Irrigation Water Productivity Research Articles

Effect of establishment methods in rainy season (kharif) and tillage practices in winter season (rabi) on yield and economics of rice (Oryza sativa)–maize (Zea mays) cropping system under coastal saline ecosystem

Effect of establishment methods in rainy season (kharif) and tillage practices in winter season (rabi) on yield and economics of rice (Oryza sativa)–maize (Zea mays) cropping system under coastal saline ecosystem

Optimizing Crop Water Productivity in Greenhouse Pepper

Although advanced production systems have been developed in the last 20 years, water scarcity is still a growing problem in agriculture. This study aims to evaluate the effect of different strategies that combine the application of seaweed and microbial biostimulants with regulated deficit irrigation (RDI) strategies on the irrigation water productivity (WPI), fruit quality parameters and soil enzymatic activity in pepper plants (Capsicum annum sp.) under two commercial greenhouse conditions. In each trial, two treatments were applied: (i) irrigation according to Farmer criteria without biostimulant applications and (ii) a combined treatment of RDI and the same biostimulation program, composed of Bacillus paralicheniformis and Ascophillum nodosum extracts. RDI was applied in different phenological stages in each greenhouse after the establishment until the 1st harvest in trial 1 or during the ripening and harvest period in trial 2. On average, the irrigation was reduced by 600 m3 ha−1 compared to the Farmer irrigation schedule. In both trials, biostimulation promoted an increase in fruit numbers, punctually in trial 1, leading to yield precocity, or generally in trial 2, obtaining a higher yield. Globally, WPI was increased when RDI was combined with biostimulation. This combined treatment also enhanced the root water absorption and improved the soil enzymatic activity in both greenhouses, suggesting that nutrients in the soil would become more available to plants. Thus, the combined action of biostimulation under different RDI strategies has been proved to be a useful strategy to improve agricultural sustainability.

Impact of “Dry Sowing and Wet Emergence” Water Regulation on Physiological Growth Characteristics and Water Productivity of Cotton Fields in Southern Xinjiang Province

Determining a suitable “dry sowing and wet emergence” water control program for cotton fields in the arid regions of Northwest China is of great significance in saving water resources, improving economic efficiency, and promoting sustainable development of agriculture. The objective of this study was to analyze the effects of different “dry sowing and wet emergence” water control treatments on dry matter accumulation, chlorophyll fluorescence, yield quality, and water productivity of cotton, and to determine the optimal “dry sowing and wet emergence” water control program for cotton growth in arid areas. A two-year experiment was carried out in 2021 and 2022 in mulched drip-irrigated cotton fields, with a total of 13 treatments of different seedling water quantities (2021: 67.5 mm, 90 mm, 112.5 mm; 2022: 6 mm, 10.5 mm, 15 mm) and different drip frequencies (frequencies means number of drops at seedling stage) (2021: one, two, three times; 2022: two times, four times) in the “dry sowing and wet emergence”. Results indicated a positive correlation between increased seedling water quantity and growth indexes. High seedling water quantity treatment demonstrated a 14.33% higher cotton yield than the low seedling water quantity treatment. In comparison with low-frequency treatment, the high-frequency treatment exhibited significantly larger cotton plant height, dry matter accumulation, and yield. Over two years, the average values increased by 8.69%, 16.4%, and 15.91%, respectively, with a 14.55% increase in the coefficient of photochemical quenching of the leaf blade (qP). The high frequency and larger amount of seedling water quantity treatments showed significantly higher irrigation water productivity, with increases of 39.2% and 70.2% compared to the winter irrigation control treatment. In summary, the appropriate “dry sowing wet emergence” water regulation mode (the first drip: 15 mm, the second drip: 4.5 mm, the third drip: 22.5 mm, the fourth drip: 15 mm) can ensure crop yield quality under the premise of significantly reducing the agricultural irrigation water, which can provide certain theoretical support for the green, efficient, and sustainable development of the local cotton industry.

