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Jojoba (Simmondsia chinensis) is cultivated for its seeds, which contain a high-value liquid wax. There is little known regarding irrigation requirements of intensively cultivated jojoba. The project's objectives were to evaluate the effects of irrigation regime on water status, growth, yield, and water productivity (WP, wax yield per unit of water applied) of intensely cultivated jojoba. An experiment was conducted over six years in a 14-year-old commercial plantation in Israel's Northern Negev Desert. Treatments included: Control irrigation according to best commercial practice of returning reference evapotranspiration multiplied by a crop coefficient (Kc) of 0.5; Low irrigation providing 75% (Kc = 0.375) of the control; High irrigation providing 125% (Kc = 0.625) of the control; Regulated deficit irrigation (RDI) according to the control treatment, terminated for one to two months, after the wax accumulation stage. Stem water potential (SWP) consistently indicated jojoba water status. Increasing water application from − 25% to the control and further to + 25% led to augmented vegetative growth and number of seeds, but yield was increased at rates lower than the differences in water application by the treatments, such that WP was negatively associated. Effects on yield were limited to higher yielding 'On' years. The RDI treatment resulted in yield not different from the control and 15% higher WP, but significantly inhibited seed removal during mechanical harvesting. The results suggest commercial potential for increasing profits through water savings. Further research is needed to determine RDI regimes without detrimental effects on harvesting efficiency. [ABSTRACT FROM AUTHOR]

Installing a pressure regulator for lateral (PRL) on a cost-effective non-pressure compensating drip tape inlet can greatly reduce system investment while ensuring system uniformity and safety. This approach plays a critical role in achieving low-cost, scalable precision irrigation systems in developing countries. Once the PRL is installed, it alters the hydraulic characteristics of the system. The lack of comprehensive evaluation standards for PRL that consider both irrigation uniformity requirements and PRL characteristics is impeding the widespread adoption and application of this technology. In this article, a comprehensive evaluation system for the PRL is established through a combination of theoretical deduction and field measurements. The main conclusions are presented as follows: (1) A comprehensive evaluation index is proposed for the hydraulic performance of the PRL, which considers both single-factor influences and multifactor influences such as manufacturing deviation, inlet pressure, and flow rate. (2) A statistical relationship was established between the comprehensive evaluation indices for PRL (CV) and irrigation uniformity (CU). The CV should be less than 10% for a CU above 90% and less than 17% for a CU above 85%. (3) Classification evaluations of PRL products were conducted based on their usage conditions, and a design selection chart for PRL products was provided. [ABSTRACT FROM AUTHOR]

Limited water resources and successive droughts in Iran have limited crop production. Therefore, modern irrigation methods to increase water use efficiency can become more necessary. A 2-year (2020, 2021) field experiment was carried out to determine the effect of irrigation method and nitrogen fertilizer on maize physiological traits, grain yield, water use efficiency, and soil temperature and moisture. The experimental design was factorial in the randomized complete block with three replicates. The studied irrigation and fertilizer treatments were the four levels of irrigation (wick irrigation, surface irrigation with 50, 70, and 100% of plant water requirement) and the two levels of nitrogen fertilizer (50 and 100% of the recommended urea fertilizer). Totally, wick irrigation with 100% fertilizer increased SPAD, leaf relative water content, leaf porometer, total dry weight, ear dry weight, ear diameter, number of rows per ear, number of grains per ear, and 100-grain weight compared to other treatments. Wick irrigation significantly increased soil moisture and decreased soil temperature compared to surface irrigation with 50, 70, and 100% plant water requirement at a depth of 10 cm. Although there was no significant difference between wick irrigation and 100% surface irrigation regarding grain yield, on average, for both years, wick irrigation reduced water consumption by 57.88% compared to 100% surface irrigation. Furthermore, wick irrigation with 100% fertilizer had the highest water use efficiency. Therefore, wick irrigation with 50% fertilizer application is the best treatment, because water and fertilizer are saved. [ABSTRACT FROM AUTHOR]

Many collective irrigation systems have been operating for decades, facing high degradation of existing infrastructures and huge water-energy efficiency problems. Predominantly composed of open canals, they have been partially or entirely converted into pressurised pipe systems, implying a considerable increase in energy consumption and operation and maintenance costs. Simple, easy-to-use, and comprehensive approaches for energy efficiency assessment in collective irrigation systems are needed for diagnosis and assisting decision-making on implementing adequate improvement measures. This research proposes and demonstrates an innovative approach based on the water and energy balances and performance indicators to assess the effect of water losses, network layout and operation, energy recovery, and equipment on energy efficiency. A novel methodology for energy balance calculation is proposed for open canal, pressurised and combined systems. The application to a real-life open canal system and network areas allowed the identification of efficiency problems mainly due to water losses in canals, followed by the dissipated energy in friction losses. Less critical are pumping and manoeuvring equipment inefficiencies. Also, a considerable excess of gravity energy is recovered in hydropower plants. In raising pipe systems, in which shaft input energy predominates and costs for pumping play a key role, surplus and dissipated energy in friction losses are the most relevant issues. Significant energy is lost in the water conveyance and distribution in both systems. Consequently, the potential to improve energy efficiency through water loss management, network layout, and operation improvement, besides pumping and manoeuvring equipment replacement, is considerable. [ABSTRACT FROM AUTHOR]

The CERES-Maize model performance was investigated in simulating maize phenology, grain yield, soil–water, evapotranspiration, and water productivity under different irrigation and nitrogen (N) levels under a variable rate lateral (linear)-move sprinkler irrigation system. The irrigation levels were rainfed, full irrigation treatment (FIT) and 75% FIT. The N levels were 0, 84, 140, 196, and 252 kg/ha. The field experiment was conducted in the form of split plots with the irrigation levels as the main treatment and N levels as a sub-main treatment. The root mean squared error (RMSE), normalized RMSE (RMSEn), R2, T test, and model prediction error (Pe) statistics were used to evaluate the performance and accuracy of the model. Calibration of the model was done using the data of 2011 and 2012 and validation of the model was conducted for 2013 and 2014 by considering days after planting to flowering (DAPF), days after planting to maturity (DAPM), grain yield, crop evapotranspiration (ETc), water productivity (WP), and soil water content (SWC). The DAPF simulations based on the average values of Pe (0%), RMSE (2 days), and RMSEn (3%) and the DAPM simulation results based on the average values of Pe (2%), RMSE (4 days), and RMSEn (3%) showed that the model had an acceptable accuracy. In calibration years, RMSE, RMSEn, and R2, respectively, were 0.57 ton/ha, 5%, and 0.91; and in validation years, the same statistics, respectively, were 0.86 ton/ha, 10% and 0.94, indicating good performance of the model in estimating the grain yield. Good accuracy was observed in the estimation of ETc and WP. In most cases, the model accuracy was greatest for 75% FIT and FIT treatments than the stressed conditions in the rainfed treatment. The model accuracy can be enhanced by improving the model coefficients in response to low levels of water and N supply. R2 values obtained in rainfed (0.83), 75% FIT (0.81) and FIT (0.67) treatments in calibration years and R2 values in rainfed (0.75), 75% FIT (0.77) and FIT (0.86) treatments in validation years showed that the model predicted the SWC relatively well. The comparison of ETc values with respect to N levels showed that there was no considerable difference between levels of N applications impact(s) on the ETc magnitude in the rainfed treatment. Comparison of different levels of N in rainfed and FIT showed that the application of 252 kg/ha of N resulted in 2.37 kg/m3 and 2.56 kg/m3 of WP, respectively, which was significantly different from other levels of N fertilizer applications. In general, CERES-Maize model can be a useful tool for predicting plant phenology, grain yield, ETc, WP, and SWC for the conditions similar to those presented in this research. The CERES-Maize model can provide valuable data and information for sustainable maize production by examining the long-term grain yield and WP, which can be beneficial to growers, advisors, and stakeholders to enhance the maize production efficiency by accounting for irrigation and N management strategies. [ABSTRACT FROM AUTHOR]

Cotton is a relatively new crop in southern Kansas and its effective irrigation scheduling requires information on crop water requirement and water productivity in a given climatic condition. This study aimed to: (1) assess cotton crop actual evapotranspiration, irrigation water requirement, (2) evaluate lint yield and quality, and (3) determine the water productivity related to total water (irrigation and rainfall), irrigation, and evapotranspiration under different irrigation technologies and rainfed conditions in semi-arid climate of western Kansas. Field experiments were conducted in 2020, 2021, and 2022 at the Southwest Research and Extension Center (SWREC) in Garden City, KS, to evaluate cotton production under four irrigation technologies which were low elevation spray application (LESA), low energy precision application (LEPA), mobile drip irrigation 1 (MDI1 with 3.79 L/h), mobile drip irrigation 2 (MDI2 with 7.57 L/h) and a rainfed treatment under a randomized complete block design with the variety PHY 205 W3FE. Crop management was similar across all treatments for three growing seasons. The results showed that the seasonal actual evapotranspiration (ETa) varied among the irrigation technologies, the rainfed treatment, and years. On average, LESA recorded the highest ETa value of 463.9 mm and LEPA had the lowest ETa value of 457.2 mm. The lint yield and lint quality (micronaire, length, strength, uniformity, color grade) varied significantly among the irrigation technologies and the rainfed setting. The highest lint yield of 1061.94 kg ha−1 was obtained under LEPA, while the rainfed registered the lowest lint yield of 224.13 kg ha−1. The irrigated cotton had a high value for lint quality parameters with the LEPA having the best lint quality. Furthermore, on average, LEPA recorded the highest evapotranspiration-water, total-water, and irrigation-water use efficiencies, and the values were 0.23, 0.33, and 0.39 kg m−3, respectively. The cotton ETa and water productivity are valuable parameters for effective irrigation scheduling for cotton production under similar climate and soil conditions. [ABSTRACT FROM AUTHOR]

