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Optimizing tillage practices to improve crop yield and crop water productivity (CWP) is essential for promoting sustainable dryland agriculture. This meta-analysis used the water supply during the growing season (WS, total soil water storage at sowing time, and growing-season precipitation) instead of mean annual precipitation (MAP), to assess the effects of different tillage practices on the yield and CWP of winter wheat and spring maize in northern China. The results showed that WS had a stronger correlation with crop yield than MAP, especially for winter wheat. Compared with conventional tillage, no-tillage combined with straw mulching (SM) increased winter yield by 36.56 % and CWP by 17.93 % when WS ≤ 650 mm, and subsoiling tillage increased winter wheat yield by 21.17 % and CWP by 9.29 % in winter wheat yield when WS > 650 mm. SM and subsoiling tillage performed better in regions with higher mean annual temperature (MAT) than that with lower MAT. For spring maize, no tillage, no-tillage combined with plastic film mulching (PM), subsoiling tillage and rotary tillage significantly increased yield and CWP under different WS conditions and the highest effect was showed in PM under higher WS condition; meanwhile, PM and subsoiling tillage performed good under various temperature conditions, while rotary tillage performed better in areas with lower temperature. Thus, the recommended tillage practice for spring maize is PM in northeast China, and subsoiling tillage in north-central and northwest China; for winter wheat, subsoiling tillage is recommended for north-central China, and SM is recommended for northwest China. Taken together, our results indicate that it is more accurate to use WS rather than the MAP to evaluate appropriate tillage practices in drylands. Furthermore, WS can also replace MAP for yield estimation and prediction.

The optimal allocation of water resources is crucial for addressing regional water scarcity, adapting to climate change, and promoting sustainable development. This study focused on the Shule River Basin and considered three climate scenarios (SSP1–2.6, SSP2–4.5, SSP5–8.5), which is combinations of Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways (RCPs). A water resources optimal allocation model including water supply and demand prediction, multi-objective optimization, decision-making and analysis on optimal water allocation schemes was constructed. This model aims to analyze the optimal allocation of water resources in the Shule River Basin over three planning years (2025, 2030, 2035), considering guarantee rates of 50 % and 75 % under various climate scenarios. The obtained results indicate that: (1) An increasing trend in water demand in the planning year. For instance, under the SSP1–2.6 scenario, the basin's water demand is projected to reach 1.920×10^9 m3, 2.037×10^9 m3, and 2.103×10^9 m3 in 2025, 2030, and 2035, respectively. (2) The total water supply with a guarantee rate of 50 % (75 %) in the planning years is projected to be 1.939 (1.483)×10^9, 1.957(1.502) ×10^9, and 1.974 (1.519) ×10^9 m3, respectively. (3) In the three scenarios of SSP1–2.6, SSP2–4.5, and SSP5–8.5, the water demand for domestic and ecology is met in each planning year. There is a slight water shortage in the industrial sector, with a shortage rate ranging from 0 % to 13.41 %. The agricultural sector experiences the highest water shortage, with a rate of 1.93–44.77 %. (4) The water supply structure of each optimal allocation scheme of water resources was optimized. The economic benefits mainly depend on the industrial and ecological sectors. These findings offer valuable insights for optimizing the distribution of regional water resources in response to changing climatic conditions. • The optimal allocation model of water resources in Basin based on climate change scenario was constructed. • The total water demand of Shule River Basin based on climate change scenario was predicted. • The optimal allocation scheme of water resources in Shule River Basin under three climate scenarios was obtained. [ABSTRACT FROM AUTHOR]

Water availability explains a large part of the spatial and temporal yield variability of ware potato in the Netherlands. Climate change is projected to lead to greater variability in water availability. Therefore, an accurate simulation of crop yield as a function of water availability is of high importance. Many crop models can simulate water-limited potato yields, but as detailed experimental data on drought and oxygen stress are scarce, models are often not well calibrated and evaluated. We set up a large experiment and an on-farm observational trial to calibrate and evaluate the simulation of water-limited yield of different potato cultivars across the Netherlands. In addition, we investigated the required model complexity to accurately simulate water-limited potato yields. The crop growth model WOFOST was used for simulations either as a single model or coupled with SWAP. Yields were simulated applying either only drought stress or by including both drought and oxygen stress. We employed two methods for simulating oxygen stress in SWAP-WOFOST. The calibration improved accuracy of simulated water-limited yields as demonstrated in our model evaluation. Both on sandy and clayey soils, water-limited yields were best simulated using SWAP-WOFOST while simulating oxygen stress using a process-based method in combination with a rooting density that decreases linearly with rooting depth. On sandy soils, the bottom boundary condition of free drainage was applicable. On clayey soils measured groundwater levels (or soil water pressure heads when measurements are not available) should be used as bottom boundary condition. On sandy soils both WOFOST and SWAP-WOFOST may be used, as results were similar. On clayey soils, WOFOST is less suitable, as it cannot simulate capillary rise. SWAP-WOFOST however has many options and parameters, which can result in large differences in results. Hence, a careful model set up and evaluation is required for each application. • The models WOFOST and SWAP-WOFOST have been recalibrated for water-limited potato yields. • On clayey soils with shallow groundwater levels SWAP-WOFOST outperformed WOFOST. • On clayey soils there seemed to be an effect of oxygen stress on yield. • Effects of oxygen stress were smallest in WOFOST, and largest in SWAP-WOFOST using a process-based method. • On sandy soils there was an inconsistent benefit of using SWAP-WOFOST over WOFOST. [ABSTRACT FROM AUTHOR]

In West Africa, long dry spells are likely to become more frequent and intense as a result of global climate variability, which may significantly impact cocoa tree performance (i.e. morphology, physiology, growth and production), and asks for improved water management. Potassium (K) application may mitigate drought impacts on cocoa, yet knowledge on how shorter, drier wet seasons affect cocoa and on the potential mitigating effect of K application is limited. This study investigated the effects of reduced water availability via shelters and K application on cocoa leaf traits, root growth, reproductive dynamics and yield of cocoa trees in a 6-year old plantation. Two soil moisture levels and two K treatments were considered: a control (no shelter) and sheltered (67 % rainfall reduction) treatment, either with or without 200 kg ha−1 K application. Results indicated rain sheltering significantly decreased soil moisture by 9 %, root interceptions by 50 %, root mass density by ∼50 %, stomatal conductance (Gs) by ∼60 %, flush intensity by ∼70 %, leaf greenness ∼48 % and leaf size by ∼68 %. While individual pod mass remained unchanged, flower intensity, healthy cherelles, pod, and bean numbers per tree dropped, leading to a dry bean yield reduction from ∼2100 kg ha−1 to ∼1450 kg ha−1 (∼31 %). The beneficial impact of K application was primarily noticeable under control conditions, where it increased Gs, leaf size and greenness. Also, about 35 % of precipitation is intercepted by and directly evaporates from the cocoa canopy and thus never reaches the soil. Future agro-meteorological crop models need to take this into account. Overall, results indicate a strong negative effect of reducing water availability during the wet season on leaf physiology, pod production and cocoa yield. Yields were mostly reduced because of a lower number of pods and much less by an effect on individual pod size. However, K application may not mitigate drought effects and sustaining cocoa yield would require integrated water management. • In a mature cocoa plantation, ∼65 % of precipitation reaches the soil. • Rain sheltering during the wet season decreases cocoa yield by 31 %. • Potassium application increased stomatal conductance, leaf greenness and hence yield. • Potassium did not mitigate yield reduction in rain sheltering treatment. • Rain sheltering reduced root length and density, while potassium had reverse effect. [ABSTRACT FROM AUTHOR]

Agroecosystems play an important role in carbon sequestration and water consumption of global terrestrial ecosystems. However, the magnitude, pattern, and regulation of the ratio of transpiration to evapotranspiration (T /ET), and also water use efficiency at ecosystem (WUE e) and canopy (WUE c) scales, remain unclear in agroecosystems in arid areas. In this study, a six-year synchronous observation of water-carbon fluxes and sap flow by the eddy covariance and sap flow techniques was conducted in an irrigated vineyard in northwest China. We found that T /ET, WUE e , and WUE c changed dynamically at the daily (1.0–98.6%, 0.3–4.9 g C kg–1 H 2 O, 0.4–5.9 g C kg–1 H 2 O) and monthly (26.0–71.0%, 0.8–1.8 g C kg–1 H 2 O, 2.3–3.2 g C kg–1 H 2 O) scales. At the annual scale, the range was relatively narrow, with mean values of 61.7% ± 3.7%, 1.5 ± 0.1 g C kg–1 H 2 O, and 2.4 ± 0.3 g C kg–1 H 2 O, respectively (mean ± standard deviation). Biological and environmental factors regulated their dynamics on different temporal scales. Specifically, leaf area index (LAI) and canopy conductance (g c) mainly determined the seasonal variation of T /ET, WUE e , and WUE c at the daily and monthly scales. However, at the annual scale, vapor pressure deficit (VPD) and air temperature (T a) became the main influencing factors. These results highlight the complexity of water-carbon coupling in agroecosystems and the necessity of considering specific factors at different temporal scales when modeling and managing agricultural water resources. In addition, there is still great water-saving potential from the perspective of WUE in the cultivation of vines in Northwest China. • Sap flow and water-carbon fluxes are measured synchronously for 6 years in an oasis agroecosystem. • The ratio of transpiration to evapotranspiration (T /ET) is 61.7% ± 3.7% during growing season. • Water use efficiency (WUE) at the ecosystem scale is 1.6 times than that of the canopy. • Gas exchange metric and WUE explain 73.7% of the multi-dimensional space variation of plant traits. [ABSTRACT FROM AUTHOR]

Benchmarking is an effective management tool to improve irrigation performance through comparison with other irrigation management units; however, its application is often limited by the data available to support the analysis. This study developed a benchmarking system that reduces reliance on local data by using satellite-based estimates and quantifies benchmarking uncertainty due to alternative data sources. We benchmarked the relative irrigation supply (RIS satellite) (i.e. the ratio of irrigation supply to crop net irrigation demand) for more than 300 farms growing corn/maize, cotton and rice crops in the Coleambally Irrigation Area in Australia from 2011 to 2019. Three key inputs to RIS satellite , namely irrigated cropping area (ICA), start and end dates of a season (SOS/EOS) and crop coefficient (K c), were derived from Landsat time series data. To understand the uncertainty in satellite-based benchmarking, RIS satellite was compared with RIS non-satellite estimates derived from non-satellite datasets. The variation in RIS with respect to input data sources and the reliability of data sources were also quantified. RIS satellite was highly variable across farms in any particular year, and over-irrigation (RIS satellite >1) was common. In addition, each farm tended to have a consistent RIS satellite ranking across years, indicating the role of farmers' irrigation management practice in RIS. ICA from different datasets contributed most to the random variation in RIS, while satellite-based ICA presented more reliable estimates with a median absolute percentage error of 5 %, which is half the error for survey-based ICA. We conclude that our satellite-based benchmarking system is effective in overcoming data limitations and is likely to be more reliable than systems using survey data. This system can support improved irrigation performance monitoring in this district and is transferable to other irrigation areas with irrigation supply information available. • We developed an irrigation benchmarking system that uses satellite and observed water supply data. • Over-irrigation is found in most farms across crops and years (RIS>1). • Farms tend to have similar RIS when growing the same type of crops in two different years. • Crop area is the input leading to the largest variation in RIS. • Satellite-derived cropping areas show good consistency with ground truth (R2=0.96). [ABSTRACT FROM AUTHOR]

