Determining a suitable “dry sowing and wet emergence” water control program for cotton fields in the arid regions of Northwest China is of great significance in saving water resources, improving economic efficiency, and promoting sustainable development of agriculture. The objective of this study was to analyze the effects of different “dry sowing and wet emergence” water control treatments on dry matter accumulation, chlorophyll fluorescence, yield quality, and water productivity of cotton, and to determine the optimal “dry sowing and wet emergence” water control program for cotton growth in arid areas. A two-year experiment was carried out in 2021 and 2022 in mulched drip-irrigated cotton fields, with a total of 13 treatments of different seedling water quantities (2021: 67.5 mm, 90 mm, 112.5 mm; 2022: 6 mm, 10.5 mm, 15 mm) and different drip frequencies (frequencies means number of drops at seedling stage) (2021: one, two, three times; 2022: two times, four times) in the “dry sowing and wet emergence”. Results indicated a positive correlation between increased seedling water quantity and growth indexes. High seedling water quantity treatment demonstrated a 14.33% higher cotton yield than the low seedling water quantity treatment. In comparison with low-frequency treatment, the high-frequency treatment exhibited significantly larger cotton plant height, dry matter accumulation, and yield. Over two years, the average values increased by 8.69%, 16.4%, and 15.91%, respectively, with a 14.55% increase in the coefficient of photochemical quenching of the leaf blade (qP). The high frequency and larger amount of seedling water quantity treatments showed significantly higher irrigation water productivity, with increases of 39.2% and 70.2% compared to the winter irrigation control treatment. In summary, the appropriate “dry sowing wet emergence” water regulation mode (the first drip: 15 mm, the second drip: 4.5 mm, the third drip: 22.5 mm, the fourth drip: 15 mm) can ensure crop yield quality under the premise of significantly reducing the agricultural irrigation water, which can provide certain theoretical support for the green, efficient, and sustainable development of the local cotton industry.

A novel method, ECWS, is proposed for measuring soil initial salinity content (b), based on the soil electrical conductivity EC and soil moisture content WS. This pioneering model rigorously establishes and incorporates the inherent potential correlation among soil bulk conductivity ($E{C}_a$), soil solution conductivity (${EC}_w$), volume water content (${\theta }_c$), and soil salinity content (SSC). First of all, in order to delve the deeper relationship between $E{C}_a$, ${EC}_w$, ${\theta }_c$ and SSC, the soil salinity conductivity conversion coefficient ${\rho }_a$ and soil leaching solution salinity conductivity conversion coefficient ${\rho }_w$ were employed based on the formula of parallel conducting channels of the soil–water system, and a new measurement model of salinity content was constructed. After that, a mathematical analysis method was used to transform the coefficients of multiple sets of regression equations into matrices to solve ${\rho }_a$, ${\rho }_w$ and b. Finally, to validate the accuracy of the proposed ECWS method, verification tests were conducted by utilizing TDR and PWMER sensors. The results with different salinity contents showed that the b size obtained by ECWS model were ${\mathrm{K}}_2{\mathrm{SO}}_4$ (1.84 g/kg), NaCl (1.91 g/kg), and KCl (1.92 g/kg). The maximum deviation was less than 0.08 g/kg (relative error less than 5%). The results showed that the influence of different anions and cations on the measurement of salinity content Cl⁻ is greater than that of ${\mathrm{SO}}_4^{2-}$, and K⁺ is greater than that of Na⁺. This study revealed the relationship between soil electrical conductivity and soil salinity content to a certain extent, and realized the transformation between them, which provided a new method for the measurement of soil salinity content, and also provided a reference for related research on the measurement of soil salinization.

The problem of poor water and fertilizer retention in sandy soils can lead to physiological growth restriction and yield and quality decline in apples. Sodium carboxymethyl cellulose (CMC) formula can improve the soil structure and increase the water- and fertilizer-holding capacity of the soil, and Biogenic Stimulant (BS) can improve the drought stress resistance of crops and promote the physiological growth of crops. Considering that CMC and BS may improve the physiological characteristics of sandy soil apples, in this study, CMC was coupled with BS in sandy apples, and the effects on the physiological characteristics, yield, and quality of apples were systematically investigated. The results showed that CMC and BS could increase leaf N, P, and K content, with the greatest increases seen in the Y2C2 treatment (9.28, 0.61, and 0.56 g kg⁻¹, respectively) compared with the CK treatment. The SPAD values of leaves following the coupled CMC and BS treatment compared to the CK treatment were elevated in the range of 4.47–24.29% at the flowering and fruiting stage, 2.84–26.50% at fruit expansion stage, and 6.64–19.41% at maturation stage. In the light response data of different treatments, the maximum net photosynthetic rate occurred in the Y2C2 treatment, and the net photosynthetic rate, transpiration rate, and stomatal conductance were all the highest in the Y2C2 treatment during the fruit expansion stage, with the net photosynthetic rate being higher than that of the CK treatment by 5.09 µmol m⁻² s⁻¹. The combination treatments of CMC and BS increased apple yield by 10.69 to 27.62% as compared to the CK treatment, and also increased soluble reducing sugar, soluble solids, and VC and reduced the titratable acid content. There was no correlation between the SPAD value during fruit expansion (p > 0.05) and the other physiological indexes (p < 0.05). Through the established functional relationship between the application rate of CMC and BS and apple yield, the recommended BS application rate of 27 kg ha⁻¹ and CMC application rate of 20.625 kg ha⁻¹ could yield up to 43,357.8 kg ha⁻¹.