Irrigation forecasting is essential for improving water management in agriculture. This study proposed a novel and practical framework for irrigation forecasting for paddy rice. Public weather forecasts in China were selected to forecast ETo and quantitative rainfall. For the latter, a simple deterministic model and a probabilistic model based on a Pearson-III representation of the data were considered. A modified Python version of the AquaCrop model (ACOP-Rice model) was adopted to generate the probability distribution of forecasted irrigation events and rule-based irrigation recommendations. The performance of weekly irrigation forecasting was then evaluated. The analysis of the weather forecasts revealed that the accuracy of the temperature and ETo predictions was acceptable, whereas the quality of the rainfall forecasts was poor. The performance of the scenarios that using probabilistic rainfall forecasts outperformed scenarios that relied on deterministic rainfall forecasts, despite the lower quality of the probabilistic rainfall forecasts compared to the deterministic forecasts. The irrigation recommendations exhibited a systematic bias (i.e., the inclination toward overirrigation or underirrigation) when using weather forecasts, and this bias was lower when using probabilistic forecasts. Additionally, compared to ETo forecasts, the inaccuracy of rainfall forecasts had a much greater impact on irrigation forecasts. [ABSTRACT FROM AUTHOR]

Potato (Solanum tuberosum L.) requires high levels of water and potassium to achieve optimal yield and quality. This is of importance for the sustainable agriculture, and therefore, it is quite concern of agronomists to define the proper irrigation level and potassium rates in potato. In this study, we tested three irrigation levels (full irrigation (I100), 66% full irrigation (I66; 33% deficit), 33% full irrigation (I33; 66% deficit)), and six potassium doses (K0:0 kg ha−1 of K, K1:40 kg ha−1 of K, K2:80 kg ha−1 of K, K3:120 kg ha−1 of K, K4:160 kg ha−1 of K and K5:200 kg ha−1 of K) in Agria. The study was conducted in Niğde (Central Anatolia, Türkiye, 37°56′31.8′′N 34°38′04.2′′E) as a two-year field experiment. In the experiment, the respective values were recorded for each variable; plant height 36.0–92.0 cm, maturation period 82.0–98.0 days, number of stem per plant 3.4–4.7, number of tuber per plant 4.1–7.7, tuber yield per plant 247.1–846.2 g, marketable tuber ratio 79.4–99.4%, discarded tuber ratio 0.6–5.7%, secondary structured tuber ratio 0.0–16.6%, total tuber yield 11.8–38.7 t, dry matter 19.2–21.6%, specific gravity 1.072–1.087 g cm3, and starch 13.2–15.9%. Besides, it was determined that the optimum irrigation × potassium interaction was achieved at I100×K3 and I100×K4 in terms of plant and yield parameters, and I33×K3 and I33 × K4 in terms of tuber quality parameters. In our work, we concluded that a water need of average 590–720 mm (not including the effective rainfall amount) and potassium supply of 120–160 kg ha−1 in Central Anatolia will be optimal for the potato cultivation. The findings of this study will contribute to potato cultivation practices by providing proper information about the optimal irrigation need and potassium dose. [ABSTRACT FROM AUTHOR]

The effects of climate change on water availability affect the performance of surface irrigation, which is the oldest and most common method of water application to row crops worldwide. A paradigm shift towards strategies aimed at increasing flexibility of irrigation scheduling and improving the design and management of field layouts and irrigation practices should be explored to promote water conservation at the farm scale. In this study, we investigate how by adopting a more flexible irrigation scheduling and optimizing irrigation management variables and field layout it is possible to increase the efficiency of border irrigation and thus achieve water conservations and improve quality of crop production. The analysis of the actual performance of border irrigation was carried out on two maize fields located in the Padana Plain (Northern Italy) in 2 years characterized by different rainfall patterns (i.e. 2021 and 2022). Based on this information, continuous monitoring of soil moisture status combined with the AquaCrop-OS agro-hydrological model was used to manage flexible irrigation scheduling over the experimental fields, while the optimization of irrigation management (flowrate per unit width and cutoff time) and field geometries (border width and slope) was studied using WinSRFR 5.1 USDA software, which was properly calibrated by measures of waterfront advance and recession. The results show that with flexible irrigation scheduling and proper irrigation management and field layout, significant water conservation can be achieved. Specifically, in the case study, seasonal water conservation of about 10% was obtained just by scheduling irrigation based on actual crop water needs in a very dry agricultural season, while water conservation reached up to 60% in a wetter season. On average, an additional 7% of water conservation was achieved over the agricultural season when the irrigation duration was correctly applied to each border of the experimental plots, while approximately 20% of water was conserved when the border width was correctly designed based on inflow availability. These results provide useful information for improving the management of border irrigation in practice, both under current conditions and in prospective of increasing freshwater scarcity in the future. [ABSTRACT FROM AUTHOR]

Water shortages in the Western United States will continue to be one of the foremost American agricultural challenges in the coming years. As agriculture is the largest consumer of water in the western US, improvements in irrigation scheduling and modeling are needed to maximize production under limited water. Various satellite-based remote sensing models have been developed to estimate crop water use. However, water balance-based evapotranspiration (ET) models need field-scale irrigation information for initiating the seasonal soil water balance. This initialization has been challenging due to the lack of remotely sensed irrigation event data. In this study, we utilized a recently launched satellite constellation (Planet) with high temporal and spatial resolution data (daily, ~ 3 m) to evaluate if Planet data can facilitate early season irrigation detection. We utilized normalized difference vegetation index (NDVI), moisture index, and individual spectral bands to detect moisture and ultimately infer irrigation. As part of this comparison, a hybrid two-source energy and water balance model BAITSSS (Backward-Averaged Iterative Two-Source Surface temperature and energy balance Solution) was used to estimate ET with Planet-based vegetation indices and irrigation information. We also compared the results to eddy covariance (EC) located at lettuce fields in Yuma, Arizona in the lower Colorado River basin between 2016 and 2020. Overall, the results indicated that Planet's data helped to establish the field-scale onset of irrigation, which assisted to initiate soil water balance in the BAITSSS model, thus ultimately improving ET. Further, these results should support the development of near-real-time landscape-scale ET and should be highly beneficial to agricultural communities for sub-field-scale effective water management. [ABSTRACT FROM AUTHOR]

The drip emitter type used influences the dissolved oxygen concentration (DOC) distribution in a drip irrigation system. Understanding the spatial and temporal DOC distribution in the irrigation system and its change pattern and determining the optimal irrigation emitter and aeration concentration threshold are important to reasonably apply aerated irrigation. Here, we designed three common drip irrigation emitter treatments under a drip irrigation system, i.e., an inserted in-line labyrinth emitter with a flow rate of 1.0 L h−1 (T1) and 2.2 L h−1 (T2), respectively, and a pressure-compensating emitter with a flow rate of 2.0 L h−1 (T3). Each irrigation emitter was associated with five initial DOC treatments, i.e., 3–5 mg L−1 (CK), 10 mg L−1 (C1), 15 mg L−1 (C2), 20 mg L−1 (C3), and 25 mg L−1 (C4). The results showed that the DOC values gradually increased in nonaerated water (CK) but gradually decreased in aerated water with standing time. Each emitter type significantly increased the DOC values after nonaerated water (CK) passed through different drip irrigation systems, and the highest increase (73.7%) was observed in the T1CK treatment. However, the DOC values significantly decreased after the aerated water passed through the drip irrigation systems, especially in the T2 treatment (33.2%). In addition, the reduction (or increase) in DOC in aerated water (or nonaerated water) in the first 10 m of the capillary pipe was smaller than that in the last 10 m for all treatments except T1C1. Furthermore, the T3 treatment had the most stable attenuation at different initial DOC treatments, with a maximum laying length of 20 m. More importantly, aeration can significantly increase DOC in the soil water (DOS), and the maximum value occurred when the initial DOC was 19.8 mg L−1. Hence, for practical application, the recommended initial DOC range for aerated irrigation is 15 ~ 20 mg L−1 combined with a pressure-compensating emitter at a flow rate of 2.0 L h−1 (T3). This study provides technical support for the optimal design and rational application of aerated drip irrigation systems. [ABSTRACT FROM AUTHOR]