China's agricultural sector has long realized innovation to meet burgeoning food demand, yet often innovation has occurred without concurrent consideration of trade-offs on blue water security. We contend that food security and blue water security should be given equal priority if sustainable production and consumption policies are to be defined. Here, we quantify the interplay between blue water and food security in China from 1990 to 2020 using blue water footprint (BWF) and blue water boundary as lenses. We find that national agri-food BWF has grown over time, being only 4 % below the sustainability boundary in 2020, and with the number of provinces with unsustainable system states increasing from nine in 1990s to 17 in 2010s. While blue water security and minimum food security have been achieved since 2012, the food consumption BWF has surpassed national food production and the BWF boundary by 32 % and 26 % in 2020, respectively. Assuming trends continue ceteris paribus , we project that China's BWF will transgress the sustainability boundary by 2025. Even so, with appropriate intervention in production, supply chains, and consumption guidelines, the food demand/water supply conundrum could be equitable and sustainable, notwithstanding higher food consumption in 2030. This study clearly addressed the contradictions potential balancing between blue water and food security in China at the national scale, and we articulate a simple, scalable approach for nations facing water scarcity to deconstruct drivers of, and develop alternative futures for, sustainable water and food security. • China achieved a balance between blue water and basic food security since 2012. • Actual food consumption far exceeded the basic food security target since 2008. • Food production within the blue water boundary can support up to 1.22 billion people. • Food production below the blue water boundary by 4 % and would exceed it by 2025. • Balancing blue water and food security is possible through further optimizations. [ABSTRACT FROM AUTHOR]

The Turkestan region in the southern part of Kazakhstan is currently facing a water scarcity issue due to various factors. These factors include the declining transboundary flow of the Syr Darya River, the effects of climate change, the increasing population, and the economic growth of neighboring countries in Central Asia. The water availability of the operating irrigation systems in the region fluctuates between 75 % and 95 %, dropping to 50–60 % in dry years, leading to a significant shortage of water resources. In particular, the agro-industrial complex, the largest water consumer, is heavily affected, with over 80 % of available water resources needed for irrigation. Therefore, this research aimed to investigate the potential use of groundwater and collector-drainage water to enhance water availability in the Maktaaral district of this region. The research methodology consisted of analytical and experimental studies to examine the formation and contribution of groundwater to total water consumption based on its depth and to determine the qualitative composition of collector-drainage water for reuse in irrigation. The study results indicate substantial losses of irrigation water due to filtration in the region, leading to a significant rise in the groundwater table. Consequently, the area of irrigated lands with groundwater depths up to 1 m (hydromorphic regime) in the Maktaaral district increased from 105 ha in 1994–378 ha in 2002 and to 2562 ha in 2021, representing an 18-fold increase. Under these conditions, the contribution of groundwater to total water consumption was 74 %, with irrigation water accounting for 26 %. In areas with a semihydromorphic soil regime where the groundwater table varies within 2–3 m, the volume of groundwater consumption decreased, amounting to 51 % of the total water consumption. Moreover, under the automorphous soil regime, where the groundwater table is greater than 3 m, the total water consumption was fully supported by irrigation water. Research on the qualitative composition of collector-drainage water in the Maktaaral district revealed a predominance of toxic salts (74.3–76.6 %), indicating that their use for irrigation would lead to soil salinization and alkalinization. The reuse of these waters is feasible only through mixing them with irrigation water to reduce salinity and increase the volume of suitable water resources for irrigation. However, regular monitoring of the chemical composition of such waters is essential. • Water scarcity exacerbated by reliance on transboundary inflows. • Severe water deficits in Aral-Syrdarya watershed's irrigated lands. • Collector-drainage water production contributes significantly to supply but poses pollution challenges. • Urgent need to enhance water usage efficiency, especially in Maktaaral district. [ABSTRACT FROM AUTHOR]

Soke Plain, located within the Büyük Menderes River Basin is one of the highest producers of cotton in Türkiye. The overall irrigation water supply is based on scarce conventional water resources that are being depleted at an increasing pace due to climate change impacts in B. Menderes. The inclusive objective of this research is to pave the way for a "water efficiency action plan" incorporating non-conventional (alternative) water resources for irrigation in Soke Plain to address adaptive management. Integrated Water Resources Management (IWRM) principles help decision makers (DMs) to identify and apply the most adequate alternatives among other possible ones in resource planning processes. Therefore, the preference ranking of DMs among possible water resource alternatives for irrigation is vital for implementation. This paper marks the first instance of using a multi-criteria decision-making (MCDM) method to evaluate both conventional and non-conventional water resource alternatives for cotton irrigation. The evaluation and ranking of water resource alternatives is processed using the hybrid MCDM method, integration of "Hesitant Fuzzy-Analytic Hierarchy Process" (HF-AHP) and "Hesitant Fuzzy Evaluation based on Distance from Average Solution" (HF-EDAS), namely HF-AHP-EDAS. This procedure implies several possibly contradictory qualitative and quantitative criteria, incorporates ambiguity, vagueness, and hesitancy in decision-makers' decisions, and achieves a consistent, dependable ranking of alternatives. Eight different water resources for irrigation are evaluated by 5 experts, for 15 assessment criteria, in Soke Plain. Conventional water resources blended with drainage water is concluded to be the best irrigation water resource alternative, with HF-AHP-EDAS and also with HF-AHP-PROMETHEE II (Preference Ranking Organization Method for Enriching Evaluations II), that is used for comparison analysis. This choice aligns well with the outlined arguments, culminating in an overall result deemed compliant with the field survey. [Display omitted] • B. Menderes is an example of water stressed river basin (water stress index > 0,8). • Knowing preference ranking of DMs for irrigation resources helps to restructure water management. • Using an MCDM method to evaluate irrigation water alternatives marks the first instance. • The HF-AHP-EDAS and HF-PROMETHEE II methods are utilized to rank irrigation water alternatives. • Reuse necessitates associated sewerage infrastructure, quality standards and pricing policy. [ABSTRACT FROM AUTHOR]

Optimizing tillage practices to improve crop yield and crop water productivity (CWP) is essential for promoting sustainable dryland agriculture. This meta-analysis used the water supply during the growing season (WS, total soil water storage at sowing time, and growing-season precipitation) instead of mean annual precipitation (MAP), to assess the effects of different tillage practices on the yield and CWP of winter wheat and spring maize in northern China. The results showed that WS had a stronger correlation with crop yield than MAP, especially for winter wheat. Compared with conventional tillage, no-tillage combined with straw mulching (SM) increased winter yield by 36.56 % and CWP by 17.93 % when WS ≤ 650 mm, and subsoiling tillage increased winter wheat yield by 21.17 % and CWP by 9.29 % in winter wheat yield when WS > 650 mm. SM and subsoiling tillage performed better in regions with higher mean annual temperature (MAT) than that with lower MAT. For spring maize, no tillage, no-tillage combined with plastic film mulching (PM), subsoiling tillage and rotary tillage significantly increased yield and CWP under different WS conditions and the highest effect was showed in PM under higher WS condition; meanwhile, PM and subsoiling tillage performed good under various temperature conditions, while rotary tillage performed better in areas with lower temperature. Thus, the recommended tillage practice for spring maize is PM in northeast China, and subsoiling tillage in north-central and northwest China; for winter wheat, subsoiling tillage is recommended for north-central China, and SM is recommended for northwest China. Taken together, our results indicate that it is more accurate to use WS rather than the MAP to evaluate appropriate tillage practices in drylands. Furthermore, WS can also replace MAP for yield estimation and prediction. • There is a strong correlation between water supply and crop yield in northern China. • Water supply could consider the mismatch between the growing period and rainfall. • Optimizing tillage practices based on water supply is accurate in northern China. [ABSTRACT FROM AUTHOR]

Large-scale agricultural activities can intensify atmospheric–terrestrial interactions, of which precipitation recycling plays a critical role. During 1982–2018, irrigated area has dramatically expanded in Northwest China (NWC). In this study, a regional precipitation recycling model—the Brubaker model was used to investigate the precipitation recycling ratio (PRR) and recycled precipitation (RP). Evapotranspiration (ET) estimated by the atmospheric–terrestrial water balance method (A–T) was employed to investigate precipitation recycling. Statistically, there was a turning point in 2002 for the rate in irrigated area increase, from 0.07 × 106 ha/year before 2002–0.217 × 106 ha/year after 2002. There were significant shifts in ET , PRR, and RP in NWC, using the turning point of irrigated area expansion as the line of demarcation. The contribution of the change in irrigated area to PRR increased from 18.3% (1982–2002) to 22.9% (2003–2018) in NWC. Prior to 2002, enhanced RP offset the increased ET by 72.9%. After 2002, the positive effect of irrigated area expansion on precipitation recycling disappeared in NWC. Due to the different climate and irrigation practices at the province level, the variations in irrigated area and their contributions to PRR were examined in three provinces, Xinjiang, Gansu, and Shaanxi. Results based on the Brubaker model and Budyko framework indicate that in Xinjiang and Gansu, the contribution of the irrigated area change after the turning point to PRR were 24.5% and -95.6%, respectively, and there is no potential for continued expansion of irrigated area. In Shaanxi, however, there is potential for continued expansion of irrigated area. The methodology for quantifying the impact of irrigated area change on PRR provides reliable references for the sustainable use of cultivated land and the protection of agricultural water resources. • Enhanced recycled precipitation offset ET increase induced by irrigated area expansion before 2002 in Northwest China. • Irrigated area in Northwest China exceeded the threshold and had the opposite effect on precipitation recycling ratio after 2002. • There is potential for continued expansion of the irrigated area in Shaanxi. [ABSTRACT FROM AUTHOR]

Studying rice water requirements (ET c) and area is crucial for developing irrigation schedules and adjusting crop structures. The cold rice cultivation region is China's main high-quality rice production base and has the lowest temperature, highest latitude, and greatest sensitivity to climate. However, little research has focused on its past rice distributions and ET c , and its future variations are not yet clear. Past ET c was calculated by the Penman–Monteith and crop-corrected coefficient method, and past rice distribution patterns were analyzed based on the annual paddy rice planting area datasets. Future reference crop evapotranspiration (ET 0) was projected by the statistical downscaling model (SDSM) based on the CMIP6 ensemble of daily predictor variables. The food and agriculture projections to 2050 datasets were used to project future rice areas, and the patch-generating land use simulation (PLUS) model simulated rice distribution. Finally, we projected future rice water supply demand. The results showed that ET c showed a decreasing trend, and the total rice area and production increased by 4.52 and 5.49 times from 1990 to 2020. Both in the past and future, rice was densely distributed in and expanded into the Sanjiang and Songnen Plains, and the spatial characteristic of ET c was as follows: the west was larger than the east, the north was larger than the south, and the central was in between. In the four future periods, the total ET c demonstrated an upward trend, increasing by 7.44–21.04, 15.64–34.74, 24.74–45.84, and 16.14–41.14 mm under the SSP126, SSP245, SSP370, and SSP585 scenarios, respectively, compared to the historical period. And it is generally ranked as SSP370 > SSP245 > SSP126. Finally, we projected future rice water supply meet the demand caused by rice area expansion. • Rice area and production increased by 4.52, and 5.49 times in past, respectively. • Future ETo and precipitation were predicted by SDSM model based on CMIP6 data. • ETc was estimated by the crop corrected-coefficient method. • ETc showed a decreasing trend in past, and an increasing trend in future scenario. • Future agricultural irrigation will meet the demand caused by rice area expansion. [ABSTRACT FROM AUTHOR]

