Reduce Irrigation Water Research Articles

Performance of irrigation regimes and water salinity on winter wheat as influenced by planting methods

Shortage and salinity of irrigation water are two major constraints that influence wheat production in arid and semi-arid regions of Iran. In this study, effects of deficit furrow irrigation with different salinity levels and planting methods (in-furrow and on-ridge) as strategies for coping with water and salinity stress on yield and yield quality of winter wheat was investigated in a two-year experiment. Irrigation treatments were full irrigation (FI), 0.65FI, and 0.35FI, and salinity levels of irrigation water were 0.6 (well water), 5.0, 7.5, and 10.0 dS m−1. In the first year, grain yield was reduced by 20% and 26% in irrigation regimes of 0.65FI (381 mm) and 0.35FI (217 mm), respectively. These reductions were 17% and 30% in the second year, respectively. The corresponding irrigation water reductions were 33% and 62% in both years for 0.65FI (381, and 355 mm compared to 573 mm) and 0.35FI (217, and 203 mm compared to 533 mm), respectively. Therefore, it is indicated that the proportion of irrigation water reduction to the grain yield reduction is 2:1 in benefit of the deficit irrigation mostly due to the seasonal rainfall of 363 and 439 mm in the first and second years, respectively. Although the majority of rainfall occurred in winter, the winter wheat growth is at rest. Results also indicated that in FI with irrigation application efficiency of 80% (leaching fraction of 20%), the salinity level of 3.36 dS m−1 produced no grain yield reduction. Furthermore, salinity level of 7.5 dS m−1 for irrigation regimes of 0.65FI and 0.35FI, respectively did not show significant difference in grain yield compared with that obtained in 0.6 dS m−1 salinity level. Therefore, by deficit irrigation, higher salinity level is applicable due to lower salt accumulation in soil. In-furrow planting resulted in 4% (statistically significant) higher grain yield compared with that obtained in on-ridge planting with 5% higher irrigation water productivity (IWP). By considering acceptable grain yield production in 0.65FI, its IWP (1.03 kg m−3 and 1.1 kg m−3 in the first and second year, respectively) was significantly higher than those obtained in FI (0.85 kg m−3 and 0.87 kg m−3 in the first and second year, respectively). In in-furrow planting, grain yield in salinity level of 7.5 dS m−1 was suitable with irrigation regime of 0.65FI; whereas, for on-ridge planting appropriate salinity is 5.0 dS m−1. Therefore, in non-limited irrigation water condition, FI with salinity level of 5.0 dS m−1 and in-furrow planting is the appropriate irrigation management for winter wheat. However, with limited water supply, 0.65FI with salinity of 7.5 dS m−1 and in-furrow planting would be appropriate in winter wheat irrigation management in the study region. The root water uptake was predicted by Homaee-Feddes method with higher accuracy and its value was used in grain yield prediction with Doorenbos-Kassam yield-ET function with higher accuracy.

Raised bed planting through broad bed furrow

In recent years, it is imperative to improve sowing techniques through preferred seedbed preparation and early crop growth. Sowing techniques and type of seeding machines play an important role in seed placement and seedling emergence which ultimately affect crop growth and grain yield. The selection of suitable planting methods is dependent upon the time of planting, irrigation methods, amount of residue in the field and type of planting machines. The present work deals with the review of research work done by using broad bed furrow (BBF) worldwide to study the effect of raised bed planting on soil health, yield, water saving, fertility of soil etc. From the study it is revealed that raised bed (RB) farming systems combine most of the elements of conservation agriculture and have produced encouraging production results under various environmental conditions. RBs offer the opportunity of reducing field compaction and restoring physically degraded soil structure, as well as, the potential to reduce irrigation water and increase crop yield while reducing the risk of water logging. Different raised planting configurations are used throughout the world depending on soil type, available machinery, farmer preference and expertise. In general, increasing the width of the bed reduces total water used and increases land use efficiency and yield by reducing the uncropped furrow area.

