To investigate the effects of subsurface drainage configuration on soil bacterial communities, cotton yield, and water and nitrogen use in saline-alkaline soils of Xinjiang, a field experiment was conducted from April to October in 2024 with three drain burial depths, namely 0.8 m (M1), 1.1 m (M2), and 1.4 m (M3), and three drain spacings, namely 10 m (J1), 15 m (J2), and 20 m (J3). Aboveground dry matter, seed cotton yield, water and nitrogen use efficiency, and plant nitrogen accumulation were measured, while bacterial alpha diversity (Chao1 and Shannon indices), beta diversity (Bray-Curtis distance and principal coordinates analysis), community structure, and community assembly mechanisms were analyzed. The effects of different drainage configurations on soil bacterial communities, cotton yield, and water and nitrogen use were systematically evaluated. The results showed that: 1) in terms of yield and water and nitrogen use, treatment M2J1 achieved the highest seed cotton yield and water and nitrogen use efficiency, with a seed cotton yield of 7 418.98 kg/hm². Under M2J2, seed cotton yield increased by 29.66% compared with M3J2, and under M2J3, it increased by 21.67% compared with M3J3. At 125 days after emergence, nitrogen accumulation under M2J1 reached 320.26 kg/hm², which was significantly higher than that of the other treatments. 2) Regarding the soil bacterial community, alpha diversity did not differ significantly among drain burial depth treatments, whereas it showed a decreasing trend with increasing drain spacing. Principal coordinates analysis indicated that drain burial depth significantly altered soil bacterial community structure (P < 0.001), whereas drain spacing had no significant effect on community structure (P = 0.116). Bray-Curtis distance increased significantly with increasing burial depth. Null model analysis showed that the median betaNTI values in all treatments ranged from -2 to 2, indicating that soil bacterial community assembly was mainly governed by stochastic processes; however, the role of deterministic processes was markedly enhanced in the M2 treatment. Structural equation modeling further showed that drainage configuration could influence nitrogen accumulation in cotton organs by regulating the soil environment, water use efficiency, and bacterial community characteristics. These findings provide a theoretical basis and technical reference for optimizing subsurface drainage configuration, improving cotton yield, and enhancing efficient water and nitrogen use in saline-alkaline cotton fields in Xinjiang.

Excessive fertilizer application is common in the management of winter wheat (Triticum aestivum L.) in northwest China. However, this practice does not necessarily guarantee higher wheat yield and also causes a waste of resources and environmental pollution. The nitrogen (N), phosphorus (P), and potassium (K) fertilizer application rates need to be optimized to reduce the nitrate residue in the soil while maintaining a high wheat yield. Field experiments were conducted in three consecutive growth seasons (2018-2021) on winter wheat in Northern Xinjiang of China with four reduced fertilization (N-P₂O₅-K₂O) rates (FS1: 166-80-30 kg/hm², FS2: 0-80-30 kg/hm², FS3: 166-0-30 kg/hm², FS4: 166-80-0 kg/hm²) and the local fertilization rate (CK: 240-105-38). The soil nutrients, nutrient uptake content of organ, dry matter accumulation, yield, and fertilization use efficiency were investigated. The results showed increasing $\mathrm{N}{\mathrm{H}}_4^{+}$-N concentrations in the soil over the three growing seasons, while $\mathrm{N}{\mathrm{O}}_3^{-}$-N concentrations decreased in the later experimental years. High soil $\mathrm{N}{\mathrm{H}}_4^{+}$-N concentration and low soil $\mathrm{N}{\mathrm{O}}_3^{-}$-N residues were observed in FS3. When the control fertilization (CK) was applied, the grains had a higher proportion of N and P, while the N content in grains was relatively low at the high fertilization rate. When the fertilizer supply was insufficient (FS2, FS3, and FS4), the proportion of vegetative organs to the total biomass was relatively low. Lower fertilization rates resulted in higher N, P, and K use efficiencies in 2019-2020 and 2020-2021, in comparison to those at higher rates, while FS2 exhibited the highest fertilizer use efficiency. When fertilization (CK) was sufficient, the dry matter accumulation decreased by 3.33%-17.08%, and the harvest index increased by 0.87%-47.40%. FS1 had the highest spike number, which significantly increased by 17.98%, 17.80%, and 9.64% compared with CK during 2018-2019, 2019-2020, and 2020-2021, respectively. In conclusion, a reduction in fertilizer application compared with CK could provide excellent production results. The optimal drip fertigation approach for winter wheat production in the arid regions of northwest China was determined to be the N-P₂O₅-K₂O application rate of 166-80-30 kg/hm² when comprehensively considering the winter wheat yield, soil $\mathrm{N}{\mathrm{H}}_4^{+}$-N, and $\mathrm{N}{\mathrm{O}}_3^{-}$-N, N use efficiency, P use efficiency, and K use efficiency. This research can provide a scientific basis for the responses of winter wheat production to nutrient uptake of drip-irrigated winter wheat in arid and semi-arid regions.