It is likely that climate change will increase irrigation water demand and, consequently, reduces water security in the Mediterranean Basin if current irrigation supply and demand conditions are maintained. Climate change adaptation can be achieved by (1) decreasing irrigation water demand through more efficient irrigation techniques, (2) increasing irrigation water supply by adopting new technological advances, (3) converting to rainfed agriculture, and (4) implementation of Nature-based Solutions for water retention. The aim of this study was to assess the effectiveness of different combinations of these adaptation options on water security through analysis of contrasting scenarios of socio-economic development. We defined plausible scenarios of climate change, land use change and adaptation measures for an intensively irrigated catchment in south-eastern Spain under three Shared Socioeconomic Pathways (SSP), representing different storylines of socio-economic development. We considered three SSP scenarios, including the Sustainability pathway (SSP1), the Middle of the Road pathway (SSP2) and the Fossil-fueled Development pathway (SSP5). Future land use distributions were obtained with the iClue land use change model by accounting for differences in irrigation water demand and supply, resulting in a decrease (SSP1), a constant (SSP2) and an increase (SSP5) in irrigated agriculture. The impact of each scenario on a series of water security indicators was quantified using the SPHY-MMF hydrology-soil erosion model. The SSP2 scenario, which considers very limited climate change adaptation, projects the most severe impacts on water security, including an increase in plant water stress, flood discharge, hillslope erosion and sediment yield. Under SSP1, which accounts for most climate change adaptation strategies, irrigation water demand is significantly reduced due to a shift from irrigated to rainfed agriculture and the implementation of reduced deficit irrigation, while Nature-based Solutions reduce the impact on other water security indicators. Under SSP5, a conversion from rainfed to irrigated agriculture causes a significant increase in irrigation water demand, which is met by increasing irrigation water supply from desalination. SSP5 shows intermediate impacts on other water security indicators, which is explained by a strong decrease in annual precipitation. This study helps exploring how different future socio-economic pathways affect water security and thereby supports evidence-based policy development. [Display omitted] • We considered contrasting Shared Socioeconomic Pathways in a Mediterranean catchment. • Future irrigation water supply and demand define the socio-economic scenarios. • The impact on water security was assessed using the SPHY hydrology-soil erosion model. • Climate change adaptation alleviates the impact on water security. • Policymakers should consider the benefits and trade-offs of each socio-economic path. [ABSTRACT FROM AUTHOR]

The location of water and fertilizer supply directly affects the distribution of soil moisture and nutrients, thereby affecting crop yield and fertilizer use efficiency. However, the impact of water and nitrogen (N) supply location on cotton water and N use efficiency and yield is not yet clear, especially under drip irrigation conditions. A field experiment was conducted in 2022 and 2023. Four water and N supply patterns were set as: water and N supply at the same location (narrow row (PN) or wide row (PW)), water and N supply at spatially distinct (SD) and spatially and temporally distinct locations (STD). Soil water and N leaching, cotton root growth, water productivity (WP) and recovery efficiency of N (REN), and yield were quantified. The soil moisture and NO 3 --N vertical distribution range (0–60 cm) were deeper at the same location for water and N supply than at spatially distinct locations for water and N supply (0–40 cm). Compared to water and N supply at the same location, supply at spatially distinct locations significantly increased cotton root weight, root length density, and root surface area. In addition, water and NO 3 --N leaching of water and N supply at spatially distinct (SD and STD) were 12%-50% and 32%-59% lower, respectively, than those from the same location (PN and PW), while the yield and WP increased significantly by 7%-11% and 7%-10%, respectively. The REN of water and N supply at spatially and temporally distinct locations was the highest. Therefore, water and N supply at spatially distinct or spatially and temporally distinct locations can improve water productivity, recovery efficiency of N, and yield of cotton, and reduce soil water and N leaching loss under drip irrigation. [Display omitted] • Water and N supply at the narrow row had the highest soil water and NO 3 --N leaching. • Water and N supply at spatially distinct locations promoted cotton root growth and reduced soil NO 3 --N leaching. • Water and N supply at spatially and temporally distinct locations promoted cotton N uptake and increased yield. • Water and N supply at spatially and temporally distinct locations enhanced water productivity and N use efficiency of cotton. [ABSTRACT FROM AUTHOR]

Despite the key role of irrigation in the Earth system, we lack fundamental information regarding the distribution of irrigated fields, irrigation timing and the amount of water utilized. In the past years, the SM_Delta and SM_Inversion approaches have been independently developed to provide estimates of irrigation timing and water amounts based on satellite soil moisture data. The SM_Delta approach retrieves irrigation from variations in soil moisture between an individual pixel and the surrounding rainfed area, while the SM_Inversion approach estimates the total amount of water entering the soil, then irrigation is derived by subtracting precipitation. In this study, we perform a comprehensive assessment of irrigation estimates from the SM_Delta and SM_Inversion algorithms based on Sentinel-1 surface soil moisture retrievals at 1 km resolution. Our analysis focuses on the Ebro basin, an irrigated region in Spain covering 83000 km2, during the period 2017–2019. We assess the ability of the two methods to discriminate irrigated and rainfed pixels, then we quantify the agreement of irrigation timing and water volumes with reference irrigation data. An inter-comparison between estimates from the SM_Delta and SM_Inversion methods is carried out considering both temporal and spatial features, i.e., monthly irrigation peaks and spatial irrigation patterns. Finally, we explore two potential applications of satellite-derived irrigation estimates: attributing irrigation water volumes to specific irrigation systems and to individual crops. We observe that both methods erroneously retrieve irrigation over rainfed pixels, and are therefore not suitable to map irrigated and rainfed fields. However, when auxiliary information on irrigated fields is available, we find a satisfactory agreement between district-scale reference data and satellite-retrieved irrigation, using both the SM_Delta and SM_Inversion approaches (Pearson R equal to 0.67 and 0.71, bias equal to −4.99 and −4.75 mm/15 days, respectively). When aggregated in space or time, the irrigation estimates exhibit coherent temporal dynamics and spatial patterns. For instance, estimates from both SM_Delta and SM_Inversion capture the delayed irrigation that occurred in 2018 due to wetter than usual conditions in spring. However, at the pixel-scale, limited consistency exists between irrigation estimates from the two methods due to different assumptions and parameterizations, e.g., use of constant vs pixel-specific soil water capacity (in the SM_Delta and SM_Inversion, respectively). Overall, the study demonstrates the reliability of irrigation estimates derived from the SM_Delta and SM_Inversion approaches, especially when shifting from small spatial and short temporal scales (pixel level, sub-weekly) to larger and longer scales (district level, seasonal). Hence, satellite-based irrigation estimates could inform water resources managers and basin authorities, as well as serve the modelling community by providing reliable information on the timing and the amounts of water employed at the basin level. • Assessment of two irrigation retrieval approaches based on Sentinel-1 soil moisture. • Good agreement between satellite-based and in-situ irrigation at district-scale. • Irrigation from satellite data captures inter- and intra-annual temporal dynamics. • Limited consistency among irrigation estimates from the two approaches at pixel-scale. • Satellite-based irrigation estimates are reliable when aggregated in space or time. [ABSTRACT FROM AUTHOR]

Water scarcity threatens food security and leads to various economic, social, and environmental challenges, particularly in arid and semi-arid regions. As the agricultural sector consumes the most significant amount of water, conserving water resources in this sector is particularly important. Cultivation of low-water-demand (LWD) crops with high value-added is one of the effective measures to reduce agricultural water demand and improve farmers' livelihoods. However, changing water-intensive crops to LWD crops (e.g., medicinal plants) is voluntary pro-environmental behavior. Considering the role of psychological theories in understanding and explaining human behaviors, the main purpose of the current paper is to explore the socio-psychological determinants underlying farmers' intention to adopt an LWD cropping pattern using the Health Belief Model (HBM). In this regard, data were collected using face-to-face interviews with 184 farmers living in Zanjan province, Iran to examine their intention to cultivate LWD medicinal plants. Using structural equation modeling for data analysis, the HBM explained 49% of the variance in farmers' behavioral intentions. The structural equation modeling outcomes also revealed that self-efficacy, perceived barriers, cues to action, and perceived benefits are significantly related to farmers' intention to choose medicinal plants. Overall, the findings indicated the effectiveness and applicability of the HBM in illustrating farmers' intention to change their cropping pattern. Applying some strategies such as providing the necessary facilities and training programs for farmers, as well as, advertisements aimed at promoting the cultivation of medicinal plants can significantly contribute to conserving water resources in the study area. • Evaluating farmers' intention to medicinal crops using the Health Belief Model. • The HBM accounted for 49% of the variance of the farmers' behavioral intentions. • Self-efficacy, perceived expectations, and cues to action affect farmers intentions. • Self-efficacy was identified as the main predictor of farmers behavioral intentions. • Cultivating medicinal crops help conserving water resources in the study area. [ABSTRACT FROM AUTHOR]

About 70% of water withdrawals in the Yellow River Basin (YRB) are used for irrigation, and deeply explanation of the effects of climate change on runoff in the YRB provides a guarantee for agricultural production. Analysis and prediction of climate change were implemented according to the meteorological and hydrological data from 1967 to 2016, and the responses of the catchments of the six hydrological stations on the Yellow River to the different combinations of precipitation and temperature change conditions were explored adopting the Budyko framework, then the results based on the climate scenario simulation and climate elasticity were compared. Our results revealed that the precipitation in the YRB indicated a downward trend (p>0.05) while the temperature showed a upward trend (p<0.01), both which were predicted to climb in the future; the sensitivities of upstream, midstream and downstream runoff to climate change were gradually increased and the catchment characteristics acted a decisive role in determining sensitivities rather than climatic factors, generally, the runoff of different catchments increased by 17.1–30.2% with only 10% increase in precipitation and decreased by 4.2%-12.4% with only 1℃ increase in temperature; compared to the climate elasticity, the climate scenario simulation tend to be more accurate as it captured the changes in sensitivities when climate change. The results of this study provide a foundation for the regional development and utilization of water resources in the YRB under the influences of climate change. • Seasonal climate change in the Yellow River Basin was explored in spatial. • Budyko framework was used to assess the runoff responses to climate change. • Runoff responses to climate change were nonlinear. • Middle and lower reaches were more sensitive to climate change. [ABSTRACT FROM AUTHOR]

Alterations in annual temperature and precipitation patterns are imposing heightened strain on both urban and agricultural systems. The insufficiency of available water resources to satisfy the escalating demand necessitates a concerted effort to optimize alternative sources. In the context of agriculture, the utilization of treated water is currently executed on a sporadic basis. The elevated energy expenditures and the absence of regulatory frameworks in these systems contribute to a substantial portion of these resources being discharged into natural water bodies, or in the case of coastal municipalities, near the sea. This research endeavors to proffer a comprehensive strategy aimed at eliminating the discharge of treated water into the sea. It proposes the annual allocation of 16.7 hm3 of treated water to irrigation communities grappling with acute water deficits. The strategy, when applied to a tangible case study, ensures the reliable provision and distribution of the entire designated volume. This approach takes into account the fluctuating agricultural demands through the implementation of hybrid systems boasting an installed capacity of 15 MW. Additionally, it establishes the deployment of pumped hydro-storage reservoirs to regulate and secure the requisite energy for distribution and the osmosis process involved in treating a portion of the reclaimed water, thereby presenting a high-quality solution amenable to agricultural consumption. • Optimized strategy to reduce the irrigation deficit in Mediterranean area. • Reused wastewater to increase the water resources in irrigation communities. • 15 MW of installed photovoltaic systems to transfer 16.7 hm3 annually. • Zero discharge from wastewater treatment plant to sea, increasing the sustainability. [ABSTRACT FROM AUTHOR]