Effects of microbial biofertilizer on growth, physio-biochemical traits, fruit yield, and water productivity of okra under drought stress

Drought poses a major challenge to global agricultural crop production, as it is considered one of the most severe abiotic stresses. Understanding the effects of exogenous microbial biofertilizer on okra [Abelmoschus esculentus (L.) Moench] under drought stress can lead to new strategies for coping with drought conditions. The objective of the study was to examine the effects of microbial biofertilizer on growth, physio-biochemical traits, fruit yield, and water productivity of okra under drought stress. A factorial pot experiment, consisting of eight biofertilizer treatments applied as a soil drench (autoclaved inoculum [control], and inoculation with arbuscular mycorrhizal fungi [AMF], phosphate-solubilizing fungi [PSF], plant growth-promoting rhizobacteria [PGPR], AMF + PSF, AMF + PGPR, PGPR + PSF, and AMF + PSF + PGPR) and three soil moisture regimes (50%, 75%, and 100% field capacity [FC]), was carried out. The results indicated that decreasing soil moisture level severely affected growth and fruit yield of okra. The application of microbial biofertilizer effectively enhanced growth, fruit yield, and physio-biochemical traits of okra under different soil moisture levels. Among the biofertilizer treatments considered, the combined application of AMF and PGPR showed remarkable efficacy in enhancing growth and productivity of okra plants under both 75% and 100% FC conditions. This co-inoculation significantly boosted shoot dry matter by 51%, root dry matter by 73%, fruit yield by 113%, and irrigation water productivity by 122% compared with plants grown without inoculation, irrespective of soil moisture levels. Furthermore, the plants treated with AMF and PGPR exhibited a noteworthy decrease in free proline accumulation by 31% compared with their non-inoculated counterparts. The results suggest that application of both AMF and PGPR biofertilizer to soil is an effective strategy to alleviate moderate drought stress. It is recommended to apply AMF and PGPR in combination to improve okra yield and water productivity under drought stress.

Water productivity in pineapple (Ananas comosus) cultivation using plastic film to reduce evaporation and percolation

Irrigated agriculture needs significant amounts of water for increasing irrigated areas to meet the increase food demand. New alternatives with high water use efficiency are needed to increase crop productivity. This work evaluates the use of plastic film mulch either as groundcover or as a percolation barrier to increase yields and water use efficiency of pineapple (Ananas comosus L.). An experiment was carried out with pineapple on a loamy sand-soil. The treatments were: (i) soil tillage with plastic film as groundcover combined with plastic film as a percolation barrier installed at 0.40 m below the soil surface; (ii) soil tillage with no groundcover combined with a percolation barrier; (iii) soil tillage with plastic film as groundcover only; (iv) soil tillage without groundcover and percolation barrier. The use of plastic mulch maintained the levels of soil water availability at least 80% during the crop cycle, while without it soil water values ranged from 15% to 70%. Groundcover with plastic mulch contributed significantly to decrease evapotranspiration and the medium crop coefficient. The plastic groundcover combined with or without the plastic percolation barrier yielded the better results of productivity, irrigation water productivity, and water footprint. The mean irrigation water productivity and water footprint were 667.12 kg mm−1 ha−1 and 109.0 L kg−1, respectively, for the use of a plastic groundcover combined with a plastic percolation barrier. The percolation barrier was more effective for saving water than for increasing yield. The use of percolation barrier with plastic contributed for saving 92–103 L kg−1 ha−1 when combined with or without ground cover.

Optimizing crop water productivity and delineating root architecture and water balance in cotton–wheat cropping system through sub-surface drip irrigation and foliar fertilization strategy in an alluvial soil

