Agricultural Water Use Efficiency Research Articles

Improving dryland maize productivity and water efficiency with heterotrophic ammonia-oxidizing bacteria via nitrification and cytokinin activity

A two-year field experiment conducted under dryland conditions in semi-humid and drought-prone regions of China aimed to assess the effect of ammonia-oxidizing bacterial on maize water use efficiency and yield. A heterotrophic ammonia-oxidizing bacteria (HAOB) strain S2_8_1 was used. Six treatments were applied: (1) no irrigation + HAOB strain (DI), (2) no irrigation + blank culture medium (DM), (3) no irrigation control (DCK), (4) irrigation + HAOB (WI), (5) irrigation + blank culture medium (WM), and (6) irrigation control (WCK). Results revealed that HAOB treatment increased maize growth, yield, and water use efficiency over controls, regardless of whether the year was wet or dry. This improvement was attributed to the accelerated nitrification in the rhizosphere soil due to HAOB inoculation, which subsequently led to increased levels of leaf cytokinins. Overall, these findings suggest that HAOB inoculation holds promise as a strategy to boost water use efficiency and maize productivity in dryland agriculture

Soil water dynamics and deep percolation in an agricultural experimental area of the North China Plain over the past 50 years: Based on field monitoring and numerical modeling

The unregulated irrigation systems used in the late 20th century have led to increasingly severe deep percolation (DP) in the agricultural irrigation areas of the North China Plain. This has become an important factor limiting the efficient utilization of water resources and sustainable environmental development in these irrigation areas. However, the thick vadose zone is hydrodynamically exceptionally complex. The soil hydrological cycle is constantly changing under the influence of major climate change and human activity, thereby causing changes in DP that are difficult to quantify accurately. Here, the Luancheng Agricultural Irrigation District in North China was selected for a continuous 20-year in situ experiment. Soil-water dynamics were monitored using neutron probes and tensiometers, to determine the complete annual soil-water cycle and the hydrodynamic properties of the thick vadose zone irrigation district. For 1971–2021, DP was simulated using the HYDRUS-1D model and was verified by fitting observed values. Soil water content (SWC) exhibited similar trends in years that differed in terms of the amounts of irrigation and precipitation. The 0–100 cm soil layer was significantly affected by precipitation and other factors, and recharge >60 mm/d caused percolation. DP occurred mostly after irrigation or during the period of intensive precipitation in July–October. The maximum percolation rate was 16.9 mm/d under the present irrigation method. The main factors leading to DP were soil water storage capacity (R2 = 0.86) and precipitation (R2 = 0.54). Under the evolution of irrigation measures in the last 50 years, the average DP has gradually decreased from 574.2 mm (1971–1990) to 435.5 mm (2005–2021). However, a substantial amount of precipitation and irrigation water infiltrated the soil and percolated into the deep soil layer without being utilized by the crop. Therefore, there is an urgent need to consider measures to reduce DP to improve water-use efficiency in agriculture.

Deficit Irrigation with Silicon Application as Strategy to Increase Yield, Photosynthesis and Water Productivity in Lettuce Crops.

In regions where water is a limited resource, lettuce production can be challenging. To address this, water management strategies like deficit irrigation are used to improve water-use efficiency in agriculture. Associating this strategy with silicon (Si) application could help maintain adequate levels of agricultural production even with limited water availability. Two lettuce crop cycles were conducted in a completely randomized design, with a factorial scheme (2 × 3), with three irrigation levels (60%, 80% and 100%) of crop evapotranspiration (ETc), and with and without Si application. To explore their combined effects, morphological, productive, physiological and nutritional parameters were evaluated in the crops. The results showed that deficit irrigation and Si application had a positive interaction: lettuce yield of the treatment with 80% ETc + Si was statistically similar to 100% ETc without Si in the first cycle, and the treatment with 60% ETc + Si was similar to 100% ETc without Si in the second cycle. Photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate and total chlorophyll content increased under water-stress conditions with Si application; in the first cycle, the treatment with 80% ETc + Si increased by 30.1%, 31.3%, 7.8%, 28.46% and 50.3% compared to the same treatment without Si, respectively. Si application in conditions of water deficit was also beneficial to obtain a cooler canopy temperature and leaves with higher relative water content. In conclusion, we found that Si applications attenuate water deficit effects and provide a strategy to ameliorate the yield and water productivity in lettuce crops, contributing to more sustainable practices in agriculture.