Water-Yield Relationship Responses of Maize to Ridge-Furrow Planting Systems Coupled with Multiple Irrigation Levels in China’s Horqin Sandy Land

Water scarcity threatens the sustainability of irrigated agriculture in semi-arid regions, and ridge-furrow planting systems (RFPS) can be a prospective rainwater harvesting approach. In this study, we aimed to develop a promising water-saving strategy to boost maize productivity and water use efficiency (WUE). In 2017, we carried out a field experiment to study the effects of various RFPS with multiple irrigation levels on the yield-water relationship of maize (Zea mays L.). Eleven treatments were set up: RFPS with film mulching on both ridges and furrows and without water supply after seed emergence, abbreviated as QF; RFPS with film mulching on continuous ridges, abbreviated as MD, including SMD, MMD, and LMD (S, M, and L—three water supply (irrigation plus precipitation) levels of 650 mm, 500 mm, and 350 mm during the whole growing season); RFPS without film mulching, abbreviated as DD, including SDD, MDD, and LDD; conventional flat planting with no film mulching, abbreviated as GG, including SGG, MGG, and LGG; localized full irrigation (actual amount of irrigation excessively exceeding the quantity needed), abbreviated as NM. A positive linear relationship (R2 = 0.95–1), a quadratic curve, and a negative linear relationship were observed between the irrigation water level and actual crop evapotranspiration (ETc), grain yield, and WUE, respectively. The ETc of QF (292 mm) was substantially lower than that of the other treatments (p < 0.01), saving 649 mm of irrigation water and increasing the yield by 2.24% compared with those of NM. Meanwhile, the WUE and irrigation water use efficiency (IWUE) of QF reached maximums of 6.3 and 47.36 kg m−3, respectively, which were significantly higher than those of other treatments (p < 0.001). The results showed that planting in an RFPS with film mulching on both ridges and furrows (a ridge-to-furrow ratio of 50:30, with a 38 mm irrigation level) is suitable for maize to obtain high yield and reduce irrigation water use significantly.

Precipitation and irrigation dominate soil water leaching in cropland in Northern China

Studying the effects of precipitation and irrigation on soil water leaching are critical for maintaining agricultural environment in Northern China, where uneven irrigation has been applied coupled with a broad spectrum of climatic conditions. We conducted consecutive a 4-year field experiment from 2008 to 2011 with lysimeters buried 90 cm deep to determine soil water leaching. Results indicated that amounts of soil water leaching in greenhouse croplands were significantly higher than that in open field croplands. Rainy season is the key period for soil water leaching in semi-humid areas in open fields, accounting for 88.6% of the annual amount of leachate, while excess irrigation was a significant factor for soil water leaching in semi-arid areas. Irrigation pattern affects soil water leaching by determining irrigation volume. There was significant leaching with border irrigation, particularly in the Winter-Spring seasons (from Jan. to Jun.), while drip irrigation led to a 62–74% reduction of irrigation water with no leaching happened. With water-saving irrigation, the effects of fertilization on nitrogen leaching were not significant.

Effect of water and rice straw management practices on yield and water productivity of irrigated lowland rice in the Central Plain of Thailand

Rice cultivation techniques with less irrigation water input are crucial for global food security in the context of changing climate scenarios. Alternate wetting and drying (AWD) is among such water-saving techniques, which could potentially reduce irrigation water input for rice cultivation through alteration of soil submergence period with period of soil non-submergence (unsaturated soil conditions) during the growing season. Rice straw is often scattered in the field after harvest or burned in intensive rice cultivation systems. Response of irrigated lowland rice with respect to grain yield and water use under different water and rice straw management practices largely remains unknown. Field experiments were conducted at the Ayutthaya Rice Research Center, Ayutthaya, Thailand, in two consecutive rice-growing seasons (wet and dry) of 2016–2017 to evaluate the growth, yield and water productivity of irrigated lowland rice under different water and rice straw management practices. The treatments included were two water (continuous flooding [CF] and AWD) and three rice straw management practices (rice straw incorporation [RS-I], rice straw burning [RS-B] and without rice straw incorporation and burning [WRS-I + B]). AWD increased grain yield by 15% in the wet season and by 7% in the dry season compared with CF. Other yield components such as panicle number m–2, spikelet number panicle–1 and 1000-grain weight were also higher under AWD compared with CF depending on the growing season. AWD reduced total water input by 19% in the wet season and by 39% in the dry season resulting in an improvement in total water productivity by 46% in the wet season and by 77% in the dry season relative to CF. Rice straw application either as soil incorporation or open-field burning had no effect on grain yield, water-saving potential and water productivity of the tested variety regardless of the growing season. Although its positive role in supplying plant nutrients and maintaining soil fertility, rice straw incorporation in the field or burning should be discouraged due to negative environmental impacts. AWD (15 cm threshold water level below the soil surface for irrigation or with soil water potential of ≥ −20 kPa [AWD15]) is recommended for irrigated lowland rice cultivation from a point of view of reducing total water input without jeopardizing yield.

