Increasing Irrigation Water Productivity Research Articles

Water productivity, yield response factors, yield and quality of alfalfa cultivars in semi-arid climate conditions

This study was carried out for 2 years (2020 and 2021) to elucidate the effects of water stress on yield and quality of alfalfa cultivars, to determine the water-yield and quality relations and the susceptibility of cultivars to water stress. Three different irrigation treatments (100%, 75% and 50% of full irrigation, I100, I75 and I50) and 12 different alfalfa cultivars (SHN, Osmanağa, Şahin 42, Minerva, Elçi, Riviera Vicentina, Magna 601, Magnum V, Prosementi, Ezzelina, Sunter, Nimet) were used in present experiments conducted in randomized-blocks split-plots design with 3 replications to investigate effects of irrigation levels on water, yield and quality parameters of alfalfa. Present findings revealed that water stress decreased crop water productivity, but increased irrigation water productivity of alfalfa cultivars. Herbage yields of the cultivars varied between 48.20 and 64.98 t/ha, hay yields between 11.42 and 14.67 t/ha and protein yields between 2.22 and 3.07 t/ha. Alfalfa was found to be sensitive to water stress in terms of herbage yield, but more tolerant in terms of hay and protein yields. Morphological characteristics (plant height, number of stems per plant, number of main stem branches and root crown diameter) decreased with increasing water stress levels. In terms of quality traits, while acid detergent fiber (ADF), neutral detergent fiber (NDF), crude fiber and crude ash ratios increased, crude protein ratios decreased with increasing irrigation water levels. It was concluded based on present findings that water stress resulted in different responses of different alfalfa cultivars and although it increased quality traits in general, it decreased herbage, hay and protein yields. Again, based on present findings, Magna 601 cultivar could be recommended for semi-arid regions.

Asparagine and nitric oxide jointly enhance antioxidant capacity and nitrogen metabolism to improve drought resistance in cotton: Evidence from long‐term field trials

AbstractAsparagine (Asn) and nitric oxide (NO) can enhance plant tolerance to abiotic stress, but their interaction is not well understood. Cotton is a vital resource for the textile industry, but its yield is reduced by drought stress, which could threaten its global supply in a warming and stressful world. Improving cotton's drought tolerance is crucial for supporting the textile industry. Two simultaneous field experiments were conducted to study the effect of Asn and sodium nitroprusside (SNP), a NO donor, on cotton's drought tolerance. Two irrigation treatments were applied: control (C: 100% A pan) and drought stress (50% A pan). The plants were also sprayed with two plant stimulants before imposing drought stress: Mock control, 20 mM Asn, and 0.2 mM SNP, either alone or together. Drought stress impaired plant growth, photosynthesis, yield, nitrogen metabolism, and antioxidant defense, while increasing oxidative stress and free amino acid levels. However, Asn and SNP treatments alleviated these negative effects and improved antioxidant enzyme activity, plant growth, yield, and nitrogen content. The Asn + SNP treatment also increased irrigation water productivity under water‐limited conditions, suggesting its potential for enhancing water use efficiency in cotton production. The combined treatment was more effective than the single treatments, indicating a synergistic effect of Asn and SNP in enhancing drought tolerance in cotton. These results imply that Asn and SNP could be useful tools for sustaining cotton production under drought conditions by boosting nitrogen metabolism and antioxidant defense, thereby contributing to the global supply of cotton and supporting the textile industry.

The effect of irrigation management on rice grain yield, irrigation water productivity and methane emissions in northern Iran

AbstractThis experiment aims to study the effect of water‐saving irrigation on rice production and methane emissions. Three irrigation methods, that is, flooding irrigation, deficit irrigation (DI) and alternate partial root‐zone drying (APRD), were employed in a 2‐year field trial. The experiment was conducted in a randomized complete block design with three replications. For the DI and APRD treatments, plots were not irrigated until the soil matric potential reached −10 (DI10 and APRD10), −30 (DI30 and APRD30) and −60 kPa (DI60 and APRD60). In the APRD treatments, two adjacent furrows of each plant row were alternately irrigated in consecutive irrigation events. The DI and APRD treatments did not affect yield components when the soil matric potential was −10 kPa. Applying APRD treatments increased irrigation water productivity by 45%, 51% and 31% for soil matric potentials of −10, −30 and −60 kPa, respectively. On average, water stress treatments reduced methane emissions by 78% compared to flooding treatment. On average, the APRD treatments decreased the water input by 10% compared with the DI treatments while achieving a 2.5% higher yield. This is the first study to outline the effect of APRD on methane emissions and rice production. These findings suggest that APRD could be a valuable strategy to mitigate methane emissions without risking rice yield reduction.