Assessment of Broccoli (Brassica oleracea) Cultivation under Two Irrigation Systems in Central Iraq

A field experiment was conducted in the Abbasiya area of Najaf Governorate, located in the Middle Euphrates region during the winter season of 2022-2023. The primary focus of the study was to evaluate the performance of two irrigation systems, nano-irrigation, and subsurface drip irrigation, on broccoli plants grown in clay soil. The experimental design followed a Complete Randomized Block Design (CRBD). Nano-irrigation demonstrated several advantages over subsurface drip irrigation. It exhibited a reduction inater con-sumption and lower energy requirements for water pumping opera-tions. Notably, the root length of broccoli plants was significantly greater under the nano-irrigation system, with an increase of 18.2 cm compared to the drip irrigation system. The use of nano-irrigation resulted in better water use efficiency and energy efficien-cy, leading to improved root development in the broccoli plants. The study results indicated that nano-irrigation offers benefits in terms of water conservation and plant growth promotion, ultimately leading to increased overall productivity. This makes nano-irrigation an appealing option for improving water use efficiency in agriculture, particularly in regions that face water scarcity. Moreo-ver, there was no significant difference in yield between the nano-irrigation and subsurface drip irrigation systems.

Optimal allocation of soil and water resources in agriculture under the total regional evapotranspiration indicator: A case study in Guangping, China

There is a mismatch between crop water demand, the spatial and temporal distribution of natural rainfall, surface water sources, and arable land resources in the North China Plain. This has been compensated for by massive groundwater exploitation, and as a result, ground water levels have continuously declined and groundwater landing funnels have formed in some areas. Consequently, there is an urgent need for the rational allocation of soil and water resources. In this study, regional soil types and the corresponding crops in Guangping County, Hebei Province, China, alongside the regional annual average total water consumption were used to determine reasonable allocations for crop planting structures, with an aim of maximizing the water utilization efficiency and economic benefits while also achieving a regional groundwater dynamic equilibrium. Daily meteorological data from 1973 to 2021, including precipitation, temperature, sunshine hours, wind speed, and humidity, as well as crop data, including irrigation systems and crop growth status, were collected. Water consumption models for eight soil types and seven typical crops forming 56 calculation partitions were established to obtain annual average water consumption values for the different crops. The maximum economic benefit and water-use efficiency were then used as the objective functions and total water consumption as the control condition for the non-dominated sorted genetic algorithm-Ⅱ (NSGA-II), to optimize the allocation of soil and water resources in the region; the adjusted quantities for the different crops cultivated under different soil types in the study area were obtained. The areas growing sweet potato and vegetable-fruits were found to increase by 0.5255 km2 and 4.4452 km2, respectively, when compared to the pre-optimization period, whereas the areas with winter wheat-summer maize, millet, peanut, cotton, and summer maize decreased by 1.3481 km2, 0.1812 km2, 0.7316 km2, 2.0896 km2, and 0.62 km2, respectively. The economic benefit increased from 810.37 to 853.64 million yuan, while the water-use efficiency increased from 1.5426 kg/m3 to 1.5859 kg/m3. The results provide a basis for soil and water resource management in the region and a technical reference for similar areas to improve agricultural water-use efficiency and economic benefits.