Cost-benefit analysis of irrigation modernization in Guadalquivir River Basin

In water scarce areas, policy makers frequently opt for water conservation and saving technologies (WCSTs) as a measure to ensure resource use sustainability, although this policy is subject to scientific and political debate. This paper presents an application of an integrated methodological approach for analysing the costs and benefits of using WCSTs to achieve water policy objectives. The focus is on the measures aimed at reducing irrigation water abstraction under the 1st and 2nd cycle of Water Framework Directive implementation in the Guadalquivir River Basin (Southern Spain). The method is a combination of a multicriteria assessment of the main effects of water-saving investments at basin level, estimated using a selected group of indicators. In a second stage, a cost-benefit analysis is conducted. The study finds a benefit-to-cost ratio of 4.1/1 for the Guadalquivir River Basin, thus concluding that irrigation modernization in this case study has been a good social investment. The method can be extended to other hydrological systems (aquifer basins) to draw general conclusions.

Rice Drain Management to Reduce Seepage Exports in the Sacramento-San Joaquin Delta, California.

Many deltas worldwide face subsidence issues due to increased anthropogenic activity. The Sacramento-San Joaquin delta similarly faces ongoing subsidence, more than 8 m in some areas, that increases levee failure risks and threatens the security of this water source for 25 million California residents and 1.2 million ha of agriculture. Rice ( L.) fields are an integral part of a proposed new strategy for managing subsidence because they have been shown to stop subsidence and provide an alternative crop for growers. Two important considerations for implementing rice fields are additional water requirement and the effect on water quality from mobilized dissolved organic carbon (DOC) and disinfection byproduct precursors. To understand constituent transport and potential management opportunities for rice farming, a plug flow reactor mass balance model was used to quantify surface and subsurface hydrologic pathways. Management of adjacent drainage ditch water levels under low and high scenarios were tested as a strategy to reduce seepage and water quality loads. Under high drains, groundwater met 10% of evapotranspiration (ET). Low drains resulted in a 100% increase in ET demand, which was met by surface water applied for irrigation. High drains reduced subsurface seepage by 95%. Subsurface DOC, trihalomethane, and total dissolved nitrogen loads were reduced 10-fold in high drains compared with low drains. Flow rate accounted for 74 to 90% of load variance and was the primary determinant of constituent loads. Thoughtful implementation of rice cultivation, with high water levels in adjacent drains, can be leveraged to reduce irrigation water demand and constituent load outputs.

Regional responses to future, demand-driven water scarcity

This paper explores regional response strategies to potential water scarcity. Using a model of integrated human-earth system dynamics (GCAM), we test a wide range of alternate water demand scenarios to explore regional response strategies. We create a typology that categorizes countries and basins according to their responses in electricity and agriculture to potential water scarcity. Three different categories are found. First, little response is observed for many basins because water demands do not increase enough to create scarcity. Second, the primary response is adjustments in the electricity sector (e.g. most basins in Western Europe, the United States and China) with a transition to water-saving cooling systems but marginal impact on total power generation or the fuel mix. Third, where there is a lack of sufficient responding capacity in the electricity sector (e.g. Pakistan, Middle East and several basins in India), additional response occurs through reduced irrigation water withdrawals, either by switching from domestic production to imports or from irrigated agriculture to rain-fed production. The primary response mechanism to demand-based water scarcity for individual basins is quite robust across the range of water demand scenarios tested. The results and typology in this paper will be valuable for future research exploring global water scarcity due to both demand and supply drivers.

