A sustainable irrigation system is known to improve the farmland soil water-salt environment and increase crop yields. However, the sustainable use of saline irrigation water under proper drainage measures still needs further study. In this study, a two-year experiment was performed to assess the sustainable effects of saline water irrigation under subsurface drainage condition. A coupled model consisting of the HYDRUS-2D model and EPIC module was used to investigate the effects of irrigation water salinity (IWS) and subsurface drainage depth (SDD) on soil water-salt content and summer maize yield when saline water was adopted for irrigation under different subsurface drainage measures. Summer maize in the two-year experiments were irrigated with saline water of three different salinity levels (0.78, 3.75, and 6.25 dS m⁻¹) under three different drainage conditions (no subsurface drainage, drain depth of 80 cm, and drain depth of 120 cm). The field observed data such as soil water content, soil salinity within root zone, ET and grain yield in 2016 and 2017 were used for calibration and validation, respectively. The calibration and validation results indicated that there was good correlation between the field measured data and the HYDRUS-EPIC model simulated data, where RMSE, NSE (> 0.50), and R² (> 0.70) satisfied the requirements of model accuracy. Based on a seven × seven (IWS × SDD) scenario simulation, the effects of IWS and SDD on summer maize relative grain yield and water use efficiency (WUE) were evaluated in the form of a contour map; the relative grain yield and WUE obtained peak values when drain depth was around 100 cm, where the relative yield of summer maize was about 0.82 and 0.53 at IWS of 8 and 12 dS m⁻¹, and the mean WUE was 1.66 kg m⁻³. The proper IWS under subsurface drainage systems was also optimized by the scenario simulation results; the summer maize relative yield was still about 0.80 even when the IWS was as high as 8.61 dS m⁻¹. In summary, subsurface drainage measures may provide important support for the sustainable utilization of saline water in irrigation. Moreover, the coupled HYDRUS-EPIC model should be a beneficial tool to evaluate future sustainability of the irrigation system.

Brackish water has been utilized extensively in agriculture around the world to cope with the global water deficit, but soil salt accumulation caused by brackish water irrigation cannot be ignored. Straw incorporation has been confirmed an effective sustainable means to inhibit soil salt accumulation. An experiment was conducted in growth tanks over two consecutive growing seasons to investigate the effects of wheat straw incorporation on soil moisture and salinity under brackish water irrigation (5g NaCl L⁻¹). Furthermore, the trial investigated the effects of three wheat straw cutting lengths (CK = 0 cm; L1 = 5 cm, L2 = 10 cm, and L3 = 20 cm) on soil water-salt dynamics and summer maize growth. The results showed that soil properties and maize yields were favorably and significantly affected by the shorter straw segments incorporated into the cultivated field (p < 0.05), as indicated in the decrease in soil bulk density (7.47%–7.79%) and the rise of soil organic matter (SOM) content (2.4–4.5g kg⁻¹) and soil total porosity (4.34%–4.72%) under treatment L1. Meanwhile, treatment L1 produced the greatest dry above-ground biomass (14447 ± 571 kg ha⁻¹), 100-grain weight (34.52 ± 1.20 g) and grain yield (7251 ± 204 kg ha⁻¹) of summer maize. Soil water content in the cultivated layer increased 4.79%–25.44%, and the soil salt accumulation rate decreased significantly due to the straw incorporation and the highest value of soil moisture content (19.10%–21.84%), as well as the lowest value of soil salt accumulation rates (2.12–9.06) obtained at treatment L1. Straw incorporation with cutting length in 5 cm is the optimal choice for alleviating the adverse effects due to brackish water irrigation and improving soil properties, which could be helpful for agricultural mechanization and straw field-returning practices.