Enhancement of Soil Organic Carbon, Water Use Efficiency and Maize Yield (Zea mays L.) in Sandy Soil through Organic Amendment (Grass Peat) Incorporation

The efficient use of organic amendment (OM) is considered an economic, environmental and sustainable practice to improve soil quality, especially the accumulation of organic carbon (C) and water use efficiency (WUE) in dryland agriculture. However, the effect of different OM on soil nutrients, organic carbon fractions, water content and maize yield is unclear in arid and semi-arid regions with sandy soil. Field experiments with four OM, grass peat (GP), biochar (BC), organic fertilizer (OF) and maize straw (MS), were conducted with an equivalent amount of C input on the southeastern edge of Mu Us Sandy Land in China. Results indicated that the soil nutrients and labile organic carbon (DOC, MBC, KMnO4-C and POC) concentrations were higher under OM (GP, BC, OF and MS) treatments than in CK in the 0–0.10 m soil layers. GP treatment remarkably improved carbon pool index values (1.63, 2.51 and 2.24, respectively) in all layers compared to CK (1.00). At maturity stages of maize, the soil water content (SWC) under GP and OF treatments (11.3–13.4%) was remarkably higher than that in CK treatment (around 10.0%). Yield and WUE were remarkably greater in GP and OF treatments compared to CK. The results proved that GP amendment is superior for barren sandy soil than BC, OF and MS treatments in improving soil nutrients, organic carbon sequestration, WUE and crop yield in China.

Influence of energy poverty on agricultural water efficiency using a panel data study in China

The research attention is increasingly directed towards the effective integration of the 17 United Nations Sustainable Development Goals (SDGs) within the limitations of the real world and amidst intersectoral conflicts. In light of the inextricable relationship between irrigation and energy, the objective of this study is to identify potential avenues for achieving the SDG6 and SDG7 goals of enhancing water use efficiency in agriculture and eradicating energy poverty, respectively. Utilizing data from 30 Chinese provinces from 2002 to 2017, this study explores the dynamic influence of energy poverty on agricultural water efficiency with a system generalized method of moments methodology. The findings suggest that energy poverty may greatly reduce agricultural water efficiency. The heterogeneity study shows that when agricultural water efficiency grows, the negative impacts of energy poverty continue to fade. Based on an assessment of various processes, results suggest that non-farm employment and cropping structure modification is a prominent conduit via which energy poverty negatively influences agricultural water efficiency.

Surface temperature adjustment in METRIC model for monitoring crop water consumption in North China Plain

Evapotranspiration is the real water consumption element in agricultural water management. In order to improve the efficiency of agricultural water use and maintain the sustainable development of agriculture, more and more attention has been paid to the improvement of monitoring and management of farmland evapotranspiration. In this study, MODIS data and the Temperature Vegetation Dryness Index (TVDI) were used in the METRIC model to estimate evapotranspiration for winter wheat and summer corn in the North China Plain. In order to decrease the error caused by the spatial heterogeneity of air temperature in the estimation of evapotranspiration, based on the characteristics of cold pixels with surface temperatures close to their air temperature, the TVDI was used to assist the selection of cold pixels and obtain the spatial variation trend of air temperature with latitude from all cold pixels in the study area. The influence of the spatial heterogeneity of air temperature on the surface temperature at the time of the satellite overpass was corrected accordingly, thereby the estimation accuracy of evapotranspiration was improved. A METRIC-TVDI model was established and the evapotranspiration of winter wheat and summer corn in Hebei Plain was estimated from 2017 to 2019. The average evapotranspiration of the winter wheat over these three years were 361 mm, 327 mm and 354 mm respectively, and that of summer corn were 394 mm, 388 mm and 405 mm respectively. Based on the farmland water balance, the irrigation water consumption (evapotranspiration minus precipitation) of winter wheat and summer corn rotation were 324 mm, 134 mm and 360 mm respectively. This kind of crop rotation pattern consumed more groundwater for irrigation, especially the winter wheat. In order to realize the balance of groundwater between exploitation and replenishment in Hebei Plain, more water-saving irrigation technologies should be adopted to reduce the evapotranspiration and improving water use efficiency.

