Estimation of wheat yields and water savings with deficit irrigation in water-stressed NW India

Effect of water saving management practices and nitrogen fertilizer rate on crop yield and water use efficiency in a winter wheat–summer maize cropping system

Supplemental irrigation for dry-spell mitigation of rainfed agriculture in the Sahel

The effects of regulated deficit irrigation (RDI) and crop load on Japanese plum were investigated. RDI applied during phase II of fruit growth and post-harvest was compared with irrigation to match full crop evapotranspiration. Each irrigation treatment was thinned to a commercial crop load (described as medium) and to approximately 40% less than the commercial practice (described as low). The RDI strategy allowed for 30% water savings, increasing tree water use efficiency, with minimal effect on crop yield and fruit growth providing that plant water stress during the fruit growth period was low (stem water potential > −1.5 MPa), trees could recover optimum water status well before harvest, and crop load was low. However, the economic return, calculated from fruit weight distribution by commercial categories, was more affected by RDI than yield. The combination of medium crop load and RDI shifted fruit mass distribution towards the low value categories. This lead to similar or even higher economic returns in the RDI treatment with low crop level than with the medium one. In addition, since both, low crop level and RDI, increased fruit total soluble solids (TSS) concentration, fruit under RDI and low crop levels had the highest values of TSS.

Winter wheat is widely irrigated by graded furrow application on the Central and Southern High Plains of the United States. A study was conducted to determine the effectiveness of blocking furrow ends and cutting-off furrow inflow earlier to eliminate runoff and save water, rather than using the common practice of 4- to 6-h runoff to wet the beds on the lower ends of fields. Earlier cutoff is feasible with wheat because flow retardance by the plants in furrows increases transient flow volume, thus causing soil wetting to closely follow furrow advance. Both adequate (3 to 4 applications) and deficit (1 to 2 applications) irrigation regimes were evaluated during the study. With adequate irrigation, the elimination of runoff with blocked furrows and earlier cutoff reduced average gross irrigation applications from 430 to 335 mm (16.9 to 13.2 in.) or 22% without reducing grain yield. Seasonal water use savings averaged 95 mm (3.8 in.) with adequate irrigation. With deficit irrigation, water savings were 17% or 48 mm (2 in.). Grain yields averaged 5.6 Mg/ha (83 bu/acre) and 4.2 Mg/ha (63 bu/acre), respectively, with adequate and deficit irrigation on blocked furrows.

Yield, fruit quality and water use efficiency of tomato for processing under regulated deficit irrigation: A meta-analysis

Comparison of deficit and saline irrigation strategies to confront water restriction in lemon trees grown in semi-arid regions

India has the largest area under onion (Allium cepa) crop but its average productivity (14.21 t ha -1 ) is considerably lower than the world’s average of 19.4 t ha -1 . Besides low productivity, irrigation efficiencies are also very low i.e. 30-35% in India. Managing onion crop with less than adequate irrigation water availability is a challenge in several parts of the country. Options of i) deficit irrigation (DI) i.e. 20% or 40% less water application at one of the growth stages of the crop and ii) controlled deficit of 20% or 40% on all growth stages i.e. regulated deficit irrigation (RDI) were explored for maximizing IWUE of onion under deficit water application through subsurface drip irrigation. A field experiment was conducted on onion (var. Agrifound light red) for three years from October to May in 2007-08, 2008-09 and 2009-10 to study the effect of DI and RDI on onion yield and its quality under subsurface drip irrigation. In DI treatments, the crop was provided the irrigation with 60% and 80% of ETc creating water stress of 40 and 20%, respectively at developmental (2 nd ), bulb formation (3 rd ) and bulb maturity (4 th ) crop growth stages. In case of RDI treatments, 20% and 40% water stress was created throughout the crop season by applying the irrigation water at 80% and 60% ETc. The maximum yield (44.7 t ha -1 ) was obtained in the full-irrigation treatment (T1). In RDI, 20 and 40% deficit water application saved 19.2 and 41.7% water and resulted in 20 and 32% reduction in yield, respectively. In DI, 20% water deficit in the growth stages of 2 nd , 3 rd and 4 th saved 2.1, 13.2 and 4.6% of water with 19.8, 18.3 and 11.2% reduction in yield, respectively in comparison to full irrigation water application. This suggests that RDI is better option of water saving than DI. Saving of water through RDI may be used to irrigate additional cropped area. Strategy suggested for productions of onion crop can be adopted in large scale to offset high cost of onion, which is cause of concern for all stake holders.