The estimation of irrigation water requirements (IWR) amount and timing is crucial for designing water management strategies at the regional scale. Irrigation requirements can be estimated with different types of models: very complex and detailed crop models, agent-based models, or simplified modeling approaches. Because simplified approaches are often preferred, in this study, we evaluate the consequences of using simplified approaches for IWR assessment at a catchment scale and the consequences of various modeling choices, providing information on the uncertainties. To this end, different simple modeling approaches based on the CropWat model are compared with an agent-based approach (MAELIA), which serves as a benchmark. To assess simulations in detail, partial variance is calculated for several indicators characterizing daily simulated irrigation. Our sensitivity analysis, applied over a sub-catchment of the Aveyron River (southwestern France), shows a high variability in simulations produced by CropWat between the modeling assumptions tested, principally explained by the rules for irrigation triggering and the quantification of daily irrigation. The analysis also shows that several simplified approaches are able to reproduce the irrigation simulated by the high-accuracy MAELIA model, but not necessarily corresponding to an optimal irrigation scheme. Hence, this study confirms the possibility of assessing daily irrigation with simplified approaches, but warns about high modeling uncertainties, reflecting uncertainty in effective irrigation practices. This uncertainty can be taken into account by water managers and modelers through the combination of a set of irrigation models. [ABSTRACT FROM AUTHOR]

The objective of the present study was to investigate the impacts of potassium and different levels of irrigation on the yield, cracking, quality, net economical return, and water consumption of the pomegranate (Punica granatum L. -cv. Hicaznar), and was carried out at the Alata Horticultural Research Institute in 2012, 2014, and 2015 growing season in the Eastern Mediterranean region of Turkey. The main plots and subplots were set up as the potassium doses (K0: 0 g/tree; K1:300-350-400 g/tree; K2:600-650-700 g/tree) and irrigation level (I75:0.75; I100:1.00; I125:1.25). An experiment was a split-plot design with three replications for the arrangement and analyses of the aforementioned 9 treatment combinations. Irrigation was conducted when the cumulative evaporation was found to be 30 ± 5 mm. According to the experimental results, the potassium and the irrigation levels were found to profoundly affect the total pomegranate yield and yield components at a statistical error of 1% and 5%. The lowest yield was found to be at K0I75, and the highest yield was found to be at K1I125 for all 3 years. It was observed that lower irrigation levels led to lower yield. When irrigation levels were studied concerning potassium levels, the I75 level was found to produce the lowest yield. The total irrigation water for all treatments was 254–416 mm and the seasonal evapotranspiration (ET) was 387–670 mm according to the treatment. It was illustrated that potassium dose and irrigation levels significantly influenced water productivity (WP) and irrigation water productivity (IWP). The lowest level for WP was 4.77 kg m−3 at the K0I125 level, and the highest level for WP was 9.54 kg m−3 at the K1I75 level. The lowest level for IWP was 6.84 kg m−3 at the I125 level, and the highest level for IWP was 13.49 kg m−3 at the I75 level. The potassium and irrigation levels were found to affect the pomegranate yield, cracking rate, and amount of fruit, as well as parameters that represent quality, such as fruit rind thickness and amount of aril, at a statistically significant level. As a result, K1I125 levels can be recommended for a high amount of yield in the field of pomegranate cultivation with drip irrigation. The WP, IWP levels, total yield, waste yield levels, and economic net return support the use of K1I100 irrigation in conditions of drought. Over the 3-year combined economic analysis, the K1I125 treatment produced the maximum net income followed by the K1I100 treatment. [ABSTRACT FROM AUTHOR]

In recent decades, worldwide wine-growing regions have been affected by increasingly more frequent effects of climate change, such as long period of droughts during the growing season, summer heat waves, and late spring frost events, thus causing concern for the grape quality and production. In this context, it is necessary to develop innovative agronomic practices to counter the various negative effects from those extreme weather events, by equipping the vineyards with effective and reliable multifunctional systems, which are also economically sustainable. Particularly, a multifunctional irrigation system can be used to reduce the risk of extreme weather events and, at the same time, to improve quality and quantity of grape production, reducing their inter-annual variability as well, by providing an optimized plant water nutrition. In a vineyard situated south of Lake Garda (Northern Italy), a multifunctional irrigation system equipped with drippers and mini-sprinklers (the latter to protect from both late spring frost and summer high-temperature event) was assessed. The results obtained for the growing season 2020–21 showed that the optimized drip irrigation reduced water consumption without affecting the grape yield, both in quantity and quality. The frost protection operated by mini-sprinklers increased the air temperature at bud's level of about 1 °C, suggesting a positive effect on plant production. Finally, in 2020, must quality was positively affected by summer sprinkler irrigation, increasing the levels of malic acid and titratable acidity of over 0.7 g L−1 while lowered total soluble solids. Further activities in the 2022 season intend to better assess the water use efficiency of this promising multifunctional system. [ABSTRACT FROM AUTHOR]

Because of an increased incidence of drought, irrigation has become an important agricultural practice in formerly mesic regions. Efficient irrigation scheduling depends on a good knowledge of tree water relations. For three growing seasons, we monitored stem water potential (Ψstem) in two apple tree cultivars (Malus × domestica cv. 'Red Jonaprince' and 'Gala Brookfield') with and without irrigation. We also determined xylem potentials at 12% and 50% percent loss of conductivity (Ψ12, Ψ50) and vessel diameters in current-year shoots. To evaluate if trees are capable of osmotic adjustment, we measured turgor loss point (TLP), osmotic potential at full turgor, and the concentrations of organic osmolytes (proline, glucose, sucrose, and sorbitol) in leaves throughout the growing season. We found that Ψstem did not drop below − 1.6 MPa, which is well above the Ψ50 and TLP. Irrigated trees (ETc-100) had slightly higher Ψstem than trees without irrigation (ETc-0). The observed conditions in one of the 3 years resulted in similar yields but smaller fruit sizes of the non-irrigated trees. The triploid cultivar 'Red Jonaprince' had typically more negative Ψstem than the diploid cultivar 'Gala Brookfield', but 'Gala Brookfield' exhibited higher limitations in fruit growth during drought and shoot growth during wet periods. Concentrations of all measured osmolytes were higher in leaves of non-irrigated trees of 'Gala Brookfield' and increased during the season, while the pattern was more variable in 'Red Jonaprince'. In summary, our results indicate that 'Red Jonaprince' favours hydraulic efficiency against safety, while 'Gala Brookfield' adopts a more conservative growth strategy. [ABSTRACT FROM AUTHOR]

Yield and oil quality responses to different degrees of water stress have often reported for olive trees, but few studies have addressed how midday stem water potential (Ψstem), stomatal conductance (gs), net assimilation (An), and oil yield respond to rewatering after experiencing water deficit. The objective of this study was to evaluate the responses of Ψstem, gs, and An in olive leaves to rewatering after irrigation cut-off (ICO) periods during 2011/2012, 2012/2013, and 2013/2014 growing seasons. The drip-irrigated olive trees were located in the Pencahue Valley (Maule Region, Chile) and trained to a superintensive hedgerow system with a spacing of 1.5 m within rows × 5.0 m between rows. The experiment included a treatment irrigated to satisfy their water requirement based on a previous study (Ψstem > − 2.5 MPa, T0) and two ICO treatments in a completely randomized design. For the ICO treatments, irrigation was cut-off from fruit set until reaching Ψstem thresholds between − 3.0 and − 3.5 MPa for T1 and − 5.0 and − 5.5 MPa for T2. Once these thresholds were reached, the irrigation was restored to that of the T0 treatment level. In the T1 treatment, Ψstem, An, and gs were all fully recovered from moderate water stress, although the time needed for recovery varied between growing seasons. Except 2012/2013 season, the Ψstem values were fully recovered 14 days from rewatering after severe water stress in the T2 treatment. An and gs values were, however, 19–36% and 33–41%, respectively, less than those observed in T0 treatment after even 14 days of rewatering. Finally, the total oil yield per plant was significantly reduced in most study seasons after severe water stress (T2). These results suggest that the evolution of plant water status must be carefully monitored when water deficits are imposed in superintensive olive orchards to avoid unwanted delays in the recovery of photosynthesis and potential reductions in oil yields. [ABSTRACT FROM AUTHOR]

Irrigation's mineral composition affects plants' water utilization. However, limited data concerning minerals' interactive effects on transpiration hinder the integration of the mineral matrix into irrigation planning. Hence, we set to (1) characterize the effects of mineral availability on almond trees' transpiration and (2) integrate climatic variables and physiological measurements to predict irrigation requirements under various mineral compositions. We constructed 0.9 m3 lysimeters to measure trees' transpiration, hydraulics, growth, and reproduction in a wide range of nitrogen, phosphorus, or potassium concentrations. At peak summer, almond trees' with optimal fertilization transpired 6.5 mm day−1, meeting the potential environmental demands. Potassium had a negligible effect on transpiration, while low phosphorus (≤ 1 mg L−1), low nitrogen (≤ 10 mg L−1), and high nitrogen (≥ 100 mg L−1) concentrations in the irrigation reduced maximal transpiration to 3 mm day−1. Transpiration changes corresponded to the trees' canopy and stem growth rates rather than their stomatal conductance or water potential. We tested multivariable interactions to select parameters for transpiration predictions. A general boosting model (GBM) exhibited better training and validation performances than three alternative computations (linear, nonlinear, or support vector machine), integrating physiological parameters through machine learning. The transpiration predictions were reinforced by their correlation to yield, implying that almond trees' basic annual water requirements are 360 mm, yet they require 900 mm to reach full potential. Our work highlights that irrigation planning could account for fertilization's effects on trees' physiology through computational tools, meteorological data, and physiological parameters that are readily accessible. [ABSTRACT FROM AUTHOR]