EVALUATION OF TOMATO RESPONSE TO DEFICIT IRRIGATION AT HUMBO WOREDA, ETHIOPIA

Water scarcity, erratic rainfall distribution and better management of water are the most sever constraint for the development of agriculture. To cope with scarce supplies, deficit irrigation is an important tool to achieve the goal of reducing irrigation water use and increase water use efficiency (WUE) under scarce water resources. This research was carried out at Southern Agricultural Research Institute of Areka Agricultural Research Center of Hubo Woreda in farmers’ fields during 2016/2017–2017/2018 to identify the level of deficit irrigation which allow achieving optimum Tomato yield. The experimental design was arranged in RCBD with four treatments with three replications. The irrigation treatments were 100 % ETc, 85 % ETc, 75 % ETc and 50 % ETc. The result showed that a maximum fruit yield of 43.4 ton/ha was obtained under full irrigation. A deficit irrigation strategy applied at 85%, 70% of crop water requirement gives relatively better fruit yield i.e. 34.2 ton/ha and 32.1 ton/ha. For Tomato in water scarce area applying 85% and 70% of crop water requirement is recommended with a minimum reduction of yield.

A Multi-disciplinary Modelling Approach for Discharge Reconstruction in Irrigation Canals: The Canale Emiliano Romagnolo (Northern Italy) Case Study

Agriculture is the biggest consumer of water in the world, and therefore, in order to mitigate the effects of climate change, and consequently water scarcity, it is important to reduce irrigation water losses and to improve the poor collection of hydraulic status data. Therefore, efficiency has to be increased, and the regulation and control flow should be implemented. Hydraulic modelling represents a strategic tool for the reconstruction of the missing hydraulic data. This paper proposes a methodology for the unmeasured offtake and flowing discharge estimation along the open-canal Canale Emiliano Romagnolo (CER), which is one of the major irrigation infrastructures in Northern Italy. The “multi-disciplinary approach” that was adopted refers to agronomic and hydraulic aspects. The tools that were used are the IRRINET management Decisional Support System (DSS) and the SIC2 (Simulation and Integration of Control for Canals) hydraulic software. Firstly, the methodology was developed and tested on a Pilot Segment (PS), characterized by a simple geometry and a quite significant historical hydraulic data availability. Then, it was applied on an Extended Segment (ES) of a more complex geometry and hydraulic functioning. Moreover, the available hydraulic data are scarce. The combination of these aspects represents a crucial issue in the irrigation networks in general.

Comparison on physiological adaptation and phosphorus use efficiency of upland rice and lowland rice under alternate wetting and drying irrigation

As one of the most widely promoted water-saving irrigation strategies for rice, alternate wetting and drying irrigation (AWD) can not only save water but also increase mineral nutrient use efficiency. In this study, we compared the growth conditions of four rice varieties (two lowland and two upland varieties) under three irrigation regimes: continuously flooded (CF), alternate wetting and moderate soil drying (AWD15) and alternate wetting and severe soil drying (AWD30). AWD15 and AWD30 enabled the plants to receive fewer irrigation events and less irrigation water than CF, thereby saving both water resources and labor. AWD15 reduced redundant vegetative growth, promoted root growth, and increased the root-shoot ratio and harvest index. AWD15 increased the grain yield, water use efficiency (WUE) and phosphorus use efficiency (PUE) of upland rice and maintained the grain yield while increasing the WUE and PUE of lowland rice. More developed root systems under AWD helped upland rice to maintain a higher water status than lowland rice when plants were subjected to soil drying, which resulted in superior performance in grain yield in upland rice. AWD30 could not reconcile the demands of higher yield and the desire to reduce irrigation water use because it decreased grain yield. The results indicate that AWD15 irrigation of rice can not only increase rice yield and WUE but also enhance PUE, which can potentially reduce the use of phosphorus fertilizers. The results provide theoretical and technical support for improving rice cultivation.

Alternative cereals can improve water use and nutrient supply in India.

Humanity faces the grand challenge of feeding a growing, more affluent population in the coming decades while reducing the environmental burden of agriculture. Approaches that integrate food security and environmental goals offer promise for achieving a more sustainable global food system, yet little work has been done to link potential solutions with agricultural policies. Taking the case of cereal production in India, we use a process-based crop water model and government data on food production and nutrient content to assess the implications of various crop-shifting scenarios on consumptive water demand and nutrient production. We find that historical growth in wheat production during the rabi (non-monsoon) season has been the main driver of the country's increased consumptive irrigation water demand and that rice is the least water-efficient cereal for the production of key nutrients, especially for iron, zinc, and fiber. By replacing rice areas in each district with the alternative cereal (maize, finger millet, pearl millet, or sorghum) with the lowest irrigation (blue) water footprint (WFP), we show that it is possible to reduce irrigation water demand by 33% and improve the production of protein (+1%), iron (+27%), and zinc (+13%) with only a modest reduction in calories. Replacing rice areas with the lowest total (rainfall + irrigation) WFP alternative cereal or the cereal with the highest nutritional yield (metric tons of protein per hectare or kilograms of iron per hectare) yielded similar benefits. By adopting a similar multidimensional framework, India and other nations can identify food security solutions that can achieve multiple sustainability goals simultaneously.

