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In this study, we assessed the efficiency of a deficit irrigation program (DIP) on groundnut (Arachis hypogaea L.) yield and economic profits. The DIP was designed to combine frequency and volume of irrigation to develop an appropriate irrigation water management (IWM) strategy for groundnut. Two field experiments were conducted at the Agricultural College and Research Institute, Madurai, Tamil Nadu, India, with a bunch variety of groundnut, VRI 2, under a randomized block design (RBD) with three replications. The treatments included DIP in combination with a foliar application of pink-pigmented facultative methylotrophic bacteria (PPFM). The irrigation frequencies adopted for the first set of treatments were high frequency (5/5), medium frequency (7/5), and lower frequency (7/7) starting from 14 days after sowing (DAS). The effects of early water stress on groundnut pod yield and water use efficiency were investigated in a second experiment by starting irrigation at 21 DAS. The number of irrigation frequencies and irrigation volume was fixed to develop an easily readable irrigation chart for end-users. The number of irrigation frequencies was fixed as three, and the volume of irrigation was fixed as a depth of 3 cm. In the first experiment, a mini mobile pumping unit was used for scheduling irrigation frequencies; in the second experiment, the surface drip method was used. In both experiments, we also assessed the effects of foliar application of PPFM, widely used as a growth stimulant for several crops, especially under drought conditions. Overall, we observed that DIP led to up to 25.6% water saving compared to surface irrigation. Use of the DIP at the medium frequency with PPFM spray had a significantly positive influence on water use efficiency (WUE) and irrigation water use efficiency (IWUE) compared to conventional drip irrigation (CDI). Compared to surface irrigation (SI), DIP had a positive impact on growth parameters, yield attributes, and economic profitability with a higher benefit-cost ratio. Additionally, there were only minor differences between deficit irrigation (DI) results starting from 21 DAS and 14 DAS. Irrespective of the irrigation techniques, PPFM application had a positive effect on the yield attributes and WUE. Our results indicated that DI at a medium frequency (7/5) with PPFM spray, starting from 21 DAS under drip fertigation, is the best irrigation management innovation (IMI) strategy for optimum utilization of irrigation water without significant reduction in pod yield. This management had a positive influence on WUE and IWUE of summer groundnut in sandy clay loam soil. However, the exact scheduling of the irrigation may differ in different environments as well as soil types. Nevertheless, we propose that the application and further optimization of the DIP devised in this study would help the farmers attain a similar yield using a lower amount of irrigation water and lead to significant economic profits for the farmers.

The cultivation mode of planting offseason crops, such as cucumber, with drip irrigation has been widely used in greenhouses in North China to achieve high yields, obtain large economic benefits, and improve water use efficiency. The objectives of this study were to evaluate the effects of drip irrigation on the irrigation water amount, irrigation water use efficiency (IWUE), and cucumber yield and the corresponding economic benefits. These objectives were achieved using data from a seven-season experiment in a commercial greenhouse with cucumber plants in North China. Local furrow irrigation was used as the control. The results showed that the cucumber yields and income with drip irrigation were 4.3% and 3.1% higher than those under furrow irrigation, respectively. However, the seasonal total irrigation depth for drip irrigation was approximately 50% lower than that for furrow irrigation. The IWUE averaged 0.41 in furrow irrigation but increased to 0.79 in drip irrigation. The irrigation water productivity and the economic irrigation water productivity for drip irrigation were approximately 100% higher than those for furrow irrigation. The mean economic irrigation water productivity was 19.8 US$ m−3 for drip irrigation, which is 7 times higher than the 2019 value of 2.7 US$ m−3 in the agricultural sector in China, indicating potential high economic benefits. In conclusion, drip irrigation is recommended in greenhouses to reduce irrigation water by approximately 50% and increase cucumber yield and economic benefits by approximately 3–4% compared to traditional furrow irrigation in North China.

Understanding the characteristics of soil solute transport is fundamental to the design and management of furrow irrigation systems. This study determined the soil hydraulic and solute transport parameters by inverse solution with HYDRUS-2D and then verified them. The experimental data were obtained from the infiltration of clay loam and sandy loam of different potassium nitrate (KNO3) concentrations under furrow irrigation. Then, the initial soil water content (θ0), KNO3 concentration, and water depth (h0) affecting the transport characteristics of nitrate nitrogen (NO3−-N) and potassium (K+) were analyzed. The results indicated that the soil hydraulic and solute transport parameters determined from the inversion solution with HYDRUS-2D were reliable. The soil saturated water content, saturated hydraulic conductivity, and empirical parameter n in the van Genuchten–Mualem model increase with the increase of KNO3 concentrations, whereas the empirical parameter a shows a decreasing tendency. The distribution range of NO3−-N increased with the increases of θ0 and the KNO3 concentration, which had barely any effect on the range of K+ distribution. The horizontal distribution range of NO3−-N and K+ increased with the increase of h0, but it had no obvious influence on the vertical range. HIGHLIGHTS Soil hydraulic and solute transport parameters were determined by inverse solution with HYDRUS-2D, and then the reliability was verified.; θn, n and Ks (VG-M model) increased with increasing KNO3 concentration, while a exhibited a decreasing trend; The initial soil water content, KNO3 concentration and water depth have an obvious effect on the distribution of NO3−-N.; K+ was mainly distributed within 10 cm of the furrow bottom.

Plastic mulched ridge-furrow irrigation is a useful method to improve crop productivity and decrease salt accumulation in arid saline areas. However, inappropriate irrigation and fertilizer practices may result in ecological and environmental problems. In order to improve the resource use efficiency in these areas, we investigated the effects of different irrigation amounts (400 (I1), 300 (I2) and 200 (I3) mm) and nitrogen application rates (300 (F1) and 150 (F2) kg N/hm2) on water consumption, salt variation and resource use efficiency of spring maize (Zea mays L.) in the Hetao Irrigation District (HID) of Northwest China in 2017 and 2018. Result showed that soil water contents were 0.2%–8.9% and 13.9%–18.1% lower for I2 and I3 than for I1, respectively, but that was slightly higher for F2 than for F1. Soil salt contents were 7.8%–23.5% and 48.5%–18.9% lower for I2 than for I1 and I3, but that was 1.6%–5.5% higher for F1 than for F2. Less salt leaching at the early growth stage (from sowing to six-leaf stage) and higher salt accumulation at the peak growth stage (from six-leaf to tasseling stage and from grain-filling to maturity stage) resulted in a higher soil salt content for I3 than for I1 and I2. Grain yields for I1 and I2 were significantly higher than that for I3 and irrigation water use efficiency for I2 was 14.7%–34.0% higher than that for I1. Compared with F1, F2 increased the partial factor productivity (PFP) of nitrogen fertilizer by more than 80%. PFP was not significantly different between I1F2 and I2F2, but significantly higher than those of other treatments. Considering the goal of saving water and nitrogen resources, and ensuring food security, we recommended the combination of I2F2 to ensure the sustainable development of agriculture in the HID and other similar arid saline areas.

This study examines the importance of generating proper water accounts for large gravity-based irrigation schemes in order to assess scheme performance. It shows how the use of simplistic criteria ...