Water-intensive agricultural practices in tandem with conventional irrigation methods such as flood irrigation, has caused severe water scarcity in south-Asian Indo-Gangetic Plains (IGPs). The adoption of micro-irrigation systems (sprinker, surface drip and sub-surface drip) instead of flooding offers a great promise in water saving and enhanced fertilizer-use efficiency, and thus, improved productivity. The change in irrigation and fertilization methodology may affect the behavior of plant root growth, root architecture and, crop and water productivity. Hence, current study aimed at evaluating the influence of sub-surface drip-irrigation and fertigation strategy on crop and water productivity besides delineating root architecture and soil water balance in cotton–wheat cropping system (CWCS). Results showed that sub-surface drip irrigation (SSDI) enhanced the root system by stimulating the development of new secondary roots which actively participated in physiological responses. Root length at boll opening stage of cotton increased significantly under SSDI at 60% ETc (60% of evapo-transpiration) over other treatments. Root mass density in wheat was also significantly higher under SSDI particularly at 15–30 cm depth over surface drip and flood irrigation during 2020–21. SSDI at 100% ETc (100% of evapo-transpiration) produced statistically similar seed cotton yield, wheat grain yield and the system productivity (wheat equivalent yield) to 80% ETc. SSDI at 80% ETc (80% of evapo-transpiration), resulted in water-saving of ∼43.2% over flood irrigation in CWCS. Further, fertigation through SSDI resulted in ∼20% reduction in fertilizer needs, while achieving the yield equivalent to that of conventional fertilization. Irrigation water productivity and bio-physical water productivity of this system were ∼46.1 and 5.7% higher under 80% ETc along with F80 (80% recommended dose of nitrogen, RDN) and Mfoliar (foliar application of KNO3 & MgSO4 at flower initiation and boll development stages of cotton) over flood irrigation. Overall, SSDI at 80% of evapo-transpiration along with 80% RDN and foliar application of KNO3 & MgSO4 may prove highly beneficial to enhance the crop and water productivity in CWCS, besides saving irrigation water-use by ∼43.2% over flood irrigation in water-scarce agro-ecologies of south-Asia.

Soil water distribution and water productivity in red cabbage crop using superabsorbent polymeric hydrogels under different drip irrigation regimes

The water issue has emerged as a significant barrier to agricultural productivity, particularly in dry and semiarid agro-ecologies, particularly during the winter season. Superabsorbent hydrogels have been identified as effective tools for improving crop and water productivity in arid locations by enhancing moisture retention. The application of hydrogel to soil is commonly done as a basal application, and its effectiveness is heavily influenced by the moisture level present in the soil. Therefore, a two-year field study was carried out to study the effects of various hydrogels and their application techniques and to assess the efficacy of recently developed cross–linked hydrogels (SPG 1118 and Pusa hydrogel) on soil water distribution (both spatial and temporal), water productivity and profitability of red cabbage. The experiment consisted of two irrigation regimes [full irrigation (100% ETc) and limited irrigation (75% ETc)] assisted in main plots, with two type of hydrogels (Pusa Hydrogel and SPG 1118) and two methods of application [root dipping and soil application of hydrogels and Control with no application of hydrogel] assisted in sub plots. The field experiment was conducted using spilt plot design with three replications. The analysis of soil water distribution patterns reveals that the utilization of hydrogels has resulted in a notable increase of 3–6% in soil water content (SWC) under full irrigation conditions, as compared to plots subjected to limited water conditions. In comparison to plots without hydrogel application, the plots treated with SPG 1118 and Pusa hydrogel exhibited enhanced soil water content of 5–6% and 2–4%, respectively. Additionally, the application of hydrogels in the root dipping showed increased water availability in the crop's root zone compared to soil application in throughout the crop season. Thus, hydrogels with reduced irrigation application resulted in significantly higher crop water productivity (14%) and irrigation water productivity (8 – 14%) compared to full irrigation levels. Likewise, root dipping of SPG 1118 led in considerable improvement in CWP (12–14%) and IWP (11–12%) over no hydrogel applied plots. In relation to profitability, the adoption of full irrigation in conjunction with SPG 1118 hydrogel resulted in an 8% increase in the benefit cost ratio compared to the control plots. Hence, the use of the unique SPG 1118 hydrogel through direct application to the roots, whether under conditions of full or limited irrigation, presents an inventive approach to address the growing issues of water shortages and sustainability in countries experiencing water stress.

