Effect of Irrigation Amount on Cotton Growth and Optimization of Irrigation Regime Using AquaCrop in Southern XinJiang

• DOI: 10.3390/agronomy15051101
• Publication Date: 2025-05-01T07:50:43Z
• Authors: Menghan Bian; Tingbo Lv; Wenhao Li; Conghao Chen; Xiaoying Zhang; Maoyuan Wang

The cotton-growing region in Southern Xinjiang is plagued by perennial drought and water scarcity, and there is a lack of research on the irrigation mechanism for the “one film, three tubes, four rows” new model of dry sowing and wet emergence of cotton. Therefore, this experiment explores the optimal irrigation regime for cotton under the “one film, three tubes, four rows” planting model in Southern Xinjiang, where a two-year field plot experiment was conducted. Three irrigation levels (W1: 360 mm, W2: 450 mm, W3: 540 mm) were set, with three replications each, to study the effects of different irrigation amounts on cotton growth, soil water content (SWC), irrigation water productivity (IWP), water productivity (WP), and yield (Y). Additionally, the AquaCrop model was used to optimize the irrigation regime. The results showed that irrigation amount significantly affected cotton growth, with plant height, stem diameter, and leaf area index following the order of W3 > W2 > W1. Compared to W1 and W2 treatments, the final biomass (B) and average SWC in the W3 treatment increased by 32.71%, 19.59% and 8.26%, 3.23%, respectively. The seed cotton yield under the W3 treatment was significantly higher than other treatments, being 6575.91 kg/ha in 2023 and 7252.16 kg/ha in 2024. IWP and WP were inversely related to irrigation amount. After two years of data calibration and validation, the model showed good simulation performance for canopy cover (CC), B, WP, and Y (with a concordance index d ≥ 0.904 and a coefficient of determination R2 ≥ 0.846). Among the 11 simulated irrigation scenarios (ranging from 360 to 660 mm in 30 mm increments), yield increased with irrigation amount but began to decline slowly beyond 570 mm, peaking at 7.45 t/ha, with IWP and WP being 1.307 kg/m3 and 1.294 kg/m3, respectively. Considering both water conservation and yield increase, an irrigation level or amount of 570 mm under the one-film, three-pipe, four-row planting pattern for dry sowing, wet emergence cotton in Southern Xinjiang can achieve good yields, benefiting the sustainable production of the local cotton industry.