THE ECONOMIC VALUE AND COST RECOVERY OF WATER IN THE EGYPTIAN IRRIGATED AGRICULTURE

This article provides estimates for on-farm irrigation costs paid by farmers and the imputed economic value of water for the main crops in the study sample and identifies the appropriate method for the Egyptian conditions, and measures the impact of irrigation water consumption, water savings and gross margin in Egypt. Data were collected from a formal survey for 80 farmers conducted in 2016/2017 to collect data on the farm budgets of the crops prevailing in Al Satamony Village located at Dakahlia Governorate (Belkas District). A residual method was employed to impute the economic value of water and an assessment of crop-based irrigation water cost recovery policy was made in terms of its impact on irrigation water consumption and gross margin. Besides, the study conducted an online opinion poll about the possibility to recover a part of the operation and maintenance (O&M) costs of irrigation in Egypt and the irrigation cost recovery method relevant to the Egyptian case. The results from this study confirm the need for additional investments to improve the efficiency of the existing irrigation system whereas, such investments are regarded as public good putting more pressure on the national budget. However, Egyptian farmers do not pay for water used in their farms. They bear only the on-farm irrigation costs. Thus, the Government of Egypt (GoE) considered more direct methods of recovering costs from farmers in order to reduce the government’s recurrent fiscal burden while improving the efficiency and sustainability of O&M services. Rice and clover ranked first in terms of high shadow price of irrigation water, followed by sugar beet, wheat and maize whereas, sugar beet and clover gained the highest water productivity. The analysis showed that the crop-based scheme is the irrigation cost recovery policy most relevant to the Egyptian case. Such policy achieves water saving of at least half a million cubic meters for the old lands of Dakahlia Governorate. However, farm gross margin decreases as the total on-farm irrigation costs based on the crop-based irrigation water tariff increase. This implied the importance of such a policy that directly affects farmers’ behavior towards reducing irrigation water consumption and slightly decreases farm gross margin, as well. To conclude, there is a need for sufficient farmer’s access to knowledge and improving communication channels between farmers and skilled agricultural extension personnel about the harmful effect of over-irrigation, the recommended crop water requirements, the role of water user associations (WUAs), and water-saving management techniques before introducing the proposed irrigation cost recovery policy. Besides, a public-awareness campaign on the need to recover a part of the O&M irrigation costs is one of the key actions needed before introducing the proposed irrigation cost recovery policy in order to sustain the water supply and delivery system, upgrade poorly served areas, and ensure continued provision of services. Ensuring farmers acceptability for the cost recovery mechanism and the irrigation water tariff is clearly understood to represent no more than the cost of services rendered should be put into consideration before introducing such policy. Finally, introducing the proposed irrigation cost recovery policy in Egypt helps recovering part of O&M costs, encourage efficient resource use, encourage efficient provision of

Reducing Substrate Moisture Content (SMC) during Greenhouse Production and Postproduction of Angelonia and Heliotrope Improves Crop Quality and Economic Value

Retail environments are rarely optimal for ornamental plants, and wilting caused by water stress is a major cause of postproduction shrinkage. The objective of this study was to determine the effect of two levels of substrate moisture content (SMC) applied during greenhouse production on angelonia (Angelonia angustifolia) ‘Angelface Blue’ and heliotrope (Heliotropium arborescens) ‘Simply Scentsational’ growth and physiological parameters and subsequent postproduction quality during simulated retail conditions. At the end of production, angelonia total plant shoot dry weight (DW) was reduced with 20% SMC compared with 40% SMC, and plants grown with 20% SMC had higher shoot coloring percentage, reduced internode length, and required less irrigation labor–related costs compared with 40% SMC. Heliotrope grown at 20% SMC produced the same size plant as 40% SMC, but had a higher shoot coloring percentage at the end of production and postproduction, indicating lower SMC resulted in higher visual quality compared with 40% SMC. For both species, 20% SMC increased plant visual quality compared with 40% SMC and reduced irrigation water input throughout production, resulting in reduced production costs and increased floral crop economic value.