The spatiotemporal pattern of root water uptake (RWU) depends on multiple factors, such as plant root biomass, soil water availability, and prevailing weather conditions at the site. The water uptake reduction due to the nonuniformity in soil water contents is often mitigated through compensated root water uptake (CRWU) and hydraulic redistribution (HR). Although previous studies have often considered these two processes independently due to the simplicity and feasibility of analyzing them separately, CRWU and HR can coexist in field conditions. Therefore, this work demonstrates the importance of considering CRWU and HR simultaneously in estimating daily transpiration and RWU distribution for nonuniform soil moisture conditions. For that, we have implemented the mechanistic RWU models developed by de Jong van Lier et al. (denoted below as the DJ model), Couvreur (CR), and Nimah and Hanks (NH) (see the references in the main text) into the widely-used HYDRUS-1D model, in addition to the previously available Jarvis (JF) and Feddes (FD) models. The performance of these models was then compared for varying soil water contents and boundary conditions using experimental data and hypothetical modeling scenarios. Our analysis has shown that these models are beneficial in estimating RWU with varying degrees of accuracy. The DJ and CR models are effective in simultaneously simulating CRWU and HR. NH and JF models can simulate CRWU but cannot simulate HR satisfactorily. Implementing these models into the HYDRUS platform for simultaneously considering CRWU and HR will significantly improve the accuracy of RWU predictions. • Analysis of five root water uptake (RWU) models implemented in HYDRUS is performed. • Compensated RWU (CRWU) and hydraulic redistribution (HR) improved RWU estimates. • The de Jong van Lier (DJ) and Couvreur (CR) models provided realistic RWU. • HR and CRWU are pronounced for deep-rooted plants or when groundwater is available. • The DJ and CR models in HYDRUS will facilitate future research in RWU modeling. [ABSTRACT FROM AUTHOR]

With global climate warming, the variability of climate and weather tends to increase driving the water resources available for vegetation become more uncertain. Therefore, there is still a debate as to how vegetation response to, and to which extent it is constrained to water availability. In this study, we analyzed the correlation between vegetation growth and water availability in the Northern Hemisphere from 1982 to 2018. The condition of vegetation growth was characterized by Normalized Difference Vegetation Index (NDVI) and Leaf Area Index (LAI), while the Standardized Precipitation Evapotranspiration Index (SPEI) represented water condition. Our results suggest that the water deficit stress on vegetation growth in the Northern Hemisphere caused by global warming may not be as severe as described in previous studies. Although there was an increasing trend in areas where vegetation growth was constrained by water deficit in the Northern Hemisphere, such trend was not significant; in contrast, there was a significant decreasing trend in areas where vegetation growth was constrained by surplus water. In addition, there was a spatial variability in water availability for vegetation growth at mid and high latitudes. We further found that the response time of vegetation to both water deficit and water surplus was increasing, indicating that the cumulative effect of water availability on vegetation growth was delaying, and that vegetation tends to be affected by climatic extreme events such as drought with longer time scales. Our results highlight the need to reconsider the response of vegetation activities to water availability, and shed light on a more divers reaction pattern of vegetation to water in the context of climate change. • Water deficit of vegetation growth may not be as severe as previous studies thought. • Areas where vegetation growth is constrained by surplus water decrease significantly. • Spatial variability exists in water availability of vegetation at different latitudes. • The cumulative effect of water availability on vegetation growth is delaying. [ABSTRACT FROM AUTHOR]

The prediction of the agricultural water resources carrying capacity (AWRCC) is important for evaluating the ecological security of water resources and ensure healthy and sustainable socio-economic development. However, the AWRCC is influenced by many important factors such as water resources volume, socio-economic structure and technology level. The existing prediction methods were mainly based on the policies and economic activities under predefined scenarios. It is difficult to fully reflect the future AWRCC and generate regulation schemes based on AWRCC target requirements. The paper proposed a stochastic simulation method to simulate the evaluation indicators, which were selected based on principal component analysis (PCA) and iterative strategy, and structured a support vector machine model to solve the problem of complicated calculations to realize the probability distribution prediction of the AWRCC. Furthermore, the important indicators affecting the improvement of the AWRCC were explored, and finally a regulation schemes that met the AWRCC target were generated. The results of the calculations for Zhangjiakou, Hebei Province, indicated that there is a 97.5% probability that the AWRCC evaluation value will be Level III in 2025 and there is a 2.5% probability that it will be Level II. The probabilities of achieving close to saturated, transition, and close to weakly carriable states for the corresponding Level III are 27.5%, 61%, and 9%, respectively, and the root mean square error of the prediction is 0.0057. In addition, by adjusting the important indicators, the probability of the AWRCC reaching Level IV is 72.5%, and AWRCC improves from Level III to Level IV. The proposed method can achieve higher efficient and accurate AWRCC evaluation, which can better meet the requirements of modern water resources management, effectively reduce the misjudgment risk and provide support for water resources regulation. • The prediction framework was based on the stochastic simulation method. • The value and its probability of agricultural water resources carrying capacity (AWRCC) was obtained. • The impact of indicators on AWRCC was explored. • The schemes to reach the target level of AWRCC were recommended. [ABSTRACT FROM AUTHOR]

The expansion and intensification of human activities have resulted in excessive nitrogen (N) in rivers, causing worldwide concern. To effectively manage agricultural non-point source pollution and ensure a safe drinking water supply in watersheds, it is crucial to trace and quantify the primary sources and spatial distribution patterns of N. In response to the challenge of unclear sources and agricultural non-point source pollution, this study utilised the Bayesian isotope mixing model and Soil and Water Assessment Toolmodel to identify the dominant nitrate sources and transformation processes. These models were employed to quantify N retention by the mainstream and tributaries in the Bai River Basin, which directly impacts the safety of drinking water in Beijing. Total N (TN) concentrations in the Yunzhou Reservoir (4.22 ± 0.04 mg.L˗1) and Miyun Reservoir (2.88 ± 0.62 mg.L˗1) inlets in autumn and winter were V class (2 mg.L˗1) category as per GB 3838–2002 standards. This implies higher risks of eutrophication and algal blooms exceeding the standards at individual points and seasons in the Bai River. Fertilisers were the main nitrate source in the Bai River Basin, contributing 44.6% during the dry season and 62.9% during the wet season, suggesting that nitrate is more susceptible to leaching and runoff during rainy periods. Rainfall was not a major contributor, with only 3.2% and 2.9% originating from the Hebei and Beijing areas of the Bai River, respectively. Annually, the Bai River Basin exports loads of approximately 629.3 t.a˗1 of TN and 433.7 t.a˗1 of organic N (Org-N) from the Bai River Basin land to the river. The TN and Org-N loads at the final destination in the Miyun Reservoir were 521.3 t.a˗1 and 100.3 t.a˗1, respectively. Of the exported TN and Org-N, 17.16% and 76.87%, respectively, were retained in the river network. Consequently, N transformation occurred in the Bai River, with nitrification–denitrification being particularly dominant. Nitrification was more evident in the nitrate-enriched river. • Pollution risks persist in the Bai River during certain seasons. • Nitrification is more evident in the nitrate-enriched river. • Mainstream had a significant retention effect on the Organic N in the Bai River • Fertiliser is the dominant source of nitrate in the Bai River Basin [ABSTRACT FROM AUTHOR]

The optimal allocation of agricultural water and land resources is of great significance in ensuring sustainable food production and economic benefits of farmers. However, agriculture, as an important carbon cycle ecosystem, has paid limited attention to carbon sequestration in the optimal allocation of water and land resources. Therefore, this study developed a new water-carbon-economy coupling model (WCECM) for optimal allocation of agricultural water and land resources. In this model, the minimum water scarcity, maximum carbon sequestration and maximum economic benefits are taken as the optimization objectives. In addition, surface water volume and groundwater volume and planting area etc. were defined as constraints, respectively. Then, the model was solved using the Non-dominated Sorting Genetic Algorithm III (NSGA-III) and the Entropy-weighted-TOPSIS evaluation method. The developed model was demonstrated in the largest Farm, Youyi Farm, which is one of commercial grain production base in China to analyze the optimization of water and land resources from 2010 to 2019. We found that the new WCECM, based on the simulation of a complex coupled water-carbon-economy system, can realize the optimal allocation of agricultural water and land resources to protect regional water resources, increase carbon sequestration and adjust the agricultural planting structure. In detail, through the multi-objective optimization model, the planting structure and the allocation ratio of surface water and groundwater irrigation water consumption are more suitable for this study area. After the optimization, the area planted with Rice was significantly reduced, the area planted with Maize was increased, and the area planted with Soybean did not change significantly compared with the first two crops. The planting structure has changed from focusing on paddy cultivation to dryland cultivation, with the ratio of Rice area, Maize area and Soybean area being 3:6:1. The water consumption is constrained within manageable limits, with an average annual irrigation water consumption of 2.01 × 108 m3. The amount of carbon sequestered has increased significantly, with an average annual increase of 7.8 × 108 kg. Meanwhile, the optimized economic benefits increased slightly, with a value of ¥2.35 billion. In short, optimization of water and land resources is beneficial for improving farmers' incomes, increasing carbon sequestration in agriculture, and conserving water resources. [Display omitted] • A new water-carbon-economy coupling model was developed. • Optimizing planting structure is beneficial for improving carbon sequestration. • Optimizing resource allocation contributes to sustainable food production. [ABSTRACT FROM AUTHOR]

Since the implementation of the Grain for Green Project, the vegetation coverage of Loess Plateau has been greatly improved. However, the contradiction between the increasing vegetation water demand (VWD) and the regional rainwater utilization potential (RUP) has become an important factor threatening the sustainable development of vegetation. In order to figure out whether the available water can support the water consumption of vegetation restoration, it is necessary to quantitatively explore the balance between the RUP and the VWD. Based on these, this study utilized the Soil and Water Assessment Tool (SWAT) and Penman–Monteith (PM) method to quantitatively evaluate the vegetation–water mutual suitability of a typical area in the Loess Plateau's Helong Region (HLR). The results showed that both RUP and VWD exhibited significant increasing trends (95 % confidence level) from 1982 to 2018, with a rate of 18.19 mm/10a and 25.22 mm/10a, respectively. Spatially, RUP was lower in the northwest and higher in the southeast and south regions, whereas VWD decreased from the southeast to the northwest. According to the evaluation results, the annual average vegetation–water mutual suitability matching degree was 0.64 in Period I (1982–1999) and 0.67 in Period II (2000–2018). The matching degree was higher in the northwest and middle regions, lower in the southeast, and above 0.60 in most regions. Under the future climate scenarios of RCP 2.6 and RCP 8.5, the matching degree of water supply and demand also improved to 0.69 and 0.72. Overall, the available water resources can basically support vegetation growth in the HLR. Future vegetation restoration in HLR should try to select annual herbaceous plants that consume less water, and it is not recommended to continue vegetation restoration in the southeast. The results of this study can provide scientific guidance and reference for vegetation restoration policies in HLR. • Rainwater utilization potential was quantified by hydrological cycle simulation. • Vegetation water demand was quantified by remote sensing-based PM method. • The spatiotemporal differences of vegetation-water mutual suitability were clarified. • Future vegetation restoration should prioritize annual herbaceous plants. [ABSTRACT FROM AUTHOR]

