Effects of water and fertilizer application and film mulching on Cyperus esculentus yield and soil properties

To explore the effective water and fertilizer application measures for Cyperus esculentus in extremely arid areas, this study conducted a dual-factor experiment of water-fertilizer application and mulching on wind-blown sandy soil in the desert-oasis transition zone of Hetian region. Three water-fertilizer treatments, i.e., 60%, 80%, and 100% of water or fertilizer levels, and three mulching treatments, i.e., no mulch, liquid film, and white film, were set up, with a total of nine treatments. The effects of different water and fertilizer treatments and mulching methods on the yield of C. esculentus, soil nutrients, and soil salinity were analyzed. The results showed that different water-fertilizer treatments had no significant effects on the growth and yield of C. esculentus, whereas mulching treatments significantly affected the plant density, number of tubers, thousand-grain weight, and tuber yield. The biomass of C. esculentus leaves and tuber yield were the highest under white film, whereas tuber yield was the lowest under liquid film. Both water-fertilizer application and mulching treatments had significant effects on soil nutrients. There was a significant interaction effect between water and fertilizer treatments on soil organic matter content, hydrolytic nitrogen, and available potassium in the 0－20 cm soil layer as well as hydrolytic nitrogen, available phosphorus, and available potassium in the 20－40 cm soil layer. Planting C. esculentus significantly reduced soil organic matter content and increased the contents of other nutrients. Soil organic matter content was the highest under white film with 60% water and fertilizer. Moreover, planting C. esculentus significantly reduced soil salt content in deep layers, but excessive water and fertilizer could lead to soil salinization in the surface layer. Our study suggests that under the condition of white film mulching, choosing a lower amount of water and fertilizer application can reduce cost and achieve maximum economic and ecological benefits while obtaining a higher yield of C. esculentus. Therefore, for barren and water-deficient sandy land, planting oil safflower under white film mulching with 60% water and fertilizer is recommended.