Minimize water deficit in wheat crop to ameliorate groundwater decline in rice-wheat cropping system

There is a notion that more withdrawal of groundwater for irrigating the rice crop in rice-wheat cropping system is responsible for water table decline in central Punjab of India. Any reduction in irrigation water by the improved irrigation schedules in rice like alternate wetting and drying, and based on soil moisture potential; shifting planting date, crop diversification of higher irrigation requirement to lower, direct seeded rice, laser levelling etc.; and appropriate tillage system to reduce percolation losses save water and increase water productivity. However, the present study showed that water deficit [evapotranspiration – (rainfall + surface water)] can approximate the water table decline/rise rather than groundwater withdrawal alone. In rice-wheat system though irrigation water requirement of wheat crop is less (300–400 mm) than rice (1500–2000 mm) yet the water deficit, responsible for water table decline, is more in wheat crop than rice. In rice transplanted at recommended time, evapotranspiration (ET) is almost equal to the rainfall, while in wheat ET is 3.9 times that of rainfall. It warrants the ET reduction in wheat, overlooked so far, for supplementary amelioration of water table decline in rice-wheat cropping system. Reduction in ET and saving of energy by different technologies in wheat crop has also been discussed.

The intention of irrigators to adopt water use efficient measures: case studies in the north and south of the Murray–Darling Basin

ABSTRACTAs part of water reform in the Murray–Darling Basin (MDB), water is being reallocated from irrigated agriculture to the environment. The adoption of on-farm water use efficient (WUE) measures is one way irrigators might adapt and remain viable. There has been limited evaluation of the potential of WUE measures for irrigators' adaptation. This paper addresses that gap by bringing together results from a case study in the Southern MDB and published results for the Northern MDB. Responses from irrigator surveys were used to determine the current and future intention to adopt existing WUE measures and then calculate the potential reduction in irrigation water applied. A moderate estimate suggests that about 10% less irrigation water can be applied. What this will mean for entitlement cuts under the Basin Plan will depend on how return flows (i.e. excess irrigation water previously contributing to surface and groundwater) are accounted for. These results suggest that irrigators in the MDB are willing to adapt to some reduction in water availability. This information should contribute to debate about water reform impacts on irrigators and their communities, but those managing the MDB must take into account that on-farm WUE gains may lead to reduced return flows.

Effect of zeolite application on phenology, grain yield and grain quality in rice under water stress

Plant growth and grain yield of various upland crops in response to zeolite application have been extensively studied, but little information is available on the impact of zeolite application on rice grown in the lowlands under water stress. A two-year experiment was conducted using lysimeters in the field to evaluate the influence of zeolite application (15 t ha–1) on phenology, grain yield and grain quality in a local rice cultivar (Shennong 9765) under three irrigation regimes (CF, continuous flooding irrigation; IAWD, improved alternate wetting and drying irrigation; and AWD, alternate wetting and drying irrigation). Regardless of water supply, zeolite application significantly increased leaf area index (LAI) at all the measured stages except for tillering, SPAD values at the jointing–booting and heading–flowering stages, photosynthetic rate (Pn) at heading–flowering stage, and grain yield and water use efficiency (WUE). Moreover, zeolite addition significantly increased the head rice rate and decreased the chalk rice rate and chalkiness. The IAWD and CF treatments had similar SPAD values and Pn at the heading–flowering stage, and grain yield, while the AWD treatment significantly reduced those values, relative to the CF treatment. The IAWD and AWD treatments significantly increased WUE, milled rice rate, head rice rate, peak viscosity, and breakdown, but decreased water use, LAI, chalky rice rate, chalkiness, cool viscosity, and setback. These results suggest that the adoption of IAWD with 15 t ha–1 of zeolite application could reduce irrigation water use, increase grain yield and improve grain quality in rice.