The prolonged issues regarding the quantitative and qualitative characteristics of the water resources in the River Basin District of Thessaly (TRBD) have resulted in the environmental degradation and the reduction of the availability of water. Agriculture is the major water user, constituting up to 95% of total water demand. The pressures anticipated from the ongoing climate change are expected to cause further degradation, given the present status of the water resources. This research attempts to examine and quantify the water saving potential of TRBD, mainly for the agriculture sector, following the recommendations of the European legislation, the principles of sustainable development and environmental protection. Water saving tools are documented in several countries, including technical measures, such as drip irrigation systems and the modernization of the transfer networks, as well as deficit and scheduled irrigation practices and water reuse. These measures and practices are tested for their potential effect on water demand in TRBD, in addition to changing a portion of cotton cultivation areas to olive groves. To this end, the volume of irrigation demand is estimated at 2088×106, while total water demand stands for 2204×106. Afterwards the study proceeds to the evaluation of the water saving potential both independently and combined. The potential of water savings in TRBD is proven high, 14.3% of total water demand for technical measures, 10.7% if deficit irrigation is applied to specific crops, while it may reach 28.8% in case the measures are combined.

Comparing sprinkler and drip irrigation systems for full and deficit irrigated maize using multicriteria analysis and simulation modelling: Ranking for water saving vs. farm economic returns

Long-term productivity of early season peach trees under different irrigation methods and postharvest deficit irrigation

Opuntia species grow in arid and semiarid lands, where water for irrigation is scarce. However, supplemental irrigation can be a feasible strategy for commercial cactus pear orchards. From 2018 to 2020, a commercial cactus pear orchard was managed to validate the effect of supplemental irrigation on fruit yield, crop water use efficiency, fruit quality, and storability of ‘Roja Lisa’ cactus pear grown in the semiarid region of Mexico. The irrigation treatments were no irrigation and supplemental irrigation, with four replications. Crop water use was less and, therefore, water productivity greater in non-irrigated plants than in plants with supplemental irrigation. Mean fruit yield, mean fruit mass, and proportion of commercial fruit increased with supplemental irrigation. These differences were more pronounced in growing seasons with less rainfall. Fruit quality at harvest or after room temperature or cold storage was examined. Fruit mass loss rate was reduced in fruit receiving supplemental irrigation in both storage conditions. In addition, supplemental irrigation was consistent with water savings and food security programs in marginal areas: this irrigation strategy improved both pre- and postharvest some quality components of cactus pear fruit. Therefore, this irrigation strategy is suggested for cactus pear growers, depending on the availability of water for irrigation.