Improving water and fertilizer use efficiency in arid and semi-arid regions can not only promote the sustainable development of regional crop production, but also effectively meet the challenges of future global water shortage and food security. Bubbled-root irrigation is a new water-saving irrigation technology developed for arid and semi-arid areas. It not only has the characteristics of precision irrigation (improving water and fertilizer utilization and irrigation efficiency), but also has the advantage of not being easily blocked. In this study, the infiltration capacity, wetting front transport characteristics, water and nitrogen transport, and transformation characteristics of Bubbled-root Irrigation under water and fertilizer coupling conditions were investigated in the arid region of Northwest China. The results showed that under the same infiltration time, the higher the fertilizer concentration, the greater the cumulative infiltration and wetting front (horizontal, vertical upward, and vertical downward wetting front) transport distance. Based on the results, a mathematical model with cumulative infiltration or wetting front as the dependent variable, fertilizer concentration and infiltration time as independent variables was constructed. The model has high reliability (The relative deviation between the fitted value and the measured value is within ± 10%), and can be used to guide the layout of emitters in the field and crop production. Under the same infiltration time, the higher the fertilizer concentration, the higher the content of water, ammonium nitrogen, and nitrate nitrogen in the same soil node. For example, the soil water content of C = 12, 35, 60 g L−1 was 8.35%, 14.37%, 23.31% higher than that of C = 0 g L−1 at 10 cm horizontal and 40 cm vertical to the emitter. At the soil depth of 40 cm, the soil mass water content is 21.46%, 17.06%, 15.50%, and 10.37% at the end of irrigation and 1, 3, and 5 d of redistribution. The contents of ammonium nitrogen in soil are 228.13, 215.43, 183.16, and 116.43 mg kg−1 at the end of irrigation, 3, 5, and 10 d of redistribution, respectively. Redistribution of 5–10 d, soil NH 4 + N content decreased significantly. Distribution of 1–10 d, soil NO 3 - N content showed varying degrees of increase. The research results are helpful to promote the application of spring root irrigation in the world, improve the utilization efficiency of water and fertilizer, and provide a new way to alleviate the pressure of water resources and food security. [ABSTRACT FROM AUTHOR]

We conducted this study considering the global greenhouse effect and world food security to determine a water-saving planting pattern that results in fewer carbon emissions and stable crop yields in the North China Plain (NCP). From 2015 to 2019, we conducted a two-factor winter wheat experiment composed of four treatments, with planting patterns (W, wide-precision planting pattern; and C, conventional planting) as the primary factor and different irrigation timing (I1, 60 mm irrigation at the jointing stage; and I2, 60 mm irrigation 10 days after the jointing stage) as the secondary factor. The treatments were as follows: WI1, WI2, CI1, and CI2. The soil respiration rate, soil carbon emissions, grain yield, and carbon emissions efficiency (CEE) were measured for each treatment. The W treatment resulted in a lower soil respiration rate and reduced soil carbon emissions. The W and I2 treatments resulted in significantly increased grain yields and reduced soil carbon emissions compared to the C and I1 treatments, respectively. The CEE of the WI2 treatment was higher than that of the other treatments. This study demonstrated that the combination of the W planting pattern and delayed irrigation 10 days after the jointing stage was effective in reducing soil carbon emissions while ensuring a stable grain yield in the NCP. The results of this study provide practical evidence for the sustainable development of winter wheat in the NCP. The combination of the W planting pattern and delayed irrigation 10 days after the jointing stage is an agronomic technique worth popularizing. [ABSTRACT FROM AUTHOR]

Cascade rice flood distribution (CASC), the predominate method used for rice irrigation in the lower Mississippi River basin (LMRB), is inherently water intensive owing to the need to overfill rice paddies to move irrigation water from one paddy to the next. The objectives of this research were to devise practices that make CASC more water efficient, assessing how early cascade rice irrigation shutoff (ECIS) impacts applied irrigation, run-off, and flood depth under LMRB rainfall conditions. This research used a conservation-of-mass model to show that using flood depth in the penultimate rice paddy to trigger irrigation shutoff in a 16-ha simulated rice field results in nominal irrigation water savings of 23% relative to CASC. This savings was reduced to 15% when supplemental irrigation was added to the last paddy at two critical stages of rice production. Field run-off estimates for ECIS were reduced by up to 78% relative to a CASC for both clay and silt loam soils, demonstrating how with ECIS the last paddy of a rice field acts as a 'catch basin' for excess up-field irrigation and uncaptured rainfall. Flood depth estimates for the last paddy resulting from ECIS resembled those of alternate wetting and drying flood management (AWD), suggesting that the agronomics developed for AWD could be used to help address production issues arising in the catch basin from ECIS. Success in coupling ECIS with irrigation automation technologies could reduce aquifer withdrawals across the rice producing areas of the LMRB. [ABSTRACT FROM AUTHOR]

Indian pennywort (Centella asiatica (L.) Urban) is an important herbal plant with valuable medicinal properties. Irrigation with optimum freshwater is a basic crop requirement for plant growth, development, and secondary metabolite enrichment. The objective of the study was to evaluate the effect of different irrigation regimes on plant morphological, physiological, and biochemical responses as well as total centelloside content. Leaf greenness (SPAD), maximum quantum yield of PSII (Fv/Fm), and photon yield of PSII (ΦPSII) in plants grown under 64% field capacity (FC) were significantly reduced by 31.60%, 7.65%, and 25.91%, respectively, compared with plants grown under well irrigation (control; 100% FC). Remarkably, net photosynthetic rate (Pn), stomatal conductance (gs), and transpiration rate (Tr) in plants grown under 64% FC were more sensitive to water shortage, leading to a decline by 68.76%, 87.50%, and 84.08%, respectively, over the control. Leaf temperature (Tleaf) and crop water stress index (CWSI) under limited irrigation conditions (64% FC) were, respectively, increased by + 3.97 °C and 0.72 over the control in relation to decreased Tr (0.43 mmol H2O m−2 s−1) and altered stomatal functions indicated by low gs (0.02 mmol H2O m−2 s−1). Enhancement of glucose (2.70-fold over the control), fructose (2.14-fold over the control), and total soluble sugar (2.52-fold over the control) played a key role in osmotic adjustment when plants were exposed to moderate irrigation conditions (75% FC). Asiaticoside, asiatic acid, and total centellosides in the leaf tissues were enriched under limited irrigation conditions than those in the control, leading to the maximum centellosides yield at 75% FC. Number of green leaves, leaf area, stolon length, and shoot fresh weight in moderately irrigated plants (75% FC) were increased by 1.23, 1.24, 1.13, and 1.15-folds, respectively, over the control. The basic information obtained from this investigation provides a better understanding of the response of Indian pennywort under limited irrigation schedule and suggests an alternative way to manipulate biomass production and yield of total centellosides using moderate level of irrigation (75% FC). [ABSTRACT FROM AUTHOR]

Sustainability in irrigation has become a major concern as water scarcity threatens sustainable development. In the present study, an Irrigation Sustainability Index (ISI) has been developed and proposed for application in agricultural basins. The ISI uses indicators of four dimensions of sustainability: economic, social, institutional, and environmental, and it was tested in the Segura River Basin in southeastern Spain. The results evidence the (un)sustainability of the system in 17 out of the 62 irrigation districts in the Segura Basin, mainly due to farmers' low income, the overexploitation of aquifers, and the high demand for water for crops. On the other hand, 45 out of 62 irrigation districts showed moderate and high irrigation sustainability, mostly located along the Segura River and other streams, in the so-called "traditional agroecosystems". The index application evidenced the prioritization of economic over environmental aspects and generated data to develop future policies in the region. [ABSTRACT FROM AUTHOR]

Irrigation water is an expensive and limited resource and optimal scheduling can boost water efficiency. Scheduling decisions often need to be made several days prior to an irrigation event, so a key aspect of irrigation scheduling is the accurate prediction of crop water use and soil water status ahead of time. This prediction relies on several key inputs including initial soil water status, crop conditions and weather. Since each input is subject to uncertainty, it is important to understand how these uncertainties impact soil water prediction and subsequent irrigation scheduling decisions. This study aims to develop an uncertainty-based analysis framework for evaluating irrigation scheduling decisions under uncertainty, with a focus on the uncertainty arising from short-term rainfall forecasts. To achieve this, a biophysical process-based crop model, APSIM (The Agricultural Production Systems sIMulator), was used to simulate root-zone soil water content for a study field in south-eastern Australia. Through the simulation, we evaluated different irrigation scheduling decisions using ensemble short-term rainfall forecasts. This modelling produced an ensemble of simulations of soil water content, as well as ensemble simulations of irrigation runoff and drainage. This enabled quantification of risks of over- and under-irrigation. These ensemble estimates were interpreted to inform the timing of the next irrigation event to minimize both the risks of stressing the crop and/or wasting water under uncertain future weather. With extension to include other sources of uncertainty (e.g., evapotranspiration forecasts, crop coefficient), we plan to build a comprehensive uncertainty framework to support on-farm irrigation decision-making. [ABSTRACT FROM AUTHOR]