Irrigation water economic value and productivity: An econometric estimation for maize grain production in Italy

Climate change, characterized by rising temperatures and limited precipitation, has intensified the demand for irrigation water while simultaneously restricting its availability. This challenge poses significant risks to agricultural and food production, particularly in the Mediterranean regions where, recently, water deficits have led to substantial production losses and quality issues. Water is a critical determinant of crops' economic viability, especially for water-intensive crops, making it essential to estimate its economic relevance, especially in the absence of reliable water market prices. This study has two primary objectives: first, to evaluate the shadow price of irrigation water for maize grain at the farm level, which is defined as the value generated by the marginal unit of water consumed; and second, to analyse its heterogeneity. Leveraging a Farm Accountancy Data Network (FADN) panel of 1625 Italian farms over a decade (2010–2020), an econometric production function approach is employed. Moreover, quantile regressions reveal variations in the shadow price linked to geographical, managerial, and structural farm characteristics. Our findings underscore water’s key role in economically viable maize grain production, significantly enhancing the productivity of other inputs like fertilizers and pesticides. The average shadow price is 0.29 €/m³, with a median of 0.20 €/m³ and water total productivity accounts for one-third of maize’s average gross output. Quantile regressions uncover how factors like geographic location, altitude, farm management, irrigation water source, and farm size influence the distribution of water productivity, reflecting either efficient use or scarcity of this resource. Our estimation provides valuable insights for policymakers by offering accurate shadow price estimates for irrigation water in Italian maize grain production. Furthermore, it enhances our understanding of irrigation water’s role in the economic viability of this crop, while contributing to support evidence-based water management strategies, identifying vulnerable areas and farms and allowing for future methodological developments.

Effects of irrigation scheduling on the yield and irrigation water productivity of cucumber in coconut coir culture

Optimum irrigation scheduling is important for ensuring high yield and water productivity in substrate-cultivated vegetables and is determined based on information such as substrate water content, meteorological parameters, and crop growth. The aim of this study was to determine a precise irrigation schedule for coconut coir culture in a solar greenhouse by comparing the irrigation, evapotranspiration (ET), substrate water content (VWC), as well as the crop growth indices and yield of cucumber, and irrigation water productivity (IWP) under three irrigation schedules: the soil moisture sensor-based method (T-VWC), the accumulated radiation combined with soil moisture sensor-based method (Rn-VWC), and the crop evapotranspiration estimated method using the hourly PM-ETo equation with an improved calculation of Kc (T-ETc). The results showed that the daily irrigation and evapotranspiration amount were the highest under T-VWC treatment, while the lowest under T-ETc treatment. In different meteorological environments, the change in irrigation amount was more consistent with the ET,and the VWC was relatively stable in T-ETc treatment compared with that under T-VWC or Rn-VWC treatments. The plant height, leaves number, leaf area, and stem diameter of T-VWC and Rn-VWC treatments were higher than those of the T-ETc treatments, but there was no significant difference in cucumber yield. Compared with the T-VWC treatment, total irrigation amount under Rn-VWC and T-ETc treatments significantly decreased by 25.75% and 34.04%, respectively (P<0.05\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {P}<0.05$$\\end{document}). The highest IWP values of 25.07 kg m-3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{-3}$$\\end{document} was achieved from T-ETc treatment with significantly increasing by 44.33% compared to the T-VWC treatment (17.37 kg m-3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{-3}$$\\end{document}). In summary, the T-ETc treatment allowed more reasonable irrigation management and was appropriate for growing cucumber in coconut coir culture.

Economic productivity of irrigation water in large-scale irrigation schemes with different typologies: the case of Fincha’a and Koga irrigation schemes in the Abbay River Basin, Ethiopia

Economic productivity of irrigation water in large-scale irrigation schemes with different typologies: the case of Fincha’a and Koga irrigation schemes in the Abbay River Basin, Ethiopia

Adoption of irrigation scheduling in the South African sugarcane industry: the use of a demonstration trial to bring about change