Two field experiments were conducted to determine the optimum irrigation method and drip fertigation rate in menthol mint during the spring of 2015 and 2016. Experiment I comprised combinations of four drip irrigation rates [60, 80, 100, and 120% of crop evapotranspiration (ETC)] and three fertigation rates [60, 80, and 100% of the recommended dose of fertilizers (RDF), i.e. 75 kg N and 40 kg P2O5 ha−1] with an additional control (furrow irrigation and soil application of RDF). Experiment II had a split-plot design, with three irrigation methods [sprinkler, drip, and furrow irrigated raised bed (FIRB)] used in main plots and four irrigation regimes [(120, 100, 80, and 60% of cumulative pan evaporation (CPE)] for drip and sprinkler methods while maintaining irrigation water (IW): CPE of 1.2, 1.0, 0.8, and 0.6 for FIRB in subplots. Drip irrigation at 120% ETc resulted in significantly higher fresh herb and oil yield than at 100, 80, and 60% ETc. While being statistically similar with each other, fertigation with 100 and 80% RDF recorded significantly higher oil yield than that with 60% RDF. Drip irrigation at 100 or 120% ETc and fertigation with 60, 80, and 100% RDF recorded significantly higher oil yield than the control treatment. Drip irrigation led to 51.4 and 135.0% higher oil yield than FIRB and sprinkler irrigation, respectively. Drip irrigation at 120% ETc with fertigation at 80% RDF resulted in 25.4% higher oil yield, 10.1% higher biophysical water productivity, 27.1% higher economic water productivity, and saving of 34.4% IW and 20% fertilisers than the control treatment.

Drip irrigation and fertigation, being advocated for higher crop and water productivity require optimization of irrigation and fertilization schedules. Field experiments were conducted during 2016–2018 to evaluate water and energy-efficient drip irrigation and fertigation schedules for higher productivity and profitability from oilseed rape. The treatments comprised of a combination of three levels of drip irrigation {60, 80 and 100% of cumulative pan-evaporation (CPE)} and three levels of fertigation {60, 80 and 100% recommended dose of fertilizers (RDF)} along with one absolute control (flood irrigation and soil application of RDF). The yields of crop under drip irrigation at 100 and 80% of CPE were statistically similar but significantly higher than irrigation at 60% of CPE. The irrigation use efficiency (IUE) and water use efficiency (WUE) were maximum at 80% of CPE followed by 100 and 60% of CPE. Drip irrigation at 80% of CPE resulted in 18% higher yield along with a water-saving of 35.4% than absolute control. Energy use efficiency (EUE) was higher at 100% of CPE followed by 80 and 60% of CPE. Whereas, energy productivity at 100 and 80% of CPE being statistically similar but significantly higher than 60% of CPE. Highest benefit: cost (B:C) ratio and net returns were obtained with drip irrigation at 100% of CPE and lowest at 60% of CPE. Fertigation at 100 and 80% RDF recorded significantly higher seed yield than 60% RDF and absolute control.

Accurate estimation of irrigation return flow plays an important role in the effective management of groundwater, especially in arid and semiarid irrigation regions. However, there is a lack of sufficient research to clarify hydrological process dynamics associated with irrigation return flow. In this study, first, a two-dimensional/three-dimensional model, HYDRUS-2D/3D, was adopted to analyze two different irrigation types in the Delingha Depression, which is located at the northeastern margin of the Qaidam Basin, China. Then, a 3D saturated flow model was established. This study determined the effect of agricultural water application on the dynamics of irrigation return flow. A large difference in the irrigation return-flow coefficient (IRFC) was seen during the growing season; an IRFC of 0.3 was obtained using flood irrigation, whereas ditch irrigation resulted in an IRFC of only 0.1. The lag time of recharge was approximately 150 days. It was necessary to consider the lag time for the 3D numerical model to obtain satisfactory results. Flood irrigation led to a groundwater recharge rate of 90 mm/year. These results indicate that the lag time should be considered when groundwater recharge is estimated or modeled.

High water consumption and inefficient irrigation management in the agriculture sector of the middle and lower reaches of the Amu Darya River Basin (ADRB) have significantly influenced the gradual shrinking of the Aral Sea and its ecosystem. In this study, we investigated the crop water consumption in the growing seasons and the irrigation water requirement for different crop types in the lower ADRB during 2004–2017. We applied the FAO Penman-Monteith method to estimate reference evapotranspiration (ET0) based on daily climatic data collected from four meteorological stations. Crop evapotranspiration (ETc) of specific crop types was calculated by the crop coefficient. Then, we analyzed the net irrigation requirement (NIR) based on the effective precipitation with crop water requirements. The results indicated that the lowest monthly ET0 values in the lower ADRB were found in December (18.2 mm) and January (16.0 mm), and the highest monthly ET0 values were found in June and July, with similar values of 211.6 mm. The annual ETc reached to 887.2, 1002.1, and 492.0 mm for cotton, rice, and wheat, respectively. The average regional NIR ranged from 514.9 to 715.0 mm in the 10 Irrigation System Management Organizations (UISs) in the study area, while the total required irrigation volume for the whole region ranged from 4.2×109 to 11.6×109 m3 during 2004–2017. The percentages of NIR in SIW (surface irrigation water) ranged from 46.4% to 65.2% during the study period, with the exceptions of the drought years of 2008 and 2011, in which there was a significantly less runoff in the Amu Darya River. This study provides an overview for local water authorities to achieve optimal regional water allocation in the study area.

Soil salinization is a key problem limiting the sustainable development of agriculture in arid areas. To explore the quantitative influence of irrigation on soil salinity and groundwater quality, spatial variability of salt at different soil depths and total dissolved solids in groundwater before and after irrigation was analysed in the Hetao Irrigation District, China. The spatial variability of soil salinity before and after irrigation was moderate, with high coefficients of variation observed in shallow soil. After irrigation, amounts of salt were transferred into the groundwater, leading to the deterioration of groundwater quality, the average salt flux through each interface was −153.66, 169.12, 130.13 and 318.48 g/m2, for 20, 50, 100 and 150 cm soil depths, respectively. All salt moved downward vertically except for 0–20 cm soil layer, and the average soil salt flux of shallow layers was significantly lower than that of deep layers. Compared soils of different depths and land types, salt discharge occurred in cultivated land, while salt accumulation occurred in shallow soil in wasteland after irrigation. Irrigation could help remove salt from cultivated land and deeper soil; however, it had almost no effect on shallow soil of other land uses. HIGHLIGHTS There was a positive correlation between variations in soil moisture and salinity at the shallower depths.; Irrigation activities had more effect on the spatial variability of shallow soil but less on the salinity of deep soil.; The average salt storage showed that salt accumulation still existed in the shallower soil layer.; The ions Cl− and Na+ played the dominant role in the variation of soil salinity.