Assessment of the impact of irrigation management on soybean yield and water productivity in a subhumid environment

As an effect of climate change, a considerable increase in irrigation demand is expected in subhumid regions. This poses a future challenge for agriculture, which often does not meet the requirements for highly efficient irrigation management. Field experiments in combination with modelling approaches can help in the development and evaluation of alternative irrigation strategies. The aim of this study was to parameterize the FAO AquaCrop model for soybeans in order to evaluate irrigation systems and strategies used by farmers in Austria. Moreover, this study aims at proposing a deficit irrigation strategy to increase irrigation water productivity (WPIrrig). Three irrigation methods were investigated: sprinkler, drip, and hose reel boom. Rainfed conditions were also assessed. Data sets from 2018 and 2019 were used for the parameterization of AquaCrop. Based on threshold values for the percentage of readily available water (RAW), full and deficit irrigation strategies were defined and tested for the years 1990–2019. The parameterization results showed good agreement between the simulated and observed canopy cover and yields from the four water management practices, with Nash-Sutcliffe efficiency coefficients between 0.76 and 0.96. Large errors resulted from the soil water content simulations, mainly due to poor sensor performance. It was concluded that a moderate deficit with RAW thresholds of 150% and 140% for the vegetative and reproductive stages, respectively, was an adequate strategy to improve yields and WPIrrig. Conversely, a severe deficit with an irrigation threshold of 180% RAW throughout the season considerably reduced yields, especially in years with high irrigation demand. Moreover, a significant improvement in WPIrrig was observed when drip systems were used compared to sprinklers, due to the higher efficiency of the former. These results can help scheduling irrigation for soybeans and increasing WPIrrig, thereby reducing pressure on limited water resources.

A water-energy-food-carbon nexus optimization model for sustainable agricultural development in the Yellow River Basin under uncertainty

Water scarcity, limited land resources and global warming are the most challenging issues facing sustainable agricultural development, and modern agriculture requires efficient and environmentally friendly agricultural water and land management practices. This paper proposes a water-energy-food-carbon nexus system optimization model, which aims to formulate a scientific and rational water and land resource allocation strategy for sustainable agricultural development to increase irrigation water productivity, reduce carbon emissions and enhance regional agriculture competitiveness. First, the carbon footprint life cycle assessment method was used to measure carbon sinks and carbon emissions across the ecosystem. Second, a multiobjective nonlinear programming model with the goal of maximizing irrigation water productivity, minimizing carbon emissions, and maximizing the competitiveness of low-carbon agriculture is established. Finally, an empirical study is performed in the Yellow River Basin, and an elitist nondominated sorting genetic algorithm is used to solve the model. The research results show that the water-energy-food-carbon nexus system optimization model based on uncertain conditions established in this paper, can maximize resource utilization efficiency and effectively measure the impact of regional agricultural production on the environment. It has reference significance for the realization of carbon neutrality in the region.

Impacts of deficit irrigation and organic amendments on soil microbial populations and yield of processing tomatoes

Altered precipitation patterns and increased water demands from urban, industrial, and environmental needs often reduce the volume of irrigation water available for agriculture. Strategies that reduce irrigation water inputs, e.g., deficit irrigation (DI), need further evaluation to determine potential impacts on yield and soil microbial communities driving critical soil biogeochemical cycles. Whether soil organic amendments can stabilize DI effects on yield and microbial communities remains unknown. Processing tomato beds were established in a full factorial experimental design of soils unamended or amended with a one-time application—four to five years before sampling—of either biochar or biochar with compost and three irrigation regimes: full (100 % of plant water demand), or DI treatments at 75 % or 50 % of full irrigation. We profiled soil bacterial and archaeal community compositions for two growing seasons and determined soil C and N metabolic potentials and biomass of microbial groups using high throughput sequencing of 16S rRNA genes and phospholipid fatty acid analysis. We tested the discrete and interactive effects of DI and soil amendments on soil chemical and biological properties, and crop yield. DI had stronger effects on the bacterial and archaeal community composition than soil organic amendments. However, 75 % DI did not strongly affect bacterial and archaeal community composition or the total and individual biomass of microbial groups, but it increased irrigation water productivity of processing tomatoes. Although soil amendments did not stabilize the compositional shifts induced by DI, their recalcitrant C still had residual effects on the bacterial and archaeal community composition years after their incorporation. Furthermore, soil moisture correlated with bacterial and archaeal community's C and N metabolic potentials, likely augmenting the amendments' C and N residence time in DI soils. Our results provide insight into water-saving mechanisms that could increase profit margins in water-scarce years without affecting microbial populations that support plant growth and productivity.

