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Soil amendments such as humic acid (HA), a biochar-based microbial agent (M), and vermicompost (V) can improve soil quality and promote crop growth. However, it remains unclear whether the co-application of the three soil amendments (HMV) has a synergistic effect on alleviating soil quality deterioration obstacles caused by dry sowing and wet emergence technology in Xinjiang cotton fields. A three-year field experiment was conducted in saline–alkali soils using plastic-film-mulched drip irrigation in Xinjiang, China. Through the orthogonal experiment method, the application amounts of HA, M and V were 75 kg ha−1, 75 kg ha−1 and 225 kg ha−1 respectively in 2021. In 2022, three application amount gradients were used for HA, M and V: 60 kg ha−1, 90 kg ha−1 and 120 kg ha−1 respectively. In 2023, the application amounts of HA, M, and V were 60 kg ha−1, 120 kg ha−1, and 120 kg ha−1. It should be pointed out that V contains HA in the range of 20–35%. This study aimed to explore the improvement effect of a single or combined application of HA, M, and V on soil quality and cotton emergence rate using dry sowing and wet emergence technology in Xinjiang cotton fields. The results showed that the single and combined applications of HA, M, and V improved the soil quality and water–heat–salt environment of the cultivated layer. In the combined application, the cotton seedling emergence rate and yield increased by 1.9–22.8% and 7.0–54.1%. Therefore, it is recommended to jointly apply HA, M, and V to promote cotton seedling emergence and increase yield using dry sowing and wet emergence technology in Xinjiang cotton fields. [ABSTRACT FROM AUTHOR]

To study the effect of soil water and salt environment factors on the root growth of cotton under different moisture control, three different emergence water volumes（60, 105, and 150 m³/hm²）, two different frequencies（high frequency and low frequency） and one double film cover winter irrigation control treatment（CK: 2 250 m³/hm²） were set up to analyze the spatial distribution patterns of soil water and salt environment and root density in dry sown and wet emerged cotton fields under diffe-rent moisture control conditions. The results show that the soil water content and water infiltration range gradually become larger with the increase of seedling water quantity, and the larger the seedling water quantity, the higher the soil water content. With the same seedling water quantity, the soil water content of the high-frequency（HF） treatment becomes obviously larger. The soil conductivity of each treatment tends to decrease gradually with the increase of seedling water and drip frequency, among which the distribution of soil conductivity of S6 treatment is closest to that of CK. With the increase in soil depth, the soil conductivity tends to increase first and then decrease. Compared with the low-frequency（LF） treatment, the high-frequency treatment shows a significantly deeper soil salt accumulation layer. The root length density（RLD） of cotton gradually increases with the amount of seedling water and the frequency of dripping. The soil layer of root distribution gradually deepens with the amount of seedling water in the vertical direction, and the RLD value in the horizontal direction is significantly greater in the mulched area than that in the bare area between films. This research can serve as a solid scientific foundation for the use of dry sowing and wet emergence techniques in cotton fields in southern Xinjiang. [ABSTRACT FROM AUTHOR]

Interlayer soil is common in southern Xinjiang, because interlayer can reduce the infiltration rate of soil water. To simulate the interlayer soil in heavy saline–alkali cotton fields, this paper adopted a vertical one-dimensional infiltration test. T1 (315 mm), T2 (270 mm), and T3 (225 mm) and different interlayer positions (T5, 315 mm) and thicknesses of the interlayer (T6, 315 mm) with the same irrigation volume, as well as one perforation and sand filling treatment (T4, 315 mm), were set. The influence of different irrigation amounts, locations, and thicknesses of the interlayer and sand injection on water infiltration was analyzed. The analysis results showed that with the increase in irrigation amount, the water infiltration rate and the migration distance of the wet front increased, but did not penetrate to the bottom soil (90 cm). Under the same irrigation volume, the increase in interlayer thickness (T6) compared with the increase in interlayer position (T5), the change in soil moisture content in the upper and lower layers of the interlayer was greater, and the advance time of wetting front migration and cumulative infiltration were slightly higher. After tunneling and sand filling (T4), the infiltration rate of water was increased, the migration time of the wet front was reduced, and the profile water content of each soil layer was improved. The Kostiakov model could better simulate the water infiltration characteristics of interlayer soil with different profile configurations in heavily saline–alkali land. The results showed that in all of the treatments, only the wet front of the soil moisture reached 100 cm in the T4 treatment, and the maximum was only 87.8 cm in the other treatments, indicating that too little irrigation water or the upward movement and thickening of the interlayer were not conducive to water infiltration. For the interlayer soil area in the heavy saline–alkali land in southern Xinjiang, the appropriate irrigation water should be more than 315 mm. The treatment of drilling first and then filling sand can be used as a simple but effective measure to increase the water infiltration rate of the interlayer soil, and can thus be applied to the layered soil structure in the interlayer position of 60–80 cm. [ABSTRACT FROM AUTHOR]