In recent decades, the scarcity of fresh water has become a significant issue, particularly in arid regions, leading to increased competition for water among agricultural, industrial, and urban users. The widespread limitations on water for agriculture highlight the need for strategies that enhance the efficiency of irrigation water use. Pomegranates and persimmons, although considered minor fruit trees, have gained considerable attention in Spain and worldwide due to their organoleptic characteristics and health benefits. As a result, they present interesting options for diversifying fruit production in the Mediterranean basin, especially since these species are known to tolerate water stress. A three-year study investigated the agronomic responses of both crops to deficit irrigation, specifically focusing on sustained deficit irrigation (SDI) and regulated deficit irrigation (RDI). For pomegranates, RDI - where water applied is reduced to 33% of the total irrigation requirements during the flowering (RDI1) and fruit set (RDI2) periods - has been identified as a viable strategy under water-limited conditions. On the other hand, the tested SDI strategy (applying 50% of the irrigation water requirements throughout the crop cycle) should be reserved for extreme water scarcity situations. For persimmons, the tested SDI strategy, which reduces water applied to 70% of the water requirements, is recommended as it achieves a 30% water saving while maintaining production levels comparable to the control group, thereby enhancing water productivity. In contrast, RDI - where water is reduced during the flowering and fruit setting stages (60% in RDI1 and 40% in RDI2) -  yielded intermediate results, providing lower water savings without increasing production relative to the SDI. In conclusion, both studies suggest that pomegranates and persimmons could serve as alternative options to citrus fruits in Valencia, considering their positive productive responses to deficit irrigation.

Biochemical and enzymatic responses to long-term regulated deficit irrigation (RDI) at harvest, during cold storage and after the retail sale period of 'Flordastar' early peaches were evaluated. Irrigation strategies were Control, and two RDI applied during post-harvest period (RDI1 , severe; RDI2 , moderate), based on different thresholds of maximum daily shrinkage signal intensity (RDI1 , 1.4 to dry; RDI2 , 1.3 to 1.6). Both RDI provoked stress in the plant. This meant higher antioxidant concentration [averaging 1.30 ± 0.27 g ascorbic acid equivalents (AAE) kg(-1) fresh weight (FW) for control and 1.77 ± 0.35 and 1.50 ± 0.30 g AAE kg(-1) FW for RDI1 and RDI2 , respectively]. Antioxidant levels decreased with storage by polyphenoloxydase action, which increased (from 0.04 ± 0.01 U mg(-1) protein to 0.32 ± 0.08 U mg(-1) protein). Vitamin C was initially higher in RDI samples (44.22 ± 0.05 g total vitamin C kg(-1) FW for control vs. 46.77 ± 0.02 and 46.27 ± 0.03 g total vitamin C kg(-1) FW for RDI1 and RDI2 , respectively). The way RDI was applied affected bioactive fruit composition, being catalase and dehydroascorbic acid good water stress indicators. RDI strategies can be used as field practice, allowing water savings while enhanced healthy compound content in early peaches.

