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The crop water relationship quantification is conducive to decision-making for regional food safety and resource conservation. However, irrigation water and crop water footprint (CWF) was observed separately in previous studies, which leads to incomplete evaluation of water resource occupation in agricultural system. The crop water resource use (WRU), combining WF and irrigation water accounting, in 31 provinces of China from 1999 to 2018 was estimated in current paper. The driving forces of WRU were analyzed using the logarithmic mean divisia index (LMDI) model, based on its spatial and temporal patterns demonstration. The results showed that national WRU increased from 1051.6 Gm3 in 1999 to 1676.4 Gm3 in 2018, with an average annual growth rate of 2.48%. The provinces with high WRU were mainly distributed in North China and Northeast China. Hebei, Shandong, and Henan jointly contributed 28.9% of the national WRU. In addition, economic level was the largest contributor to promote the growth of WRU, and water use intensity was the most important contributor to inhibit the growth of WRU. Economic level, resource endowment, and population size had a promoting effect on WRU in Northeast, Northwest, North China, and Southeast provinces, while water use intensity, irrigation technique, and urbanization degree showed inhibitory effect in Northeast, Northwest, and Southwest provinces. It is meaningful to combine water footprint and irrigation water use for agricultural water management and conservation. The arid North China Plain should adopt water-saving irrigation and rainwater recycling technologies to control WRU, and the Northeast granary should reduce WRU by strengthening water pollution prevention and improving water resources scheduling to ensure food security and sustainable use of water resources. [ABSTRACT FROM AUTHOR]

Water use efficiency (WUE) improvements in agricultural production are of great significance to regional food security and ecological sustainability. Based on modified water footprint (WF) calculations for corn cultivation in China, WUE indices of water productivity (WP) and water efficiency (WE) for production capacity and the effective ratio of water resources were developed and quantified in the current study. Approaches to achieving national productive and effective improvements concurrently were sought by determining the spatial-temporal patterns and determinants of WP and WE during 1996–2015. The results show that the annual crop WF was estimated at 197.3 m³, including 14.1 % blue, 62.4 % green and 23.4 % gray components. WP and WE were calculated as 0.781 kg/m³ and 0.687, respectively, both of which increased over time in all subregions. Both WP and WE showed obvious spatial differences in the observed period. Low-value provinces were concentrated in the northwest and on the Huang-Huai-Hai Plain, and most high-value regions were distributed in the southeastern coastal zone. Agricultural production technology improvements contributed to WF reductions in specific areas, while meteorological elements and planting structure were the main factors affecting the spatial distribution of WP and WE. WF suppression in northwestern China and expansion of the production scale in southern China were conducive to increasing productive and effective agricultural water resource use in corn cultivation nationally. Agricultural production technology progress and crop spatial arrangement optimization are equally important to agricultural WUE enhancement in the WF framework. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Water footprint scarcity (WFS) was quantified based on blue-green water availability and appropriation. • WFS increased in drought agriculture-based region and dropped in economic developed area. • WFS increased in drought agriculture-based region and dropped in economic developed area. • Controlling the development of irrigation can reduce WFS and alleviate regional water scarcity. Abstract The mitigation of water stress in crop production is important for relieving the growing global water shortage. The water footprint scarcity (WFS) for regional water stress evaluation integrating blue and green water resources and the water footprint of the crop production industry were developed in this paper. Three subregions in China, industry-based southern Jiangsu (SJS), agriculture-based northern Jiangsu (NJS) and middle-type central Jiangsu (CJS), were selected to study the spatiotemporal pattern and driving mechanism of WFS. The results show that green water accounts for 56.6% and 71.8% of agricultural water resources available (AWA) and crop water footprint (CWF) of Jiangsu Province. The WFS of Jiangsu was calculated to be 2.26, and almost all prefectures for every year from 1996 to 2015 faced very high water stress (WFS > 1.20). The WFS value increased in NJS and CJS and decreased in SJS over time; meteorological and social factors affected the WFS at the same time. Land irrigation was the main factor to explain the growing water stress in the agriculture-based NJS. The WFS revealed the water shortage more clearly, especially in the water-poor agriculture-based areas, than the results of the conventional water stress index. The strategies for environmental change adaptation suggested by this study are to use WFS for agricultural water suitability evaluation and water resource management policy formulation; to reduce WFS through irrigation efficiency and crop variety promotion worldwide; and to implement compensation measures for agricultural products and virtual water trade to help underdeveloped agricultural production areas improve their agricultural production technology and control irrigation expansion. [ABSTRACT FROM AUTHOR]

