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Water shortage consider on of the main threats facing the agriculture, mainly in the Mediterranean area. So that there is a great need to apply new methods to water resource management. The crop models are used to achieve this objective. Tomato is a significant vegetable crop globally and represent an important part of horticultural production with 180 million tons produced on over five million hectares even though few studies have validated the AquaCrop model, especially in Egypt. This study was conducted in a protected cultivation experimental farm, Agricultural Research Center (ARC), Dokki, Giza, Egypt during the winter seasons of 2019/2020 and 2020/2021. Different irrigation levels (IL): 55%, 70%, 85%, 100%, and 115% of evapotranspiration (Eto) were applied on tomato. Plant growth parameters, relative chlorophyll content (SPAD), yield, fruit quality and plant nutrients (NPK) were recorded at both seasons. Also, the aforementioned irrigation levels were used to validate the AquaCrop model on different climate change scenarios on tomato productivity in 2050 and 2100. The findings revealed that the highest plant growth parameters were obtained in 85% and 100% Eto as compared to all treatments at both seasons. In contrast, the 55%of Eto obtained the lowest values of all plant growth parameters. The number of fruits/plant, early yield, and total yield of 100% Eto were ranked secondly. Fruits quality was significantly affected by the tested ILs. The highest values of TSS, firmness and vit C of tomato fruits were obtained by 55% followed by 70% Eto. The lowest proline content was recorded at 115% of Eto in both seasons. The content of proline in plants of 70% Eto ranked secondly after 55% of Eto in both seasons. The results of AquaCrop model (Version 7.0) revealed that the crop productivity decreased by 4% and 33% of RCP4.5 and RCP8.5 scenarios, respectively, of the years 2050, 14% and 44% for the same scenarios, respectively, of the year 2100.

The irrigation water requirements of different crops are becoming a pivotal driver for the governance strategies of water allocation and management. This paper estimates the impact of irrigation water requirements on economic value in terms of the yields and gross saleable production of 13 different crops cultivated in the Emilia-Romagna region (Italy) over the 2010–2020 period by exploiting a generalized propensity score matching approach. Results show that the overall irrigation water requirements affect crops' economic value. There is a causal effect of water irrigation on economic value: positive only for high levels of water irrigation in the case of yields, while it reverses and assumes a concave shape for gross saleable production. However, the effect is mediated by the irrigation water requirements of different crops. In water scarcity conditions, the allocation of water to arboreal crops, given the effect of water irrigation on gross saleable production, is also positive for small quantities of water. This paper can help guide the design of more sustainable water management strategies and agricultural development policies to face climate change. [ABSTRACT FROM AUTHOR]

Water shortage consider on of the main threats facing the agriculture, mainly in the Mediterranean area. So that there is a great need to apply new methods to water resource management. The crop models are used to achieve this objective. Tomato is a significant vegetable crop globally and represent an important part of horticultural production with 180 million tons produced on over five million hectares even though few studies have validated the AquaCrop model, especially in Egypt. This study was conducted in a protected cultivation experimental farm, Agricultural Research Center (ARC), Dokki, Giza, Egypt during the winter seasons of 2019/2020 and 2020/2021. Different irrigation levels (IL): 55%, 70%, 85%, 100%, and 115% of evapotranspiration (Eto) were applied on tomato. Plant growth parameters, relative chlorophyll content (SPAD), yield, fruit quality and plant nutrients (NPK) were recorded at both seasons. Also, the aforementioned irrigation levels were used to validate the AquaCrop model on different climate change scenarios on tomato productivity in 2050 and 2100. The findings revealed that the highest plant growth parameters were obtained in 85% and 100% Eto as compared to all treatments at both seasons. In contrast, the 55% of Eto obtained the lowest values of all plant growth parameters. The number of fruits/plant, early yield, and total yield of 100% Eto were ranked secondly. Fruits quality was significantly affected by the tested ILs. The highest values of TSS, firmness and vit C of tomato fruits were obtained by 55% followed by 70% Eto. The lowest proline content was recorded at 115% of Eto in both seasons. The content of proline in plants of 70% Eto ranked secondly after 55% of Eto in both seasons. The results of AquaCrop model (Version 7.0) revealed that the crop productivity decreased by 4% and 33% of RCP4.5 and RCP8.5 scenarios, respectively, of the years 2050, 14% and 44% for the same scenarios, respectively, of the year 2100. [ABSTRACT FROM AUTHOR]