Streamlining Different Plant Breeding Methods to Enhance Water Use Efficiency in Agricultural Systems

The relevance of Water in human life and agro-ecosystems has been extensively illustrated for decades around the globe. Despite the reality that the earth is mostly surrounded by water, its utility has been limited to domestic consumption and agricultural purposes. Thus, tweaking water usage in agricultural systems has been a tricky problem in order to meet the requirements of the growing population and to obtain more crop yield per drop of water in agriculture. In this review, an attempt has been made to revisit the methods available to improve water use efficiency in agriculture.

Analysis of the Spatial Correlation Network Structure of Agricultural Water Use Efficiency in Northwest China

There are some problems in Northwest China, such as the fragile ecological environment, poor basic conditions of agricultural production, low efficiency of agricultural water use, and difficulty in clarifying the path of agricultural water use efficiency (AWUE) improvement. Based on the superefficiency data envelopment analysis (DEA) model, this study increases the amount of ‘green water’ resources in the agricultural water consumption index of the input index and increases the wastewater pollutants (total chemical oxygen demand emissions; total ammonia nitrogen emissions) in the undesired output index to measure the AWUE in the northwest region. Based on the calculation results of AWUE, combined with the modified gravity model, the connection strength of AWUE between any two provinces in Northwest China is calculated, and the spatial structure and network characteristics of AWUE in this area are analysed via the social network analysis (SNA) method. The results show that the average AWUE in 2020 is nearly two times higher than that in 2011. From the situation of the northwest provinces, the average AWUE of the five provinces is in the order of Qinghai > Shaanxi > Gansu > Ningxia > Xinjiang. The AWUE value, total population, real GDP and per capita GDP of the capital cities of the five provinces in Northwest China are the key factors for the improvement of the connection intensity of AWUE. From 2011 to 2020, the connection intensity and closeness of AWUE in Northwest China increased, and there was a clear network hierarchy. The improvement in overall AWUE in the region is mainly due to the radiation and driving effect of the central province on other provinces. Based on this, the study proposes policy recommendations for gradually realising the AWUE improvement path of the central province (Shaanxi; Gansu)—cooperation circle (Shaanxi–Ningxia; Gansu–Qinghai)—the whole region. The results provide theoretical support and a quantitative basis for optimising the spatial pattern of agricultural water resources and improving AWUE in Northwest China.

Analysis of the Scale Effect and Temporal Stability of Groundwater in a Large Irrigation District in Northwest China

The depth to groundwater table (DGT) and the stability sites of groundwater were closely related parameters in groundwater research. Controlling the DGT and identifying stability sites of DGT were of great significance to prevent soil salinization and improve groundwater monitoring. In this study, using DGT data from the Hetao Irrigation District (HID) from 1991 to 2015, combined with spatial interpolation and coefficient-of-variation methods, this study explored the spatiotemporal variation characteristics and scale-effect problems of DGT from four hierarchical scales: the irrigation district, irrigation subdistrict, main canal, and branch canal. The Spearman correlation coefficient, average relative difference, and standard deviation were also used to further clarify the characteristics of groundwater time stability and its periodic variation rule. The results indicated that the spatiotemporal variation in DGT in the HID, and showed moderate variation characteristics, consistent with scale-effect features, which was deeply influenced by the regional climate and human activities. The DGT in the HID showed different temporal stabilities before and after 2000 caused by the application of Water-saving practices (WSPs). The stability sites were not entirely the same in different years or time periods, but they were all at the moderate DGT level in the HID. The results of this study can provide more insights for improving soil salinization and groundwater monitoring and provide more information for agricultural water-use efficiency and management.

Developing a Subsurface Drip Irrigation Scheduling Mode Based on Water Evaporation: Impacts Studies on Cucumbers Planted in a Greenhouse in the North China Plain