Efficient utilization of water resources contributes to regional food, water and ecological security. An indicator, generalized efficiency (GE), was established based on a blue-green water framework for evaluating regional effective use of water resources. GE is defined as the ratio of total water consumption (TWC) to total water inflow (TWI) into an agricultural production system over a single year. Then, the spatial pattern of GE in the irrigated, rain-fed and total cropland of China in 2010 was analysed based on the quantification of provincial TWI and TWC, taking grain production as a case study. The results show that TWI in China was approximately 978.6 Gm 3 , of which rain water was close to 70.0%; national TWC was approximately 577.5 Gm 3 in the study year, including 72.0% green and 28.0% blue water; and rain-fed cropland made up approximately 33.0% of the TWI and TWC. The spatial distributions of TWI and TWC per unit arable land differs greatly; national GE in irrigated, rain-fed and total cropland were 0.584, 0.603 and 0.590, respectively; and regional rain-fed GE was larger than that in irrigated farmland due to the uneven distribution of precipitation. This work expanded the applicability of evaluation of effective use rate of water resources from blue water and irrigated cropland, to generalized water resources and any designated region. GE cannot be replaced by other exciting indicators in either scientific connotation or spatial distribution. Hence, the establishment of GE is a more advanced agricultural water use efficiency evaluation indicator system. [ABSTRACT FROM AUTHOR]

There was presently a lack of multidimensional investigation on the impact of virtual water flow (VWF) on regional water use and scarcity. A framework for impact analysis of VWF in consideration of blue, green and grey water differentiation, taking the crop-water relationship estimation in 31 provinces of China as case study, was established in current paper. Results showed that, VWF, which mainly from northern to eastern plain and southeast, reduced agricultural water footprints by 8.3 (blue), 322.0 (green) and 52.5 (grey) G m3. National water stress index reduced from 1.20 (severe water stress) to 0.92 (high water stress), comparing crop consumption to production perspectives. VWF alleviated the resource-based water scarcity attributed to green water stress in south of the Yangtze River, and transformed the resource-based to systematic water scarcity in Xinjiang (XJ). Clarifying the influences of VWF on blue, green and grey water is the innovation of the analytical framework proposed in current paper. • Influences of virtual water flow (VWF) on blue, green and grey water footprint scarcity were quantified. • Green and grey VWFs and their effects on water resources were more impressive than blue water. • VWF alleviated water stress and changed water scarcity type in crop production of China. • Crop production improvement and optimization are proposed to increase the benefits of VWF. [ABSTRACT FROM AUTHOR]

Reducing water use and relieving negative environmental consequences contribute to regional water and ecological sustainability. This work examined water resource efficiency (WRE) and the effects of effective crop water use from the perspective of the water footprint. WRE was defined as the ratio of consumptive field water use (CWU) to the total crop water footprint (CWF), including the blue water footprint applied (BWFA), green water footprint (GWF), and grey water footprint (GYWF). WRE for the cultivation of the main crops (rice, wheat, maize, beans, and tubers) produced in China during the period of 1996–2015 was determined from estimates of provincial CWFs and CWUs. The results show that national CWF was estimated as 678.5 Gm³, of which GWF comprised 55.1%; the national crop CWU was approximately 455.6 Gm³ in the period considered, and this included 82.1% green and 17.9% blue water. The spatial patterns of CWF and CWU densities differed greatly but were stable over time, with increasing trends exhibited from 1996 to 2015. The national WRE for crops was 0.672, and that for beans was 0.869, an efficiency larger than that of any other crop. The indices for rice and wheat were approximately 0.630. WRE cannot be replaced by the global efficiency (GEF) or generalized efficiency (GE) indices, either for scientific evaluations or for considerations of spatial distributions. This study aids in the evaluation of effective water resource consumption by considering the process of agricultural water use, and also the impact of crop production on water quality and quantity. Hence, WRE is an advanced indicator linking measurements of water footprint with assessments of crop management and the sustainability of regional water resources. [Display omitted] • Water resources effectiveness (WRE) was assessed from the water footprint perspective. • WRE was 0.672 and varied among crops in grain production of China. • It's needs to reduce crop water footprint and improve WRE in rice production of China. • WRE is an improvement of agricultural water use efficiency evaluation index system. [ABSTRACT FROM AUTHOR]

