Irrigation In Arid Areas Research Articles

Simulation of water-salt transport and balance in cultivated-wasteland system based on SWAP model in Hetao Irrigation District of China

Water and salt transport among different use type land is important to irrigation management in arid area. In this study, a typical irrigation unit including cultivated land and wasteland in Hetao Irrigation District of China was selected to explore water and salt transport between cultivated land and wasteland system. Soil water-salt dynamics, groundwater depth and salinity were observed within the period of crop growing and autumn irrigation period in 2018 and 2019. Calibrated SWAP model was used to simulate water and salt flux of cultivated land and wasteland during the crop growing period and autumn irrigation period. Furthermore, water-salt transport exchange capacity was calculated between cultivated land and wasteland system in study area. Groundwater was recharged by soil water and soil salt was leached in cultivated land during the crop growing period. Soil water was recharged by groundwater and soil salt was accumulated in saline wasteland during the crop growing period. During the crop growing period, the total leaching of soil salinity was 15.64 t·ha−1 in cultivated land. Soil salt accumulation was 2.03 t·ha−1 in saline wasteland. During the autumn irrigation period, the total leaching of soil salinity was 14.93 t·ha−1 in cultivated land. Total leaching of soil salinity was 1.56 t·ha−1 in saline wasteland. Overall, saline wasteland had an important role to receive salt from cultivated land and maintain salt dynamic balance in arid irrigation area with shallow groundwater.

Study on the Appropriate Degree of Water-Saving Measures in Arid Irrigated Areas Considering Groundwater Level

Irrigated areas are major vectors of agricultural development and components of ecosystems. The groundwater level maintains the irrigated areas’ ecology safety and sustainable development. Under the influence of irrational irrigation practices—such as flood irrigation or extreme water saving without consideration of ecological impact—different areas within an irrigation district may experience anomalies in groundwater levels (either too deep or too shallow). It is of great significance to carry out research on water resource allocation and future water-saving strategies, taking into consideration groundwater depths. In this study, a method for the optimal allocation of irrigation water resources that considered groundwater level was used to regulate irrational irrigation practices and to reveal the future direction of water saving. Helan County in Ningxia province, an ecologically fragile and arid irrigated area, was selected as a case study. Multiple scenarios of different water use and different degrees of water-saving were analyzed. The results showed that non-engineering water-saving measures (such as adjusting the planting structure and controlling the amount of irrigation for rice) had better benefits compared to engineering measures (such as efficient water-saving irrigation and channel lining). When implementing only one water-saving measure, the strategy of replacing 75% of the rice area with corn yielded the best results. This approach can reduce the irrigation water shortage rate to 11% and increase by 4.58% the acreage where the groundwater level is reasonable. When multiple water-saving measures are implemented together, the most effective strategy for future water-saving efforts involves the joint implementation of several measures: replacing 75% of the rice area with corn, limiting irrigation for rice to no more than 11.85 thousand m3/ha, adopting high-efficiency water-saving irrigation in 90% of the pump-diverted water irrigation region and 40% of the channel-diverted water irrigation region, and maintaining the channel’s water utilization coefficient at 0.62. This strategy can keep the irrigation water shortage below 3.66% and increase the acreage where the groundwater level is reasonable, by 4.58% per year. The conclusions and research approaches can provide references for the formulation of water-saving measures for irrigated areas’ sustainable development.

No-tillage with total green manure incorporation: A better strategy to higher maize yield and nitrogen uptake in arid irrigation areas

The efficacy of integrating green manure in arid irrigation regions to enhance maize yield and nitrogen (N) uptake efficiency has been extensively explored. However, limited research has delineated the contribution of green manure N versus soil N on crop N utilization efficiency. This study integrated field experiments with micro-plot experiments to examine green manure (common vetch) management practices for achieving high maize yield and N uptake. In a micro-plot experiment, 15N technology was utilized to label green manure crops. Five treatments were applied in the research methodology: conventional tillage without green manure as the control (CT); tillage with total green manure incorporation (TG); no-tillage with total green manure mulching (NTG); tillage with only root incorporation (T); and no-tillage with removal of above-ground green manure (NT). The results in the micro-plot experiment were the same in the field, and both demonstrated that the utilization of green manure led to a substantial increase in maize yield and nitrogen uptake efficiency (NUPE) compared to conventional tillage (CT). In particular, under NTG, N uptake by maize from green manure was higher than NT and T, accounting for 59.1% of maize N uptake. Furthermore, the application of NTG boosted the NUPE of soil N in maize to 50.7%, which is higher than TG by 5.5%. Meanwhile, it decreased the proportion of soil N in the maize. The difference between NTG and TG was primarily shown in the maize grains. For N transport in the soil, NTG decreased N loss while increasing soil N retention. Also, it facilitated the mineralization of soil organic N before the flowering stage. In conclusion, the adoption of no-tillage with total green manure mulching not only increased N uptake both from green manure and the soil but also decreased the proportion of soil-derived N in maize.

