China's most fabulous cotton-producing area is Xinjiang. In Xinjiang, soil salinization and water shortage are now the two key challenges limiting agricultural productivity and sustainable growth. Water wastage and secondary soil salinization in the area are still being made worse by irrational irrigation during the growth period and salt leaching during the off-growing period. A breakthrough in solving these problems is the development of sensible irrigation and salt-leaching techniques throughout the growing period to preserve water efficiently, cut expenses, and guarantee cotton crop yields. Following calibration of the model parameters and validation using field experiment data from 2020 and 2021, respectively, the optimal scheduling of cotton field irrigation and salt leaching was investigated to clarify the applicability of the Aquacrop model to the growth and production of simulated cotton fields under membrane and subsurface drip irrigation in northern Xinjiang. Then the calibrated model was used to reveal the effects of three irrigation levels (100%ETc (D₁), 80%ETc (D₂), and 60%ETc (D₃)), three salt leaching amounts (0 (Q₁), 120 mm (Q₂), and 240 mm (Q₃)), three irrigation frequencies (5 (F₁), 7 (F₂), and 10 d/time (F₃)) and three types of precipitation year (rainy years(H₁), normal years (H₂), and dry years (H₃)) on cotton yield and irrigation water productivity. The results showed that canopy cover, aboveground biomass NRMSE (Normalized root mean square error)≤20.998%, d (Index of agreement)≥0.967, and R² (Coefficient of determination)≥0.914 for all treatments in 2021, and yield RMSE, NRMSE, d, and R² were 0.389 t/hm², 6.797%, 0.836, and 0.754, respectively, and the model simulated well overall. Model simulations based on 58 years of meteorological data showed that the effects of irrigation level, salt leaching quota, and precipitation year type on cotton yield and irrigation water productivity were statistically significant, and irrigation frequency effect was not significant; in the cotton planting area with average soil salinity ranging from 12 to 18 g/kg, accounting for yield, irrigation water productivity, and actual production, the total irrigation and salt leaching quota of 80% ETc+120 mm (D₂Q₂) was recommended for rainy years, and the total irrigation and salt-leaching quota of 100% ETc+120 mm (D₃Q₂) was recommended for both normal and dry years; it was suggested that the irrigation frequency be increased to 10 d/time to reduce the frequency of irrigation and save costs. The optimal irrigation and salt leaching strategy proposed in this study was limited by model function and evaluation perspective. It was based on water conservation and optimal yield in cotton fields and did not consider the desalination conditions of membrane and subsurface drip irrigation. To develop more rigorous and convincing irrigation and salt leaching strategies, the Aquacrop model must be coupled with other water and salt transport models to improve the model's functionality and comprehensively assess soil desalination and cotton field production conditions.

Xinjiang's cotton industry plays an important role in global cotton production. However, the current strategy of surface drip irrigation cannot meet the high efficiency water saving and salt leaching requirement, seriously limiting sustainable development. Therefore, a field experiment was conducted in 2021 to explore the effects of surface-subsurface relay drip irrigation on soil water and salt movement, crop growth, cotton seed yield, desalination efficiency and irrigation water use efficiency in saline soil. The experiment based on crop water requirment (ET_c) and leaching amount included three irrigation levels of 0.8ET_c+120 mm (W1), 0.8ET_c+240 mm (W2) and 0.8ET_c+360 mm (W3), and three irrigation water level distribution modes of 100% surface drip (membrane under drip irrigation) irrigation (F1), 75% surface drip irrigation + 25% subsurface drip irrigation (F2), and 25% surface drip irrigation + 75% subsurface drip irrigation (F3). Finally, the feasibility was verified by the water-salt numerical model. The soil water content (SWC), soil salt content (SS), crop growth and seed yield were determined. The results showed that different irrigation level and distribution modes significantly affected soil water and salt distribution, cotton growth and yield (P<0.05). Under the low irrigation level treatment (W1), the soil desalination and desalination efficiency of each distribution mode were low, making it unsuitable for salt leaching and achieving high crop yields. Under the high irrigation level treatment (W3), the relay drip irrigation significantly improved soil water and salt conditions compared to drip irrigation under the film mulching. Due to better water and salt conditions, under the medium (W2) and high (W3) water treatments, the seed cotton yield of F2 and F3 was significantly higher than that of F1. The F2 ranked the highest, followed by F3 and F1. As the irrigation level increased, the seed cotton yield, irrigation water productivity and desalination efficiency under the surface-subsurface relay drip irrigation were significantly better than drip irrigation under the film mulching . Optimal conditions were found with an leaching level of 222-282 mm, the ratio of surface drip irrigation to subsurface drip irrigation was 1.00-1.94, resulting in the best comprehensive benefits for soil salinity, yield and irrigation water use efficiency in saline cotton fields. This study provides a theoretical basis for the implementation of relay drip irrigation in saline areas of Xinjiang.

To investigate the issue of seasonal water scarcity limiting the growth of kiwifruit in the Guanzhong Plain of Shaanxi Province and to propose optimal irrigation amounts and mulching measures, this study conducted an experiment using kiwifruit as the subject. The experiment included three irrigation gradients: W1 (irrigation upper limit of 85% θf, where θf is the field capacity), W2 (75% of W1), and W3 (60% of W1), additionally, four ground mulching were implemented: FG, FN, NG, and NN (F: intra-row horticultural fabric mulching, G: inter-row grass mulching, N: clean tillage), resulting in a total of 12 treatments. Through two years of field experiments, the soil water storage, kiwifruit growth, yield and quality were analyzed. The results showed that F mulching significantly increased intra-row soil water storage under the W1 treatment, while G mulching significantly enhanced inter-row soil water storage under the W2 treatment (P < 0.05). The FG treatment increased intra-row soil water storage by 2.21–42.23 mm while maintaining inter-row water storage. The FGW2 treatment improved photosynthetic parameters (Pn, Tr, and Gs) during the fruit expansion to maturation stages, increasing single fruit weight by 30.38%, yield per plant by 76.38%, and soluble sugar and soluble solid content by 15.15% and 44.26%, respectively (P < 0.05). The FGW1 treatment significantly reduced the organic acid content by 19.70% and increased the sugar-to-acid ratio by 37.75% (P < 0.05). The combination of mulching and irrigation influenced leaf photosynthesis during critical growth stages by enhancing soil water storage, thereby improving yield and quality. Among them, the soil water storage during the fruit expansion stage was most closely related to kiwifruit growth, yield, and quality. In the Guanzhong region, adopting FG mulching combined with W2 irrigation can effectively improve soil water storage and photosynthetic efficiency of kiwifruit orchards, ensuring yield and enhancing fruit quality, providing a feasible measures for kiwifruit production.