Optimizing planting density and irrigation depth of hybrid maize seed production is important for ensuring food and water security. A higher planting density increases grain yield to a certain level, but decreases seed vigor. Therefore, the aim of this study was to establish an integrated model that optimized planting density and sufficient border irrigation depth to increase yield, ensure the vigor, and save water for hybrid maize seed production in an arid region. The integrated model was based on the modified AquaCrop and single crop coefficient models to predict grain yield and evapotranspiration, respectively. Kernel weight was estimated by grain yield and kernel number, and a monomolecular model was used to fit kernel number per plant and plant growth rate during the flowering stage. An exponential relationship was found between kernel weight and seed vigor. The maximum grain yield and minimum irrigation depth were weighted in the objective function, and different scenarios of seed vigor were constrained. Integrated model parameters were calibrated and validated using data from experiments conducted during 2012 and 2015 and 2018 to 2019 in Gansu Province of Northwest China. The modeling results showed that although the highest grain yield of 685.1 g m–2 was obtained for the planting density of 12.47 plants m–2, seed vigor decreased by 20% (decreased kernel weight by 5.5%). Comparison with different scenarios, a planting density of 11.30 plants m–2 was recommended, which increased grain yield by 5.7%, and ensured seed vigor by 90% (decreased kernel weight by 2.7%). To ensure sufficient irrigation in the median water year, the optimal irrigation depths for this planting density at the vegetative, flowering, and grain filling stages were 79.8, 140.0, and 145.3 mm, respectively, which reduced total irrigation depth by 27.0%. The integrated model is a useful tool to decrease irrigation amounts and increase yield of hybrid maize seeds in the arid areas of Northwest China. [ABSTRACT FROM AUTHOR]

There are multiple methods being used for scheduling irrigation applications that range from weather-based to ground-based methods. Growers must choose a method that is ideally both accurate and economical to use in a production agriculture system. One method that has been used is model-based scheduling. In this study, the CROPGRO-Soybean model in the Decision Support System for Agrotechnology Transfer (DSSAT) was used to simulate the growth and development of irrigated soybean for a production soybean field throughout the 2018 and 2020 growing seasons. Model predictions were compared to soil moisture data recorded from 44 sensor sets placed across the field on a 55- × 55-m grid at depths of 31 and 61 cm. Results showed that the model accurately predicted plant height and LAI in 2018 and 2020. In both seasons, the model underpredicted soil moisture and occasionally did not respond to irrigation or rainfall. Even though the model underpredicted soil moisture, it predicted fewer irrigation events and half the cumulative amount in 2018 than the farmer applied and similar irrigation events and quantity in 2020. DSSAT predicted yield well for both years as compared to measured yields, indicating the farmer may have over-irrigated in 2018. This study advances the application of DSSAT for estimating soybean vegetative characteristics and irrigation scheduling in a production environment. [ABSTRACT FROM AUTHOR]

Desalinated seawater (DSW) is currently considered a reliable alternative supply of agricultural water in south-eastern Spain able to alleviate the looming water crisis as it buffers natural hydro-climatic volatility. However, irrigation with DSW may pose an agronomic risk because reverse osmosis permeates usually have high boron concentrations, representing a real toxicity damage risk for sensitive crops. Boron reductions to at least 0.5 mg/L, either on-farm or at the coastal seawater desalination plant, should be performed before irrigating with DSW, especially in areas with sensitive crops. The regional economic impact of reducing boron in diverse irrigation districts covered with different crops has never been evaluated. In this article, that impact is analyzed considering three scenarios replacing traditional irrigation water resources with DSW, and two boron reduction technologies: reverse osmosis membranes (RO) and ion exchange resins (IX).The results reflected that: (i) boron reduction by IX is notably cheaper than by RO; (ii) at seawater desalination plant scale, the boron reduction cost remains constant regardless of the crop type, whereas at on-farm scale the higher the surface area covered by vegetables the lower the boron reduction cost; and (iii) the volume of by-product generated in resin regeneration is 40 times lower than that in the RO process, so consequently its handling and management would be far easier and less costly. Additionally, the study corroborates that the combined use of DSW with traditional resources is the most economically efficient option from the different perspectives of the study, compared to irrigating with DSW alone. [ABSTRACT FROM AUTHOR]

Surface irrigation methods need less capital investment and energy than pressurized systems, and therefore they have a wide range of use in many regions. However, inaccurate system design and irrigation applications lead to non-uniform distribution of water in the soil profile. Therefore, the water loss caused by deep percolation increases, and the water application efficiency decreases. In this investigation, a new method was devised for the optimum design of a blocked end furrow system. The new method simulates the movement properties of water in the soil. It analyzes interactively and simultaneously the infiltration characteristics of the soil, the inflow to the furrow and the irrigation water requirement of the crop. The spatio-temporal variation of the wetting pattern which occurs during the water application period and of the components of the wetting pattern can be determined momentarily for any time point during the irrigation application. This process is carried out by running the movement equations of water in the soil, which are described in this investigation. The proposed method was run for two different sample applications of blocked end furrow systems without slope. In the verification process of the model, the sample applications were compared with the results of the USDA SCS method. The results from the two different methods were compared and analyzed in detail. In conclusion, the results from the proposed method gave the optimum solution for different conditions. [ABSTRACT FROM AUTHOR]

Following reduced irrigation strategies in the north China plain (NCP), nitrogen (N) fertilizer application must be optimized in terms of the food production and resource use efficiency. In this study, experiments were conducted for three consecutive winter wheat seasons in 2013–2016. Treatments included pre-sowing irrigation of 750 m3 ha−1 season−1 with no subsequent irrigation during the whole season (W0) and irrigation of 750 m3 ha−1 season−1 at pre-sowing, jointing and anthesis (W2). N fertilizer was applied at sowing with three levels, i.e., 180 (N1), 225 (N2) and 270 (N3) kg ha−1 for each irrigation regime. Results exhibited that the average wheat yield of W0 was 17.3% lower than that of W2, however, the increased thousand kernel weight under W0 upheld relatively high yield averaging 7328 kg ha−1. In addition, increased water stress under W0 aided to improve pre-anthesis dry matter and N remobilization to grain which in turn, made larger N use efficiency and N harvest index. Furthermore, grain protein content ranged from 13.4 to 13.7% under W0, 13.0 to 13.3% higher than that of W2. At both irrigation levels, grain yield and grain protein content increased with an increase in N application rate, while no significant difference was observed between N2 and N3 under W0. Additionally, the N2 achieved the highest water use efficiency of 1.92 kg m−3 under W0. Overall, N2 appeared to be the optimized N level under W0 in terms of yield and nitrogen use, though it was 13.6% less than the largest net income under W2N3 due to 18.9% of yield loss. Moreover, W0N2 could reduce 1500 m3 ha−1 season−1 irrigation water, 45 kg ha−1 N fertilizer and 289.77 $ ha−1 total input and attain highest cost efficiency. The study demonstrated that disposable water and nitrogen applied at sowing of wheat is feasible, and N application rate of 225 kg ha−1 was recommended for the W0 regime to maximize wheat yield, grain quality, ecological and economic benefits. [ABSTRACT FROM AUTHOR]

Centrifugal filters commonly used in irrigation systems are able to separate coarse-grained sediments larger than 100 μm. Improving the filter structural characteristics and separation efficiency of fine-grained sediment has become an issue that needs to be solved. Therefore, a combination of experiment and numerical simulation was used to assess the effect of volute optimized design and semi-closed inlets on centrifugal filter separation efficiency and energy consumption. The results show that balancing the relationship between the separation efficiency and head loss, the improvement of the filter structure optimizes its internal flow field, and the filter head loss can be appropriately increased to greatly improve the separation efficiency of fine sediment. Compared with a conventional centrifugal filter, the volute optimized centrifugal filter synergistically improved the fine particle separation efficiency (22.83–123.19%) and reduced the head loss (39.06–45.98%), while the semi-closed inlet improved the separation efficiency of particle diameters above 30 μm by 14.29–60.56% and increased the head loss (18.73–28.16%). The combination of the two previous improvements and the reduction of the filter volume further improved the separation efficiency (21.99–65.10%) but gradually increased the head loss. This study provides a new perspective for improved centrifugal filters with an efficient, broadly applicable experimental design for studying the potential implications for highly Turbidity water utilization in irrigation. [ABSTRACT FROM AUTHOR]

For a drip irrigation system, different lateral layouts and water feeding modes may be used. Furthermore, the actual operating conditions may greatly deviate from the designed ones, deteriorating system performance of irrigation and fertigation. Field experiments were conducted to evaluate the seasonal variation of the hydraulic performance of three drip irrigation subunits with either single end or dual ends water feeding modes. The results showed that the dual water feeding mode reduced the pressure variation (hvar) by 15% compared with the single end feeding subunit when the system was operated at an extremely low pressure of around 0.011 MPa, which obviously improved the uniformity of water and fertilizes applied. A reduced statistical uniformity of water (Usw) was observed during the irrigation season, from 80–86% at the beginning of the irrigation season to 62–67% at the end of the irrigation season. The evaluation also revealed that the statistical uniformity of fertilizers applied (Usf) was about 5% lower than the Usw due to the inconsistent distribution of water and fertilizers in the subunit. Quantification of the influencing factors that led to nonuniform water distribution in a subunit indicated that more than 50% of the water nonuniformity was caused by pressure imbalance in the early irrigation season. Then the progressively increasing emitter clogging became a major contributor since the middle irrigation season whether the water was fed from one end or dual ends of the laterals. This study showed that dual ends water feeding mode was promising to improve the water and fertilizers distribution for a drip irrigation system, especially when the system was operated at a low pressure. [ABSTRACT FROM AUTHOR]