China is a country short of water resources, and improving the water use efficiency (WUE) in agriculture has become the only way to ensure sustainable development. In this article, subsurface drip irrigation (SDI) experiments of cucumber were implemented with a randomized block design comprising two factors and three levels, and the two factors were depth of drip belt buried and irrigation amount, which were determined by a 20 cm diameter pan’s water evaporation times its coefficient (Kp). The effects of schedule of SDI on soil evaporation (Es), evapotranspiration (ET), Kp, root dry matters, yield, and WUE of cucumber were studied. The results indicated that the Es and the ET decreased along with increasing depth of drip belt buried or decreasing amount of irrigation water applied. The relationships between ET and its total irrigation amount were significant linear positive correlations. Proportions of plant transpiration accounting for the ET were about 41~69% in two years, and it became bigger along with the increase of ET within a year. The Kp became smaller along with the reducing of ET. The roots of cucumber were mainly concentrated in the soil layer of 0~20 cm, and the two factors could only influence root dry weights of 0~60 cm soil layers significantly. The relationships between yield and ET were quadratic polynomial correlations. At last, an ultimate SDI scheduling mode based on water evaporation was established.

Agricultural Total Water Consumption Coefficient and Its Spatial Correlation Network in Yangtze River Economic Belt

Agriculture contributes extensively to the economic development of countries; however, it is one of the main water-consuming industries. Revealing the characteristics and network structure of agricultural water use efficiency (AWUE) is conducive to green and coordinated development of agriculture. Considering that analyzing the variation of AWUE is helpful to calculating the AWUE, this study aims to calculate the total water consumption coefficient of the agricultural sector in the Yangtze River Economic Belt (YEB) by using the China interregional input-output tables in 2012 and 2017. The gravity model was modified to deduce the spatial correlation network of agricultural total water consumption coefficient (ATWCC), and the social network analysis method was used to analyze the network structural characteristics. The results show that: (1) compared to 2012, the AWUE of YEB in 2017 improved, with a decrease of ATWCC from 532.5 to 387.5 m3/10,000-yuan, account for 27.2%; (2) The network relevance of ATWCC of YEB’s 11 provinces (cities) enhanced, the rank relationship within the network and the network structure was relatively stable; (3) The spatial correlation network formed several network centers, Zhejiang and Jiangsu in the eastern coastal area were the main destinations of the spatial spillover of the spatial correlation network.

A Step toward Water Use Sustainability: Implementing a Business Model Canvas for Irrigation Advisory Services

Some major future global challenges are linked to more efficient use of water for irrigation to respond to the growing water scarcity coupled with the increasing food demand. Although irrigation advisory services (IASs) are considered effective instruments to increase water use efficiency in agriculture, their diffusion remains limited. This is due to several constraints mainly linked to their low accessibility and high costs. To overcome the bottlenecks associated with IASs’ adoption, this paper proposes a business model (BM) as a tool for scaling up IASs within a business perspective, with the aim of encouraging the diffusion of this technology while enhancing the associated environmental and social benefits. Drawn from the experience of the OPERA project, we structured the business model taking advantage of the opinion of relevant stakeholders and IASs’ potential users to identify specific limitations and understand their needs. It turned out that farmers are willing to adopt IASs but require that the service is easily accessible, with high-quality information that are delivered at an affordable cost. Indeed, here a BM with an innovative way to produce and deliver value is proposed. The value proposition is built upon key features namely, integration, customization, accessibility, and sustainability that reflect users’ needs and preferences. Our BM also provides a detailed revenues strategy that guarantees the financial sustainability of IASs. To design and represent our BM, the “Business Model Canvas ©” has been adopted. We concluded that an innovative and well-structured BM has the potential to leave the IASs profitable and capable to ensure environmental and social sustainability.

Climate Resilient Water Management for Sustainable Agriculture

The management of water resources in both irrigated and rain-fed agriculture is becoming an increasingly complex worldwide due to anticipated water scarcity, and compounded by the challenges of global warming and climate change. Climate-smart water technologies viz. Drip irrigation, Central pivot irrigation, Hydrogel and SWAT method need to be judiciously applied to overcome these challenges. Agriculture is a critical sector in India and other developing countries, providing substantial employment opportunities to rural populations and supporting efforts to achieve food and nutritional security. This paper addresses the challenge of increasing food production and improving rural livelihoods while safeguarding critical water resources for sustainable use, particularly in drought-prone regions, through adaptive measures for effective water management. An integrated approach is necessary for agricultural water management through the adoption of innovative technologies such as water harvesting, micro-irrigation, and resource conservation farming to increase water-use efficiency in agriculture and other critical services to humans and animals. The study aims to enhance understanding of the potential implications of climate change and adaptation options for agricultural water management, thereby enabling them to take up adaptation challenges and develop measures to reduce the farming sector's vulnerability to climate change.