Response of plastic film mulched maize to soil and atmospheric water stresses in an arid irrigation area

Water stress can severely decrease crop productivity by restricting photosynthesis, while the use of plastic film mulching can mitigate these water stress effects. However, the intricacies of photosynthetic and stomatal responses to soil water stress under plastic film mulching, particularly when combined with atmospheric water stress, have not been well studied, especially in arid irrigation areas. Limited research has investigated photosynthetic chlorophyll fluorescence parameters, stomatal responses, grain filling process and crop productivity to soil and atmospheric water stress under plastic film mulching. Our study addresses this knowledge gap through a comprehensive field experiment in an arid irrigation area involving maize (Zea mays L.). Well-watered and water deficit conditions with and without plastic film mulching treatments, alone or combined with atmospheric water stress (different vapor pressure deficits) were conducted. Our findings revealed that soil water stress significantly increased stomatal limitations (by 6.4–12.4 %) and may cause non-stomatal limitations. Plastic film mulching significantly improved plant photosynthetic performance (increased net photosynthesis rate by 12.2–39.8 %), chlorophyll fluorescence parameters, and stomatal regulation. Under mulched conditions, soil water stress primarily affected photosynthetic performance through stomatal limitations. Moreover, plastic film mulching significantly improved grain filling process (increased grain-filling rate by 6.3–78.5 %) and productivity (increased grain yield by 12.1–45.8 %) in spring maize subjected to soil water stress. Atmospheric water stress, alone or combined with soil water stress, influenced plant photosynthetic performance, decreasing the net photosynthesis rate and stomatal conductance. Mulching enhanced photosynthetic performance under atmospheric water stress. Overall, the positive effect of mulching on spring maize photosynthetic performance and productivity under soil and atmospheric water stresses holds promise for alleviating water resource shortages and addressing global climate warming issues in arid irrigation areas.

Effect of landscape pattern on river water quality under different regional delineation methods: A case study of Northwest Section of the Yellow River in China

Study regionA typical arid irrigation area of the Yellow River, Ningxia, Northwest China. Study focusAt present, few studies have evaluated the effects of nested watershed and runoff process on the relationships between landscape patterns and water quality. In this study, we aimed to quantify the relationships between landscape pattern and river water quality using two delineation methods. One method involved a water quality monitoring site only corresponding only to its own sub-watershed, while the other method involved a water quality monitoring site corresponding to all of its upstream sub-watersheds. New hydrological insights for the regionWe collected water quality monitoring data, including DO, CODMn, NH3-N, TP, TN, pH for the irrigation period (May, 2021 – August, 2021) and the non-irrigation period (December, 2021 – March, 2022) for seven sub-watersheds. Our results revealed that when a water quality monitoring site corresponded to all the sub-basins involved in the runoff process, the correlations between landscape composition and water quality parameters were stronger. Additionally, the degree to which landscape configuration explained the overall water quality was greater in such cases. We also found that the buffer zone scale accounted for more than 97.3% of the overall water quality variation. These results highlight the importance of aligning water quality monitoring sites with the corresponding sub-watersheds and emphasize the significance of land-use management in the riparian scale near the Yellow River for water quality protection.

Effect of Autumn Irrigation on Salt Leaching under Subsurface Drainage in an Arid Irrigation District