Modelling the integrated strategies of deficit irrigation, nitrogen fertilization, and biochar addition for winter wheat by AquaCrop based on a two-year field study

Biochar application has been proposed as a promising practice for sustainability due to its potential to ensure food security while alleviating the water shortage and fertilizer overuse. Scheduling the proper integrated management of deficit irrigation, nitrogen fertilization, and biochar addition are necessary to facilitate the effective use of biochar in agriculture. The objectives of this study were to test the AquaCrop model for winter wheat under different irrigation, nitrogen, and biochar regimes and to optimize the integrated strategies. For the model calibration and validation, a field experiment of winter wheat with two irrigation levels (full and deficit irrigation) and three fertility levels (200 kg/ha N, 100 kg N + 15 t/ha biochar, 0 kg/ha N) was conducted in the North China Plain during 2017/2018 and 2018/2019 growing seasons. The results showed that AquaCrop performed well in simulating soil water content (0.82 ≤ R 2 , 0.92 ≤ d, RMSE ≤ 2.82%, NRMSE ≤ 17.34%), canopy cover (0.89 ≤ R 2 , 0.95 ≤ d, RMSE ≤ 7.58%, NRMSE ≤ 13.33%), biomass (0.96 ≤ R 2 , 0.96 ≤ d, RMSE ≤ 1.04 t/ha, NRMSE ≤ 16.75%), and grain yield (0.94 ≤ R 2 , 0.97 ≤ d, RMSE ≤ 0.34 t/ha, NRMSE ≤ 5.32%). The effects of biochar on soil moisture, fertility, and wheat production could be adequately simulated by AquaCrop using the hydraulic properties of the biochar-mixed soil layer and its semi-quantitative method for soil fertility stress. The optimal integrated strategies were deficit irrigation with three irrigations of 60 mm at the jointing, anthesis, and grain-filling stage for dry years, two irrigations of 60 mm at the jointing and anthesis stage for normal years, and one irrigation of 60 mm at the anthesis stage for wet years, combined with 100 kg/ha N and 15 t/ha biochar, which could achieve over 80% of the potential yield while substantially increasing irrigation water productivity. Nonetheless, the model tended to under-estimate soil moisture, leaf growth and senescence, and grain yield in the biochar amended treatments, particularly under drought. Further improvements in the modules of soil properties, soil water balance, and canopy cover can be performed to increase the estimation accuracy. Additionally, AquaCrop was only calibrated and validated based on a two-year experiment under the weather conditions of no drought and moderate drought. Therefore, future validation studies using the long-term field data with the larger climate variability are necessary to better identify the impacts of integrated strategies and climate change. Finally, considering its good balance in simplicity, robustness, and accuracy, AquaCrop could be a reliable tool to guide the field management of irrigation, fertilization, and biochar addition. • AquaCrop was tested under various irrigation, nitrogen, biochar regimes. • AquaCrop adequately simulated the effects of biochar on winter wheat. • Integrated strategies of irrigation, nitrogen, biochar were optimized. • Optimal integrated strategies could achieve over 80% of the potential yield.

Simulated irrigation water productivity and related profit effects in U.S. Southern High Plains cotton production

To explore management practices that increase irrigation water productivity (IWP) in U.S. Southern High Plains (SHP) cotton production, the CROPGRO-Cotton crop simulation model was used to evaluate the yield, IWP, and profit effects of irrigation amount and timing. Using 2005–2019 weather input data from 21 SHP weather stations, lint yields were simulated for each of the 315 station-years under unirrigated ‘dryland’ conditions and 18 increasing total irrigation (TIRR) levels. As TIRR was increased to 55.9 cm median lint yields asymptotically approached a maximum. However, irrigation above 35.6 cm increased the incidence of total irrigation plus growing season rainfall exceeding 100% of potential crop ET, leading to decreasing marginal yield effects and decreasing IWP. The highest median IWP (0.321 kg m−3) was found with both 33.0 and 35.6 cm of total irrigation, with 30.5 cm providing slightly lower IWP (0.320 kg m−3). In analyses of irrigated profitability under varying lint price and pumping cost conditions, 30.5 cm (12.0 in) of irrigation increases profits relative to dryland conditions under all but low lint price and high pumping cost conditions. But as TIRR is reduced the probability of these positive profit effects become similar to an evenly weighted coin flip at about 17.8 cm (7.0 in). Simulations that varied the timing of 30.5 cm of irrigation increased median IWP up to 0.434 kg m−3 by limiting irrigation to cotton’s reproductive and maturation periods, with no irrigation during the initial vegetative period. As a result, these simulations show that applying 30.5–35.6 cm (12.0–14.0 in) of irrigation during cotton’s reproductive and maturation phases, with little or no vegetative irrigation, maximizes IWP in SHP cotton production under current climate conditions.

