Salt leaching with alternate surface and subsurface drip irrigation enhance cotton yield, water use efficiency, desalination rate, desalination efficiency and economic benefit

Abstract

Context

Xinjiang's pivotal cotton industry requires improved irrigation management for sustainable production due to water inefficiency and salt accumulation, while alternate surface and subsurface drip irrigation with mulch (ADI) and salt leaching serve as promising solutions. Objective: Therefore, this study assessed the effects of ADI and salt leaching on soil water, salinity, desalination, cotton yield, water use efficiency (WUE) and economic benefits to identify the optimal strategy. Methods: A field experiment in 2020–2021 used two irrigation methods (ADI; DI: surface drip irrigation with mulch) and four leaching levels (0, 120, 240 and 360 mm). Leaching water was applied in three equal portions during the seedling and budding stages (DI) and flowering stage (subsurface drip irrigation). Results: As leaching levels increased, yield, desalination rate and economic benefits improved, while WUE and desalination efficiency initially increased, then decreased for both irrigation methods. Compared to DI, ADI had worse soil water conditions within the film, but this was mitigated with higher leaching levels. Notably, ADI improved soil salinity conditions, effectively offsetting yield reductions caused by water stress. Compared to DI, ADI boosted cotton yield and WUE by 3.1 %-26.5 %, desalination rate and efficiency by 24.1 %-114.5 %. Despite higher inputs, ADI outperformed DI economically in high salinity soils, with better salt control promoting higher yields. Conclusions: Overall, TOPSIS evaluation showed ADI offered superior benefits over DI. ADI with 252–336 mm leaching water (0.8 g·L⁻¹) was identified as optimal (≥95 % peak performance), balancing desalination, cotton yield, WUE and economic benefits. Significance: This recommendation strongly advocates for the positive impact of ADI in promoting sustainable development in saline agriculture.