To improve water use efficiency and productivity, particularly in irrigated areas, reliable water accounting methodologies are essential, as they provide information on the status and trends in irrigation water availability/supply and consumption/demand. At the collective irrigation system level, irrigation water accounting (IWA) relies on the quantification of water fluxes from the diversion point to the plants, at both the conveyance and distribution network and the irrigated field level. Direct measurement is the most accurate method for IWA, but in most cases, there is limited metering of irrigation water despite the increasing pressure on both groundwater and surface water resources, hindering the water accounting procedures. However, various methodologies, tools, and indicators have been developed to estimate the IWA components, depending on the scale and the level of detail being considered. Another setback for the wide implementation of IWA is the vast terminology used in the literature for different scales and levels of application. Thus, the main objectives of this review, which focuses on IWA for collective irrigation services, are to (i) demonstrate the importance of IWA by showing its relationship with water productivity and water use efficiency; (ii) clarify the concepts and terminology related to IWA; and (iii) provide an overview of various approaches to obtain reliable data for the IWA, on the demand side, both at the distribution network and on-farm systems. From the review, it can be concluded that there is a need for reliable IWA, which provides a common information base for all stakeholders. Future work could include the development of user-friendly tools and methodologies to reduce the bridge between the technology available to collect and process the information on the various water accounting components and its effective use by stakeholders. [ABSTRACT FROM AUTHOR]

In order to increase water productivity at the Collective Irrigation System (CIS) level it is crucial to adapt the existing irrigation infrastructure, enhancing water intake at the source, as well as its transport and delivery efficiency. Rehabilitation may involve structural changes and thus, a large capital investment. This investment should be proportionate to the increase in climate resilience associated to different rehabilitation alternatives. A methodology framework was developed to evaluate CIS resilience to climate change considering different rehabilitation alternatives. The assessed components were: (i) crop production systems; (ii) on-farm irrigation systems; and (iii) project rehabilitation alternatives for the conveyance and distribution of the irrigation water from the source to the farmer fields. This framework was applied to the Maiorga CIS, in central Portugal, to test the methodology performance in assessing the impacts of climate change on the supply-demand balance of the proposed rehabilitation alternatives and to evaluate their climate resilience, for the representative concentration pathways, RCP4.5 and RCP8.5, and two time periods, 2041–2070 and 2071–2100. For each scenario, period, and rehabilitation alternative, irrigation requirements at the source (demand) and stream flows (supply) were computed and the supply-demand balance was performed. Projected increases in irrigation water demand varied between 5.5% for RCP4.5/2071–2100 and 35.7% for RCP8.5/2071–2100. For RCP4.5, 11% (2050) and 9% (2080) reductions in irrigation water supply were projected, while for RCP8.5 the reduction ranges between 13% (2050) and 30% (2080). The proposed framework determined that the rehabilitation alternatives considering just one type of water source, without flow regularization and with open channel distribution to the farmer's field, have proved to be unviable due to low resilience to climate change. [ABSTRACT FROM AUTHOR]

The irrigation water requirements of different crops are becoming a pivotal driver for the governance strategies of water allocation and management. This paper estimates the impact of irrigation water requirements on economic value in terms of the yields and gross saleable production of 13 different crops cultivated in the Emilia-Romagna region (Italy) over the 2010–2020 period by exploiting a generalized propensity score matching approach. Results show that the overall irrigation water requirements affect crops’ economic value. There is a causal effect of water irrigation on economic value: positive only for high levels of water irrigation in the case of yields, while it reverses and assumes a concave shape for gross saleable production. However, the effect is mediated by the irrigation water requirements of different crops. In water scarcity conditions, the allocation of water to arboreal crops, given the effect of water irrigation on gross saleable production, is also positive for small quantities of water. This paper can help guide the design of more sustainable water management strategies and agricultural development policies to face climate change.

Agricultural droughts cause a great reduction in winter wheat productivity; therefore, timely and precise irrigation recommendations are needed to alleviate the impact. This study aims to assess drought stress in winter wheat with the use of an unmanned aerial system (UAS) with multispectral and thermal sensors. High-resolution Water Deficit Index (WDI) maps were derived to assess crop drought stress and evaluate winter wheat actual evapotranspiration rate (ETa). However, the estimation of WDI needs to be improved by using more appropriate vegetation indices as a proximate of the fraction of vegetation cover. The experiments involved six irrigation levels of winter wheat in the harvest years 2019 and 2020 at Luancheng, North China Plain on seasonal and diurnal timescales. Additionally, WDI derived from several vegetation indices (VIs) were compared: near-infrared-, red edge-, and RGB-based. The WDIs derived from different VIs were highly correlated with each other and had similar performances. The WDI had a consistently high correlation to stomatal conductance during the whole season (R2 between 0.63–0.99) and the correlation was the highest in the middle of the growing season. On the contrary, the correlation between WDI and leaf water potential increased as the season progressed with R2 up to 0.99. Additionally, WDI and ETa had a strong connection to soil water status with R2 up to 0.93 to the fraction of transpirable soil water and 0.94 to the soil water change at 2 m depth at the hourly rate. The results indicated that WDI derived from multispectral and thermal sensors was a reliable factor in assessing the water status of the crop for irrigation scheduling. [ABSTRACT FROM AUTHOR]