Identifying efficient agricultural irrigation strategies in Crete

Water scarcity and droughts are a major concern in most Mediterranean countries. Agriculture is a major user of water in the region and releases significant amounts of surface and ground waters, endangering the sustainable use of the available resources. Best Management Practices (BMPs) can mitigate the agriculture impacts on quantity of surface waters in agricultural catchments. However, identification of efficient BMPs strategies is a complex task, because BMPs costs and effectiveness can vary significantly within a basin. In this study, sustainable agricultural practices were studied based on optimal allocation of irrigation water use for dominant irrigated crops in the island of Crete, Greece. A decision support tool that integrates the Soil and Water Assessment Tool (SWAT) watershed model, an economic model, and multi-objective optimization routines, was used to identify and locate optimal irrigation strategies by considering crop water requirements, impact of irrigation changes on crop productivity, management strategies costs, and crop market prices. Three spatial scales (crop type, fields, and administrative regions) were considered to point out different approaches of efficient management. According to the analysis, depending on the spatial scale and complexity of spatial optimization, water irrigation volumes could be reduced by 32%–70% while preserving current agricultural benefit. Specific management strategies also looked at ways to relocate water between administrative regions (4 prefectures in the case of Crete) to optimize crop benefit while reducing global water use. It was estimated that an optimal reallocation of water could reduce irrigation water volumes by 52% (148 Mm3/y) at the cost of a 7% (48 M€) loss of agricultural income, but maintaining the current agricultural benefit (626.9 M€). The study showed how the identification of optimal, cost-effective irrigation management strategies can potentially address the water scarcity issue that is becoming crucial for the viability of agriculture in the Mediterranean region.

Water use efficiency was improved at leaf and yield levels of tomato plants by continuous irrigation using semipermeable membrane

Continuous irrigation (CI) is a newly developed irrigation technique that utilizes semipermeable membrane to release water into the plant root zone slowly and continuously. In order to investigate the effects of CI on plant gas exchange and water use efficiency (WUE) compared to conventional intermittent irrigation (II) under different soil water conditions, a field experiment was conducted on tomato plants during two growing seasons in the arid region of northwestern China. Gas exchange parameters were measured during fruit enlargement stage, which showed that the net photosynthesis rate of tomato leaf was similar between CI and II, while the stomatal conductance was significantly higher under CI for most measurements, resulting in significantly lower intrinsic WUE under CI compared to II. However, the non-stomatal limitations and lower vapor pressure deficit (leaf to air) caused significantly lower transpiration rate under CI, leading to slightly higher instantaneous WUE compared to II. Consequently, the total water consumption was reduced by CI. Moreover, CI also had significantly greater yield than II and therefore, CI improved WUE at both leaf and yield levels compared to II. CI can be used to reduce irrigation water use and increase WUE in crop production in northwestern China.

Reduction of plant water consumption through anti-transpirants foliar application in tomato plants ( Solanum lycopersicum L )

Abstract Optimizing water use efficiency (WUE) is a crucial goal worldwide. However, water savings must not be made at the expense of yield and/or fruit quality to secure economical sustainability for producers. A field study was undertaken to investigate the impact of different anti-transpirants (ATS) on WUE, water requirements (WR), net carbon assimilation rate (P-net), yield and fruit quality of tomato plants (Solanum lycopersicum L.). The aim of this study was to select the most suitable anti-transpirant (AT) that produces a satisfactory yield with less water under field conditions. Three types of ATS were sprayed at first fruit set stage: kaolin (KA) 3% and 5% as a reflective AT, Emulsion of Linus seed Oil tri-ethanolamine (ELO) 1% and 2% as a film forming AT and Fulvic acid (FA) 0.15% and 0.2% as a metabolic AT. The results showed that ATS application increased the relative water content (RWC) especially in the case of FA. However, CO2 assimilation rate was reduced with the minimum reduction observed under FA application. KA application reduced the canopy temperature (Ct) meanwhile, FA and ELO had no effect. ATS significantly reduced tomato WR where irrigation water reduction ranged between 21% up to 28% of that applied to control plants, with or without significant yield reduction or effects on fruit quality parameters depending on the ATs type and concentration. The results indicated that FA at 0.2% gave the maximum reduction in plant WR (28%) and the minimum reduction of P-net (11.13%) and marketable yield (2.3%), consequently WUE was increased by about 33.45% as compared to the untreated plants. Thus, ATS materials can be used to maintain crop yield and increase WUE in the locations where water resources are limited.