Land gradient and configuration effects on yield, irrigation amount and irrigation water productivity in dry direct seeded rice and non-puddle transplanted rice in cauvery delta zone

Field experiments were conducted in two different locations in the Cauvery delta zone - viz., old delta at Tamil Nadu Rice Research Institute (TRRI) Aduthurai, and new delta at Soil and Water Management Research Institute (SWMRI), Kattuthottam, Thanjavur.Laser levelling with 0% gradient significantly reduced irrigation amount and/or increased irrigation water productivity (WPi) in all crops/systems grown on the flat compared to farmer leveling practice. However, water advancement rate in farmer’s field generally very low because of flat configuration and or sub – optimal flow rate, resulting in high rates of drainage below root zone, more so at the head end of the field than tail end because of longer period of flooding of soil surface at the head end.It is hypothesized that formation of a uniform gradient from the head to tail end of the field increase the water advancement rate, reduce irrigation input and increase irrigation water productivity.Experiments were conducted during Kharif (Kuruvai) 2014, late Samba 2014 - 15 and Kharif (Kuruvai) 2015 at TRRI, Aduthurai and during early Kuruvai 2014, Samba 2014 - 15 and early Kuruvai 2015 at SWMRI, Kattuthottam, Thanjavur to evaluate the effect of land gradient on water and rice crop and water productivity. The experiments were laid out in Randomized Complete Block Design (RCBD) with three land slope treatments in which three observations are taken on each plots (16 m x 50 m) (at the head, middle and tail of the plot) and three replications (blocks) in dry direct seeded rice (DSR) and non – puddle machine transplanted rice (NPTR). The slopes studied are T1 - 0.0 per cent slope,T2 - 0.1 per cent slope (5 cm gradient in 50 m run) and T3 - 0.2 per cent slope (10 cm gradient in 50 m run) with precise leveling. Short duration (100 – 110 d) rice variety ADT (R) 45 was raised as a test variety in the field experiments conducted during early Kuruvai and Kuruvai seasons in both the experimental sites. For Samba / late Samba season, long duration (135 – 150 d) rice variety CR 1009 was used in both the experimental sites. With regard to different slope gradients, it was worked out as 2159 litres as water requirement to produce 1 kg of rice under 0.1 per cent slope as against 2566 litres in 0.0 per cent slope across the seasons which indicated a water saving of 407 litres (15.8%) of water per kg of rice at Aduthurai location, whereas it was 661 litres (20.7%) at Thanjavur experimental site. The results further suggested that the effect of land slope gradients was explicitly pronounced more in the sandy loamy soils as compared to clayey loamy soils.

Sustainable irrigation based on co-regulation of soil water supply and atmospheric evaporative demand

Irrigation is an important adaptation to reduce crop yield loss due to water stress from both soil water deficit (low soil moisture) and atmospheric aridity (high vapor pressure deficit, VPD). Traditionally, irrigation has primarily focused on soil water deficit. Observational evidence demonstrates that stomatal conductance is co-regulated by soil moisture and VPD from water supply and demand aspects. Here we use a validated hydraulically-driven ecosystem model to reproduce the co-regulation pattern. Specifically, we propose a plant-centric irrigation scheme considering water supply-demand dynamics (SDD), and compare it with soil-moisture-based irrigation scheme (management allowable depletion, MAD) for continuous maize cropping systems in Nebraska, United States. We find that, under current climate conditions, the plant-centric SDD irrigation scheme combining soil moisture and VPD, could significantly reduce irrigation water use (−24.0%) while maintaining crop yields, and increase economic profits (+11.2%) and irrigation water productivity (+25.2%) compared with MAD, thus SDD could significantly improve water sustainability.

Land gradient and configuration effects on yield, irrigation amount and irrigation water productivity in rice-wheat and maize-wheat cropping systems in Eastern India