Climate change is a challenging fact influencing diverse sectors in society including the agricultural one, which is heavily dependent on natural resources and climate. In the Mediterranean region, climate change-related increases in air temperature, and in the frequency and intensity of extreme weather events, such as droughts, boost the pressure on the agricultural systems and affect crop yield potential. The growth of the world population implies that production needs to increase in a sustainable manner. Therefore, this study focuses on the maize crop due to its importance for food security and because it is a crop with significant water consumption that occupies a large worldwide area. In order to study climate change impacts on crop production, plant water requirements, and provide farmers guidelines helping them to adapt, it is necessary to simultaneously evaluate a large number of factors. For this reason, modelling tools are normally used to measure the future impact of climate change on crop yield by using historical and future climate data. This review focuses on climate change impacts on maize crop irrigation requirements and compares—by means of critical analysis—existing approaches that allow for the building a set of mitigation and adaptation measures throughout the study of climate. [ABSTRACT FROM AUTHOR]

Olive (Olea europaea) is an emblematic tree in the Mediterranean regions that grows an integral part of the area. The Mediterranean vegetation often undergoes challenging periods of severe drought stress, which causes significant impairment to olive trees' growth and production performance. The practical study was designed to follow up the effect of three irrigation regimes (50%, 75% and 100% ETc) in combination with four doses (0, 2, 4 and 6 g/L) of Lithovit (CaCO3+MgCO3, micronized calcium carbonate) on growth performance, yield, and fruit quality of two olive (Picual and Manzanello) varieties during 2017 and 2018 growing seasons. Regardless Lithovit doses, irrigation regime 100% of ETc exhibited the highest values of leaf water content, leaf relative water content, total chlorophyll and N, P, K, Ca and Mg concentrations of both olive varieties compared to the other watering regimes. Interestingly, proline content in the fruit was enhanced with increasing water deficit (50% of ETc) and Lithovit dose (6 g/L). However, the highest yield and fruit oil content were obtained by the combination of 75% ETc irrigation level and Lithovit treatment at a rate of 4 g/L in both olive varieties. This study contributes to developing olive production technologies, thereby ensuring sustainable olive culture farming with high-quality yield in hyper-arid zones.

Being a water-scarce country, South Africa (SA) faces several water challenges, including drought and other effects of climate change. Therefore, there is a need to improve water-use efficiency (WUE) by accurately quantifying the water use and WUE of table grape vineyards. The objective of this review is to (i) provide an overview of water footprint (WF) studies conducted on table grape production systems in SA and globally; (ii) identify limitations in current WF assessments of table grape production systems; and (iii) establish a range of WF values for table grape production systems as an indicator of WUE and for use in decision-making regarding sustainable freshwater use. The review has demonstrated that only a limited number of detailed WF studies have been undertaken on table grapes in SA and globally. Region-specific lookup tables for quantifying blue, green and grey water use in table grape production systems are available for three table grape production regions of SA and could be used for future WF assessments. Most global studies conducted on grape WF and WUE were desktop studies and did not include actual field records from production units, nor did they distinguish between different grape types (table, raisin and wine grapes). WF values must be interpreted in context, specifically regarding the water used versus yield, quality and income, as well as the region, climatic conditions, soil characteristics, irrigation and cultivation practices. For future WF and WUE assessments, a more detailed breakdown of water use is recommended, both during the production process and postharvest. [ABSTRACT FROM AUTHOR]

Climate changes could affect the meteorological parameters and which directly lead to changes in irrigation requirements (IR) and water productivity (WP) of fruit crops. The objective of the current study was to investigate the impacts of potential climate change on irrigation requirements and water productivity of citrus and olive in four governorates of Egypt (El-Bihera, Al-Dakahlia, Matruh and North of Sinai) using a CROPWAT 8.0 model in conjunction with the climate change scenarios A1F1 and B1.The crop irrigation requirements of two crops in all future periods (2020s, 2050s and 2100s) were increased as compared to current period 1990-2019. While, the water productivity values for citrus and olive crops in all future periods (2020s, 2050s and 2100s) were decreased as compared to current period 1990-2019. The IR for citrus and olive were increased by 21.80% and 27.51% respectively. The WP values for citrus and olive were decreased by 43.21% and 17.99%, respectively. [Fundam Appl Agric 2021; 6(2.000): 144-154]

In order to increase water productivity at the Collective Irrigation System (CIS) level it is crucial to adapt the existing irrigation infrastructure, enhancing water intake at the source, as well as its transport and delivery efficiency. Rehabilitation may involve structural changes and thus, a large capital investment. This investment should be proportionate to the increase in climate resilience associated to different rehabilitation alternatives. A methodology framework was developed to evaluate CIS resilience to climate change considering different rehabilitation alternatives. The assessed components were: (i) crop production systems; (ii) on-farm irrigation systems; and (iii) project rehabilitation alternatives for the conveyance and distribution of the irrigation water from the source to the farmer fields. This framework was applied to the Maiorga CIS, in central Portugal, to test the methodology performance in assessing the impacts of climate change on the supply-demand balance of the proposed rehabilitation alternatives and to evaluate their climate resilience, for the representative concentration pathways, RCP4.5 and RCP8.5, and two time periods, 2041–2070 and 2071–2100. For each scenario, period, and rehabilitation alternative, irrigation requirements at the source (demand) and stream flows (supply) were computed and the supply-demand balance was performed. Projected increases in irrigation water demand varied between 5.5% for RCP4.5/2071–2100 and 35.7% for RCP8.5/2071–2100. For RCP4.5, 11% (2050) and 9% (2080) reductions in irrigation water supply were projected, while for RCP8.5 the reduction ranges between 13% (2050) and 30% (2080). The proposed framework determined that the rehabilitation alternatives considering just one type of water source, without flow regularization and with open channel distribution to the farmer’s field, have proved to be unviable due to low resilience to climate change.