In the South African sugarcane industry, as in many countries, poor adoption of irrigation scheduling is common, leading to ineffective use of irrigation water and loss in yield and income. The reasons for the lack of adoption include economic constraints, difficulty with implementation and human perceptions. To demonstrate the benefits of effective irrigation scheduling under local conditions, a demonstration trial was conducted over 5 years at Pongola, South Africa. Here, a fixed irrigation schedule (control) was compared with three scheduling treatments: (1) the MyCanesim® computer model with data from an automatic weather station; (2) soil-water data from a capacitance probe; and (3) a combination treatment, where MyCanesim® was integrated with a capacitance probe. The number of stress days from either under- or over-irrigation, along with the RV (recoverable value) yield, irrigation applied, irrigation water productivity (IWP) and financial benefits was used to assess each treatment. The adoption of irrigation scheduling was also evaluated through farmer surveys before and after the trial. When compared to the fixed-cycle control, the use of irrigation-scheduling techniques resulted in an increase of up to 13% in RV yield, a reduction of up to 58% in irrigation water applied, improved IWP of up to 23.9 t cane/100 mm of irrigation and financial benefits of up to ZAR10,487/(ha · a) (USD698/(ha · a)). The combination treatment incurred the least water-stress days, 79% lower than the control. Farmer surveys showed an increase of 45% in the adoption of irrigation scheduling, from 11% (n = 111) in 2014 to 56% (n = 100) in 2020. Although site-specific, the trial results show substantial benefits that can be realised by scheduling irrigation. The trial results compare well to other similar studies, showing that the results can be used in other areas to promote the adoption of irrigation scheduling.

Response of Sunflower Yield and Water Productivity to Saline Water Irrigation in the Coastal Zones of the Ganges Delta

The intensification of cropping systems in the salt-affected coastal zones of the Ganges Delta can boost food security in the region. The scarcity of fresh water, coupled with varying degrees of soil and water salinity are however limiting factors for the expansion of irrigated cropping in that area. In this study, we assessed the potential of growing sunflowers using combinations of low and medium saline water for irrigation. The experiments were conducted at two locations with six irrigation treatments in 2016–2017 and 2017–2018. The treatments were: T1—two irrigations at early vegetative (25–30 days after sowing; DAS) and flowering stages (60–65 DAS) with low salinity water (LSW, electric conductivity, ECw &lt; 2 dS m−1); T2—two irrigations, one at the vegetative stage with LSW and one at the flowering stage with medium salinity water (MSW, 2 &lt; ECw &lt; 5dS m−1); T3—two irrigations, one at the vegetative stage with LSW and one at seed development stage (75–80 DAS) with MSW; T4—three irrigations at the vegetative, flowering and seed development stages with LSW; T5—three irrigations, at vegetative stage with LSW, and flowering and seed development stages with MSW; and T6—three irrigations, two at the vegetative and flowering stages with LSW and one at the seed development stage with MSW. Irrigation with LSW at early growth stages and MSW at later growth stages did not significantly (p &lt; 0.05) affect the yield compared to the LSW irrigation at early and later growth stages. Crop water productivity and irrigation water productivity of sunflowers (p &lt; 0.001) increased substantially with the decreasing amount of irrigation water with an average of 1.18 kg m−3 and 2.22 kg m−3 in 2017 and 0.92 kg m−3 and 1.29 kg m−3 in 2018, respectively. Grain yield was significantly correlated with root zone solute potential. The flowering and seed development stages of sunflowers in February–March were sensitive to both low and medium saline water irrigation for seed yield. Overall, the results show that irrigation with LSW (ECw &lt; 2dS m−1) at early growth stages and MSW (2 &lt; ECw &lt; 5dS m−1) at later growth stages could be an option for dry-season sunflowers in the coastal zones of the Ganges Delta which would allow double cropping in this area.

Conveyance efficiency and irrigation water productivity under varying water supply conditions in arid lowlands of Central Asia

A proper assessment of the water allocation system and water–food production relationships is essential to identify water use reduction potentials and enhance crop water productivity in dry areas. However, limited data on crop-specific water uses and water losses in the system, especially in developing and transition countries, prevent consistent diagnosis of issues in water systems. A modeling framework based on maximum entropy approach was implemented here to simultaneously assess water system structure and ‘water use-crop production’ relationships. The framework allowed for the analysis of long-term changes in conveyance efficiency, crop-specific water application, and irrigation water productivity between 1980 and 2021 in the Khorezm region in the lower reaches of the Amu Darya Basin in Central Asia. The results showed that conveyance losses were more than 30% in the system, and approximately 40% of the water allocated to the region went to rice and cotton production, indicating the possibility of water use reduction in these three areas. Conveyance efficiency and cotton water productivity improved in drier years in the region, owing to the wide implementation of temporary and low-cost drought management measures. The expected increase in the frequency and magnitude of droughts may require long-term investment-demanding strategies for drought management to enhance the sustainable livelihoods in the region.