Non-growing season irrigation and farmland subsurface drainage play a crucial role in salt leaching and salinization control in arid irrigation areas. This study aimed to investigate the reduction of autumn irrigation quotas and drainage discharge while maintaining soil moisture retention and reducing soil salinization. Field experiments were conducted with different autumn irrigation quotas (160 mm for SD1, 180 mm for SD2, and 200 mm for SD3) combined with subsurface drainage (1.5 m drain depth and 45 m spacing). A control treatment (referred to as CK) without subsurface drainage received 200 mm of irrigation. The results showed that, after 31 days of autumn irrigation, the groundwater depth in all three subsurface drainage plots stabilized to 1.5 m, with the CK being 0.2–0.3 m shallower compared to the SD plots. The mean soil water content in the 0–150 cm soil layer of the SD1, SD2, SD3, and CK after autumn irrigation was 0.36, 0.39, 0.41, and 0.42 cm3cm−3, respectively. The combination of autumn irrigation and subsurface drainage significantly reduced the soil salt content. The mean desalination rates in the root zone (0–60 cm) soil layer were 57.5%, 53.7%, 51.9%, and 45.1% for the SD3, SD2, CK, and SD1, respectively. The mean desalination rate of 60–150 cm was not significantly different between the SD2 and SD3 (p > 0.05), and both were significantly higher than that of the SD1 and CK (p < 0.05). The drainage discharge was 31, 36, and 40 mm in the SD1, SD2 and SD3, respectively. The amount of salt discharge through the drain pipe increased with increasing irrigation quota, which was 1.22 t/ha, 1.41 t/ha, and 1.50 t/ha for the SD1, SD2, and SD3, respectively. Subsurface drainage is an effective way to prevent salt accumulation in the soil, and an autumn irrigation quota of 180 mm is recommended for leaching of salinity in the Hetao Irrigation District. These findings provide valuable insights into optimizing irrigation practices and managing soil salinization in arid regions.

Sustainable Analysis of Maize Production under Previous Wheat Straw Returning in Arid Irrigated Areas

Conservation tillage is widely recognized as an important way to improve soil quality, ensure food security and mitigate climate change. However, relatively little attention has been paid to the subject in terms of sustainable evaluation of environmental and economic benefits of the combination of no tillage and straw returning for maize production in arid irrigated areas. In this study, grain yield (GY) and water use efficiency based on grain yield (WUEGY), soil carbon emission characteristics and economic benefits were investigated, and a sustainability evaluation index based on the above indicators was assessed in maize production under a wheat–maize rotation system from 2009 to 2012. Four wheat straw returning approaches were designed: no tillage with 25 to 30 cm tall wheat straw mulching (NTSMP), no tillage with 25 to 30 cm tall wheat straw standing (NTSSP), conventional tillage with 25 to 30 cm tall wheat straw incorporation (CTSP), and conventional tillage without wheat straw returning (CTP). The results showed that NTSMP treatment could effectively regulate water consumption characteristics of maize fields and meet the water conditions for high grain yield formation, thus gaining higher GY and WUEGY. NTSMP increased GY and WUEGY of maize by 13.7–17.5% and 15.4–16.7% over the CTP treatment, and by 5.6–9.0% and 2.3–11.2% over the CTSP treatment, respectively. Meanwhile, compared with CTP, the NTSMP treatment could effectively reduce carbon emissions from maize fields, where average soil carbon emission fluxes (ACf), carbon emission (CE) and water use efficiency based on carbon emission (WUECE) were reduced by 17.7–18.9%, 11.1–11.2% and 8.8–12.8% and carbon emission efficiency (CEE) was increased by 10.2–14.7%. In addition, the NTSMP and NTSSP treatments could effectively increase total output and reduce human labor and farm machinery input, resulting in higher economic benefit. Among them, the NTSMP treatment was the most effective, net income (NI) and benefit per cubic meter of water (BPW) were increased by 16.1–34.2% and 19.1–31.8% over the CTP treatment, and by 13.2–13.3% and 9.8–15.6% over the CTSP treatment, respectively. The sustainability analysis showed that the NTSMP treatment had a high sustainability evaluation index and was a promising field-management strategy. Therefore, no tillage with 25 to 30 cm tall wheat straw mulching is a sustainable maize-management practice for increasing economic benefits and improving environmental impacts in arid irrigated areas.

Grain yield and N uptake of maize in response to increased plant density under reduced water and nitrogen supply conditions