With the rapid growth of the world’s population, the shortage of freshwater resources becomes increasingly serious. Farmland irrigation would not survive without fresh water which comes from river nearby. The low irrigation efficiency of the existing irrigation system needs to be tackled for efficient and effective usage of freshwater with low-cost. It is recognised that the water-saving irrigation technologies, such as the drip irrigation, sprinkler irrigation, micro-irrigation, furrow irrigation in horizontal direction, plastic film mulching, ditch irrigation technology, etc. should be strongly promoted in order to develop water-saving agriculture. However all these measures require cutting-edge technologies and heavy investment, which poses a big problem particularly for the developing countries. On the other hand, if water and nutrients can be applied directly to the crop at root level, the positive effects on yield and water savings can be achieved, thereby increasing the irrigation performance. The water-yield relationship has been investigated using different methods of limited water applications and programs. Therefore, designing and fabricating technological irrigation system of low cost with maximising yield that can reasonably use water for agriculture is an urgent issue to today’s world. The intelligent irrigation system provides a potential solution to solve the water shortage problems. In this study, an intelligent water-saving irrigation system is designed using Solidworks and some parts of the system are fabricated using a home-made fused deposition modelling (FDM) 3D Printer. The intelligent irrigation for different plants is successfully achieved and the irrigation efficiency is significantly improved. The employment of the home-made 3D printer not only substantially reduces the manufacture costs, but also makes it possible to fabricate any “ad hoc” irrigation system.

A meta-analysis was performed on 351 studies from 17 articles published between 1990 and 2016 to determine how a water use efficiency (WUE) treatment is affected by irrigation systems and management practices on clay and clay loam soils in a semi-arid environment relative to a rainfed control. Several explanatory variables (moderators) were examined to determine their impact on WUE such as crop type, irrigation capacity, rainfall, soil type, planting time, and nitrogen application. Results were sub-grouped by irrigation system. Overall, the impact of irrigation system on WUE directly correlated with the efficiency of the irrigation system. Subsurface drip and center pivot irrigation systems had the largest impacts on WUE with increases of 147 and 99%, respectively, compared to a 14% increase under furrow irrigation. Corn (Zea mays L.) had a higher response to WUE in subsurface drip irrigation (260%) compared to center pivot irrigation (46%), whereas WUE in cotton (Gossypium hirsutum L.) had a 71% change in center pivot systems compared to 63% under subsurface drip. The biggest increases in WUE relative to a rainfed control were for sorghum (Sorghum bicolor (L.) Moench), which had a 13% change under furrow irrigation, 160% change under center pivot and 341% under subsurface drip.

Drip irrigation is now commonly used for maize cultivation in China and other regions of the globe. The goal of this study was to compare water and fertilizer use as well as economic benefits for surface and subsurface drip irrigation and for mulched and non-mulched maize production in northeast China. An experiment was conducted during 2015 and 2016 in Chifeng in Inner Mongolia, China that included the following treatments mulched surface drip irrigation (M-DI), non-mulched surface drip irrigation (NM-DI); non-mulched subsurface drip irrigation (NM-SDI), and mulched furrow irrigation (M-FI). The results indicated that film mulching obviously improved the soil temperature and water content during the early growth period, which hastened maize emergence and growth. Compared with the M-FI treatment, the DI techniques significantly decreased the cost of field management and improved water and nitrogen use. The water use efficiency (WUE) and nitrogen partial factor productivity for DI treatments increased by 13.9–39.2% and 16.3–28.1%, respectively, on average for two years, compared to those for the M-FI treatment. The advantages of M-DI were film mulching and in-season fertigation, which improved maize development and achieved the highest yield and net output values, which were 9.2–10.1% and 4.7–19.1% higher than other techniques. The NM-SDI technique is a competitive viable alternative for maize cultivation given the lack of film residue, the ease of field management, which made the annual allocated cost of system decrease by 13.2–24.1% compared with others, and the highest WUE among the treatments. Therefore, the DI techniques showed potential to enhance maize production, but decisions regarding the use of DI should take both economic benefits and environmental impact into consideration.

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.

Scarce and scattered precipitation in arid regions is detrimental for newly planted seedlings. It is essential to provide required water storage for seedlings in restoration projects in the first year of their establishment. The subsurface irrigation can be much more effective than the surface irrigation because of the regulation of water availability and reduction in water evaporation. We studied the effect of surface and subsurface irrigation methods on the growth and survival of four common tree species including heaven tree (Ailanthus altissima (Mill.) Swingle), China berry (Melia azedarach L.), white mulberry (Morus alba L.), and black locust (Robinia pseudoacacia L.) by installing underground clay reservoirs with different permeabilities in Isfahan City, Iran. Different amounts of animal manure and wheat straw were mixed with clay fraction and cooked in a pottery kiln at 900°C to produce reservoirs with different permeabilities. The experimental treatments consisting of irrigation and tree species were considered with a factorial arrangement in a completely randomized design with three replications in 2016 and 2017. Leaf water potential of seedlings, which is indirectly related to drought resistance, was measured by a portable pressure chamber. The results showed that saplings height, basal diameter, number of leaves, chlorophyll content and stomatal conductance were significantly (P 0.05) affected by the irrigation methods and different permeabilities of clay reservoirs. The clay reservoirs with low and medium permeabilities constantly provide better conditions for plant growth, and water with lower pressure and longer time intervals to the plant roots as compared with the reservoirs with high permeability. Analysis of variance of the data showed that year and interaction between year and permeability of reservoir had significant effects (P

To develop more efficient irrigation technologies and a reasonable and convenient irrigation scheduling for winter wheat production in the North China Plain (NCP), a field experiment with five soil matric potential (SMP) treatments under irrigation with micro-sprinkling hoses was conducted in 2013–2014 and 2014–2015. The SMP thresholds were − 10, − 20, − 30, − 40 and − 50 kPa and monitored using tensiometers at 0.2 m depth and 1.2 m (horizontal distance) from the micro-sprinkling hose. The results indicated that soil moisture consumption occurred mainly in the 0–80 cm soil layer during the anthesis and grain filling stages. The different SMP values had no significant effects on winter wheat plant height, maximum leaf area index, dry biomass, grain yield and yield components and water productivity (WP), but there was a tendency for all these indicators to reach their highest value when the SMP value was around − 40 kPa. Compared with the average winter wheat yield, irrigation amount and WP from local surface irrigation, the − 40 kPa SMP threshold treatment resulted in a yield increase of 10.7%, water savings of 46.5% and WP increase of 5.7%. In the NCP, the SMP threshold of − 40 kPa is recommended to schedule micro-sprinkling irrigation for winter wheat.

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.

13 Pags.- 4 Tabls.- 9 Figs., 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., This work has been supported by the Center for International Scientific Studies & Collaboration (CISSC), Ministry of Science, Research and Technology, Iran.

Numerical methods have been proved to be useful tools for understanding different phenomena. In this paper, triggered furrow irrigation has been analyzed by means of numerical modeling. To this end, a special code is developed for simulation of triggered furrow irrigation system by coupling three-dimensional Richards’ equation and one-dimensional fully hydrodynamic form of Saint-Venant equations. The coordinate transformation technique was used for solving Richards’ equation that improves flexibility of model for simulation of water flow in irregularly shaped furrows. Furthermore, overland flow module benefits from high-resolution total variation diminishing scheme that avoids artificial oscillations commonly occurring on the advance water front. The code was validated against different analytical, numerical and experimental benchmarks. In all cases, the accuracy of model was acceptable. The code was subsequently employed to simulate all phases of triggered furrow irrigation system (including advance and redistribution phases) on a field cultivated with wheat. Finally, Taguchi technique was employed to deduct proposals to optimize performance of triggered furrow irrigation system in terms of sensor position, triggering and cutoff thresholds and inflow rate. It was concluded that optimal performance of triggered irrigation system was obtained when the water content sensor was installed close to the furrow, providing that triggering and cutoff thresholds were set as − 15 and − 3 m (close to field capacity) and inflow rate was 1 L s−1.

