The Impact of Various Water and Nitrogen Fertilization Mixtures on Cotton Growth and Development in Southern Xinjiang under Film Drip Irrigation

Objective To explore the optimal water and nitrogen ranges for cotton under film drip irrigation in the southern Xinjiang region.

Methods In this experiment, Xinluzhong 54 was used as the test cotton variety. Three irrigation levels (325 mm, 375 mm, and 425 mm) were designed, denoted as W1, W2, and W3, respectively. For each irrigation level, five nitrogen application levels were designed (base fertilizer + top-dressing: 0+0, 80+120, 80+220, 80+320, and 80+420 kg·hm⁻²), denoted as N1, N2, N3, N4, and N5, respectively.

Results Appropriate increases in irrigation and nitrogen application significantly improved cotton growth indicators and aboveground dry matter accumulation, but excessive nitrogen application inhibited its growth and dry matter accumulation. Seed cotton yield increased with irrigation amount, but the increment decreased as irrigation further increased, and yield showed a trend of first increasing and then decreasing with nitrogen application rate. Compared with W1 treatment, the average seed cotton yields of W2 and W3 treatments increased by 7.45% and 10.36%, respectively.

Conclusion Irrigation amount and nitrogen application rate significantly regulated cotton growth and development, seed cotton yield, and water and fertilizer use efficiency. The optimal irrigation range was 366.8–399.9 mm, and the optimal nitrogen application range was 300.0–326.6 kg·hm⁻².