The development of modern agriculture requires the reduction of water and chemical N fertilizer inputs. Increasing the planting density can maintain higher yields, but also consumes more of these restrictive resources. However, whether an increased maize density can compensate for the negative effects of reduced water and N supply on grain yield and N uptake in the arid irrigated areas remains unknown. This study is part of a long-term positioning trial that started in 2016. A split-split plot field experiment of maize was implemented in the arid irrigated area of northwestern China in 2020 to 2021. The treatments included two irrigation levels: local conventional irrigation reduced by 20% (W1, 3,240 m3 ha–1) and local conventional irrigation (W2, 4,050 m3 ha–1); two N application rates: local conventional N reduced by 25% (N1, 270 kg ha–1) and local conventional N (360 kg ha–1); and three planting densities: local conventional density (D1, 75,000 plants ha–1), density increased by 30% (D2, 97,500 plants ha–1), and density increased by 60% (D3, 120,000 plants ha–1). Our results showed that the grain yield and aboveground N accumulation of maize were lower under the reduced water and N inputs, but increasing the maize density by 30% can compensate for the reductions of grain yield and aboveground N accumulation caused by the reduced water and N supply. When water was reduced while the N application rate remained unchanged, increasing the planting density by 30% enhanced grain yield by 13.9% and aboveground N accumulation by 15.3%. Under reduced water and N inputs, increasing the maize density by 30% enhanced N uptake efficiency and N partial factor productivity, and it also compensated for the N harvest index and N metabolic related enzyme activities. Compared with W2N2D1, the N uptake efficiency and N partial factor productivity increased by 28.6 and 17.6% under W1N1D2. W1N2D2 had 8.4% higher N uptake efficiency and 13.9% higher N partial factor productivity than W2N2D1. W1N2D2 improved urease activity and nitrate reductase activity by 5.4% at the R2 (blister) stage and 19.6% at the V6 (6th leaf) stage, and increased net income and the benefit:cost ratio by 22.1 and 16.7%, respectively. W1N1D2 and W1N2D2 reduced the nitrate nitrogen and ammoniacal nitrogen contents at the R6 stage in the 40–100 cm soil layer, compared with W2N2D1. In summary, increasing the planting density by 30% can compensate for the loss of grain yield and aboveground N accumulation under reduced water and N inputs. Meanwhile, increasing the maize density by 30% improved grain yield and aboveground N accumulation when water was reduced by 20% while the N application rate remained constant in arid irrigation areas.

Groundwater level dynamic simulation and soil salinization prediction of the closed hydrogeological unit in the arid irrigation area

Abstract Aiming at problems such as inaccurate simulation of groundwater level in closed hydrogeological units, difficult quantitative prediction of soil salinization degree, and unclear water and salt migration, a three-dimensional simulation model of groundwater was established, and the development trend of groundwater level and soil salinization was predicted. The groundwater level simulation results are consistent with the changing trend of the observational data and the simulation model can be used to predict groundwater levels in closed hydrogeological units. When climate scenarios and human activity change are set as future scenarios, the average groundwater buried depth will continue to decrease in the next 10 years, the area with a groundwater buried depth of 0–5 m will exceed 50%, and even the groundwater will overflow to the surface. The change of soil salt content is predicted quantitatively and the salinization degree will develop from ‘saline–alkali soil’ and ‘mild saline–alkali soil’ to ‘medium saline–alkali soil’. The process of water and salt migration in three key hydrologic zones, namely ‘irrigation infiltration’, ‘solute migration’, and ‘water and salt accumulation’, is revealed in the closed hydrogeological unit. The research results can provide new ideas for the improvement of soil and water environment problems.

Tech-economic modeling and analysis of agricultural photovoltaic-water systems for irrigation in arid areas

Affected by the shortage of water resources and land degradation, the sustainable development of agriculture in more and more arid areas will face serious obstacles. The combinations of agricultural photovoltaic, water transportation and irrigation systems are considered as a potential choice to solve above problem. This study aims to investigate the competitiveness of various system configurations to transport water from water resource to agricultural irrigation systems driven by the output power of agricultural photovoltaic. Including the levelized cost of electricity and net present value, a comprehensive techno-economic assessment model is proposed to analyze the agricultural photovoltaic and irrigation systems in arid areas for six scenarios. The applicability of the proposed model in managing regional water and renewable energy nexus systems was tested through application to a real-world case study in the Gansu province, China. Assuming that the baseline transportation distance is 50 km, the results show that exporting water to farmland through electric water trucks shows the best economic performance with the net present value of 13.71 MU$, and every 10 km increase in the transportation distance can decrease the net present value by 1.32 MU$. An important finding is that when the transportation distance was greater than 100 km, pipeline transportation mode was more economical than electric water truck transportation mode. Finally, a sensitivity analysis was carried out to analyze the electricity and water prices, farmland size, photovoltaic efficiency on the economic performance of these systems. Results show that only when the electricity price was greater than 0.08 $/kWh, pipeline transport mode yielded positive benefits, and every 0.1$/m3 increase in the water price can increase the net present value by 0.2 MU$.

