To further explore the effects of different soil textures on soil leaching and cotton (Gossypium hirsutum L.) growth using a combined irrigation and drainage technique and provide a theoretical basis for the improvement of saline alkali land in Xinjiang, we used a test pit experiment to test soil moisture, salinity, soil pH, permeability, cotton agronomic characteristics, cotton yield and quality, and water use efficiency in three soil textures (clay, loam, sand soil) under the combined irrigation and drainage (T1) and conventional drip irrigation (T2). We measured the soil moisture content in different soil layers of clay, loam and sandy soil under the T1 and T2 treatments. Clay and loam had better water retention than sandy soil, and the soil moisture under the combined irrigation and drainage treatment was slightly higher than that under conventional drip irrigation. Under T1, the average salt content and pH value in the 0–60 cm soil layer of clay, loam and sandy soil decreased by 14.09%, 14.21% and 12.35%, and 5.02%, 5.85% and 3.27%, respectively, compared with T2. Therefore, T2 reduced the salt content and pH value of shallow soil. Under T1 and T2, the relative permeability coefficient (K/K0) values in different soil textures at different growth stages of cotton were ranked as follows: sandy soil > loam > clay. Under T1, the K/K0 values for different soil textures at different growth stages of cotton were >1; therefore, T1 improved soil permeability. The yield and water use efficiency of seed cotton under T1 and T2 in different soil textures were ranked as follows: loam > clay > sand, and there were significant differences between the different treatments. In loam, the cotton yield and water use efficiency of the combined irrigation and drainage treatment were 6.37% and 13.70% higher than those for conventional drip irrigation treatment, respectively. By combining irrigation and drainage to adjust the soil moisture, salt, pH value and soil permeability of different soil textures, the root growth environment of crops can effectively be improved, which is of great significance to improving the utilization efficiency of water and fertilizer and promoting the growth of cotton.

Drip irrigation has become an application trend of water-saving irrigation technology due to its excellent water-use efficiency. However, the energy dissipation form of the commonly used labyrinth channel is relatively simple, and the corresponding energy dissipation mechanism research is inadequate. This article proposes a new kind of channel structure of drip irrigation emitters based on the structure of scalariform perforation plates in plant xylem vessels. We establish a total of 16 sets of orthogonal structure schemes. Using numerical simulation and physical experiments, the hydraulic performance and energy dissipation mechanism of the perforated drip irrigation emitters (PDIE) are studied. The results show that the flow index of PDIE is 0.4665–0.5266. The hydraulic performance of PDIE in the high-pressure zone is the best, and the flow index is 0.4665–0.5046. As the pressure increases, the velocity of the flow of the upper perforation increases rapidly, the flow ratio decreases, the flow index decreases, and the hydraulic performance improves. To further verify the energy dissipation mechanism, a lower flow ratio and a better hydraulic performance were obtained through appropriately expanding the upper part of the upper perforation inlet to the channel boundary. The research sheds new insights for optimizing the hydraulic performance of PDIE. Results reported here provide a theoretical basis for the structural design of drip irrigation emitters and the energy dissipation mechanism research.

Xinjiang is short on freshwater resources and rich in ones. The unregulated use of brackish water for agriculture leads to the aggravation of secondary salinization in soil; however, magnetization can improve the quality of brackish water. To evaluate the effects of magnetized brackish water drip irrigation on the water and salt transport characteristics of sandy soil in southern Xinjiang, China, a field plot experiment was carried out in which irrigation water was treated using one or two water magnetization events at different magnetization intensities. Water was treated at five magnetization intensities: 1000, 2000, 3000, 4000, or 5000 Gs, while unmagnetized water was used as the control. The results showed that the magnetization of brackish water used in drip irrigation decreased the water transport rate and increased the water holding capacity of the root layer soil. Magnetized irrigation water enhanced the leaching of soil salt and reduced the rate of salt accumulation. Compared with the control, the salt content of the magnetized water-irrigated soil decreased by 15.0%~33.7%, and the salt storage in the magnetized water-irrigated soil decreased by 44.99%~86.78%. The lowest rate of salt accumulation (4.96%) was observed at a magnetization intensity of 3000 Gs. Magnetized water irrigation changed the composition and proportions of soil ions, and Na⁺, Cl⁻, and SO₄²⁻ leaching from the soil increased. The effect of magnetizing the irrigation water twice was greater than that of one magnetization event. Magnetizing the water twice at an intensity of 3000 Gs led to the largest decrease in the relative percentage contents of Na⁺ and Cl⁻, which were 80.90% and 82.36%, respectively. The magnetization intensity had a significant effect on the soil carbon and nitrogen contents, which showed a trend of first increasing and then decreasing as the magnetization intensity rose. The total carbon content after irrigation with magnetized water increased by 13.48%~63.35%, and the total nitrogen content increased by 11.73%~147.96%. The magnetization treatment of irrigation water can therefore reduce the risk of soil salinization and reduce salinity stress on crops in arid regions, providing a new method for alleviating the shortage of freshwater resources in Xinjiang and a means to use brackish water safely while improving salinized soil.