Oasis development relies on water supply and the supply mode can be divided into artesian piloting water (APW) mode and high-lift pumping water (HPW) mode. APW mode relies on gravity to retain and intercept water. HPW mode uses cascade pumping irrigation projects to transport water by up to 470 m, mainly serving extremely arid areas. A comprehensive analysis of the water-energy-food-ecology (WEFE) nexus to optimize water use management is conducive to the sustainable development of an oasis. Due to differences in water supply difficulty and cost, there are significant differences in socioeconomic development, water management, and drought adaptation between the APW and HPW oases. Taking the APW and HPW regions of Ningxia in the Yellow River Basin as the study areas, this study constructed a Bayesian network (BN) to quantify the causality and uncertainty in the WEFE nexus to analyze the development status and the evolving characteristics of the human-water relationships of the two regions. Scenario simulation based on BN quantified the impact and difference of management measures on the WEFE nexus in the two regions. During 2000–2020, as the APW region developed, agricultural water use decreased by 36%, showing great water-saving potential, while the development of the HPW region experienced water shortages. Excessive and inefficient agricultural water use is the main factor affecting the sustainability in both regions. Improving irrigation coefficient is the most effective way to reduce agricultural water use, and there is still a large adjustment space in agricultural water prices, channel lining rates and drip irrigation popularization areas to improve this coefficient. The adjustment of the planting structure will have great water-saving potential in the APW region, such as reducing rice area to 20,000 ha will save 5 × 108 m3 of water, but the potential is limited in the HPW area dominated by drought-resistant crops. In addition, improving wastewater treatment and ecological water use will effectively improve surface water quality and the ecological environment in the APW and HPW regions. [Display omitted] • We uniquely analyzed the water use status in the artesian piloting water area and high-lift pumping water area separately. • The Bayesian network effectively quantified the causality in the regional water-energy-food-ecology nexus. • Excessive and inefficient agricultural water use is the main factor affecting sustainable development. • Irrigation coefficient improvement is the most effective way to save water. • Adjusting the planting structure has different water-saving effects in the two areas. [ABSTRACT FROM AUTHOR]

Water availability and nitrogen (N) supply are two major issues that affect plant productivity, however, the processes of water and N utilization and their hormone regulation are not conclusive in response to varying water-N interaction. The objective of this study was to evaluate the effects of water stress (WS) at different growth stages on maize plant development, root morphology, water utilization, hormone signaling and N accumulation under various N conditions. A set of controlled drought stress at 60% field capacity was conducted from bell (V12) to tassel (VT) stage (V12-VT, denoted as W1W2), from silk (R1) to milk (R3) stage (R1-R3, denoted as W2W1) and their compound stages (V12-R3, denoted as W1W1) under high- and low-N supply, respectively. The results indicated that compared to the well-watered control (W2W2), W2W1 reduced root length, root area, and shoot dry matter by 4.68–19.15%, 5.92–11.97% and 4.38–29.61%, respectively, while W1W2 promoted the root system and improved the shoot growth, grain formation and plant water use efficiency (WUE p). High N supply tended to aggravate WS with a poorer root system and lower leaf water potential (ψ leaf) but higher leaf abscisic acid (ABA) accumulation at different growth stages. Leaf ABA significantly increased while stomatal conductance (G s) decreased under WS and N-rich environment, hence increasing leaf intrinsic water use efficiency (WUE i). Root zeatin-riboside (ZR) was higher for well-watered and N-rich conditions. Moreover, leaf ABA significantly increased with the decrease of ψ leaf (R2 =0.51 for R3, R2 =0.35 for dough stage (R4)) and the variation of ψ leaf was relatively constant (≤0.3 MPa) with different water treatments, indicating that maize performed isohydric behavior to response water stress and N-rich environment. This study suggests that to promote the potential of water- and N-saving and improve crop productivity in maize cultivation, mild water stress at vegetative growth stages and appropriate N supply are of great importance. • Water stress at 60% field capacity before silking promoted maize growth and grain formation. • Root length and surface area were increased under water stress and N-lack environment. • Leaf WUE i increased for long-term water stress and N-rich environment. • Maize possessed isohydric behavior judging from hydraulic and chemical information. • N-rich environment tended to aggravate plant water stress. [ABSTRACT FROM AUTHOR]

Water and fertilizer management in sustainable agricultural development needs to balance crop yield, quality, and soil ecological environment. Therefore, we conducted trials with nine treatments over two growing seasons in 2020 and 2021. The treatments included the three irrigation levels W1 (75% Ep), W2 (100% Ep), and W3 (125% Ep) and the three fertilization levels F1 (758.44 kg/hm2), F2 (948.05 kg/hm2), and F3 (1137.66 kg/hm2) with a N/P/K ratio of 2:1:3. The net photosynthetic rate (Pn) gradually decreased with the plant growing period, and was significantly (*) affected by fertilization at the flowering and fruiting stages. The chlorophyll content increased by 43.75% from the vine to flowering and fruiting stages and decreased by 12.50% in the mature stage, reaching a maximum following W1 application. W2F2 was the most effective in promoting total dry mass (TDM) during the vine and mature stages. Irrigation, fertilization and the interaction exerted a highly significant effect on the fruit quality and yield. Soluble solids performed best under W1F1, while free amino acid reached a maximum under W3F2. Moreover, water use efficiency increased with the fertilization amount, and was maximized in W1F3. At the same fertilizer level, soil nitrate N and available P content exhibited an increasing then decreasing trend with the increasing irrigation amount, while soil available K content increased with irrigation at all growth stages. Structural equation models of yield and quality formation were then established based on the co-occurrence analysis. Pn indirectly regulated the melon growth by TDM (0.87) (***), while growth was identified as the most important direct factor affecting the yield and quality of melon. Furthermore, soil residues indirectly affected yield and quality composition through efficiency. This study indicates that the sustainable practices for water and fertilizer management are essential to improve melon yield and quality in arid and semi-arid regions, and contribute to reducing the risk of soil contamination from agricultural production. • The chlorophyll content reached a peak at 43 days after transplanting under W1 application. • Pn indirectly regulated melon growth by TDM based on Structural equation models. • Soil residues indirectly affected yield and quality composition through efficiency. • A water-fertilization strategy to balance economic efficiency and soil environmental was determined. [ABSTRACT FROM AUTHOR]

Large fertilizer nitrogen (N) input has created favorable conditions for nitrous oxide (N 2 O) emissions in semi-arid areas. However, it remains to be determined whether the major contradictions between high yield and N 2 O emissions reduction can be reconciled by matching fertilization with water availability. A 3-year field experiment was conducted in the Loess Plateau of northwest China, monitored N 2 O fluxes over five N application rates (0, 120, 175, 230, and 285 kg N ha−1), and examined the environmental factors and crop production in a rainfed maize field. Results showed that available soil water storage at sowing (ASWS) is crucial in promoting soil N 2 O emissions by altering soil NO 3 --N, organic C, and organic N availability in semi-arid agroecosystems. The cumulative N 2 O emissions exponentially increased with increasing N rates. However, the cumulative N 2 O emissions were moderately low (1.20 kg N ha−1) at the N application rate of 230 kg ha−1, where maize yield was maximized, after which N 2 O emissions remarkably increased by 27.88 %. This result suggests that reduced N application to levels satisfying crop needs could significantly reduce N 2 O emissions with a minor yield penalty. Furthermore, water availability determines the absorption and utilization of nutrients by crops on the Loess Plateau and ultimately determines grain yield. Therefore, an N 2 O emission-yield curve was established to determine whether the target crop yield could be obtained by adjusting water availability and N fertilization rates while reducing N 2 O emissions. Our results suggest that N application rates at 218.7–230.0 kg ha−1, ensuring ASWS at 209.5–215.2 mm at sowing and precipitation within 61–90 days after sowing at 184.2–194.0 mm is ideal for matching fertilization with water availability to balancing high yield and mitigating N 2 O emissions in the study region. • Higher available soil water storage before sowing facilitated N 2 O emissions. • Water availability affected nutrient utilization and yield in semi-arid areas. • Optimized water availability and N management balanced N 2 O emissions and yield. [ABSTRACT FROM AUTHOR]

Crop performance is very dependent on roots because they determine the capture of water and nutrients, and the crop's subsequent growth and productivity. Durum wheat is a major crop in the Mediterranean region, where water and nitrogen availability limit its productivity. Therefore, the focus of this study was to uncover the response of root and shoot traits in durum wheat to different Mediterranean growing conditions and how they relate to better growth and yield performance. For this purpose, crop performance was evaluated in a set of modern durum wheat cultivars grown during four consecutive seasons and under contrasting water regimes, temperatures and nitrogen supplies, totalling 12 different growing conditions. Grain yield, biomass, other crop-growth traits (plant height, PH, and the Normalised Difference Vegetation Index, NDVI), together with physiological indicators of water (carbon isotope composition, δ13C, and canopy temperature depression, CTD) and nitrogen (nitrogen isotope composition, δ15N, and grain nitrogen yield, GNY) status were assessed. In addition, root architecture and distribution were measured using shovelomics and soil coring, and the provenance of the water captured by roots was determined by comparing the oxygen (δ18O) and hydrogen (δ2H) isotope compositions of water at the base of the stem, with water in different soil sections. Water and nitrogen status indicators combined with shovelomic traits allowed development of yield-prediction models. while higher yields were associated in most cases with better water status, root architecture was very responsive to different growing conditions. Overall, genotypes better adapted to rainfed conditions exhibited roots favouring deeper water extraction, whereas under support irrigation, the root system enabled water extraction from the topsoil as from deeper soil sections. Our study also highlights the limitation of shovelomics and soil coring as phenotyping approaches and proposes the δ18O of stem water as a promising functional phenotypic approach. [Display omitted] • Water availability is the main environmental factor limiting durum wheat yield. • Durum wheat root architecture shows high plasticity under Mediterranean conditions. • Under rainfed conditions, higher yields are associated with deeper roots. • Under irrigation, higher yielding crops combined shallow and deep roots. • We propose the δ18O of stem water as a phenotypic trait informing about soil water uptake. [ABSTRACT FROM AUTHOR]

Blue water (irrigation water) and green water (soil moisture), as natural bases in crop production, are vulnerable to natural and socioeconomic disturbances. However, quantitative resilience assessments of blue and green water for crop production are still lacking. Here we constructed a social-ecological based general water resilience assessment framework that distinguishes blue and green water for crop production in four dimensions, including resistance, absorptive capacity, adaptive capacity and transformative capacity. The framework was applied to quantify the spatiotemporal characteristics of water resource resilience for three staple crops (rice, wheat, and maize) at provincial level in mainland China over 2000–2017. Results indicate that water resilience related to crop production of China as a whole was at the lower-middle level over the study period. The green water resilience had higher initial performance, while the blue water resilience had a faster growth rate (>50%). The performance of adaptive and transformative capacity was 8.9∼153.7% better than resistance and absorptive capacity. There were significant heterogeneities in the water resilience score among crops and in time and space. Wheat had the highest resilience of green water, while its blue water resilience was the lowest among the three crops. The water resilience for crop production varied by up to 2.4-fold across provinces. Synergies and trade-offs among the four dimensions of water resilience were further evaluated. The current study provides an effective approach for assessing the state and progress of resilience of regional water resources for crop production. [Display omitted] • Spatiotemporal resilience of blue and green water for crop production was evaluated. • Crop-related water resilience in China was at the lower-middle level. • Blue water resilience increased by over 50% over 2000–2017. • Adaptive and transformative capacity exceeded resistance and absorptive capacity. [ABSTRACT FROM AUTHOR]