Drip irrigation combined with film mulching significantly improved water saving and agricultural efficiency in arid and semi-arid regions. However, the impact of various irrigation technical parameters under plastic film-mulched (PM) drip irrigation on water consumption and maize yield (Zea mays L.) for seed production is still unclear. Field experiments were conducted between 2016 and 2018 in Northwest China to investigate the effects of irrigation technical parameters (dripper discharge and irrigation interval) on biomass, grain yield, water, and nitrogen (N) use efficiency of the PM-maize for seed production. Four dripper discharges (1.38 L h−1, 2.0 L h−1, 2.5 L h−1, 3.0 L h−1) and five irrigation intervals (6 days, 8 days, 10 days, 12 days, 14 days) were selected. The normalized yield was used to analyze the effect of different treatments on the yield to eliminate the differences caused by uncontrollable factors, such as precipitation and temperature between different years. The results indicated a quadratic function among the final aboveground biomass, grain yield of maize for seed production, and irrigation intervals, with the highest value observed at 8 days irrigation interval. Both yield and nitrogen use efficiency measured as partial factor productivity of nitrogen (PFPN) decreased rapidly as the irrigation interval exceeded 10 days. When the irrigation interval increased from 10 to 14 days, the relative grain yield decreased between 6.5 and 16.0%, while the PFPN decreased between 1.1 and 99.2 kg kg−1. Crop evapotranspiration (ET) initially decreased and then increased as the irrigation interval increased. The water productivity (WPY-ET) was the highest at the irrigation interval of 8 days. The PFPN increased between 6.6 and 42.8 kg kg−1 at the dripper discharge of 3.0 L h−1 when compared with dripper discharge of 2.5 L h−1. The study showed an optimal dripper discharge–irrigation interval combination for maximizing water-resources utilization and yield increase. When biomass, grain yield, ET, and WPY-ET are considered simultaneously, the most suitable irrigation technical parameters of maize for seed production in Northwest China are the combination of 2.5 L h−1 and 8 days. Furthermore, a combination of 3.0 L h−1 and 8 days is more conducive to reducing fertilizer costs. [ABSTRACT FROM AUTHOR]

Gong et al. ([6]) develop an irrigation water optimization model that applies a crop water allocation priority model (validated in the field) to quantify the changes in three indicators: yield, economic benefits, and irrigation water productivity. However, irrigation scheduling is typically conducted based on simple water requirement calculations without accounting for the strong link between water movement in the root zone, crop yields, and irrigation expenses. Moreover, it highlights that site-specific crop coefficients, accounting for local and time-variable conditions in the field, can improve crop water requirement predictions, irrigation scheduling and thus, can also forward the implementation of precision irrigation strategies. [Extracted from the article]

Freshwater scarcity and soil salinity are amongst the main obstacles for sustainable development of irrigated agriculture, particularly in arid regions. A 2-year field investigation was conducted at an experimental field in south-east Iran during the 2017 and 2018 growing seasons to evaluate the individual and integrated effects of water-saving irrigation strategies and organic soil amendment (OSA) applications on yield and water productivity of ajwain (Trachyspermum ammi), which is known as an important medicinal plant in Iran. A split-plot design with 16 treatments was used in the field trial. Treatments were created by combining four irrigation strategies, including full irrigation with freshwater [FF], partial root-zone drying (PRD) with freshwater (PF), PRD with saline water (PS), and PRD with alternating application of fresh and saline water (PFS), were combined with four types of soil amendments, including no amendment (control), charcoal nano-biochar (NB), composted cow manure (CM), cow manure vermicompost (VM). Results showed that in the absence of OSA application, exposing crops to salinity/water stresses caused 3.7–17.6% and 4.5–17.7% reduction in the crop's seed yield and above-ground biomass, respectively, while enhancing the crop's oil concentration and oil yield by 9.1–30% and 1.4–18.3%, respectively. Along with a 34–63% freshwater saving, a 24.9–91.2% increase occurred in the crop's water productivities compared to the FF treatments. Integrating OSA application with freshwater-saving irrigation caused up to 58, 27.1, 60, 138, and 285% increase in the crop's seed yield, biomass, oil concentration, oil yield, and water productivity, respectively, compared to the FF-control treatment. However, VM performed best, and CM took second place. Based on the results, it can be concluded that such integrations provide opportunities for developing Ajwain's production in arid regions with limited access to freshwater resources. [ABSTRACT FROM AUTHOR]

The responses of rice production to irrigation and fertilization under varying field conditions have been determined in previous studies. Obtaining a better understanding of the intrinsic mechanisms by which irrigation and fertilization regulate rice production can support field operations and recommendations. This study investigated the potential role of humic acid as opposed to traditional nitrogen fertilizer (urea) for regulating rice production under different irrigation conditions by identifying dry matter, radiation use efficiency (RUE) and grain yield indicators. Fifteen treatments were designed in combination with a field test; three irrigation practices (control irrigation (C), flood irrigation (F) and wet irrigation (W)) and five fertilization levels (100% urea (T1), 30% humic acid and 70% urea (T2), 50% humic acid and 50% urea (T3), 70% humic acid and 30% urea (T4), and 100% humic acid (T5)) were tested. The results demonstrated that the humic acid applications and irrigation practices affected rice production, and the lowest leaf area index (LAI) value was obtained under the WT2 treatment. Under the T4 and T5 treatments, the dry matter contents were significantly higher than those measured under the T2 treatment under the same irrigation practices. When comparing the average RUE variation within each experiment during the whole study period, the highest RUE values obtained in 2018 and 2019 were 2.21 and 2.09 g∙MJ−1, respectively, both of which were obtained under the CT5 treatment. The grain yield and irrigation water use efficiency (WUEi) obtained under the CT5 treatment were better than those obtained under other treatments. Multi-objective decision-making and evaluations based on the improved Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS) method showed that the T5 treatment performed best under the control irrigation conditions. Planting rice under control irrigation practices combined with humic acid applications can effectively reduce the amount of irrigation water required and increase rice production. Control irrigation not only meets the current grain yield requirements but also plays a role in conserving water, while the application of humic acid reduces the required amount of urea. [ABSTRACT FROM AUTHOR]

Traditional static design approaches are often challenged by multifaceted uncertainties such as climate change, future demand, supply options, high-tech opportunities as well as budgetary constraints. However, robust approaches that incorporate the option of flexibility combined with optimization advances are likely to meet threshold performance criteria with the least amount of associated expenses. To this aim, several countries have started the process of modernizing their irrigation schemes, foreseeing their on-demand operation. The re-modernized schemes are facing the challenge of the inadequacy of the service reported by the users/ratepayers, whose livelihoods are threatened by it as they mainly rely on agricultural production, and the sustainability of the modernization process. This study develops an adaptive framework that applies a two-pronged approach: it incorporates, on the one hand, a qualitative analysis through a rapid appraisal procedure (RAP) that fills the big data-gap issue, and a top–down approach on the other hand, mainly based on an iterative process that assesses the correlation between the flexibility of the service provided under uncertainties, as well as the financial feasibility. The latter is associated with the sensitive parameters of Clément's first formula mainly used in the Mediterranean Region to design on-demand irrigation systems, and more specifically: the elasticity assigned at the feed hydrant of the distribution network, the coefficient of utilization of the network in the peak period, and the quality of the service. Applied to a Tunisian case study, the results clearly show that when adequately combining the flexibility levels of these parameters, an optimal quality service may be achieved with an average cost increment ranging between 13 and 16%, with a view of proactively increasing the resilience of the irrigators' community. [ABSTRACT FROM AUTHOR]

One of the greatest challenges in recent years is providing enough food to feed the increasing world population, while available freshwater resources become limited. However, effective fertilizer management has also a fundamental role to improve yield quality and quantity. A field experiment was conducted over 2 years, using a split-plot arrangement in a randomized complete block design. The experiments had three water deficit severity treatments: 25% (control), 40% (mild stress), and 55% (severe stress) depletion from the available water. The subplot division consisted of six fertilizer treatments; FR1: unfertilized (control), FR2: 140 kg ha−1 urea; FR3: 105 kg ha−1 urea + 3.3 ton ha−1 vermicompost; FR4: 70 kg ha−1 urea + 6.6 ton ha−1 vermicompost; FR5: 35 kg ha−1 urea + 10 ton ha−1 vermicompost, and FR6: 13.5 ton ha−1 vermicompost. The maximum essential oil (0.97%) was observed under mild water deficit stress. The highest antioxidant activity (DPPH) and superoxide dismutase activity could be monitored under unfertilized and 140 kg ha−1 urea fertilized conditions, respectively. Vermicompost-treated soils reduced antioxidant features, total phenol, and rosmarinic acid content under water deficit. These results indicate that mild drought stress can increases the synthesis of medical compound and vermicomposting can alleviate the impact of drought by conserving soil moisture and improve nutrient uptake. Therefore, the results suggest that using vermicompost as a fast-acting nitrogen amendment can improve the leaf area index. [ABSTRACT FROM AUTHOR]