Irrigation is the largest water use in the western United States. The Upper Snake Rock Conservation Effects Assessment Project in southern Idaho began in 2005 to quantify the impacts of conservation practices in this irrigated watershed. The objective of this study was to determine the changes in the watershed water balances as farmers converted furrow irrigated fields to sprinkler irrigation from 2006 to 2016. More than 75% of annual watershed inflow was irrigation water diverted into the watershed from the Snake River and distributed through canals to 82,000 ha of cropland, while annual precipitation was only 10% to 23% of the annual inflow. Approximately 30% of the annual watershed inflow flowed back to the Snake River as irrigation return flow. Water balances showed that irrigation exceeded evapotranspiration (ET) in the spring and fall, indicating that irrigation diversions could be reduced early and late in the irrigation season. Annual irrigation project efficiency, defined as ET divided by the amount of diverted irrigation water, varied from 61% to 73%, but project efficiency did not increase as the amount of cropland that was sprinkler irrigated increased from 46% in 2006 to 59% in 2016. The only significant trends indicating that increasing sprinkler irrigation impacted the water balances were increasing irrigation project efficiency in July and increasing irrigation return flow during the irrigation season. Farmers may be applying less irrigation water with sprinkler irrigation compared to furrow irrigation, which could have caused return flow to increase since irrigation diversions did not change with the supply-based water allocation. Irrigation scheduling based on soil moisture measurement or daily ET would help irrigation application match crop water needs on individual fields. For the entire irrigation project, irrigation efficiency could improve if irrigation diversions into the watershed could be adjusted to more closely match ET in the spring and fall, which may require structural changes to the canal system and policy changes for the Snake River reservoir system.

Water scarcity and saline stress are primary threats for water use and agricultural production in arid and semi- arid regions, such as the Hetao Irrigation District, China. The current study, using irrigation with saline water, developed through three seasons (2017–2019) of field experimental surveillance of mulched maize water use in two cropped weighing lysimeters. Measurements included crop characteristics (height, LAI, dates of development stages), soil and water salinity, and daily actual crop evapotranspiration (ETc act). Deficit surface irrigation was scheduled in 2017 and 2018 seasons, while in 2019 drip irrigation was used aimed at satisfying crop water requirements. Both approaches aimed at improving irrigation management while controlling impacts of salinity. The collected information was used to parameterize and calibrate the soil water balance model SIMDualKc. The model uses the FAO56 dual crop coefficient approach and considers the combined effect of water and salinity stresses due to salinity of both soil and irrigation water. Results show that the SIMDualKc model adequately simulates the dynamics of the observed ETc act throughout the three growing seasons. The goodness-of-fit in- dicators show highly appropriate model fitting of observed ETc act with low RMSE of 0.42 mm d-1 for the cali- bration and 0.53 mm d-1 for validation. The calibrated standard basal crop coefficients (Kcb) of maize for the initial, mid, and end stages were respectively 0.15, 1.15 and 0.25, which agree with those recently proposed by Pereira et al. (2021). Due to the impacts of both water and salt stress in 2017 and 2018, ETc act was much below the potential value ETc, ranging 64–83%, while in 2019 that percentage increased to 92% due to avoiding water stress by then. The average Kcb mid act range 0.58–1.06, therefore lower than Kcb mid, with the lower values occuring in the lysimeter that was irrigated with a large deficit. The irrigation scheduling practiced was assessed using water use and productivity indicators, which have shown the advantage in using drip irrigation with small time intervals between irrigations. Moreover, the current study and the calibrated model provide for adopting irrigation management practices that may save water and control salinity. info:eu-repo/semantics/publishedVersion

The cutoff technique has not been adequately investigated despite being the most practiced among smallholder farmers. This study aimed at scenarios of improving water application efficiency...

Selenium (Se) biofortification of staple cereal crops can improve the Se nutritional status of populations. A field trial employing an enriched stable isotope of Se (77Se) was undertaken over three consecutive cropping seasons in a coarse-textured, calcareous soil in Gilgit-Baltistan, Pakistan. The objectives were to (1) assess the feasibility and efficiency of Se biofortification, (2) determine the fate of residual Se, and (3) assess the consequences for dietary Se intake. Isotopically enriched 77Se (77SeFert) was applied, either as selenate or as selenite, at three levels (0, 10, and 20 g ha−1) to a wheat crop. Residual 77SeFert availability was assessed in subsequent crops of maize and wheat without further 77SeFert addition. Loss of 77SeFert was c.35% by the first (wheat) harvest, for both selenium species, attributable to the practice of flood irrigation and low adsorption capacity of the soil. No 77SeFert was detectable in subsequent maize or wheat crops. The remaining 77SeFert in soil was almost entirely organically bound and diminished with time following a reversible (pseudo-)first-order trend. Thus, repeat applications of Se would be required to adequately biofortify grain each year. In contrast to native soil Se, there was no transfer of 77SeFert to a recalcitrant form. Grain from control plots would provide only 0.5 µg person−1 day−1 of Se. By contrast, a single application of 20 g ha−1 SeVI could provide c. 47 µg person−1 day−1 Se in wheat, sufficient to avoid deficiency when combined with dietary Se intake from other sources (c. 25 µg day−1).