• Spent coffee grounds (SCG) alter soil hydraulic properties. • Water content at pot capacity of a sandy loam soil was enhanced adding SCG contents. • Lettuce plants growing was changed with the addition of SCG contents. Soil physical and chemical properties can be amended by application of organic residues, such as spent coffee grounds (SCG). In this work we examined SCG effects on the modification of some soil physical-hydraulic properties, such as soil water retention and aeration, investigating beneficial uses for this waste product. Soil properties were evaluated using pots filled with a mixture of a sandy loam soil with the contents of 0, 5, 10, 15 and 20% of SCG. The most relevant soil properties to the purposes were the moisture at container capacity (θ cc), readily available water capacity (RAWC) and drainable porosity (ϕ D). Additionally, under the hypothesis that SCG can be used as soil conditioner, lettuce crop, cultivar "Mimosa Roxa Roxanne", was transplanted to the pots where the leaf area index and the cumulative biomass throughout the growing cycle were examined. Comparing to the absence of SCG (0%), soil SCG contents of 5, 10, 15 and 20% presented larger values of θ cc and consequently larger RAWC and smaller ϕ D. Although the increase of soil water storage from 43.2 (0%) to 53.3 (20%) mm, crop development was prejudiced by the reduction on ϕ D from 0.1595 (0%) to 0.0827 (20%) m3 m−3, which affected soil aeration. This greater water availability, obtained with the increase of θ cc , was promoted by the residue addition pointing out for a possible use of SCG to increase water retention for other crops. [ABSTRACT FROM AUTHOR]

• Water withheld to maintain a certain level of reliability are a cost that are not evaluated in catchment wide studies. • Greater reliability is not always beneficial, as the value of water held to maintain a level of reliability is ignored. • Once considered on a system wide basis, the benefits of greater levels of reliability become circumspect. • Changing the level or reliability in an irrigation system will not affect all regions and parts of that system equally. Increasing water reliability in a catchment requires reducing the total quantity of water available to users in some years in order to supply it in more years when its supply is constrained. Thus, the more reliable the supply the more water that needs to be withheld. Consequently, increased levels of water reliability to a catchment, which reduces the costs associated with an unreliable supply, often comes at an incremental increase in costs that researchers do not consider; that of the water foregone that could be have been used productively if the system had been run less reliably. In this paper the trade-offs between the costs of water foregone to maintain a level of reliability and the costs associated with an unreliable supply of water at different levels of reliability in an irrigation system are discussed. The concepts developed are applied to the irrigation sector in the Musi catchment in Andhra Pradesh, India from 2011 to 2040. In this catchment it was found that the costs of water foregone to increase reliability rise as the level of reliability rises, while the benefits generally fall. When the level of reliability exceeded approximately 85% (where water is so scarce that it is used on only the most valuable output), the costs of greater reliability exceed the benefits resulting in net losses to the system. These results were found to vary in each demand centre across the catchment. These results have implications for those considering innovations that improve the level of reliability in a catchment. [ABSTRACT FROM AUTHOR]

• Synthesis of both water supply and demand policies is needed for solving the water management problems. • Targeting a limit in the irrigation water supply only for the month of peak demand had less adverse effects than limiting the annual water supply. • Scenario simulations with a PMP-based agro-economic model showed that modifying the water supply scheduling can increase water productivity. • Crop diversification decreases the impact of limiting the water supply in peak demand on the farm gross margin. The present study investigates alternative scenarios of timing and reduced water supply in terms of their impacts on agricultural land use, farm revenue and food crop production. It aims to evaluate the implications for the development of different farming systems in one of the most water-scarce irrigation districts in the Zayandeh-Rud River Basin in central Iran, the Roudasht irrigation district. A modified version of Positive Mathematical Programming (PMP) model was used to assess the scenarios. The results from the scenario simulations illustrate that there is substantial potential for improving the management of the limited water supply in the Roudasht irrigation network to reach higher water productivity, agricultural output and gross margins from agricultural activities. A management plan to target a limit in the irrigation water supply only for the month of peak demand, e.g. 60% to 80% of the baseline water supply for May in Roudasht, may have less adverse effects than planning to limit the annual water supply by the same amount but without specifying the monthly timing of the water supply. These results highlight the relevance and impact of the timing of water supply when devising adaptive measures related to the irrigation water supply. [ABSTRACT FROM AUTHOR]

• Average trunk growth rate (TGR) was not valid in irrigation scheduling. • Average TGR was related with midday stem water potential. • Frequency and absolute values of daily TGR are related with water stress. • Frequency and absolute values of daily TGR are promised tool for irrigation scheduling. Reduced water availability around the world drives the need for indicators that enable a better control of water stress at orchard level. Among the different parameters that could be used as indicators, trunk diameter fluctiations, are daily cycles suggested as tools for irrigation scheduling. These cycles can define different indicators and the trunk growth rate (TGR) was suggested as the most suitable for olive trees. Several works indicated that average TGR values are related to the tree water status even threshold values have been suggested. In addition, only daily TGR values below −0.1 mm day−1 were mentioned as water stress indicators. The aim of this work is to evaluate an irrigation scheduling approach based on those two results mentioned. To this end, an experiment was performed during the 2017 season, in a commercial, super-high-density orchard in Carmona (Seville, Spain). Four different irrigation treatments were applied based on midday stem water potential values and TGR. The Control treatment, with 100% ETc (crop evapotranspiration) and sustained deficit irrigation, was compared with two regulated deficit irrigation strategies based on TGR measurements. Severe water stress conditions were measured in the three deficit treatments. Irrigation scheduling using average TGR was not a suitable tool for the aim of the experiment because some data were lost and there were great variations in TGR values. However, it was found that average TGR values were related to midday stem water potential. The water potential and daily TGR data were grouped according to water stress levels (into values with water potential higher of −1.4 MPa and lower than −4 MPa). Daily TGR values greater than 0.3 mm day−1 were identified in response to severe water stress conditions. Weekly frequency of daily TGR values between −0.1 and 0.3 mm day−1 decreased from 60% to 25% when water stress level increased. Therefore, frequency and value of daily TGR are suggested as irrigation scheduling tools for olive trees. [ABSTRACT FROM AUTHOR]

• Enhanced water level of wells in the stream vicinity facilitated by groundwater recharge. • Significant increase in the cropping intensity of crops requiring assured irrigation. • Increase in the area under the high risk, high return commercial seed crop, with the availability of assured irrigation. • Livestock feed cultivation and increased water retention in streams leading to higher income from dairy. • Need for community participation in design and implementation for equitable benefit distribution. Rainwater harvesting has a crucial role in facilitating supplementary irrigation and groundwater recharge. The current research study assesses the socio-economic impacts of small rainwater harvesting structures, Doha Models – percolation tanks dug along the length of lower order seasonal streams, in semi-arid Jalna district of Maharashtra state in India. These structures facilitated recharge of wells in the agricultural fields close to streams. Facilitated by an increased water availability for irrigation, cropping intensity, cropping diversification and crop yields – especially for winter crops requiring assured irrigation – on these agricultural fields grew more than on the agricultural fields away from streams. High risk commercial seed crop cultivation also increased on the agricultural fields close to streams. At two of the four study sites, well recharge led to improvement in drinking water supply and also led to a reduction in physical drudgery associated with fetching water. Ownership and income from livestock also record a growth owing to better water and feed availability for livestock, facilitated by rainwater harvesting. The cost benefit analysis yields an internal rate of return of 16% for Doha Models. However, the study highlights that the benefits from Doha Models are limited to the agricultural fields which are downstream and are close to streams, leaving a large portion of agricultural land. Also, no community institutions are managing these structures. Based on this analysis, the study suggests increasing community participation in the designing and implementation of these structures. [ABSTRACT FROM AUTHOR]

• Water scarcity is threatening the sustainability of food production systems in Middle East and North Africa (MENA). • Non-conventional water resources (NCW), are alternate option for agriculture, landscaping, and forestry. • NCW could impact soil physical, chemical and biological properties. • Desalination, rainwater and treated municipal wastewater are strategies to use NCW. • Water treatment technologies should be advocated and implemented for safe use of NCW. • NCW may be used according to policy guidelines of MENA countries. Land and water are the most basic resources for the food production systems. However, the looming water scarcity is threatening the sustainability of food production systems and is causing the food security challenges. Crop production on marginal and degraded lands using non-conventional water resources may help achieve the food security for the future generations. Non-conventional water resources (NCW), viz. saline water, wastewater and greywater, can be used for food production systems after proper treatment for the rehabilitation of marginal and degraded lands. In this review, experiences and perspectives of use of NCW in the Middle East and North Africa (MENA) region are discussed. The availability of NCW, their quantity and potential utilization in agriculture, landscaping, and forestry have been highlighted. Apart from Saudi Arabia, Oman, United Arab Emirates (UAE), Kuwait, Qatar and Jordan, wastewater treatment facilities are limited in the MENA region. However, consumption is increasing due to population increase. The changes in soil physical, chemical and biological characteristics, with the use of untreated wastewater, are also elaborated. The pragmatic strategies for NCW treatments including desalination, wastewater treatment, reuse of agricultural drainage water, groundwater extraction and rainwater collection have also been described. Here we reviewed that, (i) Legislation should be done to encourage farmers to use NCW and to grow crop species (safflower, sorghum, millet, carrots, radish, cucumber, tomatoes, eggplant, lettuce) which accumulate relatively very low amounts of metals in their edible parts, especially in pre-urban areas. (ii) Water treatment technologies should be advocated and implemented for the use of NCW. (iii) The NCW reuse should be promoted as an integral component in every country's national development strategic plan. Safe reuse of NCW has great potential, however, that can be effectively used through wise resource planning, and environmental management and financing arrangements. [ABSTRACT FROM AUTHOR]

• FAO estimations fit irrigation needs (IN) of Mediterranean avocados groves. • Over-irrigation of avocados does not involve better yields. • Leaf water potential is a good plant-based water stress indicator in avocado. • Water supply below IN negatively affects yield and fruit quality in avocado. The subtropical Mediterranean climate of southeastern Andalusian coast allows Spain to be the largest European producer of subtropical fruit, with the avocado as the main representative. In this region, precipitations are scarce and erratic and limit water availability for irrigation. Under this climatic uncertainty, appropriate water use is required for assuring crop environmental sustainability and increasing water productivity (WP) of avocado orchards. For this purpose, it is necessary to evaluate if current water endowments in the region match crop water requirements and to what extent water use can be improved. In this study, water productivity was assessed in a mature avocado (cv. 'Hass') orchard along six consecutive seasons. The physiological and agronomical responses of avocado trees to five water treatments (T1-T5) were also evaluated during two consecutive seasons. Water amounts supplied by irrigation were compared with FAO's estimations. For the six seasons, averaged FAO irrigation needs were 7916 ± 395 m3 ha−1 season−1 but averaged water supplied was 6503 ± 328 m3 ha−1 season−1 (˜18% below FAO's) with yields 11 ± 2 t ha−1, meaning a WP of 1.7 kg m-3. FAO's recommendations matched T2 and irrigation over or below T2 affected avocado yield, fruit quality (i.e. size) and WP. Water supplies 15% above FAO's (T3) did not involve better yields but decreased WP. Conventional irrigation for mature orchards (T1) was ˜20% lower than FAO's and entailed yield decreases (˜16%) but similar fruit sizes and WP. Water supplies 40% and 60% below FAO's (T4 and T5, respectively) caused significant water stress and decreased yields and fruit quality of avocado trees but increased WP. These effects were more noticeable during the productive season, in which T5 trees showed weakening symptoms and marked fruit drop. Results are discussed in the context of viability of avocado cropping in the Mediterranean region under low water resource scenarios. [ABSTRACT FROM AUTHOR]