Ridge planting with transparent plastic mulching improves maize productivity by regulating the distribution and utilization of soil water, heat, and canopy radiation in arid irrigation area

Ridge planting with transparent plastic mulching improves maize productivity by regulating the distribution and utilization of soil water, heat, and canopy radiation in arid irrigation area

Photosynthetic Physiological Basis of No Tillage with Wheat Straw Returning to Improve Maize Yield with Plastic Film Mulching in Arid Irrigated Areas

Surface mulch is an efficient plant production technique widely used in arid and water-scarce areas. In this study, a field experiment was conducted to determine whether plastic film combined with wheat straw returning could boost grain yield of maize via optimizing photosynthetic physiological characteristics and coordinating yield components. The results showed that no tillage with wheat straw mulching and straw standing treatments had better regulation on photosynthetic physiological characteristics and had a greater impact on the increase in grain yield than conventional tillage with wheat straw incorporation and without wheat straw returning (the control treatment) in plastic film-mulched maize. Meanwhile, no tillage with wheat straw mulching had a relatively higher yield than no tillage with wheat straw standing through better regulation of photosynthetic physiological characteristics. No tillage with wheat straw mulching decreased the leaf area index (LAI) and leaf area duration (LAD) of maize before the VT stage and maintained higher LAI and LAD after the VT stage, which effectively regulated the growth and development of maize at early and late stages of development. From VT to R4 stage of maize, no tillage with wheat straw mulching had greater chlorophyll relative content, net photosynthetic rate, and transpiration rate by 7.9-17.5%, 7.7-19.2%, and 5.5-12.1% than the control, respectively. In addition, leaf water use efficiency was increased by 6.2-6.7% from the R2 to R4 stage of no tillage with wheat straw mulching in comparison to the control treatment. Thus, no tillage with wheat straw mulching had a greater grain yield of maize by 15.6% than the control, and the high yield was attributed to the synchronous increase and cooperative development of ear number, grain number per ear, and 100-grain weight. Collectively, no tillage with wheat straw mulching had a positive effect on regulating the photosynthetic physiological traits and can be recommended to enhance the grain yield of maize in arid conditions.

Introducing water factors improves simulations of maize stomatal conductance models under plastic film mulching in arid and semi-arid irrigation areas

Plastic film mulching (PFM) in the cropland may alter biophysical conditions for crop growth, which may not be accounted for in existing stomatal conductance models. This can affect the accuracy of carbon–nitrogen-water cycle simulations for the soil-crop systems and hamper our understanding of internal mechanisms that control plant leaf stomatal conductance (gsw). To evaluate the simulations of PFM effects on gsw, the three models (i.e., Ball-Woodrow-Berry (BWB), Ball-Berry-Leuning (BBL), and unified stomatal optimization (USO) models) were used. The two model modification factors were leaf-air temperature difference (ΔT) and a water response function (f(θ)). A two-year maize (Zea mays L.) field experiment was conducted under different PFM (black, transparent, and no-mulch). The performance of the BWB model was poor under varying water status in the arid irrigation area. As for the BBL and USO models, the coefficient of determination and modified efficiency coefficient of the modified models increased 5.8%–90.6% and 6.5%–145.4%, respectively, compared with the initial models. The root mean square error and relative error of the modified models decreased 3.5%–67.9% and 4.8%–65.6%, respectively. The ΔT and f(θ) factors effectively improved the BBL and USO models, but the f(θ)-modified models performed better than ΔT-modified models under PFM. Overall, our results suggest that the maize land implemented with plastic film mulching has altered biophysical conditions, leading to significant changes in crop photosynthesis, leaf-air temperature difference and top-soil water conditions. Accurate estimates of stomatal conductance require the model to consider water response functions and leaf-air temperature difference, particularly in environmental conditions associated with different extents of water deficit or drought.