The contribution ofwastewater irrigationwith the improvement of irrigation practices to the productivity ofsilagemaize is a priority issue to investigate considering the saving of scarcefreshwater resourcesand the necessity to disposewastewater. The aim of this study was to evaluate the effect of different irrigation levels (L100, L67 and L33) of recycledmunicipal wastewater(RW) compared to freshwater (FW) using subsurface drip (SSDI), surface drip (SDI) andfurrow irrigation(FI) methods on yield and some physiological traits of silage maize in semi-arid conditions at a high altitude. When the total daily referenceevapotranspirationvalue reached 50±5mm, irrigation quantities corresponding to 100%, 67% and 33% of soil moisture deficit based on field capacity in fully irrigated plots with freshwater were applied in different irrigation levels. Crop actual evapotranspiration (ETa) values were found close in both water types. SSDI reduced ETa by 18.5% and 45.6% in L100 level, 15.2% and 38.9% in L67, and 11.6% and 32.6% in L33, respectively compared to SDI and FI. The highest fresh biomass yield was determined in the SSDI-RW-L100 combination as 77.55t ha-1, and resulted in 5% and 12.9% higher values than in SDI and FI. Leaf relative chlorophyll and water contents, leaf area index and electrolyteleakageshowed strong linear correlations with yield and evapotranspiration values. The highest water productivity was determined in the SSDI-RW-L100 combination as 21.48kgm-3and it was higher by 28.2% and 99.4% than those in SDI and FI, respectively. Improvement of productivity with increased irrigation quantities in SSDI delivered the high yield response factor of 1.70–1.77. Therefore, it is concluded that the SSDI method can be a successful practice to improve productivity by alleviating the need for water for silage maize especially under full irrigation with RW. The contribution ofwastewater irrigationwith the improvement of irrigation practices to the productivity ofsilagemaize is a priority issue to investigate considering the saving of scarcefreshwater resourcesand the necessity to disposewastewater. The aim of this study was to evaluate the effect of different irrigation levels (L100, L67 and L33) of recycledmunicipal wastewater(RW) compared to freshwater (FW) using subsurface drip (SSDI), surface drip (SDI) andfurrow irrigation(FI) methods on yield and some physiological traits of silage maize in semi-arid conditions at a high altitude. When the total daily referenceevapotranspirationvalue reached 50±5mm, irrigation quantities corresponding to 100%, 67% and 33% of soil moisture deficit based on field capacity in fully irrigated plots with freshwater were applied in different irrigation levels. Crop actual evapotranspiration (ETa) values were found close in both water types. SSDI reduced ETa by 18.5% and 45.6% in L100 level, 15.2% and 38.9% in L67, and 11.6% and 32.6% in L33, respectively compared to SDI and FI. The highest fresh biomass yield was determined in the SSDI-RW-L100 combination as 77.55t ha-1, and resulted in 5% and 12.9% higher values than in SDI and FI. Leaf relative chlorophyll and water contents, leaf area index and electrolyteleakageshowed strong linear correlations with yield and evapotranspiration values. The highest water productivity was determined in the SSDI-RW-L100 combination as 21.48kgm-3and it was higher by 28.2% and 99.4% than those in SDI and FI, respectively. Improvement of productivity with increased irrigation quantities in SSDI delivered the high yield response factor of 1.70–1.77. Therefore, it is concluded that the SSDI method can be a successful practice to improve productivity by alleviating the need for water for silage maize especially under full irrigation with RW.

usc Land suitability assessment for irrigation is critical to inform as well as manage current and future irrigated agriculture production systems. Land suitability analysis determines whether a given land area could potentially be used for specific crop production. The objective of this study was to identify the availability of suitable land for surface irrigation systems for the production of millet, sorghum, sugarcane, and wheat production in the Lower Omo Gibe plain, Southern Ethiopia. Land suitability analysis was performed by a parametric method using factors such as soil texture, effective soil depth, Calcium Carbonate (CaCO3), soil electrical conductivity (ECe), drainage class, and slope. Five land suitability classes were identified that include highly suitable (S1), moderately suitable (S2), marginally suitable (S3), currently not suitable (N1), and permanently not suitable (N2). Results showed that 6.6, 7.5, 6.6, and 6.6% of the study area mostly located in the western part of the basin, were highly suitable (S1) for irrigated millets, sorghum, sugarcane, and wheat crops production, respectively. However, the mountainous areas in the central part of the basin were classified as N2 due to the steep slope and shallow soil depth. Overall, the results of the study revealed that the use of various suitability analysis techniques could assist in identifying suitable land for irrigated agriculture. Refereed/Peer-reviewed

Site selection of different irrigation systems can lead to higher water productivity in drought conditions. The present study intends to evaluate suitable regions along the Izeh plain (Iran) for different pressurized and gravitational irrigation systems using Analytical Hierarchy Process (AHP) based on Geographic Information System (GIS). To that end, a variety of inputs such as climate, topography, skilled labor and system costs, etc. were identified and classified into two main categories of socio-economic and environmental criteria. Each criterion was subdivided into several criteria to make the site selection more specific. A matrix of the pair-wise comparison was, in turn, used to compare these criteria and sub-criteria, and to evaluate them based on their relative importance based on the region’s suitability for different irrigation system alternatives. Geographical layers were then obtained for each sub-criterion to select the most suitable sites for different irrigation systems in the study area. Pressurized irrigation systems including wheel move irrigation system, drip irrigation system and solid-set sprinkler irrigation system, together with gravitational irrigation systems consisting of surface irrigation system, and low-pressure irrigation system were considered as irrigation system alternatives during the site selection process in this study. The result map of site selection for different alternatives showed that surface irrigation, drip irrigation and low pressure systems were the best irrigation system alternatives for the region studied.

In order to investigate the radiation utilization efficiency and soil temperature with different irrigation methods in cold region and black glebe, northeast, China, three irrigation methods namely control irrigation (CI), wet irrigation (WI) and flood irrigation (FI) were carried out in the field conditions. The radiation utilization efficiency (RUE) and soil temperature with different irrigation methods were analyzed. The results demonstrated that the chlorophyll content (SPAD) was higher in CI plot than in WI and FI plots, while the dry biomass increase (ΔD) and leaf area index (LAI) in CI plot were lower as compared to WI and FI plots. Among the three irrigation methods, FI had the best value of RUE and approached its highest value at the heading stage during the two seasons. The lowest light interception was obtained in CI regime. The soil temperature of 5 cm and 10 cm in CI plot was greater than in WI and FI plots. By contrast, soil heat dissipation and heating quickly while water absorbed more slowly, leading to a large temperature difference between day and night in CI plot, a small temperature difference between day and night in WI and FI plots. Therefore, in cold region and black glebe, northeast, China, with CI method, it could increase the surface soil temperature but the rice growth was restricted. Conversely, FI plot had much advantage in cold region and black glebe, northeast, China.

Irrigation methods and rice straw incorporation (RSI) are two major factors influencing CH4 emissions from paddy fields. However, their effects have never been studied in an RSI/alternate-year system in the cold region of Northeast China. The present study involved a 2-year field experiment analyzing the effects of irrigation method and RSI on CH4 emissions. Our results showed that controlled irrigation (CI) significantly decreased cumulative CH4 emissions by 55% when compared to flood irrigation (FI). RSI increased CH4 emissions in both CI and FI. CI accelerated the decreasing rate of straw residual while decreasing the total cumulative CH4 over the 2 years. The cumulative CH4 emissions of treatments with RSI were higher in the first year than in the second year. Our results suggest that CI with 6 t hm−2 of RSI is an ideal strategy to mitigate CH4 emissions in an RSI/alternate-year system in Northeast China.

Besides regulating soil water movements and nitrogen cycling, water management practices, such as irrigation schedule and irrigation methods, also affects possibly soil emission rates of nitrous oxide (N2O), an important greenhouse gas. The scale of irrigation scheduling and irrigation methods affecting N2O emission from winter wheat (Triticum aestivum L.) fields remains unclear. Hence, a field experiment with three irrigation schedule levels and three irrigation methods was conducted to estimate the N2O emission qualitatively from winter wheat fields by using static chamber method during April to May in 2017 and 2018 in the North China Plain (NCP). Three irrigation methods, i.e., sprinkler irrigation, surface drip irrigation, and flood irrigation were scheduled to irrigate the winter wheat immediately as the mean moisture of soil layer 0–100 cm depleted to 50%, 60% and 70% of the field capacity (FC). The research results show that both the irrigation schedule and irrigation methods influenced significantly (P

Maize is a crop with high irrigation needs in Italy. In many cultivated areas of the world, the water used for irrigation has a high salinity. To limit the damage caused by the salts provided by irrigation, suitable irrigation strategies can be adopted in relation to the crop, soil characteristics and rainfall regime. Therefore, in order to evaluate the most appropriate irrigation strategy to be used in the cultivation of maize on a clay loam red soil, subject to salinity, a research on a four-year crop rotation was carried out in southern Italy. Maize grain yield and yield characteristics irrigated by furrow with two water salinity levels and five different irrigation regimes, were compared. Grain yield was reduced by 34% in the third crop rotation year when the soil salinity, on average, raised from 3.8 to 7.4 dS m−1. Higher yield occurred restoring 100% of maximum crop evapotranspiration, instead of leaching requirement application which did not affect yield. Soil salinity improved grain protein content and reduced grain moisture content. Rainfall was not sufficient to leach all salts supplied by irrigation. The leaching requirements did not reduce the soil salinity and the harmful effect of salinity on maize yield, because of more salts supplied by higher irrigation volumes.