Field irrigation is the largest consumer of freshwater in the world covering 63 million hectares in the 1900s to 300 million hectares in the early 2000s to provide a multitude of benefits and ecosystem services to people around the globe, such as consistent food supply, higher crop productivity, and shared resource collectivism. Field irrigation intensifies land use mostly in the arid and the semiarid regions where precipitation cannot fully satisfy human and crop water demands. Climate change impacts the distribution and the timing of water availability into humid regions as well through increases in drought frequency and intensity, further augmenting the demand for irrigation. However, designing and operating irrigation infrastructure and scheduling practices for an agricultural region requires sound contemporary and historical knowledge of the local circumstances vis-à-vis humans, crops, soils, hydrology, and climate. Sub-Saharan Africa stands as a large-scale narrative of poorly performing field irrigation against decades of investments due to designs exclusive to the socioeconomic ecosystems. Optimal water allocation in the water–energy–environment–food nexus to achieve the greatest social and economic benefit for the region invariably a task of continuous cocreation between many actors. Therefore, field irrigation remains a challenging project and most of the agricultural water use worldwide—both from groundwater and surface water—remains suboptimal in terms of design, water allocation, and monitoring for farmers, communities, and regulators. Many diversions of surface water for irrigation in both economically developed and developing countries are small-scale temporary infrastructures in and outside official plans and permits, which altogether results in severe aquifer depletion worldwide with negative impacts on food safety, economy, environment, and society. Traditional surface flooding is the dominant mode of irrigation globally and mostly applied on new agricultural fields, whereas water-saving irrigation methods are practiced on fewer and older fields. Water-saving technologies involve either scheduling of regulated deficit irrigation or local water storage to optimize crop water supply, which may be combined with drip irrigation, biodegradable soil amendments to retain soil water, and plastic mulches to minimize evaporation, whereas the use of partial root zone drying and biochar mostly remain at the experimental stage. Global analyses over the late 20th and early 21st century find no water saving by water-saving technologies at field scale because increased return flow from newly irrigated fields surpasses the reduced soil evaporation from old, irrigated fields, whereas regionally, return flow to fresh aquifers is a benefit rather than a loss, which results in some water savings. At the same time, increased crop transpiration exceeds regional water savings, which explains the paradox between the wide application of water-saving technologies and more severe regional water shortage. With nonscientific decisions on when and where to irrigate practiced by most farmers worldwide, scheduling remains the top priority task in field irrigation, as both too little and too much water leads to yield decreases and loss of nutrients to the environment. Where water is abundant, scheduling aims to keep crop transpiration and yield at a maximum with minimum use of irrigation water. In dryer areas, this luxury can rarely be sustained unless the irrigation area and therefore production is reduced. Instead, regulated deficit irrigation may be practiced on drought-tolerant crops and cultivars. Regulated deficit irrigation seeks to limit crop transpiration to a fraction of the maximum during less drought-sensitive growth stages. In this way, crop water use efficiency increases, and yield per m3 of water rather than m2 of land is maximized. Remote sensing of soil and crops through satellite and aerial multispectral and thermal products have the potential to enhance irrigation scheduling by precisely quantifying and distinguishing crop transpiration (beneficial water consumption) from soil evaporation (nonbeneficial water loss) in space and time and to facilitate regulated deficit irrigation and other water-saving measures. However, irrigation management significantly falls behind in adapting state of the art information and communication technologies. With a global rise in frequency and duration of droughts, the lack of irrigation infrastructure in humid regions and of water availability in semiarid regions induces enormous losses in agricultural production and social well-being and unveils an urgent need for a macrolevel drought governance approach in order to strengthen multisectoral water management and mitigate climate change damage to human and natural assets.

A field experiment was conducted on a sandy farmland in Northwest China to estimate on the response of maize evapotranspiration and yield to deficit irrigation. The five irrigation treatments consisted of specific combinations of full irrigation and limited irrigation in different crop growing phases (I, from elongation phase to heading; II, from heading phase to milk; III, from milk phase to physiological maturity) were designed. And for estimation of maize evapotranspiration, reference crop evapotranspiration (ET0), basal crop coefficient (Kcb), soil evaporation coefficient (Ke), and water stress coefficient (Ks) in different treatments were calculated. Results showed that; 1) the crop actual evapotranspiration (ETc) for treatments SII (deficit irrigation in phase I), ISI (deficit irrigation in phase II), IIS (deficit irrigation in phase III), SIS (deficit irrigation both in phase I and III), and III (full irrigation) were 570, 604, 579, 542, and 607 mm, respectively. (2) The phase II was the most sensitive phase to water deficit, with reductions in leaf area index (LAI), biomass, yield, irrigation water productivity (IWP), and harvest index (HI). In this phase, the effect of water stress on Ke and Ks was slight, and the evapotranspiration has no obvious difference between full irrigation and limited irrigation. (3) Deficit irrigation in phase I can slow down the crop development in early phase, and can also reduce maize biomass and yield. In this phase, water stress obviously reduced Ke and Ks, and the evapotranspiration in limited irrigation treatments were obviously lower than full irrigation treatment in this phase. (4) However, deficit irrigation in phase III has no significant effect on height and leaf area of maize, and did not also significantly reduce maize biomass and yield. In this phase, the evapotranspiration in limited irrigation treatments were also obviously lower than full irrigation treatment. It can be concluded that it was possible to reduce water consumption and maintain the maize yield by adopting deficit irrigations from milk to physiological maturity, then from elongation to heading, but not from heading to milk in this sandy farmland regions. Key words: Evapotranspiration, deficit irrigation, sandy farmland, maize.