Agricultural droughts cause a great reduction in winter wheat productivity; therefore, timely and precise irrigation recommendations are needed to alleviate the impact. This study aims to assess drought stress in winter wheat with the use of an unmanned aerial system (UAS) with multispectral and thermal sensors. High-resolution Water Deficit Index (WDI) maps were derived to assess crop drought stress and evaluate winter wheat actual evapotranspiration rate (ETa). However, the estimation of WDI needs to be improved by using more appropriate vegetation indices as a proximate of the fraction of vegetation cover. The experiments involved six irrigation levels of winter wheat in the harvest years 2019 and 2020 at Luancheng, North China Plain on seasonal and diurnal timescales. Additionally, WDI derived from several vegetation indices (VIs) were compared: near-infrared-, red edge-, and RGB-based. The WDIs derived from different VIs were highly correlated with each other and had similar performances. The WDI had a consistently high correlation to stomatal conductance during the whole season (R2 between 0.63–0.99) and the correlation was the highest in the middle of the growing season. On the contrary, the correlation between WDI and leaf water potential increased as the season progressed with R2 up to 0.99. Additionally, WDI and ETa had a strong connection to soil water status with R2 up to 0.93 to the fraction of transpirable soil water and 0.94 to the soil water change at 2 m depth at the hourly rate. The results indicated that WDI derived from multispectral and thermal sensors was a reliable factor in assessing the water status of the crop for irrigation scheduling.

Climate change is a challenging fact influencing diverse sectors in society including the agricultural one, which is heavily dependent on natural resources and climate. In the Mediterranean region, climate change-related increases in air temperature, and in the frequency and intensity of extreme weather events, such as droughts, boost the pressure on the agricultural systems and affect crop yield potential. The growth of the world population implies that production needs to increase in a sustainable manner. Therefore, this study focuses on the maize crop due to its importance for food security and because it is a crop with significant water consumption that occupies a large worldwide area. In order to study climate change impacts on crop production, plant water requirements, and provide farmers guidelines helping them to adapt, it is necessary to simultaneously evaluate a large number of factors. For this reason, modelling tools are normally used to measure the future impact of climate change on crop yield by using historical and future climate data. This review focuses on climate change impacts on maize crop irrigation requirements and compares—by means of critical analysis—existing approaches that allow for the building a set of mitigation and adaptation measures throughout the study of climate.

This work was undertaken to develop a low-cost but reliable assessment method for agricultural water requirements in semi-arid locations based on remote sensing data/techniques. In semi-arid locations, water resources are often limited, and long-term water consumption may exceed the natural replenishment rates of groundwater reservoirs. Sustainable land management in these locations must include tools that facilitate assessment of the impact of potential future land use changes. Agricultural practices in the Boufakrane River watershed (Morocco) were used as a case study application. Land use practices were mapped at the thematic resolution of individual crops, using a total of 13 images generated from the Sentinel-2 satellites. Using a supervised classification scheme, crop types were identified as cereals, other crops followed by cereals, vegetables, olive trees, and fruit trees. Two classifiers were used, namely Support vector machine (SVM) and Random forest (RF). A validation of the classified parcels showed a high overall accuracy of 89.76% for SVM and 84.03% for RF. Results showed that cereal is the most represented species, covering 8870.43 ha and representing 52.42% of the total area, followed by olive trees with 4323.18 ha and a coverage rate of 25%. Vegetables and other crops followed by cereals cover 1530.06 ha and 1661.45 ha, respectively, representing 9.4% and 9.8% of the total area. In the last rank, fruit trees occupy only 3.67% of the total area, with 621.06 ha. The Food and Agriculture Organization (FAO) free software was used to overlay satellite data images with those of climate for agricultural water resources management in the region. This process facilitated estimations of irrigation water requirements for all crop types, taking into account total potential evapotranspiration, effective rainfall, and irrigation water requirements. Results showed that olive trees, fruit trees, and other crops followed by cereals are the most water demanding, with irrigation requirements exceeding 500 mm. The irrigation requirements of cereals and vegetables are lower than those of other classes, with amounts of 300 mm and 150 mm, respectively. [ABSTRACT FROM AUTHOR]