Guayule is being produced for natural rubber in US desert areas, where irrigation requirements are high. Improved irrigation practices and methods are required to increase guayule yields and reduce its water use. Presently, there is no information available on guayule produced using subsurface drip irrigation (SDI). Therefore, we conducted an SDI guayule field study in 2012–2015 in Maricopa, Arizona, US. The objectives were to evaluate guayule dry biomass (DB), rubber yield (RY), and crop evapotranspiration (ETc) responses to water application level, and to compare these results to previously reported guayule irrigation studies. Guayule seedlings were transplanted in the field in October 2012 at 0.35-m spacing, in 100-m long rows, spaced 1.02 m apart. The field had 15, 8-row wide plots (5 irrigation treatments x 3 replicates). Irrigation treatments were imposed in a randomized complete block design starting in May 2013. Irrigation scheduling was based on the measured soil water depletion percentage (SWDp) of a fully-irrigated treatment, defined as 100% ETc replacement, and maintained at ≈20-35% SWDp. The other treatments received 25%, 50%, 75%, and 125% of irrigation applied to the 100% treatment on each day of irrigation. Destructive samples for dry biomass, rubber, and resin contents were periodically taken from each plot between February and November of each year until the guayule was bulk-harvested in March 2015. Results indicated ETc, DB, and RY increased with total water applied (irrigation + rain), which varied between treatments from 2080 to 4900 mm for the 29-month growing season. Final dry biomass and rubber yields of 61.2 Mg/ha and 3430 kg/ha, respectively, were achieved with the highest irrigation treatment level (125%) and these yields were significantly higher than those under all other irrigation levels. All SDI irrigation treatments except for the lowest 25% level had rubber yields from 24 to 200% greater than the maximum RY achieved under a companion surface irrigation study conducted simultaneously in Maricopa.

Extensive irrigation strategies are commonly and widely used for orchards in Northern China, leading to low water-use efficiency (WUE) and potential fertilizer pollution of underground water. Effective micro-irrigation strategies for orchards remain unclear and require further investigation to assist in developing orchard water-saving irrigation systems. In this study, compared with local traditional furrow irrigation, six micro-irrigation strategies (with or without mulch film) were applied to a 6-year-old cherry (Prunus avium L.) field for three years (2015–2017). The moisture spatial distribution of soil profile, water consumption, yield, and fruit quality were measured to evaluate the effectiveness of different irrigation strategies on growth and WUE of cherry trees. The results showed that the strongest variability of moisture in soil profile was in the 0–60 cm soil layer, indicating the water uptake of cherry trees is closely related to the soil moisture content in this region. Compared with furrow irrigation, micro-irrigation strategies can significantly (P

Drip irrigation can produce high rice yields with significant water savings; therefore, it is widely used in arid area water-scarce northern China. However, high-frequency irrigation of drip irrigation with low temperature well water leads to low root zone temperature and significantly reduce the rice yield compared to normal temperature water irrigated rice, for example, reservoir water. The main purpose of this paper is to investigate the effects of low soil temperature on the yield reduction of drip irrigated rice in the spike differentiation stage. The experiment set the soil temperatures at 18°C, 24°C and 30°C under two irrigation methods (flood and drip irrigation), respectively. The results showed that, at the 30°C soil temperature, drip irrigation increased total root length by 53% but reduced root water conductivity by 9% compared with flood irrigation. Drip irrigation also increased leaf abscisic acid and proline concentrations by 13% and 5%, respectively. These results indicated that drip irrigated rice was under mild water stress. In the 18°C soil temperature, drip irrigation reduced hydraulic conductivity by 58%, leaf water potential by 40% and leaf net photosynthesis by 25% compared with flood irrigation. The starch concentration in male gametes was also 30% less in the drip irrigation treatment than in the flood irrigation treatment at soil temperature 18°C. Therefore, the main reason for the yield reduction of drip irrigated rice was that the low temperature aggravates the physiological drought of rice and leads to the decrease of starch content in male gametes and low pollination fertilization rate. Low temperature aggravates physiological water deficit in drip irrigated rice and leads to lower starch content in male gametes and low pollination fertilization rate, which is the main reason for the reduced yield of drip irrigated rice. Overall, the results indicated that the low soil temperatures aggravated the water stress that rice was under in the drip irrigated environment, causing declines both in the starch content of male gametes and in pollination rate. Low temperature will ultimately affect the rice yield under drip irrigation.

The traditional flood irrigation system has led to overexploitation of ground water and low nitrogen (N) use efficiency. In north-western India, maize-based systems with lower irrigation requirement are being advocated as an alternate to rice-based systems to address the issues of declining water table. Bed planting of crops, straw mulching and drip irrigation are known to save precious irrigation water, and improve N use efficiency and grain yields. To this effect a two-year field experiment was conducted with annual wheat-maize rotation on permanent bed system to evaluate the effect of surface drip irrigation, residue management, and N application on crop and water productivity. Maize and wheat under drip irrigation with residue retention system showed significant grain yield increase of 13.7% and 23.1% compared to furrow irrigation with no residue, respectively. Surface drip irrigation with residue retention saved 88 mm and 168 mm of water and increased water productivity by 66% and 259% in wheat and maize on permanent beds compared to the conventional furrow irrigation system with residue removal, respectively. Similarly, fertigation at 10-day interval with five splits in wheat and seven splits in maize under drip irrigation system increased the mean N recovery efficiency by 16.5% and 29% compared to furrow irrigation in wheat and maize, respectively.

Accurate design, appropriate management, and knowledge of relationships between the parameters affecting on the performance of a surface irrigation system are the factors which play an effective role in increasing the efficiency of these systems. If parameters such as advance distance can be well estimated per specified flow rate, the volume of infiltrated water can be estimated, thereby preventing water loss and enhancing irrigation efficiency to a great extent. In the present study evaluated the accuracy of data-driven methods Random Forest (RF), Artificial Neural Networks (ANN), Adaptive Neuro Fuzzy Inference System (ANFIS), and M5 Model Tree and common numerical methods such as the Full hydrodynamic and Zero-inertia model (using SIRMOD software) and Zero-inertial model (using WinSRFR software) to predict the advance distance in furrow irrigation. To this end, seven series of data resulting from the evaluation of furrow irrigation system in various regions were collected. Each series included 12 input parameters of furrow length (L), furrow geometrical cross-section coefficients ( $$\sigma_{1} ,\sigma_{2}$$ ), furrow hydraulic cross-section coefficients ( $$\rho_{1} ,\rho_{2}$$ ), inflow rate (Q), Maning’s coefficient (n), field slope ( $$S_{0}$$ ), cut-off time $$(T_{\text{cutoff}} )$$ , final infiltration rate ( $$f_{0}$$ ), and the infiltration parameters of the Kostiakov equation (a and k). Comparison of the results showed that all the data-driven methods managed to estimate the advance distance of the wetting front in the furrow with higher accuracy than the numerical methods. From among these, the ANFIS model had the highest accuracy (RMSE = 1.842 m, MAE = 1.305 m) in estimating the advance distance in the furrow.