Data-Driven Modelling of Soil Moisture Dynamics for Smart Irrigation Scheduling

In the face of increasing water scarcity and uncertainties of climate change, improving crop water use efficiency and productivity, while minimizing negative environmental impacts, is becoming crucial to meet the surging global food demand. Smart irrigation has a potential of improving water use efficiency in precision agriculture especially when efficient irrigation control strategies are adopted. Conventionally, irrigation systems rely on heuristic methods to schedule irrigation which either leads to over-irrigation or under-irrigation. This influences the crop physiological characteristics as well as the water use efficiency. To tackle this menace, model-based irrigation management has been overemphasized. A closed-loop irrigation control strategy relies on a mathematical model of the system for irrigation scheduling decisions. In this study, a data-driven approach was used to learn soil moisture dynamics from a drip irrigated tomato in an open field agricultural system. A total number of 9674 data samples were collected using an ATMOS41 weather station, TERROS 12 soil moisture sensor and a YFS-201 flow sensor for crop evapotranspiration and precipitation, soil moisture and irrigation volumes respectively. Data driven modelling was then performed using the system identification toolbox in a MATLAB environment. The model formulation was a multi-input single-output (MISO) system with reference evapotranspiration, irrigation and rainfall as inputs and soil moisture as the output. Different model structures including transfer functions, state space models, polynomial models and ARX models were evaluated. Model performance was evaluated using the mean square error (MSE), final prediction error (FPE) and estimated fit of the model approaches. Simulation results indicate that the soil moisture dynamics model provides a satisfactory approximation of the process dynamics with a state space model giving an estimated fit of 97.04 %, MSE and FPE of 1.74×10−7 and 1.75×10−7 respectively. This model will be used to design a model predictive controller for smart irrigation scheduling in open field environmental conditions.

Developing an Open-Source IoT Platform for Optimal Irrigation Scheduling and Decision-Making: Implementation at Olive Grove Parcels

Climate change has reduced the availability of good quality water for agriculture, while favoring the proliferation of harmful insects, especially in Mediterranean areas. Deploying IoT-based systems can help optimize water-use efficiency in agriculture and address problems caused by extreme weather events. This work presents an IoT-based monitoring system for obtaining soil moisture, soil electrical conductivity, soil temperature and meteorological data useful in irrigation management and pest control. The proposed system was implemented and evaluated for olive parcels located both at coastal and inland areas of the eastern part of Crete; these areas face severe issues with water availability and saltwater intrusion (coastal region). The system includes the monitoring of soil moisture and atmospheric sensors, with the aim of providing information to farmers for decision-making and at the future implementation of an automated irrigation system, optimizing the use of water resources. Data acquisition was performed through smart sensors connected to a microcontroller. Data were received at a portal and made available on the cloud, being monitored in real-time through an open-source IoT platform. An e-mail alert was sent to the farmers when soil moisture was lower than a threshold value specific to the soil type or when climatic conditions favored the development of the olive fruit fly. One of the main advantages of the proposed decision-making system is a low-cost IoT solution, as it is based on open-source software and the hardware on edge devices consists of widespread economic modules. The reliability of the IoT-based monitoring system has been tested and could be used as a support service tool offering an efficient irrigation and pest control service.