Olive (Olea europaea) is an emblematic tree in the Mediterranean regions that grows an integral part of the area. The Mediterranean vegetation often undergoes challenging periods of severe drought stress, which causes significant impairment to olive trees' growth and production performance. The practical study was designed to follow up the effect of three irrigation regimes (50%, 75% and 100% ETc) in combination with four doses (0, 2, 4 and 6 g/L) of Lithovit (CaCO3+MgCO3, micronized calcium carbonate) on growth performance, yield, and fruit quality of two olive (Picual and Manzanello) varieties during 2017 and 2018 growing seasons. Regardless Lithovit doses, irrigation regime 100% of ETc exhibited the highest values of leaf water content, leaf relative water content, total chlorophyll and N, P, K, Ca and Mg concentrations of both olive varieties compared to the other watering regimes. Interestingly, proline content in the fruit was enhanced with increasing water deficit (50% of ETc) and Lithovit dose (6 g/L). However, the highest yield and fruit oil content were obtained by the combination of 75% ETc irrigation level and Lithovit treatment at a rate of 4 g/L in both olive varieties. This study contributes to developing olive production technologies, thereby ensuring sustainable olive culture farming with high-quality yield in hyper-arid zones. [ABSTRACT FROM AUTHOR]

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The aim of this research was to determine crop water requirements (soil water deficit) in years with average precipitation amounts and dry years in order to estimate the decline in maize and soybean yields in such years, as well as to determine the actual yields of maize and soybean in years with/almost average precipitation amount and both in dry and wet years. In the examined 20-year period, annual air temperature in the northeastern region of Croatia increased by 1.7o C, while a very slight negative trend in annual precipitation amount, -0.18 mm/20 yrs, has been identified. The determined soil water deficit in the years with multi‒annual mean of precipitation amount ranged from 139.3 mm (soybean) up to 152.7 mm (maize), while in the dry years, water deficit ranged from 299.7 mm (soybean) up to 316.3 mm (maize). The estimation of yield decline (%) in the years with multi‒annual mean of precipitation amount ranged from 21.5% (soybean) up to 33.9% (maize), while in the dry years it ranged from 40.5% (soybean) up to 65.0% (maize). In the 5‒year period, the lowest yields of both crops were in the year with the lowest annual precipitation amount (maize 5,175 t.ha-1 and soybean 2,153 t.ha-1), while the highest crop yields were when the annual precipitation amount was on a par with the average value (maize 9,652 t.ha-1 and 9,817 t.ha-1 and soybean 3,454 t.ha-1 and 3,584 t.ha-1). In the year with the highest precipitation amount, crop yields ranged between the value of the yield aged in the drought and the year with the average precipitation amount (maize 8,875 t.ha-1 and 8,929 t.ha-1 and soybean 3,188 t.ha-1 and 3,202 t.ha-1). Yield decline problem in the northeastern region of Croatia in dry years can be largely solved through irrigation (need to build/expand the irrigation system) and better maintenance of the existing drainage system because the problem can appear during the period with heavy rains. [ABSTRACT FROM AUTHOR]

The current research aims to build a simulation model to study the effect of Jazeera irrigation projects (North, East and South) water requirements on hydroelectric power generation from Mosul dam hydropower plant. The simulation was applied from January 1988 to December 2006 on a monthly basis. A simulation model was built utilizing (HEC-ResSim 3.0) Package, which showed high efficiency in representing and simulating the actual operation of the reservoir. Simulation model operation has been carried out through five scenarios with two cases of priority; the first was to maximize the hydroelectric power generation, and the second was to minimize the shortage in fulfilling the water requirements of Jazeera irrigation projects. The results showed that when the priority is given to meet the irrigation water requirements, the water deficit is decreased but the hydropower generation deficit is increased, and when the priority is to maximize the hydroelectric power generation, the hydropower generation increases, but the irrigation water is decreased. The study concluded that when the East and South Jazeera irrigation projects are completed and operated along with North Jazeera project, the reservoir would not be able to meet their requirements, in addition to an obvious shortage in hydroelectric power generation.

Drip-irrigation is increasingly applied in maize (Zea mays L.) production in sub-humid region. It is critical to quantify irrigation requirements during different growth stages under diverse climatic conditions. In this study, the Hybrid-Maize model was calibrated and applied in a sub-humid Heilongjiang Province in Northeast China to estimate irrigation requirements for drip-irrigated maize during different crop physiological development stages and under diverse agro-climatic conditions. Using dimensionless scales, the whole growing season of maize was divided into diverse development stages from planting to maturity. Drip-irrigation dates and irrigation amounts in each irrigation event were simulated and summarized in 30-year simulation from 1981 to 2010. The maize harvest area of Heilongjiang Province was divided into 10 agro-climatic zones based on growing degree days, arid index, and temperature seasonality. The simulated results indicated that seasonal irrigation requirements and water stress during different growth stages were highly related to initial soil water content and distribution of seasonal precipitation. In the experimental site, the average irrigation amounts and times ranged from 48 to 150 mm with initial soil water content decreasing from 100 to 20% of the maximum soil available water. Additionally, the earliest drip-irrigation event might occur during 3- to 8-leaf stage. The water stress could occur at any growth stages of maize, even in wet years with abundant total seasonal rainfall but poor distribution. And over 50% of grain yield loss could be caused by extended water stress during the kernel setting window and grain filling period. It is estimated that more than 94% of the maize harvested area in Heilongjiang Province needs to be irrigated although the yield increase varied (0 to 109%) in diverse agro-climatic zones. Consequently, at least 14% of more maize production could be achieved through drip-irrigation systems in Heilongjiang Province compared to rainfed conditions.

