Optimal use of irrigation water and fertilizer for strawberry based on weighing production benefits and soil environment

Maintaining a healthy soil environment is crucial to sustainable agricultural development. To obtain a comprehensive optimal irrigation and fertilization scheme that considers the benefits of both strawberries production and soil environmental condition, 12 treatments including four irrigation levels and three fertilization levels were conducted over two growth seasons. The experimental results show that increasing irrigation increased the strawberry yield, but the risk of soil nitrate nitrogen leaching increased as well. Excessive fertilizer application led to a large amount of nitrate residue in the soil, while appropriate reduction of fertilizer application improved fruit quality and the water and fertilizer utilization efficiency on the basis of ensuring strawberry yield. Eleven indicators of four categories from strawberry yield, quality, soil nitrate, and water and fertilizer utilization efficiency were introduced into multi-objective evaluation system and assigned with different weights. Based on multi-level fuzzy comprehensive evaluation model, T5 (I2F2) and T8 (I3F2) obtained the highest scores. Therefore, under moderate fertilization condition, appropriate deficit irrigation could account for production benefits and soil environment for strawberry production. A significant quadratic polynomial regression equation of irrigation and fertilization was established based on the evaluation results, and the effects of irrigation and fertilization on the comprehensive score for strawberry both showed a negative parabolic trend. The optimal combination of irrigation and fertilization intervals of strawberry is 74.37%- 87.64% ETc with 86.51%- 104.63% F0 (the exact value determined using target yield method). The results of this experiment provide a theoretical basis for the development of water-saving agriculture and chemical fertilizer reduction actions in arid areas of Northwest China.