Laser land levelling is expanding rapidly in the rice-wheat (RW) and maize-wheat (MW) systems of the Indo-Gangetic Plains of India and Pakistan. Current practice is to level to zero (0%) gradient, whereas a small gradient (e.g. 0.1%) is typically used in developed countries. Therefore, experiments were conducted in farmers’ plots (~15 m x 40 m) in the Eastern Gangetic Plains to evaluate laser levelling with a 0.1% gradient in comparison with 0% and farmer levelling practice (FL). The study was conducted over two years in RW and MW systems. In the MW system, raised beds in plots lasered with 0% and 0.1% gradients were also evaluated. Laser levelling with 0% gradient significantly reduced irrigation amount and/or increased irrigation water productivity (WPi) in all crops/systems grown on the flat compared to FL except for wheat in the MW system. While there was a consistent trend for higher yield with a 0% gradient compared with FL, the differences were not significant in any crop/system. For the RW system, the results suggest no to marginal benefits in irrigation amount and WPi from levelling with a 0.1% gradient in comparison with 0% gradient. In that system, by far the bigger gains were from changing from FL to laser levelling with 0% gradient. This resulted in substantial reductions in irrigation amount, which greatly increased WPi in both crops (by ~40%), while yield was not affected. Rice grown with FL was not profitable, but lasering with 0% gradient significantly increased gross margin for rice, wheat and the total RW system. As for the RW system, levelling to 0% with a flat configuration significantly increased WPi of both crops in the MW system compared to FL, but by a lesser proportion. Raised beds significantly increased yield of maize by 8% (0.5 t ha−1), reduced irrigation amount by 20% (40 mm) and increased WPi by 34% (1.0 kg m−3) in comparison with the laser levelled flat plots. Gross margin of the MW system on beds was 17–20% higher than FL, and gross margin with beds on a 0.1% gradient was significantly higher than either gradient on the flat. The results suggest that the gains from levelling with a 0.1% gradient compared to 0% are marginal; however, this may change if the goal of consolidation of small farmer plots into larger fields becomes a reality provided there is a proportionate increase in irrigation flow rates, and ability to drain.

Ridge-furrow planting promotes wheat grain yield and water productivity in the irrigated sub-humid region of China

Determining methods for increasing irrigation water productivity is important for sustaining high wheat grain yields in the irrigated region of the Loess Plateau in China. Plastic-covered ridge and furrow planting has been widely applied in dryland farming, as it markedly increases precipitation productivity and crop yields. However, whether this planting system can significantly increase irrigation water productivity and whether it can reduce the irrigation volume for high-yielding wheat production in irrigated regions of the Loess Plateau are unclear. In the present study, plastic-covered ridge and furrow planting and traditional flatbed planting were performed at four irrigation levels. The objective was to investigate whether applying plastic-covered ridge and furrow planting to an irrigated farmland system could reduce the irrigation water requirements and increase water productivity for high-yielding wheat production. The results suggested that plastic-covered ridge and furrow planting significantly increased soil moisture content and increased both grain yield and water productivity of wheat. At the 0, 400, 1200, and 2000 m3 ha−1 irrigation levels, compared with that resulting from traditional flatbed planting, the grain yield resulting from plastic-covered ridge and furrow planting was 51.7 %, 64.8 %, 25.5 %, and 5.84 % greater, respectively. At the high-grain-yield level (6–7 t ha−1), the plastic-covered ridge and furrow planting system at 1200 m3 ha−1 irrigation conserved 40 % of irrigation water during wheat production. And it coordinated the relationships among grain yield, quality, water protuctivity and for wheat production. These findings show that the plastic-covered ridge and furrow planting system with 1200 m3 ha-1 irrigation is suitable for sustainable high-yielding wheat production in the irrigated regions of the Loess Plateau of China.

Evaluation of a Decision Support System for Variable-Rate Irrigation in a Humid Region

HighlightsAn Irrigation Scheduling Supervisory Control and Data Acquisition (ISSCADA) system was tested against a soil electrical conductivity (EC) based method for variable-rate irrigation (VRI).Soil EC was used to create irrigation prescription in EC-based VRI.ISSCADA generated VRI prescriptions using canopy temperature, soil water content, and weather data.ISSCADA-based VRI reduced irrigation water use and increased irrigation water productivity.Abstract. Use of variable-rate irrigation (VRI) technology has the potential to improve irrigation water use efficiency (IWUE). VRI hardware is commercially available and can be implemented in any center pivot or lateral move irrigation system. However, practical methods and algorithms for creating VRI prescriptions have become the bottleneck in accelerating the adoption of VRI. An Irrigation Scheduling Supervisory Control and Data Acquisition (ISSCADA) system for VRI was evaluated for two years in a humid region in the Mississippi Delta. The ISSCADA system was used to manage irrigation of soybeans for two seasons. In field practice, the ISSCADA system scanned the field for canopy temperature and collected soil water data from time domain reflectometers and weather data from a nearby weather station. The ISSCADA system automatically generated VRI prescription maps. The maps were modified to include plots managed using soil electrical conductivity (EC) based VRI prescriptions. Test results indicated that there was no difference in crop yield between EC-based VRI and ISSCADA-based VRI management. However, ISSCADA-based VRI management reduced irrigation water use and increased irrigation water productivity in comparison with EC-based VRI. There is great potential for the use of ISSCADA for VRI in humid regions. Keywords: Canopy temperature, Soil electrical conductivity, Soil moisture sensor, Soil water sensor, Soybean, Variable rate irrigation.