• Estimating climate change impacts on the water availability at sub-catchment level. • Assessing the performance of an existing RWH-system with a simple model. • Investigate potential adaptive strategies to optimize a RWH-system. Climate change is believed to have a large impact on water resources system both globally and regionally. It has become a major global issue, especially in developing countries because these are most affected by its impacts. Rainwater harvesting techniques offer an alternative source of water and represent specific adaptive strategies to cope with water scarcity within future climate change. Studying the impact of climate change on rainwater harvesting techniques, however, is difficult, because the general circulation models (GCMs) which are widely used to simulate scenarios of future climate change operate on a coarse scale. We estimated the impact of climate change on water availability at the watershed level by downscaling precipitation and temperature from the GCMs using a statistical downscaling model. A water harvesting model then assessed the performance of the rainwater harvesting techniques for the Oum Zessar watershed in southeastern Tunisia under current climatic conditions and scenarios of future climate change. Annual temperature tended to increase and precipitation tended to decrease. These changes of climatic variables were used in the water harvesting model to simulate future water availability. Changing the directions of water flow between sub-catchments in combination with changing the spillway heights strongly affected the performance of rainwater harvesting under the scenarios of future climate, resulting in a sufficient water supply for 92% of all sub-catchments, compared to 72% without these changes. [ABSTRACT FROM AUTHOR]

• The phenotypic plasticity of sugarcane cultivars was evaluated under contrasting soil water conditions. • Partitioning of photoassimilates in sugarcane is not influenced by moderate levels water stress. • Sugarcane varieties can save up to 25% of the applied water under moderate deficit irrigation. • Higher water use efficiency under limit water conditions was found for specific sugarcane varities. • Under deficit irrigation, biomass yield should be prioritized to the detriment of sucrose concentration in stalks. Studies of sugarcane varieties grown under water-restrictive conditions are necessary because climate changes may result in insufficient rain for agriculture and selecting or breeding drought-tolerant cultivars will become more and more important. This study aimed to quantify the accumulation and partitioning of biomass, as well as water use efficiency of commercial sugarcane varieties under different soil water availability conditions throughout the growing season. The study was conducted during two cropping cycles in Southeast Brazil (22.7 °S, 47.6 °W). Four soil moisture availability regimens were set up to provide 100, 75, 75* and 50% of the water demand of eight commercial varieties of sugarcane (CTC15, CTC17, RB867515, RB92579, RB931011, RB966928, IAC5000, and NCo376). The total aboveground biomass was measured in both crop cycles. Our results indicate that two Brazilian varieties (CTC15 and CTC17) and one South African variety (NCo376 - Canegrow DSSAT reference), increased their water use efficiency when grown under an irrigation deficit of 75% of normal, without yielding less biomass. We did not observe any change in sucrose content under controlled water deficits; however, the studied varieties showed different biomass partitioning: RB966928 had the largest biomass fraction allocated in the stalks (0.59), while IAC5000 showed the lowest fraction (0.51). We verified that the harvest index for sucrose was not altered by reduced irrigation, but that its variability was attributed to the genotype inherited from traditional breeding programs. Thus, we conclude from these results that increased sugar yield per unit area is only possible nowadays by increasing sugarcane biomass productivity under highly efficient irrigation conditions to minimize the loss of yield from water stress. [ABSTRACT FROM AUTHOR]

• A causal link exists among irrigation water, the use of modern farm inputs, and crop revenue. • Irrigation water positively affects both crop revenue and the use of modern farm inputs. • Dam-driven irrigation water has both direct and indirect effects on crop revenue. • Around 27 percent of the total effects of availability of dam-driven irrigation water on crop revenue is indirect. • Indirect effect of irrigation water on crop revenue is mediated by the use of modern farm inputs. Development of a clear understanding of the relationship between the availability of dam-driven irrigation water and crop revenue is important in poverty reduction and food security process. As a result, large research efforts are devoted to understanding the relationship between the availability of irrigation water and crop revenue. However, earlier studies do have several limitations. For example, without considering its indirect effect, prior studies focused solely on the direct effect of availability of irrigation water on crop revue. In this study, using a structural equation model analysis, the direct and indirect effect of availability of dam-driven irrigation water on crop revenue is decomposed and quantified specifically for the Koga irrigation scheme, located in the Mecha district of Amhara region in Ethiopia. A primary data set was collected from a randomly selected sample of 450 households in the Koga irrigation scheme. More than half of the households (254) are supported by the Koga Dam irrigation water during the dry season, and the other 196 households depended only on rainfall. The results of the study showed that, in addition to its direct effect, the availability of irrigation water indirectly affected crop revenue through receptivity of the farmers to use modern farm inputs. Around 27 percent of the total effect of dam-driven irrigation water on crop revenue was mediated by farmers' receptivity to use yield-enhancing modern farm inputs. The results of this study suggested that the availability of irrigation water is essential to improve both crop revenue and receptivity of the farmers to use modern farm inputs. This finding also drives a strategic framework that the receptivity of the farmers to use modern farm inputs is crucial for utilizing the positive effects of irrigation water availability on crop revenue. [ABSTRACT FROM AUTHOR]

• Water deficit reduced seed yield by 16.3% in sunflower, 12.8% in sesame, and 9.4% in safflower. • Water deficit reduced oil yield by 22.5% in sunflower, 13.3% in sesame, and 10.2% in safflower. • Linolenic and palmitic acid were greatly reduced (29.8% and 28.5%) in safflower and sunflower. • Mild water deficit did not affect oil percentage in safflower and sesame. Water deficit stress is a common environmental factor affecting growth and yield of crops, but comparative studies on quantitative and qualitative characteristics among oilseed crops do not exist in the literature. A three-year field experiment was conducted in a calcareous soil of East Azerbaijan, Iran to determine the impact of water deficit stress on a number of quantitative and qualitative characteristics of sunflower (Helianthus annuus L.), safflower (Carthamus tinctorius L.), and sesame (Sesamum indicum L.). Four levels of irrigation, i.e., 40, 60, 80, and 100% of potential evapotranspiration (PET) were applied during the growing season. Low water availability significantly decreased seed yield in all oilseed crops, followed by a significant increase in malondialdehyde (MDA) and proline (Pro) content. Averaged over irrigation water availability levels, sunflower showed the greatest reduction in seed yield by 16.3%, followed by sesame (12.8%) and safflower (9.4%). The seed yield reduction in all crops was mainly due to a reduction in seed weight and a reduction in seed number in capitula or capsules. Averaged over irrigation water availability levels, sunflower showed the greatest reduction in oil yield by 22.5%, followed by sesame (13.3%) and safflower (10.2%). Mild lack of irrigation water availability (80% of PET) neither affected negatively nor improved oil percentage, particularly in safflower and sesame. Severe lack of irrigation water availability (40% of PET) significantly reduced oil percentage, particularly in sunflower. A significant reduction in oleic acid (OA), linoleic acid (LA), linolenic acid (LNA), and palmitic acid (PA) content due to low availability of irrigation water was observed in all crops. Apart from breeding efforts for improving crop resistance to drought, management practices should be considered to reduce drought-related issues in major oilseed crops. [ABSTRACT FROM AUTHOR]

• Small lakes support agricultural diversification and rise in fruit tree farming. • Landsat time series characterise water availability of multiple ungauged lakes. • Water scarcity and unreliability on 86% of lakes impedes agricultural intensification. • Economic water scarcity and mismanagement further constrain agricultural development. • Interdisciplinary multi-scalar approach improves understanding of socio-hydrosystems. Millions of small reservoirs built across semi-arid areas present a potential to support agricultural livelihoods of rural smallholders. The scale and geographical dispersion of these multiple lakes restrict the understanding of these coupled human-water systems and the identification of adequate strategies to support riparian farmers. This research developed a multi-scalar interdisciplinary approach to characterise the hydrological and wider drivers of agricultural water use around multiple small reservoirs in semi-arid central Tunisia. The combination of field surveys, quantitative questionnaires and qualitative, semi-structured interviews confirmed minimal withdrawals, but highlighted the diversification of practices, the rise in fruit farming and peripheral benefits generated here by the development of 56 lakes. 48% of lakes provide residual benefits for the occasional watering of on average 300 fruit trees and support to downstream wells exploited for irrigation. A further 13 lakes (23%) provide high levels of benefits (900 fruit trees each), albeit with low equity, supporting essentially established farmers. The analysis of surface water assessments every 8 days from Landsat 5–8 imagery over 1999–2014, provides unprecedented insights into the significant water scarcity and unreliability that impedes agricultural intensification on 86% of small lakes. Limited storage capacities and prolonged droughts highlight the need for small reservoirs in this climatic context to retain a supplementary irrigation objective and not strive to support widespread intensification of irrigated practices. Many farmers lack the capabilities to increase their withdrawals and suffer physical and economic water access difficulties, mismanagement, compounded through limited and short-term government assistance. Individual successes resulted from farmers' economic resilience and means to secure alternate water supplies during dry spells. [ABSTRACT FROM AUTHOR]

Highlights • A couple-based interval-bistochastic programming method is proposed to address the regional water resources allocation under uncertainties. • An appropriate water allocation plan in Zhanghe Irrigation District is developed under uncertainties of reservoir inflow and local rainfall. • The independence hypothetical situation and linear relationship hypothetical situation are also discussed and compared. Abstract In regional water resources allcoation problems, the uncertainties of hydrological variables and socio-economic parameters are bringing huge challenges to water managers. So far, the stochastic programming models have difficulty in addressing uncertain problems, in which there are two correlated random variables. In order to address regional water resources allocation under two hydrological random variables and interval parameters, a couple-based interval-bistochastic programming (CIBSP) method is proposed. The CIBSP method includes several key steps: first, the marginal distributions of the two hydrological variables are analyzed and hydrological scenarios are set; then, the copula is chosen to analyze joint probability distribution of the two hydrological variables and the joint probabilities of scenarios are calculated; last, an interval-bistochastic model is formulated by incorporating two-stage stochastic programming, interval-parameter programming, and bivariate joint distribution. The CIBSP method can describe the probability of occurrence of a hydrological scenario and then make an optimized water allocation scheme under uncertainties. To demonstrate its applicability, the CIBSP method is applied to the Zhanghe Irrigation District located in China, to optimize available water allocation under the uncertainties of the annual inflow volume of the Zhanghe Reservoir and annual rainfall volume in the irrigated district. An appropriate water allocation plan can be obtained by the method, which provides a foundation to water managers for managing water resources in Zhanghe Irrigation District. Moreover, other two hypothetical situations named independence hypothetical situation and linear relationship hypothetical situation are discussed. The difference in the results between the two hypothetical situations and the case study indicates that an appropriate description of the joint probability of the annual inflow volume and annual rainfall volume by using CIBSP method is important for water resource allocation under uncertainties. [ABSTRACT FROM AUTHOR]

