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【Objective】 Along with drought, soil salinity is a main abiotic factor limiting crop growth worldwide. Improving cultivation to alleviate salinity stress is an alternative method to safeguard agricultural production in saline soils. The aim of this paper is to investigate the efficacy of using ridge-furrow cultivation coupled with mulching to ameliorate the impact of salinity and improve cotton yield in coastal saline-alkali soils in China. 【Method】 A two-year experiment was conducted from 2014 to 2015 in a field, with conventional tillage coupled with mulching taken as the control (CK). In each treatment, we measured spatial distributions of soil water and salt, as well as seedling rate, seedling growth, root surface area, cotton yield, and yield traits. 【Result】 Mulching coupled with ridge-furrow cultivation (RF) increased soil moisture and reduced soil salinity simultaneously at significant level, thereby promoting root surface area and cotton yield, in comparison with CK. During the growth season, water content and electrical conductivity in the soil beneath the mulch in CK was 2.67% higher and 27.78% lower, respectively, than that in the soil outside the mulch. In contrast, the water content and electrical conductivity beneath the mulch in RF was 15.92% higher and 34.57% lower, respectively, than that in the soil outside the mulch. Compared with CK in the two years, RF increased root surface areas by 35.9%, seedling rate by 8.3% and 56.6%, the number of bolls per plant by 33.9% and 63.4%, cotton seed yield by 37.0% and 196.4%, respectively. 【Conclusion】 Ridge-furrow cultivation coupled with mulching increased soil water and reduced salt content in the root zones because it re-directed water flow in the soil. This boosted the growth of cotton seedlings and roots, increasing its yield as a result.

【Objective】 The purpose of this paper is to analyze the effects of contaminants originating from non-point agricultural pollution on surface water quality in China, in attempts to provide a baseline to help improve surface water management across the country. 【Method】 The analysis was based on surface water quality index (WQI) and four main nonpoint agricultural pollutants: chemical fertilizers, chemical oxygen demand related to poultry industry and livestock (COD), total phosphorus (TP) and ammonium nitrogen (NH4+-N), measured from 1999 to 2018 across the country. These data were used to analyze the correlation between WQI and each of the four pollutants. 【Result】 All four agricultural pollutants increased first and followed by decline or stabilization as time moved from 1999 to 2018. Compared with their contents in 1999, chemical fertilizer, COD, TP and ammonium in the surface water in 2018 increased by 37.1%, 21.1%, 28.4% and 15.6%, respectively. The water quality of most rivers had deteriorated until 2006, but it has seen significant improvement since then. The WQI of most rivers in 2018 improved by 13.8% compared to that in 1999. The water quality of lakes and reservoirs showed significant inter-annual fluctuation, and their WQI in 2018 increased by 6.5% and 2.4%, respectively, compared to that in 1999. It was found that COD, TP and NH4+-N originating from livestock and poultry industry were negatively correlated with WQI of rivers at significant level. Across the country, TP impacted river WQI most, followed by NH4+-N, with COD being the least. 【Conclusion】 Water quality in rivers across China has improved over the past few years, but the water quality of reservoirs and lakes remains largely unchanged. Reducing fertilizer application and disposal of wastes from livestock and poultry industry is critical to improving surface water quality and should be the main target in reducing agricultural pollution and improving surface water quality.

Crop yields are seriously threatened in saline–alkali areas with shallow groundwater levels and high evaporation. Mulching can effectively alleviate salt stress on crops in drylands, but there is limited research on winter wheat (Triticum aestivum L.) mulching in coastal saline–alkali areas. To investigate the effect of plastic film mulching on the growth and yield of wheat in coastal saline–alkali soil, three field management measures were designed: bare ground (CK), plastic film mulch (PM), and sub‐soil plastic film mulch (PMF). Compared with CK, PM and PMF significantly increased wheat grain yield by 128.2%–313.2% and 187.8%–537.0%, respectively, over the two study stages. The movement of salt to the surface is inhibited after mulching; as a result, PMF and PM significantly decreased the electric conductivity in shallow soil (0–20 cm) by 31.1% and 23.8%, on average, compared to CK, resulting in a significant increase in dry matter accumulation (DM) for winter wheat throughout the growing season. Moreover, PMF increased the overall DM by increasing the dry matter accumulation per plant (DMP), while PM achieved a similar effect to PMF by increasing the number of tillers. Compared with PM, PMF had a better inhibitory effect on shallow soil salinity, significantly increasing the effective number of spikes, effective tillering rate, DMP, and spike weight at harvest; promoting vegetative and reproductive growth of wheat fields; and ultimately increasing yield. PMF can be used to improve winter wheat production in coastal saline–alkali soils. Core Ideas: Film mulching will inhibit the concentration of deep salt in coastal saline‐alkali land to the surface.There is a significant negative correlation between shallow soil salinity and dry matter accumulation (DM) of winter wheat.Film mulching will promote the tillering ability and the DM of winter wheat.Higher dry matter accumulation per plant and rate of the available tillering are the reasons why the DM of sub‐soil plastic film mulch is higher than plastic film mulch.Plastic film mulching mainly achieves yield growth by increasing the number of spikes. [ABSTRACT FROM AUTHOR]