Effect of Fertigation Technique on Some Onion Physical Properties Using Different Emitter Types

Onion is the most widely-used flavoring vegetable in the world. And it is an important export crop in Egypt about 17%  529.631Tt., from total annually production. Scarcity of water resources in Egypt (arid and sigemi-arid regions) threatening food security. As well as, it is a limiting factor in agriculture expansion. So, maximizing irrigation water productivity by right combination of water and nutrients, and the method of fertilizer application through field water management practices (modern irrigation techniques, and fertigation) in irrigated crops, are a pre requisite for higher yields and good quality production. On the other hand it is very important to overcome water shortage and encourage environment preservation, particularly in sandy soils. Field experiment was conducted during 2016 /2017 season in private farm at Alexandria Cairo desert road, El-Behiara governorate. To study the effect of fertigation technique on some onion yield (quantity) i.e., bulb diameter “d1 and d2” (cm)., bulb mass “Bm” (g), bulb actual volume “Bv” (cm3), moisture content “MC” (%), and bulb yield “BY” (Mg fed-1)., through three emitters type, i.e., on line OT4 (I1), built in drip line GR 16 (I2) and built in drip line antiroots (I3), to obtain maximum irrigation water productivity, highest fertilizer effective, promoting yield quantity and quality and preservating environment of hyper mismanagement of water and fertilizer. Generally, results showed that using (I3) treatment recorded higher values compared with (I1) and (I2) treatments. Where, results indicated that, bulb yield “BY” (Mg fed-1) values increased about 8.32 and 2.77%., by using (I3), compared with (I1), and (I2). Also, using (I3) lead to increased irrigation water productivity “IWP” (kg m-3) about 66.1 and 33.2%., compared with using (I1), and (I2). In addition, it could be seen that bulb mass “Bm” (g), was increased by 60.77 and 14.39 %, when using (I3) compared with (I1) and (I2)

Yield and quality of potato tuber and its water productivity are influenced by alternate furrow irrigation in a raised bed system

Scarcity of irrigation water has now become the main constraint for crop production globally. Irrigation water scarcity becomes severe especially during the dry, winter season in South Asia, particularly in Bangladesh due to the decline in groundwater table and drying of surface water resources. In South Asian countries, potato is traditionally grown with furrow irrigation system in dry, winter season in which irrigation water is applied frequently to each and every furrow. Such irrigation method increases water use and lowers irrigation water productivity (WP). We hypothesized that potatoes grown on raised beds, and irrigation water applied to alternate furrows based on the principle of partial root-zone drying, would maintain yield, reduce water use and increase WP, and enhance the quality of potato tubers in drought-prone areas of South Asia. To test this hypothesis, an experiment was conducted in two consecutive dry, winter seasons (2015–16 and 2016–17) at the research field of Irrigation and Water Management Division of the Bangladesh Agricultural Research Institute, Gazipur, Central Bangladesh and assessed crop dry matter and yields, water use and WP, quality, and nutrient concentrations of potato tubers in different irrigation treatments. The experiment consisted of two levels (first, three irrigation at critical growth stages and second, four irrigation at every 12–15 days interval) and three methods (AFI – alternate furrow irrigation; FFI - fixed furrow irrigation; and EFI – every furrow irrigation) of irrigation. Dry matter and tuber yield of potato did not differ significantly (P < 0.05) between AFI and EFI but differed significantly (P < 0.01) when compared to FFI. On average, AFI and EFI had tuber yield of 21.9 and 22.2 t ha−1 with three irrigation and 23.2 t ha−1 and 23.9 t ha−1 with four irrigation, respectively during 2016 and 2017 while AFI and EFI had WP of 14.8 kg m-3 and 9.89 kg m-3 with three irrigation and 14.9 kg m-3 and 9.96 kg m-3 with four irrigation, respectively during 2016 and 2017. On average, AFI saved irrigation water by 35% and irrigation water productivity significantly (P < 0.001) improved by 50% compared to EFI over two years. Total soluble sugar, as an indicator of tuber quality, also varied significantly (P < 0.01) between AFI (6.290 Brix) and EFI (6.370 Brix). Nutrient concentrations of potato tubers were not significantly different (P < 0.05) between irrigation treatments. Results demonstrate that the alternate furrow irrigation can maintain potato tuber yield, and reduce water use and increase irrigation water productivity of potato tubers compared to every or fixed furrow irrigation in Bangladesh. This irrigation method could potentially be an attractive alternative to every or fixed furrow irrigation in South Asian countries where irrigation water is limited and appropriate water-saving irrigation methods are not available.