Improving the sustainability of cropping systems via diversified planting in arid irrigation areas

Improving the sustainability of cropping systems via diversified planting in arid irrigation areas

Optimizing Planting Density to Increase Maize Yield and Water Use Efficiency and Economic Return in the Arid Region of Northwest China

High grain yield and water use efficiency (WUE) are the key goals when producing maize (Zea mays L.) under irrigation in arid areas. Increasing the planting density and optimizing irrigation are important agronomic practices for increasing the maize grain yield and WUE. A two-year field experiment was conducted to investigate the effects of planting density and irrigation on the maize grain yield, WUE, and economic return of spring maize under a mulch drip irrigation system in Xinjiang, Northwest China. The experiment included four irrigation levels and five planting densities. The results showed that the reduction of irrigation decreased the yield and evapotranspiration (ETc) but improved the WUE. Increasing the planting density increased the ETc, but there was a quadratic curve relationship between yield and WUE and planting density. Treatment with 600 mm of water and 12 plants m−2 obtained the highest grain yield (21.0–21.2 t ha−1) and economic return (3036.0 USD ha−1) and a relatively high WUE (2.64–2.70 kg kg−1). Therefore, a reasonable increase in planting density and an appropriate reduction of irrigation combined with drip irrigation under a mulch system can simultaneously achieve high yields and economic return and high WUE in maize production.

Climate change impacts on water sustainability of South African crop production

Agricultural production in arid and semi-arid regions is particularly vulnerable to climate change, which, combined with projected food requirements, makes the sustainable management of water resources critical to ensure national and global food security. Using South Africa as an example, we map the spatial distribution of water use by seventeen major crops under current and future climate scenarios, and assess their sustainability in terms of water resources, using the water debt repayment time indicator. We find high water debts, indicating unsustainable production, for potatoes, pulses, grapes, cotton, rice, and wheat due to irrigation in arid areas. Climate change scenarios suggest an intensification of such pressure on water resources, especially in regions already vulnerable, with a country-scale increase in irrigation demand of between 6.5% and 32% by 2090. Future land use planning and management should carefully consider the spatial distribution and local sustainability of crop water requirements to reduce water consumption in water risk hotspots and guarantee long-term food security.

Salt Accumulation during Cropping Season in an Arid Irrigation Area with Shallow Water Table Depth: A 10-Year Regional Monitoring

Nowadays, irrigation takes up about 35% of agricultural water consumption worldwide, and irrigation induced secondary soil salinizationsalinization affects the crop production and sustainable development of arid irrigation areas globally. However, the regular pattern of salt accumulation in the root zone during the cropping season and the contributions of its attribute factors are still unclear. Therefore, a 10-year monitoring was conducted in the Hetao Irrigation District to reveal the soil salt accumulation during the cropping season and to relate it to influential factors, including potential crop evapotranspiration, water input (field irrigation + precipitation) and water table depth. It was found that under the climate conditions and water-saving irrigation measures of the investigated 10-year period, (1) the salt accumulated during the cropping season could be effectively leached by autumn irrigation and the root zone soil could remain suitable for crop germination, (2) the cropping season water deficit (potential crop evapotranspiration − field irrigation − precipitation) showed strong correlation with the cropping season salt accumulation, and (3) maintaining the cropping season average water table depth larger than a critical depth (roughly 3 m) might be the most economical way to alleviate salt accumulation. Therefore, it is recommended to balance the salt leaching and the water table depth controlling in the future water-saving irrigation management practices.

The Relationship Between the Distribution of Water and Salt Elements in Arid Irrigation Areas and Soil Salination Evolution

Long periods of surface water irrigation and water and salt movement have slow and continuous influence on the evolution of soil salinization in a closed hydrogeological unit of arid irrigation areas. It is of more application value to study the evolution process of soil salinization from the perspective of regional medium and long terms in the regional scale for the sustainable development of irrigated areas. In this study, the spatial–temporal evolution of soil salinization and dominant factors for soil salination, and the relationship between soil salination and the groundwater buried depth were studied through spatial interpolation and statistical analysis with long-time observed data of a closed hydrogeological unit in the Jingtaichuan Electric-Lifting Irrigation Area in Gansu Province, China. The results showed that from 2001 to 2016, the soil salt content, the groundwater mineralization, and the surface irrigated water amount in the study area enhanced slowly, while the groundwater buried depth decreased; the salinization degree in the study area was increasing slowly; there was a positive correlation between the soil salt content and the groundwater mineralization, while a negative correlation existed between the soil salt content and either the surface irrigated water amount or the groundwater buried depth; the groundwater buried depth had the strongest impact on the spatial distribution of the soil salt content; the increase rate of the soil salt content lowered as the groundwater buried depth increased, which met the logarithmic relationship; soil salination was actively developed in regions with a low groundwater buried depth below 2.5 m, and soil salinization became evident in regions with a groundwater buried depth below 5 m; 15.0 m was a critical groundwater buried depth that caused the increase or the decrease in the soil salt content. The research results provide a new way to predict the development trend of soil salinization in the medium and long terms and provide a theoretical basis for the development of salinization prevention and control measures in irrigated areas, which is of great significance to maintaining a harmonious soil and water environment in irrigated areas.