This work was undertaken to develop a low-cost but reliable assessment method for agricultural water requirements in semi-arid locations based on remote sensing data/techniques. In semi-arid locations, water resources are often limited, and long-term water consumption may exceed the natural replenishment rates of groundwater reservoirs. Sustainable land management in these locations must include tools that facilitate assessment of the impact of potential future land use changes. Agricultural practices in the Boufakrane River watershed (Morocco) were used as a case study application. Land use practices were mapped at the thematic resolution of individual crops, using a total of 13 images generated from the Sentinel-2 satellites. Using a supervised classification scheme, crop types were identified as cereals, other crops followed by cereals, vegetables, olive trees, and fruit trees. Two classifiers were used, namely Support vector machine (SVM) and Random forest (RF). A validation of the classified parcels showed a high overall accuracy of 89.76% for SVM and 84.03% for RF. Results showed that cereal is the most represented species, covering 8870.43 ha and representing 52.42% of the total area, followed by olive trees with 4323.18 ha and a coverage rate of 25%. Vegetables and other crops followed by cereals cover 1530.06 ha and 1661.45 ha, respectively, representing 9.4% and 9.8% of the total area. In the last rank, fruit trees occupy only 3.67% of the total area, with 621.06 ha. The Food and Agriculture Organization (FAO) free software was used to overlay satellite data images with those of climate for agricultural water resources management in the region. This process facilitated estimations of irrigation water requirements for all crop types, taking into account total potential evapotranspiration, effective rainfall, and irrigation water requirements. Results showed that olive trees, fruit trees, and other crops followed by cereals are the most water demanding, with irrigation requirements exceeding 500 mm. The irrigation requirements of cereals and vegetables are lower than those of other classes, with amounts of 300 mm and 150 mm, respectively.

Introduction: Atmospheric CO2 concentration has continuously been increasing during the past century and it is expected to increase from current 384 ppm to 550 ppm in 2050. This increase is expected to increase global temperature by 1.4 to 5.8 oC which can have major effects on crop plants. Since both CO2 and temperature are among the most important environmental variables that regulate physiological and phenological processes in plants, it is critical to evaluate the effects of CO2 and air temperature on the growth and yield of key crop plants. Warming of Earth's atmosphere can increase dark respiration and photorespiration in C3 plants. Rate of photosynthesis is affected by temperature, Therefore, rate of biochemical reactions, morphological reactions, CO2 and energy exchange with the atmosphere could be affected by temperature. Increase in CO2 concentration causes further yield improvement in C3 plants (Such as wheat, rice and soybeans) in comparison with C4 plants (Such as corn, sorghum and sugarcane). In general, increasing CO2 concentration affects plant processes in two ways:direct effect on physiological processes in plant and indirect effect by changes in temperature and rainfall. Studying climate change effects including increase in temperature and CO2 concentration can help understanding adaptation strategies to reach higher and sustainable crop yields. Therefore, the objective of this research was to examine the effects of temperature and CO2 changes on days to maturity, irrigation water requirement, and yield in soybean under irrigation conditions of Gorganusing SSM-iLegume-Soybean model. Materials and methods: The model SSM-iLegume-Soybean simulates phenological development, leaf development and senescence, crop mass production and partitioning, plant nitrogen balance, yield formation and soil water and nitrogen balances. The model includes responses of crop processes to environmental factors of solar radiation, temperature and nitrogen and water availability. The soybean model was used to run different scenarios including combination of -1, -2, -3, -4, 0, 1, 2, 3, 4, 5, 6, 7, 8 oC changes in temperature and CO2 concentration of 350, 400, 450, 500, 550, 600, 650, 700 ppm. Actual weather data in Gorgan (latitude 37 degrees 45 minutes north, longitude 54 degrees 30 minutes east) of 1980 to 2009 was used as baseline climate and then changed to obtained future temperature climates. To account for direct effect of CO2 concentration, two model parameters of radiation use efficiency and transpiration efficiency coefficient were changed for higher CO2 concentration (350 ppm as current conditions). Increasing CO2 concentration from 350 to 700 ppm will increase radiation use efficiency by 23% and transpiration efficiency coefficient by 37%. By running the model for each year under each scenario, output of the model recorded and analyzed using response surface method in SAS. Results and discussion: Decreasing temperature increased days to maturity from 130 to 175 days. However, increase in temperature from 1 to 6 oC decreased days to maturity from 130 to 115 days due to higher development rate. No effect of CO2 on phenological development was assumed. At each temperature, increasing CO2 concentration from 350 to 700 ppm, decreased irrigation water requirement by 30 to 40 mm which is a result of reducing stomata conductance and increase in transpiration efficiency. Temperature increase from 3 to 8oC also decreased irrigation water requirement by 90 mm due to shortening growing season and irrigation number. Decrease in temperature more than 2oC decreases crop yield by 10 to 20 g m-2, but increase in CO2 concentration will compensate this decrease. Increasing temperature by 2 to 3 oC will increase crop yield by 20 g m-2. Increase in temperature from 3 to 8 oC decreases crop yield from 400 g m-2 to 500 g m-2. Yield reduction due to this temperature rise will occur later as a result of increase in CO2 concentration. Conclusion: The effect of temperature and CO2 concentration were studied in soybean by SSM-iLegume-Soybeanmodel. The results indicated that yield reduction increase in CO2 concentration postpones the negative effect of higher temperature on soybean yield. On the other hand, super-optimal temperatures will decrease positive impact of increase in CO2 concentration. Therefore, with regard to the effect the following strategies proposed: improve in irrigation method, development of drought and high-temperature tolerant cultivars, increase in water use efficiency, early sowing and development of longer-duration cultivars.