The production of nursery crops demands substantial irrigation, with overhead irrigation the most common method of application; however, this method is inefficient with respect to water used and the precision with which it is applied, resulting in the generation of irrigation return flow and concomitant agrochemical export. Microirrigation systems such as individual container spray stakes provide water directly to crops thus applying water more efficiently than overhead systems but may be more costly in terms of installation (smaller pipes and components; however, a greater quantity of pipes and components) and maintenance. The study was conducted at the Michigan State University Research Nursery, where four ornamental shrub taxa were produced in #3 (11.3 L) containers using a control with 19 mm overhead irrigation per day and a conventional phosphorus fertilizer (Conv) (19-2.16-6.64), compared with four treatments: a static, daily (2 L per container) spray stake irrigation (SS2Lpd) and conventional phosphorus fertilizer; a static daily (2 L per container) spray stake irrigation and low phosphorus fertilizer (LowP) (19-1.62-6.64); spray stake irrigation based on substrate volumetric water content (θ) (up to 2.4 L per container) (SSθ) and conventional fertilizer; and spray stake irrigation based on θ (up to 2.4 L per container) and low phosphorus fertilizer. Spray stakes reduced irrigation by 76–80% compared to the overhead control, and reduced the generation of both surface and subsurface irrigation return flow (IRF), mitigating the movement of both N and P (over 98% reduction in surface IRF). Plant growth index (GI) was measured on 12 June 2017 and 6 October 2017, followed by a destructive harvest to measure shoot dry weight, and shoot nutritional content. For all four taxa, microirrigation systems were capable of producing plants of equivalent GI and shoot nutritional concentration; however, plants receiving the low phosphorus fertilizer produced less shoot biomass. Microirrigation is effective in reducing water use, water lost to IRF (particularly surface IRF), and associated fertilizer movement, while maintaining crop size. [ABSTRACT FROM AUTHOR]

Water-saving technologies (WSTs) have been publicized for many years in the North China Plain. However, WSTs are not well accepted and farmers have a preference for traditional irrigation technology rather than modern ones. This paper examines determinants of adopting traditional or modern WSTs, especially effects of water scarcity. Using cross-sectional data of 267 farm households, we first categorized households into two groups—poorly endowed and well endowed in terms of a water scarcity index produced by principal component analysis (PCA). Then, a bivariate probit model is used to analyze how water scarcity influences farmers' technology adoption decisions. The study found that the different factors influence technology adoptions between poorly and well-endowed households. Farm size and membership are found to have a significant effect on the adoption of WSTs only in poorly endowed households. Other factors (education, extensive service, relatives, water scarcity index, and irrigation cost) not only influence the poorly endowed but also have an impact on the well endowed. What is more, different factors are found to affect adoption of traditional technology (furrow irrigation) and modern technology (underground pipes), respectively. It is also found that family labor and plots only significantly influence the adoption of furrow irrigation while information quality and labor-saving potential are significantly associated with the adoption of underground pipes. In particular, off-farm work has a positive effect on adoption of underground pipes but has a negative effect on adoption of furrow irrigation. Therefore, different strategies of WST promotion should be taken to different households and different technologies. [ABSTRACT FROM AUTHOR]

Pressurised irrigation networks with a certain degree of automation allow centralized fertigation and maintenance operations such as cleaning subunits and preventing the proliferation of invasive species such as zebra mussels. Until now, there is no methodology that guarantees the total cleaning of the network of a substance in the shortest possible time. In the same way, it does not exist to guarantee reaching all consumption points with a certain concentration of a substance, injecting the minimum possible amount. For that purpose, a general novel methodology has been developed that makes use of the network's hydraulic model and parallel multi-objective genetic algorithms to flush the network of a certain substance or to get it to all consumption points in the shortest possible time and supplying a minimum volume. This method assumes that the available pressure at the source is always over a minimum value. The arrival times to the consumption points are minimized and the injected volume is reduced to the minimum of replacement, that is, the volume of the network pipes. The methodology applied to the study case allowed the entire network to be flushed in a minimum time of 2.46 h. On a normal irrigation day, without making any changes to the irrigation schedule the time to completely flush the network is 11.76 h. Furthermore, the injected volume differs greatly from the total volume of the pipes. [ABSTRACT FROM AUTHOR]

Improving the management of irrigation schemes is a priority in the Mediterranean countries of the EU to achieve the objectives of the Water Framework Directive 2000/60EC. In the case of schemes based on open-channel networks for water conveyance and delivery, a limitation to the management efficiency is the huge number of gates that need to be controlled and regulated manually to adapt the flow to the actual irrigation water demand. Automated and coordinated gate regulation of large irrigation schemes has been successfully implemented in some areas of the world (e.g., NSW, Australia), but it implies huge public investments that are often unavailable. Opposite to this top–down approach, the Lombardy region (the largest irrigated region in the EU) has explored an approach based on funding small projects, which should demonstrate the potential of innovation in irrigation practice and foster the expansion of the most effective measures. In this paper, we analyze the effects of one of these projects, consisting in the substitution of a manual gate, controlling the supply of irrigation to a 150 ha irrigation district, with an automated, remotely controlled gate. Nine years of daily flow measurements at the district inlet, provided by the irrigation consortium that manages the gate, were compared with the rigid flow regulation that was applied when the inlet gate was manually regulated and with the irrigation water requirements simulated with a distributed agro-hydrological model widely used in the region for irrigation accounting and planning. The results show that the flexible regulation allowed by the new gate provided an average water saving of 12,000 m3/ha/year compared to the rigid regulation system. A further, though smaller, margin of improvement of 5000 m3/ha/year can be achieved with an optimal regulation that follows exactly the crop water requirements. A further interesting empirical evidence is that the simulation model fits very well the irrigation water requirements of the district using only easily accessible meteorological input data, without exploiting any information from ground or remote sensors to update soil moisture or crop developments during the season. This indicates that it could be effectively used, with very limited costs and effort, to support and improve the gate management. Finally, a preliminary economic analysis shows that the cost of the gate installation is sustainable, but the upscaling of this type of intervention to larger areas requires the support of public funding to cover approximately half of the cost of investment needed for the networking infrastructures. [ABSTRACT FROM AUTHOR]

P1, P3, P5 are the irrigation intervals at 6, 10, 14 days, respectively. P5D are treatments with an irrigation interval of P5 The original article has been corrected. [Extracted from the article]

Conducting field experiments to determine an optimal strategy for managing water consumption in paddy fields is quite time-consuming and expensive. This study applied HYDRUS-2D model to simulate fluctuations in water level and nitrate transfer over the 2 years of 2013 and 2014 at Rice Research Institute of Iran (Rasht). To monitor water-level fluctuations, a piezometer was installed in the plot. Three irrigation management regimes were considered: first, permanent water flooding or irrigating by as much as 1.3 times the amount of evaporation from the evaporation pan (I1); second, applying irrigation treatment by one time the amount of evaporation from the evaporation pan (I2); third, irrigating by 0.7 times the amount of evaporation from the evaporation pan (I3) from the transplanting date to the end of irrigation period (10 days before harvest). Two fertilizing treatments were considered, i.e., C1 = 60 kg N ha−1 and C2 = 60 kg N ha−1 + 5000 kg compost ha−1 equal to 160 kg N ha−1. After model run, observed and simulated values were compared using EF (efficiency factor), RMSE (root-mean-squared error), and nRMSE (normalized root-mean-squared error) indices. The results of EF, RMSE, and nRMSE with respect to water-level changes at the calibration stage were 0.94, 5.39 cm, and 7.6%, respectively. At the validation stage, the results of EF, RMSE, and nRMSE were 0.96, 2.25 cm, and 3.2%, respectively. The nRMSE index showed the model's excellent performance in simulating water-level changes. In the case of nitrate transfer, at the calibration stage, the EF values at the two fertilizer levels of C1 and C2 were 0.60 and 0.85, and nRMSE values were 27 and 9.97%, respectively. At the validation stage, the EF values at the two levels of C1 and C2 were 0.60 and 0.99, and nRMSE values were 13.7 and 1.3%, respectively. Based on the values of nRMSE index, the performance of the model in simulating nitrate transfer was shown to vary in the medium-to-excellent class. Overall, the simulation results showed that the HYDRUS-2D model exhibited an appropriate ability to simulate water movement and nitrate transport either from chemical or compost sources; therefore, it can be used for irrigation and fertilizer management in the case of paddy fields to analyze different scenarios. [ABSTRACT FROM AUTHOR]

In North Florida, increasing nitrogen loads and water quality declines have become a major concern, in part as result of anthropogenic non-point source activities such as agriculture. The main objective of this study was to investigate the effect of irrigation strategies and nitrogen (N) fertility rates on maize biomass, yield and water productivity in sandy soils. The field experiment was conducted 2015–2017 in Live Oak, Florida using a randomized complete block with a split plot design and four replicates. Treatments evaluated five irrigation strategies: (i) GROW, mimicking grower irrigation practices in the region, (ii) SWB, using a soil water balance to schedule irrigation; (iii) SMS, using soil moisture sensors to schedule irrigation; (iv) RED, applying 60% of the GROW treatment; and (v) NON, non-irrigated, and three N fertility rates: (i) low (157 kg N/ha), (ii) medium (247 kg N/ha), and (iii) high (336 kg N/ha). In comparison to GROW, the SWB, SMS and RED irrigation treatments showed no differences in final biomass, N uptake nor grain yield; however, these treatments achieved on average 41, 47, and 36% irrigation reduction, respectively, without impacts on yield during the three maize seasons evaluated. For most of the variables, statistical differences were found between the low and the high N rates, but no differences compared to the medium N rate. A 26% reduction of N fertilizer was achieved using the medium N rate without negative impact on N uptake, biomass nor yield in comparison to the high N fertilization rate. During this experiment, maize N uptake reached a plateau; thus, potential N losses resulted from applications exceeding recommended rates. Furthermore, the implementation of these more efficient irrigation and N fertilizer management strategies reduced irrigation and N fertilizer applications without negative impacts in yield. Thus, these practices may prevent potential N leaching to waterbodies while improving profits. [ABSTRACT FROM AUTHOR]