To improve the yield and water-nitrogen (N) use efficiency of summer maize, a two-year field experiment with four irrigation soil layers (0–10, 0–20, 0–30, and 0–40 cm, denoted as W10, W20, W30, and W40, respectively) and three N applications (180, 240, and 300 kg ha–1, denoted as N180, N240, and N300, respectively) was performed using micro-sprinkling irrigation system in 2018 and 2019. The interaction between water and N application significantly affects dry matter accumulation (DM). Under the same N application, the grain yield of W10 was significantly lower than that of W40. The irrigation amount and evapotranspiration for W20N180 and W20N240 significantly decreased by 47.18%–52.31% and 12.32%–12.68%, respectively, over that of W40N300, and water-use-efficiency (WUE) significantly increased by 7.75%–12.47%. Compared with N180, the N partial factor productivity of N240 and N300 decreased by 21.02%~22.04% and 37.12%~38.24%, respectively; with no significant difference in yield. Grain yield was significantly positively correlated with leaf area index at tasseling, grains per ear, DM at maturity, and evapotranspiration. Overall, suitable irrigation (W20) and N application (180–240 kg ha–1) can achieve higher grain yield and WUE for summer maize in the Huang-Huai-Hai Plain of China. [ABSTRACT FROM AUTHOR]

Soil pollution caused by the residual polyethylene film is a potential threat to agricultural sustainability. Biodegradable films are generally effective alternatives to reduce this pollution. However, soil quality changes responding to continuous biodegradable film mulch are still unclear. To reveal the accumulative effects of biodegradable film mulch on soil quality, we conducted a positioning experiment from 2016 to 2019 in North China Plain (NCP). Four treatments, including transparent polyethylene film mulching (PM), transparent biodegradable film mulching (TM), black biodegradable film mulching (BM), and non-mulching (CK) were employed. The results showed that compared with CK, both BM and TM treatments significantly reduced soil bulk density and increased soil microbial activity and soil enzyme activity; however, BM and TM did not affect soil nutrient content. Compared with CK, BM treatment significantly increased soil quality index (SQI) by 7.2% (in 2019) due to higher soil fertility content and bioactivity; however, TM and PM treatments decreased SQI by 3.2% and 3.8%, respectively. Besides, compared with CK, BM significantly enhanced summer maize grain yield by 30.35%. Therefore, black biodegradable film is a potential alternative to polyethylene film to improve soil quality and maize production in NCP. [ABSTRACT FROM AUTHOR]