Yield and quality responses of Megathyrsus maximus and Cynodon spp. forage grasses to irrigation

Periodic variations in rainfall have resulted in longer periods of drought in traditional rainfed livestock systems on savanna areas in Brazil. However, irrigation management techniques and rotational grazing have improved the productivity of these systems by mitigating soil water stress on forage grasses. The objectives of this research were to evaluate the response of Megathyrsus maximus cv. Tanzania and Cynodon spp. cv. Tifton 85 (Cynodon nlemfuensis × Cynodon dactylon) forage grasses to irrigation, and to determine their irrigation water productivity (IWP). The experiment was conducted at the University of São Paulo in Brazil. Plant height (PH), dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were measured, and IWP was calculated. Tifton 85 had a higher CP content than Tanzania but a lower average DM yield. The irrigation management (IM) treatments did not influence CP levels of both forage grasses, but in most situations, did affect their average DM yield. The IWP of Tanzania and Tifton 85 forage grasses did not differ among irrigation management treatments.

The Riego Berry mobile application: A powerful tool to improve on-farm irrigation performance in berry crops

Berry crops have transformed the province of Huelva, in the Southwest Spain, transforming it into a prosperous area of Andalusia. Since the 1990 s, there has been a debate in this area about balancing agricultural production with environmental preservation, because 75% of berry production is in the vicinity of the Doñana National Park, a natural area of high ecological value designated as World Heritage by UNESCO. Therefore, it is necessary to improve the efficiency of water use in the area. The advancement of mobile devices has allowed their wide use by technicians and farmers to schedule their irrigations. For this reason, the Riego Berry App has been developed as a smartphone application that allows to make irrigation schedules in a fast and intuitive way. This tool is the result of a more than ten-year public-private partnership. In this work, a comprehensive study has been made to validate the App, using data from trials conducted on commercial farm. The average irrigation water applied (IWA) by farmers ranged from 4292 (raspberry) to 8752 m3/ha (blueberry), whereas Riego Berry’s average IWA ranged from 3053 (raspberry) to 6177 m3/ha (blueberry). Water savings of 41% for strawberry and 29% for raspberry and blueberry have resulted from the use of this tool on commercial farms. Despite irrigation differences, there were no significant differences in yields between the farmer’s and Riego Berry treatments. Farm application efficiency increased by 63% for strawberry, 42% for raspberry, and 37% for blueberry, while irrigation water productivity increased by 36% for blueberry and raspberry, and 56% for strawberry.

Quinoa growth and yield, soil water dynamics, root growth, and water use indicators in response to deficit irrigation and planting methods

To address the growing issue of scarce water in the arid and semi-arid areas, it is essential to investigate the potential of drought tolerant crops and implement promising farm management strategies to improve water productivity and yield production. Therefore, a split plot experiment to investigate how different irrigation levels (I-1:100% water requirement (WR), I-2:75%WR, and I-3: 50%WR) and planting methods (P-1: basin, P-2: on-ridge, and, P-3: in-furrow) interact and affect quinoa water use, yield, root growth, and water productivity in southern Iran over two growing seasons. The results showed high seasonal crop evapotranspiration (993–1030 mm) in I-1 as a result of the high advection ratio (α), which ranged from 1.02 to 1.46 from the early vegetative to the seed filling stages. The P-3 increased transpiration rate by 4.5% and 7.7%, and decreased soil evaporation by 17% and 29% compared to P-1 and P-2, respectively. Single (Kc) and dual (Kcb + Ke) crop coefficients varied between 0.41 and 1.38 over the two growing seasons. Grain yield in P-3 were 25%, 34%, and 44% higher compared to P-1 and P-2 under I-1, I-2 and I-3, respectively. The study revealed that nearly 67% and 80% of the total root dry matter was in the 0–30 cm and 0–60 cm of the soil profile in all experimental treatments, respectively. Regardless of irrigation treatment, root length density (RLD) and root mass density (RMD) were found to be 18.9% and 15.7% lower in P-1’s top 0–20 cm of the soil profile than those obtained in P-2 and P-3, respectively. Analyses showed that the increased root length in deeper soil layers contributed to higher soil water uptake, and consequently higher crop water productivity. In addition, root-to-shoot ratio increased as the amount of the applied irrigation water was decreased. Quinoa exhibited the highest acclimation to water stress in P-3 based on water stress sensitivity coefficients (λi) and yield response factor (Ky) values. Crop water productivity (WPC) and irrigation water productivity (WPI) for grain yield varied between 0.17 and 0.28 kg m−3. In conclusion, in terms of grain yield, shoot and root dry matter and water productivity, I-2 and P-3 (75% WR irrigation level and in-furrow planting method treatment) is recommended as the optimum water and planting management strategy for quinoa cultivation in the study area as a measure to address water scarcity and food sustainability. Still, to improve yield and irrigation water efficiency, the effect of soil management practices such as mulching and organic amendments on soil water retention and nutrient availability for quinoa should be investigated.