Fruit production development is resulting in large commercial orchards with improved water management standards. While the agronomic and economic benefits of regulated deficit irrigation (RDI) have long been established, the local variability in soils and climate and the irrigation system design limits its practical applications. This paper uses a case study approach (a 225 ha stone fruit orchard) to unveil limitations derived from environmental spatial variability and irrigation performance. The spatial variability of soil physical parameters and meteorology in the orchard was characterized, and its implication on crop water requirements was established. Irrigation depths applied during 2004-2009 were analysed and compared with crop water requirements under standard and RDI strategies. Plant water status was also measured during two irrigation seasons using stem water potential measurements. On-farm wind speed variability amounted to 55%, representing differences of 17% in reference evapotranspiration. During the study seasons, irrigation scheduling evolved towards deficit irrigation; however, the specific traits of RDI in stone fruits were not implemented. RDI implementation was limited by: 1) poor correspondence between environmental variability and irrigation system design; 2) insufficient information on RDI crop water requirements and its on-farm spatial variability within the farm; and 3) low control of the water distribution network.

Under the semiarid climate of the Southwest United States, accurate estimation of crop water use is important for water management and planning under conservation agriculture. The objectives of this study were to estimate maize water use and water productivity in the Four Corners region of New Mexico. Maize was grown under full irrigation during the 2011, 2012, 2013, 2014 and 2017 seasons at the Agricultural Science Center at Farmington (NM). Seasonal amounts of applied irrigation varied from 576.6 to 1051.6 mm and averaged 837.7 mm and the total water supply varied from 693.4 to 1140.5 mm. Maize actual evapotranspiration was estimated using locally developed crop coefficient curve and the tabulated United Nations Food and Agriculture Organization (FAO) crop coefficients, and from this maize water productivity was determined. Maize actual daily evapotranspiration (ETa) varied from 0.23 to 10.2 mm and the seasonal ETa varied with year and ranged from 634.2 to 697.7 mm averaging 665.3 mm by the local Kc curve, from 687.3 to 739.3 mm averaging 717.8 mm by the non-adjusted FAO Kc values, and from 715.8 to 779.6 mm averaging 754.9 mm with the FAO adjusted Kc values. Maize irrigation requirements varied from 758.4 to 848.3 mm and averaged 800.2 mm using the local developed Kc and varied from 835.5 to 935.6 mm and averaged 912.2 mm using FAO Kc. The net irrigation requirement varied from 606.8 to 678.6 using local Kc curve, and from 682.78 to 748.5 mm when adopting the FAO Kc values. Average irrigation requirement was 641 mm under the local Kc option and 730 mm under FAO Kc values option. Maize crop water use efficiency (CWUE) ranged from 1.3 to 1.9 kg/m3 and averaged 1.53 kg/m3, evapotranspiration water use efficiency (ETWUE) values were higher than CWUE and varied from 2.0 to 2.3 kg/m3, averaging 2.1 kg/m3. Maize irrigation water use efficiency (IWUE) was varied with years and averaged 1.74 kg/m3. There were strong relationships between maize CWUE and maize seasonal irrigation amounts of IWUE and the seasonal irrigation amounts with R2 of 0.97 and 0.92, respectively. Maize CWUE increased linearly with maize IWUE with a coefficient of determination R2 of 0.99, while IWUE showed a strong quadratic relationship with ETWUE (R2 = 0.94). The results of this study can be used as a guideline for maize water management under the semiarid conditions in northwestern New Mexico and other locations with similar climate and management conditions. Irrigation requirements for maize should be adjusted to the local meteorological conditions for optimizing maize irrigation requirement and improving maize water productivity.

