Water scarcity and imbalances in irrigation and drainage are the main factors leading to soil salinization in arid areas. There is a recognized need for effective drainage measures to prevent and improve saline−alkali land. The principal objective of this project was to investigate the effects of drainage measures on soil desalination and farmland drainage in the process of improving saline–alkali soils; these measures included subsurface pipe drainage (SPD) and open ditch drainage (ODD). The results of the tests, conducted over two years, revealed that the soil desalination rate in the SPD test area was between 25.8% and 35.2%, the cotton emergence rate was 36.7%, and a 3.8 t hm⁻² seed cotton yield could be obtained. The soil electrolytic conductivity (EC) decreased step by step over time, and the average annual decrease reached 10 dS m⁻¹. The degree of soil salinization was reduced from a moderately saline soil level (8−15 dS m⁻¹) to a weakly saline soil level (4–8 dS m⁻¹). Thus, the phased goal of improving saline–alkali land was achieved. The soil desalination rate in the ODD test area was only 1/10 of the SPD area; high soil EC (9−12 dS m⁻¹) and groundwater level (2–3 m) were the most limiting factors affecting cotton growth in the ODD test area. The current results show that the critical depth of groundwater level affecting farmland secondary salinization is 4 m. In order to improve the salt discharge standard, SPD technology should be used on the basis of ODD. For salt that has accumulated in the soil for a long time, the technical mode of drip irrigation and leaching, followed by SPD drainage, in combination with the current irrigation system can achieve the goal of sustainable agriculture development.

Soil salinity is a major soil threat, causing severe environmental problems. Soil salt stress limits N uptake and cotton growth, especially in arid regions. However, the mechanism underlying stress tolerance in cotton plants under different soil salinity levels has not been fully elucidated. Therefore, the aim of this study was to examine the proportion and mechanism of cotton N uptake and transport under salt stress using the ¹⁵N isotope labeling technique. Cotton plants were grown in four undisturbed loamy soils (CK, non-salinity, 4.0 dS m⁻¹). The N transported to cotton from the 0–20 cm soil layer in C1 treatment was higher than from the 40–60 cm layer. Furthermore, the cotton fruit cultivated in C1 exhibited a notably elevated dry matter content compared to those cultivated in the control treatment. As the soil salt stress increased from the control treatment to C1, the cotton stems and fruits demonstrated a gradual enhancement in their N uptake and regulatory capabilities, albeit with a slight decrease observed in the leaves. These findings emphasize that soil salt stress diminishes cotton nitrogen uptake and transport, potentially exacerbating nitrogen pollution in the absence of optimized nitrogen fertilization.

Asymmetric warming was bound to have a major impact on terrestrial ecosystems in arid regions during global warming. Further study was necessary to reveal the spatiotemporal patterns of asymmetric warming in Xinjiang; this study analyzed the climate and normalized difference vegetation index (NDVI) data (2000–2020). The change trends of the day and nighttime warming (DNW), seasonal warming, and the diurnal temperature range in northern Xinjiang (S1) and southern Xinjiang (S2) were determined. The findings indicated that the DNW rate showed a significant (p < 0.05) upward trend, especially in winter. The nighttime warming rate (0.65 °C (decade)⁻¹) was faster than the daytime warming rate (0.4 °C (decade)⁻¹), and the diurnal temperature range between daytime and nighttime exhibited a decreasing trend. The diurnal temperature range was the highest in spring and the lowest in winter. Extreme values of the diurnal temperature range appeared in autumn (48.6 °C) and winter (12.3 °C) and both in S1. The T_min in S1 had an abruption trend in 2006–2017, the T_max in S2 had an abruption trend in 2005–2011, and the probability of spatial abruption in S1 was higher than that in S2. The partial correlation between the NDVI and T_min was significantly higher than that between the NDVI and T_max in the area where the significance test passed; therefore, asymmetric nighttime warming had a greater impact on the NDVI than the asymmetric daytime warming.

The factors influencing the effective utilization coefficient of irrigation water are not understood well. It is usually considered that this coefficient is lower in areas with large-scale irrigation. With this background, we analyzed the effective utilization coefficient of irrigation water using the analytic hierarchy process using data from 2014 to 2019 in Shihezi City, Xinjiang. The weights of the influencing factors on the effective utilization coefficient of irrigation water in different irrigation areas were analyzed. Predictions of the coefficient’s values for different years were made by understanding the trends based on the grey model. The results show that the scale of the irrigation area is not the only factor determining the effective utilization coefficient of irrigation water. Irrigation technology, organizational integrity, crop types, water price management, local economic level, and channel seepage prevention are the most critical factors affecting the effective use of irrigation water. The grey model prediction results show that the effective utilization coefficient of farmland irrigation water will continuously increase and reach 0.7204 in 2029. This research can serve as a reference for government authorities to make scientific decisions on water-saving projects in irrigation districts in terms of management, operation, and investment.

Salt stress is a vital factor limiting nitrogen uptake and cotton growth in arid regions. The mechanisms underlying salt stress tolerance in cotton plants under high soil salinity have not been fully elucidated. Therefore, the aim of this study was to examine the proportion and mechanism of cotton nitrogen uptake under salt stress using the 15N isotope labeling technique. Cotton plants were grown in four undisturbed saline soils (1, 3, 6 and 9 dS m−1), and the experiment was designed using the ENVIRO-GRO (E-G) model. The results showed that the dry matter of roots, stems and leaves of the cotton parts in slightly saline soil (C2, 3 dS m−1) was not significant compared with the non-saline soil (C1, 1 dS m−1). The cotton fruit grown in low-salinity soil (C2, 3 dS m−1) had significantly higher dry matter than that grown in the other treatments, implying that cotton plants grown in 3 dS m−1 soil have the best nitrogen uptake and salt tolerance. Cotton plants grown in weakly (C3, 6 dS m−1) and moderately (C4, 9 dS m−1) saline soils exhibited premature senescence. The distribution of total nitrogen and nitrate content in cotton was the best explanatory variable of total 15N recovery, of which cotton 15N recovery was between 26.1% and 47.2%, and soil 15N recovery was between 7.7% and 14.9%. Our findings provide guidance for further exploitation and utilization of saline soil resources and sustainable development of the agricultural soil ecosystem in arid regions.