Climate-smart irrigation strategy can mitigate agricultural water consumption while ensuring food security under a changing climate

North China Plain suffers from the world’s most severe water scarcity and groundwater depletion due to intensive irrigation for agricultural production. It is imperative to reduce irrigation water consumption while safeguarding crop production and food security. This study conducted a quantitative analysis with deficit irrigation strategies for winter wheat using a water-driven AquaCrop model. After model calibration and validation with field experimental data, we analyzed the irrigation water demand, crop yield, and water productivity (WP) of winter wheat under various deficit irrigation scenarios. A set of optimal irrigation schedules were proposed for different climate years, which significantly mitigated irrigation water usage while sustaining high yields and WPs. The results indicated that despite the irrigation water demand of winter wheat under the future climate scenario was slightly higher than that in the historical period, their crop water sensitive periods (reviving, jointing, and flowering) remained the same. Therefore, we recommended adopting the same deficit irrigation schedules for the historical and future periods. In wet years, adopting a 50% deficit irrigation strategy only reduced crop yields by less than 5% compared with full irrigation, but it saved 1000–1100 m3 of water per hectare and contributed a WP higher than 1.88 kg/m3. While in normal and dry years, an optimal 25% deficit irrigation could sustain over 96% of the maximum yield, meanwhile it could save 650–800 m3/ha of water and achieve almost the same WP as full irrigation. These climate-smart irrigation strategies adapting to diverse climatic conditions largely mitigate agricultural water consumption while maximizing crop productivity and water use efficiency, which are essential for achieving precision irrigation and sustainable water management under a changing climate.

Impact of ET and biomass model choices on economic irrigation water productivity in water-scarce basins

Using Economic Irrigation Water Productivity (EIWP) as an indicator for on-farm irrigation decision-making is of utmost importance in addressing the challenges posed by poor policies in managing agricultural water use, particularly in water-scarce basins. Various modeling systems are available for quantifying crop actual evapotranspiration (ETa) and biomass needed for measuring the economic output obtained from each unit of irrigation water utilized. The difference in ETa and biomass estimates between the modeling systems could translate into a difference in EIWP outcomes, which influences the basin-wide irrigation water management. In this paper we examine the influence of selecting different ETa and biomass models, particularly the hybrid single-source energy balance HSEB, the Global Field-Scale Crop Yield and ET Mapper in Google Earth Engine GYMEE, and FAO’s WaPOR V2, on evaluating EIWP on a basin-wide level. The method includes combining remote sensing and economic data to compare variability in ETa, biomass, and EIWP values derived from HSEB, GYMEE, and WaPOR. The approach is demonstrated with field survey data from the upper hydrologic unit of Lebanon’s largest catchment, the Litani River Basin, in its three productive districts Baalbak, Zahleh, and West Bekaa for the year 2021. Field-scale mean monthly ETa and biomass estimates for all crops, obtained from both models, are very comparable. On a district level, the results reveal a reasonable model agreement for the four crops in the estimation of ETa with moderate to strong correlation (0.75 < r < 0.95). WaPOR consistently produces slightly higher mean ETa values for potato, wheat, and table grapes when compared to HSEB. Both models reasonably agree when estimating biomass for the four crops with high correlation (r > 0.9). Contrary to the ETa results, the GYMEE model consistently estimates slightly higher mean biomass values for all crops compared to WaPOR. The EIWP values produced by both models consistently indicate that potato holds the highest EIWP across all districts, followed by onion, table grapes, and wheat. The mean district HSEB-GYMEE model derived EIWPs are slightly higher than those derived from the WaPOR model for most crops. For EIWP obtained from HSEB-GYMEE, mean EIWP for potato is 12 times higher than that of wheat. As for that obtained from WaPOR, mean EIWP for potato is 10 times higher than that of wheat. The paper establishes a basis for future research on the application of remote sensing models in addressing water-stressed and socioeconomically challenged basins, with the potential to inform strategic irrigation management decisions based on model selection.