Plot level assessment of irrigation water savings due to the shift from sprinkler to localized irrigation systems or to the use of soil hydric status probes. Application in the French context

In order to reduce irrigation water withdrawal, the European Commission provides grants to farmers for investments in irrigation techniques that save water. However, little is known about the real extent of water savings at plot scale resulting from change in irrigation application equipment or the adoption of scheduling devices in a given agro-pedo-climatic context.The aim of this study was to evaluate irrigation water savings achievable by switching from sprinkler to localized irrigation system or by using soil hydric status probes. For this purpose, we used the French metropolitan context for our case study and compiled all available studies conducted over the past 30 years. A total of 93 records were collected from experimental field trials representative of a wide range of pedo-climatic conditions (25 different sites) and crops (field crops, fruit and vegetable production). Each record represents the water consumption of two different irrigation systems (sprinkler system vs localized system) or two scheduling systems (without soil probe vs with soil probe) at plot scale and is used to assess the water saving made when comparing the most water consuming system to the least consuming one.Results show that water savings are highly variable, ranging from 0% to more than 75% of the initial consumption. They originate in both irrigation technology and management. Their key features are the following. (1) Water savings made with localized systems, when compared to sprinkler irrigation, significantly decrease when the hydric deficit of the cropping season increases and when soil water holding capacity rises. Moreover, they tend to be higher when irrigation is managed with soil probes. (2) Water savings obtained with irrigation scheduling using soil probes (when compared to scheduling without probes) seem, on the contrary, not to be influenced by hydric deficit and soil water holding capacity. The type of soil probe (tensiometric or capacitive) used has no influence on the water savings obtained. (3) Water savings achieved with either localized systems or soil probes result in increased irrigation water productivity and are only marginally influenced by crop type.This frame of reference for irrigation water savings can guide public policies encouraging and financially supporting the implementation of water saving systems, not only on the subject of irrigation devices, but also on irrigation scheduling tools.

Irrigation management strategies to increase water productivity in Oryza sativa (rice) in Uruguay

Traditional rice irrigation systems in Uruguay are fully irrigated and early continuously flooded irrigation accounts for a high volume of water used. The purpose of this study was to determine irrigation techniques that increase irrigation water productivity (WPi) allowing a reduction in water input without negatively affecting grain yield in Uruguay. Ten experiments were conducted over a six-year period from 2009 to 2015, in three experimental units located among the major rice growing regions. Treatments included: early continuous flooding (C), alternate wetting and drying (AWD), intermittent flooding until panicle initiation (IP) and intermittent flooding during all crop growth period (I). All treatments were planted on dry soil. In treatment C flooding started 15–20 days after emergence and a water layer of 10 cm above the soil surface was maintained throughout all the crop cycle. In treatments IP and I, the water level alternated between 10 cm and 0 cm and was re-established when the soil was still saturated. The AWD treatment allowed the soil to dry periodically (water depletion of 50% of soil available water) until panicle initiation. IP and I over three seasons led to significant savings in irrigation water inputs in the North and Central regions (averaged 35% or - 3986 m3 ha−1) in relation to C. In the East region, AWD allowed for a 29%(-2067 m3 ha−1) water saving in relation to the control over four seasons but determined a significant yield loss of 1339 kg rice ha−1 (15% reduction) in relation to C. WPi was increased by 0.25 kg m−3 (23%) in IP and 0.68 kg m−3 (62%) in I, in relation to the control C. Whole grain percentage was significantly reduced with I in the North region only. Techniques that maintained the soil water at saturated conditions like intermittent flooding, allowed a reduction of water input with no significant effects on grain yield, which led to a significant increase in WPi.

Conservation agriculture based sustainable intensification: Increasing yields and water productivity for smallholders of the Eastern Gangetic Plains