The process of blue water used in crop cultivation has both natural and economic properties due to the intervention of irrigation facilities. This study revealed crop water use (CWU) from 1999 to 2018 in each province of China based on water footprint theory, and then established the blue water dependence index (BDI) to evaluate the dependence of agricultural cultivation on irrigation water from the perspective of water withdraw, and conducted a spatial and temporal pattern analysis.The influencing factors and structural pathways of BDI were explored using least squares structural equation modeling (PLS-SEM) at national and regional scales. Results indicated that the annual amount of water used for crop production in China exceeded 900.0 Gm³. The growth in CWU from 1999 to 2018 for cash crops and grain crops was 145.4 Gm³ and 74.4 Gm³, respectively.BDI of all crops was 0.281 over the study period in China, with grain crops being 2.6 times more dependent on blue water resources than cash crops. Xinjiang, with annual average BDI of 0.716, 0.805, and 0.620 for all, grain and cash crops, respectively, has the highest irrigation demand. The PLS-SEM results showed a significant causal relationship between the economy and BDI, with obvious regional differences in structural path analysis. Based on the analysis of agricultural water use, the regions can adjust the structure of crop cultivation, optimize the allocation of water and soil resources, expand the cultivation of fodder grains and promote steady economic growth, to achieve a "win-win" situation of ensuring food security and sustainable use of agricultural water resources. • Water saving in agriculture should start with the fundamental conditions of water use in agriculture. • Significant changes in spatial and temporal differences in crop water use (CWU) in China • The blue water dependency index (BDI) was constructed to assess the demand for blue water for crop production • The economic level has always been one of the main drivers of the BDI [ABSTRACT FROM AUTHOR]

Intercropping can improve productivity per unit incident radiation by increasing the interception of solar radiation and/or maintaining higher radiation-use efficiency (RUE). This study examined the changes in radiation interception and RUE of spring wheat and spring maize after the initiation of intercropping. The field experiment comprised four treatments: wheat only, maize only, six rows of wheat alternated with two rows of maize (I62), and twelve rows of wheat alternated with four rows of maize (I124). The results demonstrated that per row, wheat in I62 and I124 intercepted 17% and 9% more radiation, respectively, than the wheat sole-cropping system and maize in I62 and I124 intercepted 28% and 26% more radiation, respectively, than the maize sole-cropping system. The RUE values were 3.10 and 3.19 g MJ −1 for maize in I62 and I124, respectively, lower than that for the maize sole-cropping system (3.51 g MJ −1 ). No significant difference was observed between the RUE values of intercropped and monoculture wheat. The harvest index of maize was identical in all systems, while that of the wheat was enhanced by intercropping. The grain yields of wheat in I62 and I124 were 29.2% and 10.8% higher, respectively, than that of sole wheat on per row basis and the grain yields of maize in I62 and I124 were 16.8% and 15.0% higher, respectively, than that of sole maize. Thus, increased radiation capture was the primary factor responsible for the high productivity of the wheat/maize intercropping systems. A simple model was developed to estimate radiation interception and partitioning in strip intercropping systems, considering the heterogeneity of leaf distribution in both the horizontal and vertical directions. The model may also be applicable to other strip intercropping systems. [ABSTRACT FROM AUTHOR]