Irrigation with saline water is a possible solution to alleviate freshwater shortages. The long-term use of saline water for irrigation requires consideration of the influence of salt on the environmental conditions of the soil. The objective of this field study was to determine the effects of three continuous years of saline water irrigation on physiochemical properties and microbial communities in drip-irrigated cotton fields. The three total dissolved solid (TDS) levels of irrigation water treatments were (i) 1 g L−1 (fresh water, FWI), (ii) 3 g L−1 (brackish water, BWI), and (iii) 7 g L−1 (salt water, SWI). After three years, the electrical conductivity (EC), sodium adsorption ratio (SAR), and contents of K+, Na+, Mg2+, Cl−, and SO42− in the SWI treatment were significantly higher than those in the FWI and BWI treatments, but there were no significant differences in EC and K+ between the FWI and BWI treatments. BWI treatment significantly increased microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), urease, and sucrase contents. The diversity and abundance of bacteria and fungi were not affected by saline water irrigation, but the microbial community structure was altered. Saline water irrigation resulted in an elevation in the bacterial abundance of the phylum Chloroflexi and a decline in Proteobacteria and Actinobacteria. For fungi, the abundance of the phylum Ascomycota in the BWI treatment was greater than that in the FWI and SWI treatments. Linear discriminant analysis effect size (NMDS) results indicated clear variation in the microbiota profiles between the FWI, BWI, and SWI treatments for bacteria. Regarding the fungal microbiota profiles, the BWI and SWI treatments had similar microbiota profiles but were different from the FWI treatment. The number of bacterial biomarkers gradually increased with increasing total dissolved solids of irrigation water, while the number of fungal biomarkers gradually decreased. Additionally, cotton yield was significantly and positively correlated with the observed species of fungi, while it was significantly and negatively correlated with EC. Redundancy analysis (RDA) showed that bacterial community structure was regulated by SAR and fungal community structure was regulated by soil salinity and bulk density (BD). Future research will need to look into how the structure of the microbial community and the associated functional microorganisms are gradually changing with increased irrigation frequency under saline irrigation, as well as explore and screen for advantageous functional microorganisms. [ABSTRACT FROM AUTHOR]

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Saline water irrigation is extensively employed in many arid regions due to its capacity to effectively alleviate the scarcity of freshwater resources. However, this practice can result in an escalation of soil salinity and a decline in crop yield. Hence, it is necessary to explore measures to improve edaphic properties during saline water irrigation. This study aimed to explore the impact of biofertilizer application on soil physicochemical and biological characteristics, nitrogen use efficiency, and yield under irrigated conditions with water of different salinities and to establish the relationship between them. A two-year field experiment was conducted in 2021 and 2022 in film-mulched drip-irrigated cotton fields. Three types of irrigation water with different salinity levels of 0.48–1 g L−1 (W1, fresh water), 3 g L−1 (W2, brackish water), and 7 g L−1 (W3, salt water) and two fertilizer types of chemical fertilizer (F1) and chemical fertilizer+biofertilizer (F2) were assigned. Nitrogen, phosphorus, and potassium applications were maintained at the same amount for all treatments. The addition of biofertilizers resulted in a significant increase in lint cotton yield by 6.45–11.79 % (W1F2) and 6.69–15.51 % (W2F2) in two years under fresh and brackish water irrigation conditions when compared to conventional fertilization. Partial least squares path analysis revealed that the amplified cotton yield primarily stemmed from heightened soil nutrient effectiveness, increased soil microbial biomass, and enhanced nitrogen utilization efficiency (aNUE) facilitated by the application of biofertilizers. The addition of biofertilizers significantly lowered the soil specific gravity, improved water-salt distribution, reduced plant Na+ uptake, and alleviated the impact of salt stress under freshwater and brackish water irrigation, in contrast to conventional fertilization. Furthermore, the application of biofertilizers markedly elevated urease and invertase activities, increased soil microbial biomass (C and N), promoted nutrient uptake by crops, and increased nitrogen accumulation by plants. However, the efficacy of biofertilizer application was found to be less pronounced in saltwater irrigation. Biofertilizers can effectively improve the soil conditions under fresh and brackish water irrigation, promote nutrient absorption in crops, and significantly increase aNUE while simultaneously reducing internal nitrogen use efficiency (iNUE). An optimal combination of bio-fertilizers and chemical fertilizers can be employed to increase crop yields while effectively minimizing the application of nitrogen fertilizer under fresh and brackish water irrigation conditions. • Biofertilizers improve the soil quality under fresh and brackish water irrigation. • Biofertilizers improve nitrogen use ratio under fresh and brackish water irrigation. • Biofertilizers increase cotton yield by raising nutrients and microbial biomass. • Biofertilizers can reduce Na+ uptake by plant roots and leaves. • With the addition of biofertilizer, chemical fertilizer can be appropriately reduced. [ABSTRACT FROM AUTHOR]

Saline water irrigation presents a potential solution for addressing freshwater shortages. However, this practice can result in salinity stress for cotton plants. Hence, it is imperative to explore measures that can alleviate salinity stress when implementing saline water irrigation. The aim of this study was to determine the effects of biofertilizer (F 2) application on cotton growth, nitrogen use efficiency, yield, and fiber quality under different water: 0.48–1 g L−1 (W 1 , freshwater), 3 g L−1 (W 2 , brackish), and 7 g L−1 (W 3 , salt water) irrigation, compared to the use of chemical fertilizer (F 1) alone. A two-year field experiment was conducted in 2021 and 2022 in film-mulched drip-irrigated cotton fields. The results showed that biofertilizers significantly enhance photosynthesis and N utilization efficiency under both W 1 and W 2 irrigation, compared to treatments where chemical fertilizers were applied alone. At the same time, the cotton total biomass, and cotton fiber elongation were significantly increased, and the cotton seed yield was significantly increased by 6.15–10.56 % (W 1) and 6.49–11.81 % (W 2) in two years. The application of biofertilizers indirectly increases cotton yield by enhancing cotton biomass and improving N utilization. In conclusion, the application of biofertilizer can effectively alleviate the salinity stress on plants in both W 1 and W 2 irrigation situations. Future research on saline water irrigation should take into account the long-term effects of using biofertilizers in saline irrigation situations. • Biofertilizers enhance cotton growth and yield under fresh and brackish irrigation. • Biofertilizers can effectively alleviate the salinity stress in brackish irrigation. • Biofertilizers increase cotton yield by enhancing cotton biomass and N utilization. • Irrigation with saline water can reduce the cotton fiber FQI. [ABSTRACT FROM AUTHOR]