Highlights • Guidance for quantifying probabilistic divergences caused by time-space scales. • Method uses kernel density modelling and Kullback–Leibler divergence analysis. • Eight biophysical variables addressed, a disparity of sensitivity to scaling is noted. • Scaling effect on statistical inferences are evidenced using water resource variables. • Method tested and recommended for time-scales choice in water resource studies. Abstract Studies focusing on time-space scaling issues have not yet established guidelines for choosing a time-space scale for water resources management. This study attempts to develop a methodology to understand the deviations induced by the scaling framework on water resource variables. The study addresses eight variables: streamflow, groundwater level, precipitation, air temperature, soil moisture, solar radiation, wind speed, and relative humidity. For each variable, a 10-year (2001 to 2010) daily time-series data were retrieved from weather and hydrologic stations selected across Oklahoma. The methodology entailed three phases, including a variable rescaling, a probability analysis, and a divergence quantification. Hence, daily time-series of the selected variables were rescaled to weekly, biweekly, monthly, bimonthly, and trimonthly scales. To derive the probability density function of each variable, a kernel density estimator was applied to the rescaled time-series. The Kullback–Leibler divergence was used to evaluate the deviations pertaining to the time-space scaling. Results showed meaningful divergences that were a consequence of time-space scale variations. However, the sensitivity of variables to the scaling framework differed. For instance, air temperature was less sensitive to time-space scaling, while wind speed, soil moisture, and precipitation were highly sensitive. Correlation analysis showed that correlations tended to gradually increase with the increase in scale, even though the strength of the relation varied, depending on the variable involved. The methodology was tested via a case study where data obtained from a location outside of the study region were used to address the scaling effect on the Normalized Difference Vegetation Index's response to precipitation and soil moisture. It was concluded that understanding the divergences associated with time-space scales was critical for interpreting results in water resource studies. [ABSTRACT FROM AUTHOR]

Highlights • Farmers' preferences toward irrigation water supply reliability (WSR) are analyzed. • A discrete choice experiment (DCE) is used with stochastic variables for WSR. • Three classes of farmers are identified according to their WTP for improved WSR. • They show no, low, and high WTP, with several factors explaining class belonging. • The results can assist the design of more efficient water management instruments. Abstract In irrigated agricultural systems, a major source of uncertainty relates to water supply, as it significantly affects farm income. This paper investigates farmers' utility changes associated with shifts in the probability density function of water supply leading to a higher water supply reliability (higher mean and lower variance in annual water allotments). A choice experiment relying on a mean-variance approach is applied to the case study of an irrigation district of the Guadalquivir River Basin (southern Spain). To our knowledge, this is the first study using parameters of these probability density functions of water supply as choice experiment attributes to value water supply reliability. Results show that there are different types of farmers according to their willingness to pay (WTP) for improvements in water supply reliability, with some willing to pay nothing (47.8%) while others have a relatively low (28.0%) or high (24.2%) WTP. A range of factors influencing farmers' preferences toward water supply reliability are revealed, with those related to risk exposure to water availability being of special importance. The results can be used to assist the design of more efficient policy instruments to improve water supply reliability in Mediterranean and semi-arid climate regions. [ABSTRACT FROM AUTHOR]

Highlights • Efforts to adapt new risk management strategies should start with assessment of existing practices. • Most widely adopted measures require less technical knowledge and outside support. • Highly effective measures were low adopted by farmers, water user associations and water managers. • Efforts on technical, financial and management aspects, could considerably improve spate water management. • Weak institutions and lack of resources determine farmer's adaptation strategies downstream spate irrigated systems. Abstract In arid areas, water diverted from highly uncertain flash floods is often the only source of water for crop production. Stakeholders in spate irrigation systems have developed numerous measures to cope with uncertain water supply related to low, high and untimely floods. This research evaluates the effectiveness of these measures using the MULINO Decision Support System (mDSS4) tool which is based on the Driving force-Pressure-State-Impact-Response (DPSIR) framework. Using data from interviews with 101 randomly selected farmers, 17 water user associations (WUAs), and 7 system water managers in the Gash spate irrigation system in Sudan, we compare the effectiveness with the rate of adoption. The results reveal the most effective measures are 1) pre-flood preparedness, 2) risk sharing measures through water and land management during and after flood by WUAs, 3) crop management by farmers; and 4) flexibility in operation by water managers. Unfortunately, the most effective measures are not the most adopted ones. The level of adoption is primarily related to the capacity of the farmers, WUAs and water managers to implement the measures without outside support. Generally, measures taken by downstream farmers are less effective than those adopted by upstream farmers due to weak institutional arrangements and lack of adequate resources. Supporting farmers, WUAs and water managers for a wider adoption of the existing effective measures will greatly improve irrigation performance and hence food security in the study area. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Barley plants were grown under favourable/reduced water and ambient/reduced UV. • Element composition and other leaf traits were studied under combined low water/UV. • Low water decreased uptake of Si, Ca, P, S, Cl, but not K, with no large UV effects. • Plants resisted low water/UV without stress, but decreased leaf cuticle thickness. • Low water/UV showed generally highest leaf light reflectance and transmission. Abstract Silicon is an increasingly important element in agriculture due to benefits on plant growth and development under stress conditions. Silicon uptake is facilitated by transpiration flow, while plant resistance to drought and ultraviolet radiation are positively related. Thus, we hypothesised that water shortage in barley (Hordeum vulgare L.) will hinder uptake of silicon, and possibly other elements, and that reduced ambient ultraviolet radiation will worsen these negative effects of water shortage. Barley plants were exposed to favourable and reduced water availability during growth under ambient and reduced ultraviolet exposure. Element composition and morphological, biochemical, physiological, and optical traits of barley leaves growing under these four treatments were investigated. Water shortage affected the element composition of barley plants significantly. Silicon and chlorine levels were the most reduced by water shortage, followed by calcium, phosphorus, and sulphur, while potassium levels were not affected. Ultraviolet radiation did not have any significant effects on uptake of elements. These plants did not undergo water shortage stress, as photochemical efficiency of photosystem II and pigment contents were similar across all treatments. Water shortage affected reflectance of light across the whole spectrum, while ultraviolet radiation affected optical properties of the barley leaves in the UV region only. [ABSTRACT FROM AUTHOR]

Highlights • Estimation of small reservoir evaporation is crucial for water resources planning. • Small reservoir evaporation was estimated using Class A Pan. • Pan coefficients are developed in monthly, seasonal and annual basis. • Fifteen new equations for estimating small reservoir evaporation were developed. Abstract The Brazilian Savanna biome is the main agricultural region of Brazil and is facing a growing water shortage and conflicts that tend to expand to new areas and intensify in those already stressed, which is hindering the economic development of the region. Small reservoirs play an important role in supporting the local economy in the savanna areas of Brazil. Hundreds of small reservoirs have been built in the last twenty years in the region. They were constructed by individual farmers or projects funded by different agencies without any coordination and knowledge that the reservoirs are part of a complex hydrologic system. The lack of reservoir basic information and appropriate methods to quantify water supply, demand and losses are hindering efficient water management. In this context, evaporation is a non beneficial loss to the water system and should be better quantified. The present study aimed to improve methods for estimating small reservoir evaporation in the Brazilian savanna region. The study area was the Buriti Vermelho watershed, where the evaporation were measured in Class A pans installed inside and outside of a small reservoir. Pan coefficients were calculated on a monthly, seasonal and annual basis. In addition, equations for estimating evaporation based on climatic variables were developed. The pan coefficients values varied throughout the year from 0.72 to 0.92, with mean absolute error (MAE) ranging from 0.32 to 0.52 mm d−1. The two best climatic equations presented MAE of 0.44 mm d−1, while equations that used solar radiation and relative humidity as input also presented good performance. [ABSTRACT FROM AUTHOR]

Highlights • SOM, TN, TP, SWC and Silt content increase with the cultivation years of oasis irrigated farmland. • IWP and soil properties (except for BD) have a moderate spatial heterogeneity. • The Range of soil properties gradually increase with the sampling interval increases of the research area. • The key driving factors of IWP are AP and NO 3 -N. Abstract Reasonable uses of water resources can promote the development of oasis agriculture and avoid re-desertification of reclaimed land. Therefore, knowledge of the distribution of irrigation water productivity and its relationship with soil properties is important to cope with water scarcity and ensure food security. A total of 118 sampling points were selected within the study area of 120 km2 (1 km × 1 km grid) in the oasis field of arid Northwest China, where the soil organic matter, total nitrogen, nitrate nitrogen, total phosphorus, available phosphorus, bulk density, soil water content, silt content, sand content and irrigation water productivity (IWP, yield per unit applied irrigation water) were analyzed. The traditional statistics, geostatistics and partial least squares methods (PLS) were used to investigate: i) the spatial distribution of soil properties and their changes with the cultivation years; ii) the relationship between IWP and soil properties; iii) the key driving factors of IWP from the soil factors. The results showed that soil organic matter, total nitrogen, total phosphorus, soil water content and silt content increased with the increase of cultivation years, and the correlations were significant except for total phosphorus, while the sand content showed the opposite trend; and there was no significant relationship between bulk density, available phosphorus and nitrate nitrogen with the cultivation years. IWP of oasis irrigated fields varied from 0.55 to 3.46 kg m−3, with a moderate spatial heterogeneity (CV = 40%). The average IWP was 1.48 kg m−3. Compared with the developed areas of water-saving agriculture, the IWP of oasis farmland still has great potential for improvement. The key driving factors of IWP are available phosphorus and nitrate nitrogen, and the IWP can be improved by increasing the application of phosphorus fertilizers and reducing the amount of nitrogen fertilizer in the oasis fields of arid Northwest China. The results provide scientific basis for improving IWP of oasis fields, and have a great significance to the sustainable development of water-saving agriculture in arid areas. [ABSTRACT FROM AUTHOR]

Highlights • Influences of irrigation efficiency improvement on water use and consumption were investigated. • An agro-economic model was used in combination with the conceptualization of hydrological pathways. • Alternative restrictions on water supply and irrigatable land could effectively constrain water use and consumption. • Substantial reductions in water use would not be met at larger scales upon which the degree of water reuse is high. Abstract Improving irrigation efficiency is widely believed to be a promising opportunity for large water savings. However, more and more voices have been raised against this idea in recent years. This study investigated the impacts of irrigation efficiency improvement on water use and consumption by combining an agro-economic model with the conceptualization of hydrological pathways. The investigation was conducted under two different conditions, i.e., Case 1: unlimited water supply and restricted irrigatable land, and Case 2: limited water supply and unrestricted irrigatable land. At the scale of the WUU, we found that the water uses could be reduced significantly after improving irrigation efficiency, while the water consumptions would be of similar magnitudes for different irrigation techniques under the condition of Case 1. However, in the condition of Case 2, the water uses would be inelastic to the enhanced irrigation efficiency; and the water consumption would increase slightly if the fixed cost ratio is high. At the scale of the irrigation system, the reductions in water use, as a result of efficiency improvement, would be more and more insignificant in response to increasing water cost ratios and numbers of WUUs under the condition of Case 1. In contrast, the water uses would increase, although with small magnitudes, when the fixed cost ratios and the number of reuse cycles are relatively high under the condition of Case 2. This study demonstrated that alternative restrictions on water supply and irrigatable land could effectively constrain water use and consumption after modernizing the irrigation systems. The sensitivity of the major assumptions, and the uncertainties and limitations have been revealed and discussed, along with some implications for agricultural water managements. The findings can shed some light on the lively debate regarding the effectiveness of technological water saving measures. [ABSTRACT FROM AUTHOR]