Drought and water shortage have stimulated saline and slight saline water use for farmland irrigation in Hebei Plain. The mismanagement of irrigation with saline water has led to the expansion of secondary salinization farmland recent years. Therefore, it is urgent to explore suitable control index of soil salinity in order to avoid the reduction of crop production. This study was conducted in cotton field with five secondary salinization levels, which were caused by seven years continues irrigation with different salinity of saline water. The initial soil electrical conductivity (mass ratio of soil to water was 1:5) of the 0-60 cm soil layer depth was 0.29, 0.32, 0.55, 0.79, 0.99 dS/m, and denoted by treatment 1 to treatment 5 respectively. In this study, the response of cotton boll forming, yield and fibre quality to five soil salinity levels were analyzed, and price model for cotton was set up, at last, soil salinity control index were obtained by fitting piecewise function for crop salt-tolerance. Results revealed seasonal rainfall (450 mm) basically met the requirements of cotton water consumption under median water year (about 500 mm precipitation). Moreover, large part of the salt in soil was leached out of the 0-60 cm depth soil layer, and was controlled bellow 100 cm. When compared with the initial soil salinity for 0-60 cm depth soil layer, for treatment 1 to treatment 5, ratio of the maximum desalinization was 9.6%, 19.8%, 36.4%, 42.4%, and 45.7% respectively, and the ratio of the final desalinization was 9.4%, 1.8%, 21.0%, 24.5%, and 31.7% respectively. No significant decline in number of cotton bolls and seed cotton yield was found when the initial soil salinity for 0-60 cm depth soil layer was lower than 0.79 dS/m, while the ratio of cotton boll forming changed. With the further increment of soil salinity, the number of cotton bolls and seed cotton yield of treatment 5 were significantly lower than that of treatment 1 by 28.9% and 6.5% respectively. Lint percentage and fibre quality were affected by picking time and soil salinity. With the increment of soil salinity, increasing trend occurred in micronaire for all three batches of lint and in fibre strength for the first two batches, but the upper half mean fibre length significantly decreased for the second batch. Price model for cotton was set up, in which, cotton price of each batch was decided according to price list for different lint fiber quality published by China Cotton Association. It was observed that the control index of soil salinity decided by net earnings were lower than that decided by seed cotton yield, which proved the necessity of the consideration of fiber quality index. The initial soil salinity and mean soil salinity during the cotton season for 0-60 cm depth soil layer should be lower than 0.71 dS/m and 0.67 dS/m respectively, when the net earnings was consistent with the treatment 1. The study provides an important theoretical reference for improving the method of deciding control index of soil salinity for cotton field subject to secondary salinization. [ABSTRACT FROM AUTHOR]

Due to freshwater resources shortage and annual rainless spring, cotton cultivation in Hebei Low Plain is faced with the problems of using the shallow underground saline water. In order to evaluate the impact of long-term saline water irrigation on cotton seedling, and suggest the suitable irrigation method and irrigation water salinity to ensure optimal cotton full stand establishment, the 6 years field experiment under border irrigation and furrow irrigation with mineralized water before sowing was conducted. The response relations among different salt stress levels and cotton full stand establishment and seedling growing were analyzed in this study. The results showed that the cotton full stand establishment decreased when the salinity of irrigation water reached a threshold value, while the threshold had a large year-to-year fluctuations due to the sprout and emergence stage of cotton which was easy to be affected by multiple factors. Under the same salinity of irrigation water, the full stand establishment of border irrigation treatment was higher than the corresponding furrow irrigation treatment by annual mean 6.9%-13.1%. Under these two irrigation methods, the full stand establishment were significantly related to the soil salinity (P<0.01), and the slopes of the dependent equations were similar. However, the ground temperature and some other soil characters were both better in border irrigation treatments, which brought a 5.5-7.7 percentage point higher full stand establishment occurred in the border irrigation treatments under the same soil salinity. Although the salinity of topsoil was easily affected by factors such as rainfall, the soil salinity of treatments presented an accumulation trend with the increase of irrigation years when the salinity of irrigation water beyond 4 g/L, therefore, there is a cumulatively negative impact of long-term irrigation upon cotton emergence. With the increasing salinity of irrigation water, cotton seedling process was delayed, and plant height, leaf area and weight of dry matter etc. were all inhibited, especially for the leaf area. Cotton seedlings grew better in border irrigation treatment when the salinity of pre-sowing irrigation water was below 8 g/L rather than in furrow irrigation treatment. To keep the full stand establishment in consistent with the fresh water irrigation treatment, suitable salinity of irrigation water for border irrigation and furrow irrigation should be controlled below 6 g/L and 4 g/L, respectively. Under such condition, cotton seedling process might be delayed, and the growth of cotton seedling was overall inhibited. In conclusion, to obtain higher cotton full stand establishment and better seedling growth, border irrigation and irrigation water with salinity of lower than 6 g/L were recommended for pre-sowing irrigation; or to save water, furrow irrigation and irrigation water with salinity of lower than 4 g/L were recommended. The study provides an important reference for directing local cotton production under pre-sowing irrigation with saline water. [ABSTRACT FROM AUTHOR]

