The depth and width of drip infiltration play a critical role in designing effective irrigation strategies. However, existing models primarily focus on continuous irrigation and fail to predict wetting patterns under intermittent drip irrigation. This study developed an infiltration model to estimate soil moisture depth and width under intermittent drip irrigation and identified strategies that enhance effective water storage. Indoor soil box simulations were conducted, with continuous drip irrigation as the control. Results showed that intermittent irrigation increased infiltration width and reduced depth, maximizing water storage efficiency. We recommend adopting an intermittent irrigation system with 1.5 h of irrigation followed by a 0.5 h interval, repeated four times. This system increased effective water storage by up to 16.23% compared to continuous irrigation. The proposed method is suitable for sandy loam farmland in southern Xinjiang and can significantly improve water use efficiency in arid regions.

Variable flow emitters are used in subsurface drip irrigation to address challenges in soil moisture transport. This study investigates the impact of flow channel structural parameters on the hydraulic performance and anticlogging ability of emitters using computational fluid dynamics (CFD) simulations and experimental tests. The results show that the realizable k–ε turbulence model can be used to simulate the flow field inside the variable flow emitter flow channel. The nRMSE between the measured (q_m) and simulated (q) values of the flow rate is 11.23%, and the relative error between the measured (x_m) and simulated (x) values of the flow index is 4.66%, which gives a high simulation accuracy. A polar analysis shows that the tooth angle (A) has the smallest effect on the effluent flow rate at 0.1 MPa (q_0.1), x, and particle passage rate (η) of the variable flow emitter. Flow channel depth (D), tooth spacing (B), and tooth height (E) have a different order of precedence in the influence of the three indices, which are D > B > E > A, B > E > D > A and E > B > D > A, respectively. The value of η is positively correlated with the mean flow velocity (v) and the mean turbulent kinetic energy (k) in the flow channel, and η tends to increase and then decrease with the increase of x. The retention time of the particles in the flow channel is closely related to the magnitude of v and k. Three multivariate lin ear regression equations (R² = 0.883–0.995) were constructed for q_0.1, x, and η versus the flow channel structural parameters. The optimal design combination of channel structure parameters for different scenarios was determined using the scipy.optimize.minimize function in Python 3.8.0. The research results provide a reference for the optimal design of variable flow emitters.

This study investigates the impact of Aerated Subsurface Drip Irrigation (ASDI) on the growth and yield of mulched cotton, aiming to identify the optimal water-air combination pattern for ASDI in cotton cultivation. Conducted during 2021–2022, the experimental setup involved two aeration modes (aerated A₁ and unaerated A₀) and four irrigation quotas (W₁, W₂, W₃, and W₄), organized in a two-factor randomized block design resulting in eight distinct treatments. The findings revealed that ASDI significantly promoted soil moisture depletion from 0 to 40 cm during the cotton flowering and boll opening stages. Specifically, aerated A₁ reduced soil water content by 5.84% to 7.83% during the flowering stage and 7.45% to 13.39% during the boll opening stage compared to unaerated A₀. Additionally, both aerating and increasing irrigation quotas not only enhanced the cotton leaf area index (LAI) but also delayed leaf area decay, contributing to prolonged photosynthetic activity. Aerating also favorably influenced the distribution of above-ground biomass in cotton towards budding and boll stages, with the biomass share of buddings, flowers, and bolls averaging 62.98% under aerated conditions versus 62.27% under non-aerated conditions during the boll opening stage. Furthermore, aerating combined with increased irrigation quotas resulted in higher seed cotton yields, with aerated irrigation boosting yields by 1.79% in 2021 and 4.43% in 2022 compared to non-aerated irrigation. This approach also increased cotton’s water demand and average daily water consumption significantly (p < 0.01). Importantly, aerating improved IWUE, achieving 1.72 kg/m³ in 2021 and 1.62 kg/m³ in 2022 for ASDI, versus 1.69 kg/m³ and 1.57 kg/m³ for unaerated subsurface drip irrigation, respectively. In conclusion, from a water conservation and yield enhancement perspective, an irrigation quota of 337.4 mm during the reproductive stage under ASDI is recommended as an effective strategy for “one film three tubes and six rows” mulched cotton in Southern Xinjiang.

Selecting suitable maize hybrids and appropriately increasing planting density is a crucial strategy for improving maize yield under subsurface drip irrigation. A two-year field experiment was conducted to assess the impacts of two maize hybrids (Zhengdan 958, ZD958; Jingke 968, JK968) and four planting densities of 60,000 (PD1), 75,000 (PD2), 90,000 (PD3), and 105,000 plants ha⁻¹ (PD4), on maize growth indices, ear leaf photosynthetic parameters, nitrogen content, grain yield, and yield components. The results indicated that with increasing planting density, the plant height of ZD958 initially increased and then decreased, whereas that of JK968 continued to increase. The leaf area index of both hybrids consistently increased, while stem diameter, rind puncture strength, and stalk breaking strength gradually decreased. Dry matter accumulation initially increased and then decreased, peaking at PD3. Ear leaf nitrogen content, relative chlorophyll content, net photosynthetic rate, and stomatal conductance all decreased with increasing planting density, while intrinsic water use efficiency (iWUE) first increased and then declined, reaching its maximum at PD3. Notably, iWUE of JK968 was significantly higher than that of ZD958 during the dough stage (p < 0.01). Ear traits, including ear length, ear diameter, kernels per ear, and grain weight per ear, all decreased continuously with increasing planting density. Grain yield followed a unimodal curve, peaking at the PD3 treatment, with two-year average yields of 12.7 and 13.5 t ha⁻¹ for ZD958 and JK968, respectively. JK968 exhibited significantly higher leaf area index, stem diameter, rind puncture strength, stalk breaking strength, ear length, kernels per ear, grain weight per ear, and grain yield compared to ZD958 (p < 0.01), demonstrating superior tolerance to high planting density and enhanced source–sink coordination. In conclusion, in the North China Plain, JK968 planted at a density of 90,000 plants ha⁻¹ can synergistically optimize population structure, improve stalk mechanical strength, and enhance photosynthetic efficiency, under subsurface drip irrigation.