In the Eastern Gangetic Plains (EGP) region of South Asia cropping systems are predominantly rice-based and comprise rice and non-rice crops (e.g. maize, wheat, lentil, mungbean, jute) in rotation. There are large gaps between potential crop yields and those achieved in farmers’ fields, primarily due to poor crop and soil management practices. Increasing climate variability and injudicious use of natural resources, particularly water and soil, mean that cropping systems have little resilience and are showing signs of being unsustainable. We hypothesized that replacing traditional crop rotations, grown under conventional tillage (CT) and with full residue removal, with crops grown under zero tillage (ZT) and with partial or full residue retention would improve both crop and cropping system yields, and reduce crop water demand, thus increasing the water productivity of cropping systems across the EGP. We evaluated four tillage-and-crop-establishment scenarios in three major cropping systems (rice-wheat, RW; rice-maize, RM; rice-lentil, RL) across eight districts of the EGP in 433 farmers’ fields between 2015 and 2017. We compared farmers’ traditional crop establishment practices (T1) against three scenarios based on the principles of conservation agriculture based sustainable intensification (CASI) and comprising a “partial CASI” option (T2: only non-rice crops grown under CASI management) and two “full CASI” options in which both crops were grown under CASI management; in T3 rice was direct seeded rice (DSR) and in T4 rice was transplanted without prior land preparation such as puddling (UPTR).Rice yields under all systems were not significantly different between CT (PTR) and CASI (ZTDSR and UTPR) but there was a significant yield gain of around 5% in both full and partial CASI on the yield of wheat and maize in the RW and RM systems. There were significant spatial trends in rice yields across all cropping systems. Total in-crop water (irrigation plus rainfall) usage was similar for the rainfed PTR, DSR and UTPR in all cropping systems as rice was primarily a rainfed crop grown during the wet season, however CASI practices reduced the required irrigation water, and thus the total in-crop water, to the dry season wheat or maize (but not to lentil) crops, compared to CT. This resulted in increased irrigation water productivity (greater than 27%) and total water productivity (greater than 26%) in both the wheat and maize crops. In the RW and RM systems irrigation water productivity was increased by over 25% and total water productivity by around 10%. These results indicate that the uptake of full or partial CASI practices, particularly in RM and RW systems, can lead to improvements in both cropping system and water productivity for smallholder farmers in the EGP.

Water saving and productivity benefits of SRI: a study of tank, canal and groundwater irrigated settings in South India

Abstract Paddy, which is predominantly cultivated under the conventional inundation method, is the largest water consuming crop in India. Given looming water scarcity, the inundation method of paddy cultivation is no longer sustainable. A newly introduced method of paddy cultivation, popularly known as the System of Rice Intensification (SRI), is reportedly helping to reduce water consumption and increase land productivity. SRI has now been in practice for some years in India but the various impacts of SRI on water saving, land and water productivity as well as on profitability which are expected to vary in different ecological settings – namely in tank, canal and groundwater irrigated areas – remain largely unexplored. In this study, using data collected from a total sample of 300 farmers from three different settings in Tamil Nadu state, an attempt has been made to fill this gap. The study shows that by adopting the SRI method farmers can save about 40% of irrigation water and increase land productivity by about 46% while reducing the cost of cultivation by 23% over the conventional inundation method. While increasing irrigation water productivity and economic water productivity substantially, SRI also generates an additional profit of Rs 17,169/acre (1 USD = INR 70.12; 1 acre = 4047 m2) compared to that realised by non-SRI farmers.

Interaction Effects of Planting Method, Irrigation Regimes, and Nitrogen Application Rates on Yield, Water and Nitrogen Use Efficiencies of Winter Wheat (Triticum aestivum)

Arid and semi-arid regions in the world that produce wheat (Triticum aestivum) are faced with frequent droughts in recent years. Moreover, wheat production is highly dependent on irrigation and it is essential to increase irrigation water productivity in these regions. Therefore, the aim of this study was to investigate the effects of irrigation methods, planting methods, and nitrogen application rates on yield, water and nitrogen use efficiencies of winter wheat. The experiment arranged in split–split plot with randomized blocks with two surface irrigation methods [ordinary furrow irrigation (OFI) and variable alternate furrow irrigation (VAFI)] as the main plots, two planting methods [on-ridge planting (ORP) and in-furrow planting] as the sub plots, and three nitrogen application rates (N0 = 0, N1 = 150 and N2 = 300 kg N ha−1) as the sub–sub plot. Results indicated that VAFI reduced the winter wheat grain yield, dry matter, grain number per spike, and harvest index as 12, 9, 3, and 4%, respectively; however, these reductions were not significant in comparison with OFI method with a reduction of 33% in irrigation water; as a consequence, the straw nitrogen concentration, grain protein concentration, and also water use efficiencies (WUE), irrigation water productivity (IWP), economic irrigation water productivity (EIWP) and nitrogen use efficiency (NUE) were improved in VAFI as 14, 5, 6, 26, 25, and 8%, respectively. In spite of a slight reduction in grain yield, VAFI method increased EIWP. Economic nitrogen productivity decreased about 50% by increase in N rate, and 150 kg N ha−1 was the optimum rate to apply. Furthermore, VAFI decreased the seasonal ET, thereby improved WUE and IWP. In-furrow planting increased significantly the WUES while it did not enhance significantly WUE for grain. Generally, increasing the nitrogen rate increased the grain yield; whereas, there was no significant difference between the treatments of 150 and 300 kg N ha−1. Results suggest that application of 150 kg N ha−1 combined with in-furrow planting method and variable alternate furrow irrigation is an effective way to improve WUE, yield, yield components and NUE for winter wheat in the study area.