With the assumption that the water advance and the infiltration opportunity have an exponential relationship, a new equation was derived to estimate the time of water advance along a surface-irrigated field. Using the derived advance equation, a new method was developed for estimating the Kostiakov–Lewis infiltration parameters. The proposed advance equation and Elliot and Walker's advance equation (two-point method) were evaluated using field advance data from seven locations. The evaluation results were based on the dRMS and NSE indices, which showed the superiority of the proposed equation. The advance equations were compared based on their infiltration depth differences and a comparison showed the superiority of the proposed equation. Also, the average values of infiltration depth in the average actual and computed infiltration opportunity time of the advance phase, and the average infiltration opportunity of the total irrigation time, were compared to the average values of actual infiltration depth using the relative error index. Results showed that the proposed method more accurately estimated the average infiltration depth with an average relative error 5.27% for total irrigation time, 1.90% for average computed infiltration opportunity, 1.80% for average actual infiltration opportunity, and 3.86% for infiltrated depth difference in more than 75% of the cases. The proposed equation and the new method for calculating infiltration coefficients can be recommended for practical use. [ABSTRACT FROM AUTHOR]

Improving irrigation efficiency on farms is crucial in securing a sustainable future for irrigators as well as the environment, especially in water scarce regions such as Australia. More efficient irrigation designs are increasingly being investigated using irrigation simulation models but there is a dearth of readily available two-dimensional (2D) models for investigating surface water flow within irrigation bays. This paper adapted the 2D ANUGA open source model to simulate border and basin irrigation by incorporating an infiltration algorithm based on the modified Kostiakov equation. The algorithm was successfully incorporated in ANUGA and the adapted model, ANUGA_MK, was tested using eight border and two basin irrigation events. ANUGA_MK performance was benchmarked against the one-dimensional (1D) SISCO irrigation model for border irrigation events, against the 2D B2D basin irrigation model for basin irrigation events and against observed data. ANUGA_MK adequately simulated surface water advance and depth. SISCO's total infiltration was comparable to that of ANUGA_MK, but its spatio-temporal dynamics differed due to differences in representation of microtopography. For example, the 1D SISCO model did not account for surface depression water storage remaining long after cessation of runoff. Performance of ANUGA_MK was similar to that of B2D in simulating basin irrigation. ANUGA can represent surface water flow on complex surfaces with diverse boundary conditions, and with an appropriate infiltration algorithm, has been adapted as a surface irrigation model that can be used to investigate bay surfaces engineered to improve surface drainage. [ABSTRACT FROM AUTHOR]

The irrigating winter wheat one or two times each season was practiced in Huanghuai Winter Wheat Region in order to reduce the over-exploitation of groundwater. In this study, plant height (PH) and its relationship with yield were analyzed in a field study conducted over three growing seasons with 102 wheat varieties irrigated zero to two times at different growth stages. Here, we found that irrigation at the jointing stage increased wheat PH by 6.60–9.70%. Whereas irrigation at the early milking stage had almost no effect on it. Against the wildtype alleles Rht-B1a and Rht-D1a, the genetic background of Rht-B1b and Rht-D1b significantly reduced PH by 14.40–15.50% and 16.90–19.10%, respectively. The combined Rht-B1b and Rht-D1b can reduce PH by 29.10–32.50%. PH was strongly, negatively correlated with grain yield in jointing irrigation (W1) or jointing + milking irrigation (W2) over three growing seasons. In contrast, a significant positive correlation was detected in no-irrigation (W0) in the 2012/2013 wheat growing season, yet no correlation was found in 2013/2014 and 2014/2015. PH was positively correlated with drought coefficient (DRC) in W1 and W2. These results augment our understanding of the relationship between PH and grain yield in different irrigation regimes and provide PH traits for wheat improvement on water saving. [ABSTRACT FROM AUTHOR]

Surface irrigation, particularly furrow irrigation, is the most common method of water application into agricultural lands. Despite all its advantages, furrow irrigation has some demerits, such as a potential large volume of runoff losses. In this research, an approach was proposed to reduce runoff losses and to improve water flow characteristics by creating micro-dams, barriers inside the irrigated furrows. To control water flow and increase infiltration into the soil, experimental micro-dams were created at distances of 10 and 20 m, with a height of 5 cm. Field experiments were conducted at the research farm of the College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran in summer of 2018. Two erosive inflow rates (0.6 and 0.9 L/s) were considered. Furrow length and spacing were 100 and 0.75 m, respectively. Results indicated that micro-dams increased the advance time, leading to increased infiltration. Micro-dams also increased the recession time, due to the increase in overland water volume. Moreover, results showed that in treatments with micro-dams, runoff was reduced by up to 45.3% in comparison to the control treatment. The change in furrow cross-sectional area during the irrigation event was also reduced. Micro-dams showed a great potential to reduce irrigation runoff losses, and should be considered as a management practice aiming at water and soil conservation. [ABSTRACT FROM AUTHOR]

A 3-year field experiment was conducted to evaluate the applicability of drip irrigation, winter wheat growth and water use under different drip irrigation regimes in the North China Plain (NCP) during 2014–2017. Five irrigation regimes with the soil matric potential (SMP) thresholds at 20 cm depth immediately under the emitters were − 10, − 20, − 30, − 40 and − 50 kPa. The results showed that scheduling drip irrigation with SMP thresholds at 20 cm depth obviously affected the soil moisture status in the root zone, and the lower the SMP threshold was, the lower the average soil moisture content was. Soil moisture consumption of winter wheat occurred mainly in 0–60 cm soil layer in anthesis stage, and reached a depth of 80 cm in grain filling stage, and there was no deep percolation but groundwater recharge in 130 cm layer. SMP thresholds had significant effects on grain yield and water use efficiency (WUE), and there was a tendency for the two indicators to reach their highest values when the SMP threshold was around − 40 kPa in the normal years. Both yield and WUE decreased with the decrease of SMP in the dry year. Winter wheat evapotranspiration and irrigation amount decreased by 0.12% and 0.92%, respectively, and the irrigation water use efficiency increased by 1.22% with each unit of SMP decrease. Compared with the average grain yield, irrigation amount and WUE under local surface irrigation management, drip irrigation with the SMP threshold of − 40 kPa resulted in a yield increase of 4.3%, water savings of 46.6%, and WUE increase of 10.5%. The yield increase wasn't significant to attract farmers to adopt drip irrigation technology, but the water saving was obvious. So, in the NCP, if the investment of drip irrigation system was likely to be government subsidized, it was recommended to drip irrigate winter wheat with the SMP threshold of − 40 kPa at 20 cm depth immediately under the emitters. [ABSTRACT FROM AUTHOR]

New water-conserving irrigation technologies are vital in arid countries. We investigated the effects of (i) soil substrates made of Smart Capillary Barrier Wick (SCB-W), consisting of silt loam blocks surrounded by sand-sheathes and irrigated with a sand wick cylinder (WC) as compared to a control (homogenous soil irrigated by the same wick system, HW), (ii) WC diameters (2.54 cm vs. 1.27 cm), and (iii) 2-cm sand mulch layer on soil–water dynamics during wetting–drying cycles. Field experiments with pots and HYDRUS (2D/3D) modeling were performed in two consecutive phases (with and without sand mulch). Analysis of variance at p < 0.05 was used to assess significant differences in measured water contents, θ, between the two substrates. For the wetting/drying cycles, the modeled and measured θ are in satisfactory/tolerable agreement, as documented by the model evaluation criteria, which are within acceptable ranges (the root mean squared error, RMSE 0.01–0.06; Nash–Sutcliffe coefficient, NSE 0.51–0.97, and Willmott index, d = 0.97–1). SCB-W wets the soil substrate about two times faster than HW during the wetting cycles (p < 0.05). Reducing the WC diameter prolonged the wetting time by 1 and 2 days for SCB-W and HW, respectively, the same trend of two times faster wetting of SCB-W compared to HW was maintained. SCB-W showed higher θ storage (by 44.3–52.4%) at the bottom part of the composite than HW (p < 0.05). The sand mulch layer reduced evaporation and resulted in 20 and 38.9% higher θ during the drying cycle for both the bottom and top sensors, respectively, in both substrates (p < 0.05). SCB-W could improve water conservation in home gardens. [ABSTRACT FROM AUTHOR]

This paper proposes a new methodology for solving the scheduling problem of center pivot system irrigation timetable based on the Luus–Jaakola optimization method. The new methodology considers as influencing factors the water and energy consumed and the limit of the available flow to the areas that are being irrigated. The methodology allows the implementation of a non-linear model during an acceptable time scenario as it reduces the number of parameters that must be estimated in the optimization problem. The numerical results show that the programmed timetables, which consider a large number of parameters, were successfully processed. [ABSTRACT FROM AUTHOR]