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This paper falls within the framework of the FAO-INA Agreement that was entered into to "identify new potential irrigated and supplementary-irrigated areas in the basins of northeastern Argentina". The agreement seeks to collect information on monthly reference crop evapotranspiration (ETo), analyze its variability, and show it on isoline maps. The study comprised the central northeastern part of Argentina; the program used was CROPWAT 8.0 – FAO; and climate data were obtained from CLIMWAT 2.0. The information was plotted with ArcView 3.2ª and the variables of interest were interpolated with the Kriging method. Results show that: a) Santiago del Estero is the station with the highest annual ETo: 1767 mm.year-1, while the lowest ETo value is found in Loreto (Misiones) with 1150 mm.year-1; b) the average ETo in January ranges between 160 to 200 mm.month-1, while in July it is between 35 - 90 mm.month-1; c) the average ETo in January in the northeastern part of Cordoba ranges between 165 - 185 mm. month-1 while in July the variability is less pronounced; and d) rainfall in an average hydrological year ranges between 605 and 1825 mm.year-1 with an effective rainfall of 500 and 1400 mm.year-1 that tends to increase towards the northeast. [ABSTRACT FROM AUTHOR]

Excessive agricultural water consumption threatens safe access of billions of people to potable water. Smart irrigation systems offer more efficient water use in irrigated agriculture. Determining irrigation requirements of various soil texture classes in production fields requires more sophisticated sensing technologies such as deep learning. This study has proposed a proximal sensing system by means of using a color camera towards smart irrigation based on computer vision and deep learning to identify water requirements of three soil texture classes under different illumination conditions. An imaging station was composed to reduce the workload in obtaining training images required for training deep convolutional neural network models. Five deep learning architectures were employed to identify texture-water classes: AlexNet, GoogleNet, ResNet, VGG16, and SqueezeNet. Those models were experimented with and investigated to determine the best models in terms of detection performance and speed. By using cross-validation rules, approximately 12,214 images were studied individually for the purpose of training and testing. The AlexNet model outperformed the other deep learning models with an F1-score of 0.9973 in identifying twelve soil texture-water classes. GoogleNet and ResNet displayed the fastest detection speeds with an average processing time of 16.92 ms. The findings obtained from this study have indicated that deep learning bears a great potential in determining irrigation requirements of production fields under varying conditions [ABSTRACT FROM AUTHOR]

Results obtained within research activity from the Climesco Italian Project are summarized. These results suggest that in regards to the impact of climate change in the Mediterranean area, a decrease of water availability and a more frequent occurrence of drought periods are expected. In order to describe the main effects of climate change on water use in some agro-ecosystems in the Mediterranean area we showed that the Penman-Monteith equation can be modified to simulate future changes in reference evapotranspiration by recalibration of the crop resistive parameter. Moreover, the use of adjusted crop coefficients (Kc) can help quantify the climate change impact on water use for irrigated crops grown in Southern Italy and elsewhere in the Mediterannean. For this region temperature rise and the concomitant expected rainfall reduction may lead to an increase yearly potential water deficits. For autumn-spring crops a further increase of water deficit is not expected. In contrast for a significant increase of water deficit, and thus of irrigation needs, is expected for spring-summer crops. Another aspect considered in this review is how in the Mediterranean area, drought conditions and warmer temperatures will alter the competitive balance between crops and some weed species. We report experimental data showing how weed aggressiveness and competition is already increasing due to warmer temperatures in the Mediterranean region.

The Chinese government set up a redline for water resources in 2011, mandating water withdrawals and management criteria to the year 2030. 'How much water is required to produce sufficient crop to feed a 1.6 billion population in 2030?' becomes a crucial question to be addressed. The objectives of this study are to: (1) document crop water use and productivity from 1998 to 2017 and (2) define the redline water withdrawal for crop use (REWCU) to 2030. The study inversely inferred REWCU from broadly-defined available water for crop use (BAWCU) and associated parameters. Of all BAWCU, 66.3% had been consumed by crops, in which rainfall-derived water consumption accounted for 71.7% of it, while the irrigation-derived water consumption represented the remaining 28.2%. Of all the rainfall that was available for crop use, 72.1%, or the rainfall depletion rate, had been actually consumed by crop evapotranspiration (ET). Likewise, 55.2%, or the irrigation depletion rate, had been consumed by crops. Crop water productivity (CWP) measured by crop yield per unit ET was computed for six major crop categories. Five broad scenarios have been formulated—business as usual, optimistic, deliberative optimistic, pessimistic, and deliberative pessimistic—under lower, higher, and average population and crop projections, respectively. The projected REWCU was 4166.30 × 108 m3, and the projected agricultural water withdrawal was 4629.22 × 108 m3 to 2030, representing 66.1% of the projected nationwide redline total water withdrawal (RETWW) of 7000 × 108 m3. The study used CWP and BAWCU to inversely infer REWCU since they reflect diverse biophysical and management factors and can be used as reliable proxies. Both methodology and research results may offer references and support when making nation- and region-wide water-for-food decisions by crop and water administrations. [ABSTRACT FROM AUTHOR]