The future of the South Asia’s rice-wheat (RW) production system is at stake due to continuously depleting aquifers and increasing pressure on underground water under projected climate change scenario. Conventional management factors such as flood irrigation, intensive tillage and residue burning are threatening sustainability of RW system. With increasing adoption of conservation agriculture (CA), sub-surface drip fertigation (SSDF) provides an exceptional opportunity for complementing irrigation water saving benefits. Presently, there is no research evidence on optimum spacing and depth for drip laterals in a CA (direct drilling and residue mulch) based RW system around the globe. This study was therefore, planned to evaluate effects of residue mulch, different spacing and depths of laterals for SSDF on crop yield, irrigation water productivity (WPi), nitrogen use efficiency (NUE) and net returns for CA based RW system in a silt loam soil in northwestern India. Drip laterals were spaced either at 33.75 cm or 67.5 cm, and installation depths were 0, 15 or 20 cm beneath the soil surface and compared with conventional and zero tillage based flood-irrigated RW systems. Grain yield and irrigation water input in rice and wheat were generally similar under different SSDF treatments. Irrigation water savings were 48–53% in rice and 42–53% in wheat under combination of SSDF and CA compared to flood irrigation system. A similar trend in WPi was recorded in both the crops. Residue mulch contributed to higher irrigation water savings, wheat yield and WPi compared to no mulch. Both rice and wheat needed 20% less N fertilizer under SSDF system to obtain grain yields similar to that under flood irrigated crops. Net returns from SSDF system with 67.5 cm lateral spacing were significantly higher compared to flood irrigation system. In conclusion, SSDF system having laterals spaced at 67.5 cm and installed at 15 cm depth provides tangible benefits for substantial saving in irrigation water and energy and increasing NUE and net income for CA based RW system in South Asia.

The knowledge of suitable irrigation methods coupled with effective irrigation scheduling to improve agricultural water use efficiency has become increasingly necessary for farmers in the North China Plain to ameliorate the severe water shortage that has threatened winter wheat (Triticum aestivum L) production. A two-season field experiment was conducted in a winter wheat field amide to compare the efficiency of three irrigation methods sprinkler irrigation (SI), surface drip irrigation (SDI) and flood irrigation (FI) under three irrigation schedules by irrigating while soil moisture decreased to 70%, 60% and 50% of the field capacity respectively. It was found that irrigation methods with suitable irrigation scheduling indeed have the potential to balance the optimal yield and water use efficiency. The results showed that irrigating 180.3 mm and 175.2 mm of water in the two studied seasons respectively was optimal to achieve the highest grain yield. For SDI and SI, this could be achieved by irrigating six times each with 30 mm of water, while for FI irrigating three times each with 60 mm of water gave comparable results. Our studies suggested that irrigating while soil moisture reduced to 60% of the field capacity by SDI was the best in all aspects compared with other irrigation methods and irrigation schedules.

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

Two consecutive pilot-scale experiments were conducted to investigate the potential reuse of treated municipal wastewater (TWW) as an irrigation source for cultivating forage rice (Oryza sativa L., cv. Bekoaoba) through examining our newly developed continuous irrigation systems, namely surface and subirrigation. Although only P-fertilizer was applied in 2016 and no fertilizer was supplemented in the 2017 season, the obtained yields were comparable to that recorded from normal paddy fields (7.3 t ha−1). The yields of the subirrigation plots (9.1 and 7.5 t ha−1) were significantly higher than those of the surface irrigation plots (7.5 and 7.1 t ha−1) in 2016 and 2017, respectively. There was no significant difference in the protein content of brown rice between the two fields, and this content (11.6–13%) was significantly higher than that (8.8%) recorded in normal paddy fields. This indicates our harvested rice was more favorable for animal husbandry since it can reduce the use of costly protein feed such as imported soymeal. Accumulation of heavy metals was not found in either paddy soil or brown rice after the two experiments. An effective N removal efficiency of the examined irrigation systems along with the reduced usage of chemical fertilizers could contribute to a substantial decrease in nutrients discharged from the wastewater treatment plants into surface water bodies. This study conveys the high feasibility of continuous irrigation with TWW to achieve high production and good nutritional quality of rice for animal feeding, which could promote an effective reuse of TWW in forage rice cultivation and enhance the self-sufficient feed ratio for sustainable dairy farming in Japan.

Irrigated agriculture has created artificially high groundwater levels that are now considered the normal condition in some Montana (USA) valleys. Rural housing developments that use wells completed in these shallow aquifers depend upon the annual recharge from irrigation practices and infrastructure. However, water conservation efforts aiming to reduce the volume of irrigation water diverted from streams, by either converting fields from flood irrigation to sprinkler irrigation or lining irrigation canals, may reduce recharge to the underlying alluvial aquifers. For resource managers looking to both preserve the groundwater resource for domestic well use and reduce the volume of water diverted from rivers, knowing the primary source of groundwater recharge is key to choosing the most appropriate water-saving method. To address this question, a groundwater model of an irrigated valley was constructed to quantify the relative importance of groundwater recharge from infiltration of flood-applied irrigation water versus leakage from irrigation canals. In contrast to using assumed infiltration rates based upon irrigation method efficiency, applied irrigation recharge rates were approximated through the model by matching the magnitude and timing of measured hydrographs. Model results suggest that 1. canal leakage is the primary irrigation-related recharge source in this flood-irrigated valley, and 2. assumed applied-irrigation recharge rates based upon irrigation method can greatly overestimate recharge. Flood irrigation’s low efficiency (a high percentage of applied water is not evapotranspired) may result in groundwater recharge studies that find applied irrigation is the more important groundwater recharge pathway. Our work shows that water budgets and groundwater models that use inputs based upon irrigation method efficiency may overstate the importance of irrigation application to groundwater recharge. At this site, irrigation-water conservation efforts that also aim to maintain domestic groundwater supplies should focus on improving the efficiency of irrigation method rather than reducing leakage from the canals.