Subsurface drip irrigation can improve crop water and fertilizer use efficiency, but it can cause soil hypoxia. We report on experiments performed in Aksu Prefecture, Xinjiang (41°17′ N latitude, 80°17′ E longitude), from April 2023 to October 2024 using oxygenated drip irrigation from the surface to 50 cm depth in an apple (Malus pumila Mill.) orchard, to examine the effects of drip irrigation on inter-root hypoxia, tree growth, fruit quality, and yield. Compared with surface oxygenated drip irrigation (CK), irrigating at 10 and 30 cm increased soil water content in the root system, elevated gibberellin, zeatin ribosides, and indoleacetic acid contents and reduced abscisic acid contents in new shoot tips. Compared with CK, branch and leaf nitrogen, phosphorus, and potassium contents were increased with irrigation at depths of 10 and 30 cm. The leaf nitrogen (N), phosphorus (P), and potassium (K) contents were increased by 18.03%, 22.42%, and 16.63%, respectively, in the treatment with a burial depth of 30 cm. Among treatments, irrigation at 30 cm produced the highest average daily plant water potential, and irrigation at 50 cm was the lowest. Maximum leaf soil–plant analysis development (SPAD) values occurred when irrigated at 30 cm, and minimum values occurred at 50 cm. For both years, the largest range of light flux utilization occurred when irrigated at 30 cm and the lowest when irrigated at 50 cm. Significant correlations between indoleacetic acid (IAA), total gibberellin (GA), zeatin riboside (ZRs), leaf N content, leaf K content, plant water potential (PWP), net photosynthetic rate (Pn), SPAD, and apple yield were determined by partial mantel analysis. A significant correlation was found between abscisic acid (ABA), IAA, GA, leaf P and K content, and apple quality. Principal component analysis revealed a burial depth of 30 cm had the highest principal component composite score, indicating that this burial depth, and oxygenation and fertilization regime most favored apple growth, yield, and quality.

The lack of trace element iron has become a key factor restricting vegetable yield and quality improvement. To address the low production efficiency of water–fertilizer coupling in agricultural production, we used a combination of experimental research, theoretical analysis, and mathematical modeling to systematically determine the effects of magneto-electric water irrigation with iron application on spinach growth and physiology, its yield and quality, and soil water transport characteristics. Compared with conventional water irrigation, under magneto-electric water irrigation, the water volume and applied iron concentration average increased the total accumulation of nitrogen, carbon, and iron in the aboveground part of spinach by 3.71%, 10.16%, and 14.14%, respectively, and the aboveground part of spinach had the highest total accumulation of nitrogen and carbon when irrigation water was 3300 m³ ha⁻¹ and iron fertilizer application at 0.15%. Additionally, magneto-electric water irrigation increased spinach aboveground fresh weight and soluble sugar and protein content by an average of 13.34, 18.26, and 11.61%, respectively. Based on a comprehensive quantitative evaluation and analysis of aboveground nutrient accumulation in spinach, aboveground fresh weight, water use efficiency, and soluble sugar and protein content, we determined the optimal irrigation water and iron fertilizer application for spinach growth.

The downstream irrigation district of the Yarkant River basin has experienced increasing soil salinization driven by shallow groundwater levels, constraining the sustainable development of regional agriculture. However, the dynamic relationship between soil salinity and groundwater depth in this region remains unclear, limiting the effectiveness of saline–alkali land remediation strategies based on groundwater level regulation. In this study, field data were collected in 2025 on total soil salinity, concentrations of eight major ions, groundwater depth, and groundwater salinity in the irrigation district. The spatiotemporal distribution patterns of soil salinity, groundwater depth, and groundwater salinity were analyzed, along with their interrelationships. The soils in the irrigation district are predominantly mildly to moderately saline. Overall, soil salinity exhibits clear seasonal patterns, characterized by accumulation due to evaporation in spring and autumn and dilution through irrigation in summer. The dominant anions in the soil were SO₄²⁻ and Cl⁻, while Ca²⁺ and Na⁺ were the dominant cations, indicating a chloride–sulfate salinity type. Soil salinity shows a significant positive correlation with groundwater mineralization. A clear Boltzmann function relationship was identified between soil salinity and groundwater depth, revealing a critical groundwater depth of 2.10–2.18 m for salt accumulation in the irrigation district. The critical groundwater depths corresponding to soil salinity and major salt ions, from lowest to highest, are Cl⁻ < Na⁺ < total salts < SO₄²⁻ < Ca²⁺. Random forest regression analysis identified the main factors influencing soil salinity and their relative importance, ranked from highest to lowest as follows: groundwater depth > Na⁺ > Cl⁻ > groundwater salinity > Ca²⁺ > SO₄²⁻ > Mg²⁺ > HCO₃⁻ > K⁺ > CO₃²⁻. Maintaining groundwater depth below the critical threshold and focusing on groundwater ions that strongly influence soil salinity can effectively alleviate soil salinization in the lower Yarkant River irrigation district caused by shallow, highly mineralized groundwater.