The freshwater deficit is the major constraint to winter wheat production. Saline water irrigation could alleviate wheat water stress while increasing the risk of soil salinization, which would result in wheat yield reduction due to additional salt stress. The objective of the present study is to explore the effect of a straw-returning mode to promote winter wheat production under saline water irrigation. A field experiment was conducted during the winter wheat growing seasons of 2017–2018 and 2018–2019. Four returning modes were set, based on an equivalent carbon input: straw mulching (SM), biochar amendment (BA), straw mulching combined with biochar amendment (SM+BA), and the control without straw-returning (CK), along with three salinity levels of irrigation water: 0.47 dS m⁻¹ (I0, freshwater), 3.25 dS m⁻¹ (I1), and 6.75 dS m⁻¹ (I2). Saline water irrigation alone triggered soil salt accumulation and reduced the wheat grain yield by 9.43––18.19%. Returning straw to fields increased soil organic carbon content by 16.41––52.21% and decreased soil bulk density by 0.69––1.46%. The highest increase in wheat grain yield (16.60––21.80%) was always obtained when using treatment SM+BA, due to the increased soil moisture content (3.15––12.31%) and lower salt levels (24.79––44.29%) compared to CK. The results of the present study established that SM+BA provided better soil water–salt conditions and nutrient environment for winter wheat growth than a single treatment. Thus, the combined application of SM and BA was shown to be a proper mitigating strategy to cope with the adverse effects of saline irrigation on winter wheat production and to promote the sustainable use of saline water irrigation.

Comprehensive land improvement causes strong disturbances of land use patterns in the short term, resulting in changes in landscape structure and function. This study adopts the moving window method and semi-variation function to explore the spatial scale effect of landscape pattern metrics in the comprehensive land consolidation project area of Baimahu Farm, and the spatial variability and homologous ecological processes. The results showed that: (1) patch density, largest patch index, area-weighted average shape index, contagion, and division index all showed obvious scale effects, and the suitable first and second scale domains in the study area are 5–7 m and 35–40 m, respectively, and 5 m is the most suitable grain size for the study of landscape pattern change. (2) The block basis ratio of the semi-variogram of the six landscape level indices begins to stabilize at the window radius of 210 m. This scale can reflect the spatial variability of the landscape pattern in the study area and is the most suitable analysis range. (3) The fragmentation degree of paddy fields as landscape matrix decreased and the landscape dominance degree increased in the comprehensive land improvement; the degree of fragmentation of irrigated land and agricultural land for facilities increased, the aggregation of land for construction increased, the dominance degree of the pond surface decreased, and the overall landscape diversity of each mosaic decreased; the landscape heterogeneity of ditches, rural roads, forest and grassland corridors was weakened, and the ecosystem service function was weakened. (4) The trend of increased fragmentation, simplification of landscape types, and decreased diversity presented by the landscape pattern clearly indicates that the landscape pattern of the study area has been seriously damaged to some extent under the influence of human activities. This damage not only has a direct negative impact on the local ecological environment, but also poses a potential threat to the sustainable development of the region.

As an integrated framework linking resource use and environmental sustainability, the WEF (Water–Energy–Food) system plays a vital role in achieving sustainable agricultural development. Focusing on the irrigation districts in the lower reaches of the Yellow River, this study constructed and applied a Super-Undesirable-SBM (super-efficiency undesirable slacks-based measure) model and a GTWR (geographically and temporally weighted regression) model from a WEF perspective to systematically analyze the spatiotemporal evolution and driving mechanisms of WEFSE (Water–Energy–Food Synergistic Efficiency) from 2000 to 2020. The overall WEFSE exhibited a continuous upward trend, with the spatial pattern gradually shifting from the southwest to the northeast and regional disparities becoming more pronounced. The efficiency demonstrated a significant positive spatial autocorrelation, indicating a stable clustering pattern of “high–high” and “low–low” efficiency areas. In terms of driving mechanisms, WEFSE evolved from being dominated by socio-economic drivers to a composite system jointly influenced by ecological and structural factors. Among these, PD (population density) and WP (proportion of water area) had increasingly positive effects, whereas PRE (precipitation) and NDVI (normalized difference vegetation index) imposed notable constraints. Meanwhile, PCL (proportion of cultivated land), GP (proportion of grassland), and AT (average temperature) exhibited significant spatial differentiation. This study highlights that the assessment of WEFSE and identification of its driving mechanisms using the Super-Undesirable-SBM and GTWR models can help to uncover the spatiotemporal dynamics of agricultural resource utilization, providing methodological support and decision-making insights for optimizing resource allocation and promoting sustainable development in the Yellow River irrigation districts and other complex agricultural systems.