Future climate change impacts on mulched maize production in an arid irrigation area

Future climate change (FCC) and water scarcity significantly affect agricultural production in arid areas. Plastic film mulching (PM) combined with large irrigation amounts is popular for agricultural production in these areas. Crop model is an important tool for studying FCC’s effect on crop production and its countermeasures. In this study, after calibration and validation using measured values from a two-year field experiment, the SPACSYS (v 6.0) and modified DSSAT-CERES-Maize (v 4.7.0.0) models were used to evaluate the implementation of six management systems (three mulching measures: transparent film, black film, no film; two fertilization levels: high, low) and to optimize management measures under FCC. Both models well simulated maize’s anthesis and maturity dates, the final aboveground biomass, yield, and topsoil soil water content (SWC) compared with the measured values. SPACSYS simulated the maize growth and SWC under nitrogen stress better than DSSAT. Total 27 global climate models (GCMs) were used to drive DSSAT and SPACSYS models with different irrigation schemes, including three irrigation amounts (I1, I2, I3) and four irrigation ratios (the proportion of total irrigation amount in different growing stages: T1, T2, T3, T4) to simulate crop phenology and yield under FCC in future decades (2040s and 2080s). Both models advanced the anthesis date (by 8.1–16.2 d in the 2040s and 12.8–20.3 d in the 2080s), maturity date (by 12.7–18.9 d in the 2040s and 19.1–24.8 d in the 2080s), and length of reproductive growth period (by 3.6–6.1 d in the 2040s and 5.8–11.0 d in the 2080s). The I1T1 scenario under transparent film mulching produced the highest yields (12.14–16.07% in the 2040s and 5.36–6.07% in the 2080s higher than the average). The I3T4 scenario maintained stable yields in the 2040s, decreasing by nearly 20% in the 2080s. Consequently, the I3T4 scenario could be the optimal management practice for balancing yield and irrigation for maize production in this arid area in the future decades.

Effects of Automated Irrigation Systems and Water Regimes on Soil Properties, Water Productivity, Yield and Fruit Quality of Date Palm

Applications of modern micro-irrigation methods are inevitable for optimum water use due to the limitations imposed by irrigation water resource scarcity. Regardless of water shortages and associated challenges in dry areas, the irrigation of date palm trees consumes an excessive quantity of water annually using conventional irrigation methods. Therefore, the present study was designed to evaluate the effects of modern surface and subsurface micro-irrigation systems, i.e., subsurface drip irrigation (SSDI), controlled surface irrigation (CSI), and surface drip-irrigation methods (SDI), with different irrigation water regimes, i.e., 50%, 75%, and 100% irrigation water requirements (IWRs), on the yield and fruit quality of date palms (cv. Khalas) and water conservation in the dryland region of Al-Ahsa, Saudi Arabia. The effects of three irrigation methods and IWRs were studied on macronutrients and soil chemical properties at three depths (0–30, 30–60, and 60–90 cm), as well as on water productivity, yield, and the fruit quality of date palms. The study was carried out over two years and was designed using a two-factorial randomized complete block design (RCBD) with nine replications. The results indicated that electrical conductivity (EC) increased as the depth of the soil increased. The soil chemical properties did not change much in all experimental treatments, while soil pH values decreased with the soil depth from 0–30 to 60–90 cm. Although the maximum fruit yield (96.62 kg palm−1) was recorded when 100% irrigation water was applied in the SSDI system, other treatment combinations, such as SDI at 100% IWR (84.86 kg palm−1), SSDI at 75% IWR (84.84 kg palm−1), and CSI at 100% IWR (83.86 kg palm−1) behaved alike and showed promising results. Similarly, the highest irrigation water productivity (2.11 kg m−3) was observed in the SSDI system at 50% IWR, followed by the SSDI at 75% IWR (1.64 kg m−3) and 100% IWR (1.40 kg m−3). Fruit quality attributes were also promoted with the SSDI system at 75% IWR. Hence, the SSDI method at 75% IWR appeared to be an optimal choice for date palm irrigation in arid areas due to its positive impact on water conservation and fruit characteristics without affecting soil chemical properties.