Energy and water budget of rice under different establishment methods

A field study aimed to investigate the influence of different rice establishment methods on energy and water budget of rice was conducted during kharif season of 2022. The experiment was carried out using a randomized block design with three replications. Seven treatments were examined, including three transplanting methods viz., SRI, mechanical transplanting and conventional transplanting, and four direct seeded rice (DSR) methods viz., wet DSR (drum seeding), wet DSR (broadcasting), dry converted wet rice (broadcasting) and dry converted wet rice (line sowing). Results revealed that chemical fertilizers, irrigation water, land preparation and seeding or transplanting operations constituted ~80% of the input energy in all rice establishment methods. Among the rice establishment methods, conventional transplanting exhibited the highest input energy of 21723.9 MJ ha-1, while dry converted wet rice (line sowing) recorded the lower input energy of 18394.3 MJ ha-1. In terms of output energy, wet DSR (drum seeding) recorded the highest value of 141781.1 MJ ha-1, whereas dry converted wet rice (broadcasting) registered the lowest value of 77223.2 MJ ha-1. The output energy of wet DSR (drum seeding) was comparable to that of SRI and dry converted wet rice (line sowing). Similarly, dry converted wet rice (line sowing) exhibited higher irrigation water productivity (0.73 kg m-3) and total water productivity (0.30 kg m-3) with a reduced water requirement of 630 mm. Compared to conventional transplanting, input energy consumption and irrigation water requirement was lower by 18.1% and 51.9% in dry converted wet rice (line sowing), 17.4% and 51.9% in dry converted wet rice (broadcasting), 16.9%, 36.7% in SRI and 9.13%, 27.6% in wet DSR (drum seeding) respectively. Thus, the adoption of wet DSR (drum seeding), SRI and dry converted wet rice (line sowing) is recommended for energy and water efficient rice production in Telangana.

Quantifying and valuing irrigation in energy and water limited agroecosystems

Agriculture in regions with limited water availability is possible because of irrigation. Irrigated croplands are expanding, and irrigation water demand is increasing. Nevertheless, there is a limited understanding of how much water is consumed for irrigation and how effective irrigation increases crop productivity in various climates. In this study, we aim to understand how irrigation water affects crop productivity in different climates. To achieve this goal, we developed a simple approach to quantify irrigation quantities from SMAP satellite soil moisture observations based on a zero-dimensional bucket-type hydrology model. The central assumption is that irrigation quantities can be estimated from the gap between the modeled and observed soil moisture by iteratively providing irrigation as a model input until the soil moisture simulations agree well with the observations. We then used the estimated amount of irrigation to simulate water, energy, and carbon fluxes at two agricultural sites on the west coast of the US: one that was water-limited (Central Valley, CA) and one that was energy-limited (Eugene, OR). An agroecosystem model, AgroIBIS-VSF, was used to conduct simulations. To verify our simulations, we used data from two AmeriFlux Eddy covariance towers at each site. We found that incorporating estimated irrigation amounts into our simulations improved the accuracy of energy balance components and soil moisture predictions, reducing the root-mean-square error of soil moisture predictions by up to 22%. We also discovered that the irrigation value, in terms of increased productivity of actual irrigation water used, is more than five times more valuable at the energy-limited site than at the water-limited site. Soil hydraulic properties have a strong influence on irrigation water valuation. Our study highlights the potential of satellite soil moisture observations to improve our understanding of water productivity in different climates. By better understanding the efficiency of resources used for crop production, we can ensure the sustainability and resilience of agricultural systems, leading to better management practices.