Biodegradable films are considered ideal alternatives to polyethylene films because of their advantages in increasing crop yield and controlling soil pollution. However, the influences of biodegradable film mulching on soil physicochemical environments and water productivity after long-term mulching remain poorly understood. Therefore, a field experiment after long-term mulching (since 2016) was conducted to explore the effects of black biodegradable film (BB), transparent biodegradable film (TB), and traditional polyethylene film (PE) on soil physicochemical environments, aboveground biomass accumulation, grain yield, evapotranspiration, and water productivity (WP) of maize in the 2021 and 2022 in the North China Plain. The results showed that polyethylene films and biodegradable films had a similar ability to preserve soil moisture, promote maize growth, reduce evapotranspiration, and increase WP. Moreover, the performances of BB were more equivalent to PE, and there was no significant difference on WP and yield under BB and PE. Compared with traditional flat planting without mulching (CK), BB and PE significantly increased yield (9.5 % and 12.7 % in 2021; 5.25 % and 6.37 % in 2022) and WP (11.54 % and 21.47 % in 2021; 24.28 % and 23.42 % in 2022). Film mulching treatments increased the soil organic carbon sequestration rate, and the content of soil organic carbon, microbial activity, and urease activity in the 0–20 cm soil layer compared with CK. According to structural equation modeling, the increasing soil water storage because of films mulching positively influenced yield by enhancing enzyme activities which were related to soil nutrients. Over all, these results showed that black biodegradable film is an ideal replacement for polyethylene films under long-term mulching conditions because of its comparable agronomic performance and influence on soil physicochemical environments in the North China Plain. • Long-term biodegradable film mulching (BDM) significantly impacted soil structure. • The effects of long-term BDM on soil physicochemical environments were similar to PE. • Effects of BDM and PE on the maize production were determined after long-term mulching. • The BDM and PE increased yield through affecting soil physicochemical environments. • Agronomic performance of the black BDM was more similar to PE than transparent BDM. [ABSTRACT FROM AUTHOR]

In the context of dwindling freshwater resources, it is imperative to comprehensively evaluate crop productivity and soil resource sustainability when considering the use of saline water for irrigation (SWI). This study aimed to investigate the effects of SWI on soil salinity variation and sustainability of flat sowing cotton (Gossypium hirsutum L.) through a comprehensive 15-year field experiment conducted in the North China Plain, encompassing six levels of irrigation water salinity (EC iw of 1.3, 3.4, 7.1, 10.6, 14.1, and 17.7 dS m−1, respectively). The results of the 15-year SWI revealed an increase in soil salinity within the cotton root zone, with increases of 5%, 20%, 39%, 67%, 116%, and 156%, respectively, observed across the six treatments. In treatments with higher EC iw values (14.1 and 17.7 dS m−1), salt accumulation extended to a depth of 3.0 m. Long - term SWI has a risk of causing soil sodicity and alkalinity. Sodium adsorption ratio (SAR) and pH in the treatments with EC iw ≥ 7.1 dS m−1 increased significantly (P < 0.05) after cotton harvest in the 15th year of continuous SWI. Cotton yield performance exhibited a distinct response to varying levels of EC iw. The treatment with an EC iw of 3.4 dS m−1 yielded the highest average cotton yield of 3419 kg ha−1, while cotton yields in treatments with an EC iw of 14.1 and 17.7 dS m−1 were more than 13% and 20%, respectively, lower than the maximum yield (P < 0.05). The sustainability index of cotton yield was at its lowest (0.68) in the treatments with an EC iw of 7.1 dS m−1, with values between 0.72 and 0.75 in the other treatments. Additionally, long-term SWI resulted in changes in cotton quality, including a decrease in micronaire value and an increase in elongation index. A quadratic correlation analysis identified a threshold EC iw of 6.8 dS m−1 for optimum cotton yield. In summary, it is recommended that the EC iw should not exceed 6.8 dS m−1 to ensure the sustainability and safety of long-term SWI for cotton production in this research region. [Display omitted] • The impact of EC iw on soil salt and cotton yield was evaluated in a 15-year experiment. • Salt accumulated in 0-1.0 m depth was positively related to EC iw. • Irrigation with high EC iw (14.1 and 17.7 dS m−1) resulted in salt accumulation to a depth of 3.0 m. • The sustainability index of yield varied from 0.68 to 0.75 under the six treatments. • A threshold EC iw of 6.8 dS m−1 was determined to be the safe limit for irrigation with saline water. [ABSTRACT FROM AUTHOR]