To improve the irrigation quality and anti-clogging performance of the emitter, it is necessary to design and optimize its flow channel structure. The shunt-hedging drip irrigation emitter (SHDIE) flow channel is a new type of flow channel. Using computational fluid dynamics, by setting different conditions (such as particle size and injection position), the motion trajectory of sand particles and flow field distribution characteristics of the shunt-hedging flow channel were simulated. According to the simulation results, a new anti-clogging structural optimization scheme was proposed, and physical experiments verified its feasibility. The results showed that the flow index of the original flow channel (SHDIE1) and optimized flow channel (SHDIE2) were 0.479 and 0.486, respectively, which mainly relied on the shunting and hedging of water flow to energy dissipation. For sand particles with diameters of 0.05, 0.10, and 0.15 mm, the average values of the velocity amplitude ratio, η, were 0.9998, 0.9994, and 0.9991, respectively; the average values of the velocity phase difference, β, were −0.143°, −0.320°, and −0.409°, respectively. A larger sand particle diameter led to worse followability and a higher risk of blocking the channel. When the sand particles collided with the sensitive region of the flow channel, their movement direction would suddenly change, entering the vortex area. After colliding with the sensitive region of edge A, the maximum probability of sand particles entering the vortex area was increased to 87.5%, and then they stayed in the vortex area under the effect of the sensitive regions of edges B and C. After the sensitive regions were removed, the motion trajectories of sand particles became regular and smooth. The optimized flow channel’s (SHDIE2) anti-clogging performance was greatly improved by 60%, with a 1.46% loss of hydraulic performance. This study can provide theoretical support for designing the high anti-clogging emitter.

Capillary water, serving as a crucial intermediary between groundwater and crop root layer moisture, is important for both soil retention and crop utilization. To investigate the effect of mulched drip irrigation (MDI) on upward capillary water in cotton fields with different application years (0, 10, 14, 18, 20, and 24 years) in the saline–sodic region of Northwest China, an indoor soil column test (one-dimensional capillary water rise experiment) was conducted. The results showed that the wetting front transport law, capillary water recharge, and wetting front transport rate over time exhibited an increasing trend in the early stages of MDI application (10 and 14 years), peaking at 18 years of application, followed by a decreasing trend. The relationship between the capillary water recharge and rising height was fitted based on the Green–Ampt model, and their slopes reveal that 14 and 18 years of MDI application required the largest amount of water per unit distance, indicating an excellent water-holding capacity beneficial for plant growth. Conversely, 0 years required the smallest amount of water per unit distance. Based on the movement characteristics of upper capillary water, we confirmed that the MDI application years (0–18 years) improves soil infiltration capacity, while the long-term application years (18–24 years) reduces groundwater replenishment to the soil. Furthermore, the HYDRUS-1D model was employed to simulate the capillary water rise process and soil moisture distribution under different MDl application years. The results showed an excellent consistency with the soil column experiments, confirming the accuracy of HYDRUS-1D in simulating the capillary water dynamics in saline–sodic areas. The results would provide suggestions to achieve the sustainable development of long-term drip-irrigated cotton fields.

Aerated irrigation (AI) has emerged as a method to mitigate rhizosphere hypoxia caused by wetting front with sub-surface drip irrigation (SDI). Increasing oxygen in processing tomato’s root zone is beneficial to the improvement of the rhizosphere gas environment, crop growth, yield and quality. The relationship between aerated irrigation and irrigation quantity is not clear. A total of eight treatments, including four irrigation levels (4950 m³ hm⁻² (W1), 4750 m³ hm⁻² (W2), 4500 m³ hm⁻² (W3), 4050 m³ hm⁻² (W4)) in combination with aerated irrigation (A2) and non-aerated irrigation (A1) were used to investigate the effects of aerated irrigation on the physiological characteristics and yield of processing tomatoes under mulched drip irrigation in Xinjiang, China. The effects of aerated irrigation on plant height, stem diameter, leaf area index and dry matter, photosynthesis, fluorescence, fruit quality and yield of processing tomatoes were studied. The results showed that plant height, stem diameter, biomass accumulation and leaf area index of processing tomatoes under aerated irrigation were increased by 10.2%, 7.3%, 12.5% and 6.2% under the W1, W2, W3 and W4 conditions (p < 0.05), respectively, compared with non-aerated irrigation. Yield and the content of Vitamin C and soluble solids under aerated irrigation was 9.71%, 5.59% and 5.68% (p < 0.05) higher than that under conventional irrigation, respectively, and the sugar-acid under aerated irrigation decreased by 0.5%. Through principal component analysis, W2A2 treatment had a higher score according to the yield index (per fruit weight, fruit number per plant) and quality index (Vitamin C, soluble solids, sugar-acid ratio) than the other treatments. The results show that aerated irrigation is feasible under the existing mulched drip irrigation in Xinjiang and, in this experiment, W2A2 treatment was the most suitable planting mode.