sunflower yield and irrigation water use efficiency were increased by 14.83% and 15.35% on average, and from medium N to high N it was increased by 3.86% and 3.43% on average, respectively. The maximum yields in 2a were 3943.5kg/hm2 and 3788.7kg/hm2 under high water and high nitrogen treatments, respectively. Under the condition of controlled release fertilizer application, the relationship between irrigation amount, nitrogen application amount and economic benefit of sunflower was in line with binary quadratic regression model. The determination coefficient R2 of the predicted economic benefit and actual economic benefit in two years was 0.99. Through principal factor analysis, economic benefit was increased first and then decreased with the increase of nitrogen application amount. Under the condition of full irrigation of controlled release fertilizer, the economic benefit of medium nitrogen level was between 18000 yuan/hm2and 21000 yuan/hm2, which was the optimal treatment in this experiment. It can increase yield and reduce nitrogen loss, and provide technical reference for sunflower planting and reducing farmland non-point source pollution in Hetao Irrigation District.