A Review on Remote Sensing as a Tool for Irrigation Monitoring and Management

Remote sensing has played a vital role in advancement of agriculture and is effective technical method for agriculture crop management. It is a technology which acquisite information regarding objects on earth surface as well as atmosphere from a distance without being in contact with the object. Researchers have proved its high potential with accuracy in the field of agriculture. After various experiments, the qualitative and quantitative assessment of soil, crop and atmosphere demonstrated the better understanding between the crop and its management practices. The collected spatial and temporal data via various passive and active sensors has been utilized not only for morphological study but also for monitoring the vegetation moisture content. The paper reviews about the potential studies carried out to investigate the water content in plant to make use in irrigation management. Diverse spectral reflectance indices have been mentioned from which special emphasis on NDWI has been given. It is an index which is used in remote sensing to assess the crop water status and can be utilized in efficient operation of irrigation to improve water use efficiency (WUE) in agriculture. In order to make irrigation practices more efficient by making the lab restricted irrigation scheduling methods like IW:CPE method applicable in regular practice by using remote sensing. This paper firstly identifies areas where researches and techniques have real-world application. Next, it identifies actual issues that remote sensing could address and solve with further research and its related development. All opportunities for managing agricultural water resources effectively to be explored and made successful through precision agriculture. Using the fast, impartial and reliable information offered by remote sensing is a significant difficulty in the field of water resource management.

Factors Influencing Water Use Efficiency in Agriculture: A Case Study of Shaanxi, China

Enhancing agricultural water use efficiency can support Shaanxi Province’s transition to a sustainable agricultural economy. Using the data envelopment approach (DEA), we evaluated the water use efficiency in agriculture of various cities in the Shaanxi Province of China. Moran’s I and Dagum Gini coefficients were used to reveal spatial and temporal characteristics of agricultural water use efficiency. Furthermore, the geographically and temporally weighted regression (GTWR) model was used to investigate the effects of the agricultural economy, level of water-saving irrigation, cropping structure, environmental factors, and water supply structure on agricultural water use efficiency. The findings demonstrate that the average agricultural water use efficiency from 2011 to 2020 is low (0.796) in Shaanxi Province. Spatially there is considerable variation in water use efficiency between cities, with some highly efficient and some with very low efficiency. There is a strong negative spatial correlation between cities, with high efficiency cities tending to be adjacent to low efficiency cities. Moreover, the spatial differences in agricultural water use efficiency have increased over time, with the most significant increase within the northern region and between the north and central areas. Each influencing factor has a different impact from year to year and from city to city. Overall, the level of water-saving, the level of agricultural economics, the structure of the water supply, and environmental factors primarily have a negative influence. In contrast, the planting structure primarily has a favorable function. Therefore, to support the coordinated growth of agricultural water use efficiency, Shaanxi Province should improve its city-to-city cooperation and exchange of water use technology and experience, as well as develop differentiated water use measures appropriately for the development of each city according to local conditions.

Evolutionary Trends, Regional Differences and Influencing Factors of the Green Efficiency of Agricultural Water Use in China Based on WF-GTWR Model.

Improving the green efficiency of agricultural water use is a key way to promote the sustainable utilization of agricultural water resources and sustainable development of economy and society. This work calculated and analyzed the evolution trend, regional differences and driving factors of the green efficiency of agricultural water use in China from the perspective of the water footprint. The results show that the green efficiency of agricultural water use in China shows a fluctuation trend of first declining and then rising from 1997 to 2020, after which the average efficiency dropped from 0.538 in 1997 to 0.406 in 2009, and then rose rapidly to 0.989 in 2020, with an average annual growth rate of about 3.6%. From a regional perspective, the green efficiency of agricultural water use in the eastern region was the highest (0.594), above the national average (0.538), followed by the western region (0.522), with the central region in last (0.491), with significant regional differences. The spatial differences in the green efficiency of available agricultural water in China shows a fluctuating downward trend. The Gini coefficient fluctuated from 0.271 in 1997 to 0.182 in 2020, with an average annual growth rate of about -1.4%. The main source of this regional difference was super-variable density, followed by the difference between the eastern and the central regions. The influence of urbanization level, water-saving level and agricultural trade on the green efficiency of agricultural water use was always positive and the influence of industrialization level was always negative; among them, the urbanization level, water-saving level and industrialization level had a greater impact on Northeast China, and agricultural trade had a greater impact on Southeast China. Therefore, this work puts forward relevant policy recommendations.