Soil infiltration and Manning’s roughness values are key parameters to determine the performance of surface irrigation. However, temporal variability in these parameters due to tillage practices, irrigation, and crop growth greatly hinders efforts to improve irrigation quality. The objective of this experiment was to evaluate effects of infiltration and surface roughness variation on irrigation water movement and irrigation performance indicators for border irrigation with three border lengths. Field experiments were conducted from 2013 to 2015 in a wheat (Triticum aestivum)-maize (Zea mays L.) rotation planting system at the Jinghui Canal Irrigation Area in Guanzhong Plain of northwest China. In this work, Manning’s equation and a surface irrigation simulation model (WinSRFR) were used to estimate Manning’s roughness values and Kostiakov soil infiltration parameters. We determined that both parameters reached moderate levels of variation for both deep and shallow tillage treatments. The impacts of temporal variation in soil infiltration and surface roughness on irrigation water movement and irrigation quality were then evaluated. Results showed that water advance times varied significantly while recession times varied much more, affecting irrigation water amounts at various distances along the length of the border. Irrigation performance indicators were significantly different over various irrigation seasons, especially for borders that were 235 m in length. Finally, considering these temporal variations during the two rotation cycles, combinations of inflow rate and cut-off ratio during different irrigation seasons were optimized, and high irrigation quality could be achieved for 80 m and 120 m borders, but not for 235 m borders. Water percolation amounts during the 2013–2014 and 2014–2015 growing periods were reduced by 55 mm and 107 mm for 235 m borders, 26 mm and 23 mm for 120 m borders, and 36 mm and 39 mm for 80 m borders, respectively. Therefore, utilizing optimal combinations of inflow rate and cut-off ratio and considering temporal variation in soil infiltration and Manning’s roughness could maintain high water application efficiency and sustainable utilization of limited water resources.

In the arid lands covering Uzbekistan, furrow irrigation with low application efficiency is still widely used due to a lack of funds and shortage of labor. To save water and prevent secondary salinization caused by excessive irrigation, it is important to adopt low-cost and easy water-saving irrigation methods. Onishi et al. (2017) proposed simplified surge flow (SF) irrigation that does not require expensive equipment and merely divides the water supply into two phases at 1-day intervals. This study investigated the suitable inflow rate and furrow length of simplified SF to improve water application efficiency in Uzbekistan. Five experimental plots (total area of 2,250 m2, with 25 furrows) were set up, and the inflow rates for two plots were 5 Ls−1 (F5.0) and that for the others were 1.7 Ls−1 (F1.7). The conventional irrigation method (F5.0C and F1.7C) and simplified SF (F5.0S and F1.7S) were applied to cases of furrow length of 100 m under each inflow rate. In addition, simplified SF was applied on a 50-m furrow at F1.7 (F1.7S-50). In the first irrigation using simplified SF, water was supplied from the start point of the furrow (0 m) for half of the furrow length (50 m, 25 m). In the second irrigation, water was supplied from the start point to the end of the furrow (100 m, 50 m). The application efficiency in F1.7S and F1.7S-50 was higher than that in F1.7C and F1.7C-50, and the highest was in F1.7S-50. The water supply duration was shorter in F5.0S, but the total volume of supplied water was larger than that of F1.7C. These results indicate that shortening furrow length might be an effective way to save water using simplified SF with a low inflow rate, and in contrast, that it is necessary to extend furrow length with a high inflow rate.

Furrow irrigation is the most widely used method of irrigation in the world. The main objective of this study was to investigate the simultaneous management of water and fertilizer in furrow irrigation on corn yield and nitrogen losses. Large scale field experiments were performed in 16 treatments included 80 furrows with a length of 190 m and longitudinal slope of 0.004. The main factor included planting a row on a ridge of 37.5 cm (So) and two rows on a ridge of 75 cm (SR2), and the sub-factor included two irrigation management and 4 fertilization strategies included 3 fertilizer placement on the furrow and ridge (P1, P2 and P3) and fertigation (F). The results showed in all fertilization nitrate losses in So treatment was more than SR2 treatment. The highest nitrate losses occurred in P1 (fertilizer placement on the furrow bottom) and the lowest in P3 (fertilizer placement on the ridge) fertilization. Optimal irrigation applied increased application efficiency, root water and nitrate uptake and reduced nitrate losses up to 50% in So (P1 fertilization) and 22% in SR2 treatment (P2 fertilization) compared to conventional irrigation. Due to the higher percentage of root water and nitrate uptake in So treatment than SR2 in similar fertilizer treatments, plant height, stem diameter, ear weight and number of seeds on the cob of ear in So treatment were higher than SR2, but the grain yield was more in SR2 treatment due to plant densities. The highest grain yield and water productivity in SR2-OI-P3 treatment (wide ridge- optimal irrigation- ridge fertilization), increased by 44.2% and 67.4%, respectively. This study showed that the simultaneous management of water and fertilizer had a significant effect on the increase of water productivity and yield.

Increasing scarcity of irrigation water calls for enhancing water use efficiency (WUE) of crops, and improved planting method is a potential option. Field experiments were conducted for 3 years to evaluate effects of three planting methods of groundnut viz. flat-bed, ridge and furrow and paired-row at four irrigation regimes viz. 1, 2, 3 and 4 irrigations. Ridge and furrow, and paired-row methods resulted in an increase in pod yield by 13 and 17% and irrigation water saving by 26.7 and 41.7%, respectively compared with flat-bed method. Although highest yield level was similar in ridge and furrow and paired-row methods with four irrigations, irrigation water was 28.4% less in the latter than the former. In the three irrigation x paired-row method, pod yield reduced by only 3.8%, whereas water saving was 26.9% compared to the four irrigations x paired-row method. Better root dry weight, greater intercepted photosynthetically active radiation, chlorophyll fluorescence (Fv/Fm and ФPS II) and rate of leaf photosynthesis contributed to higher yield and nutrient uptake under paired-row at higher irrigation regime than traditional flat-bed method. Although evapotranspiration (ET) increased with higher irrigation regimes; ridge and furrow and paired-row method decreased ET by 13 and 21%, and increased crop WUE by 32.6 and 48%, respectively over flat-bed. The pod yield (Y)-ET functions were found linear; it has been revealed that the crop will achieve maximum pod yield (2109 kg ha−1) with 359 mm ET under paired-row planting. Computed elasticity of water production and crop yield response factor could well be used for making irrigation decisions. This field study confirmed that paired-row planting and furrow irrigation had increased pod yield, saved water and enhanced WUE of groundnut under hot sub-humid conditions.

For optimal water and fertilizer management under furrow irrigation, it is important to understand the water and solute dynamics on the land surface and in the subsurface. An efficient mathematical tool is required to describe these dynamic processes. We propose a coupled model in which surface water flow and solute transport are described using the zero-inertia equation and the average cross-sectional convection-dispersion equation, respectively, while the two-dimensional Richards equation and the convection-dispersion equation are used to simulate water flow and solute transport in soils, respectively. Solutions are computed numerically using finite differences for surface water flow and finite volumes for solute transports in furrow. Subsurface water flow and solute transport equations are solved using the CHAIN_2D code. An iterative method is used to couple computations of surface and subsurface processes. Both surface and subsurface water flow and solute transport modules are coded in program subroutines and functions in the Intel FORTRAN environment. The coupled model was validated by comparing its simulation results with measured data. Results showed that simulated water front advances in the furrow and water contents in the soil agreed with the observations reasonably well. Good simulations can be achieved with a relatively fine temporal resolution. Numerical oscillations can be eliminated by adopting appropriate time steps. As compared with the traditional furrow irrigation model, the proposed model can better quantify soil water and solute dynamics by considering interactions between surface and subsurface water flow and solute transport processes. The proposed model can be used as a decision tool to design and manage furrow irrigation.

Programs targeting conversion to irrigation techniques promoted as water-efficient, such as drip irrigation, are multiplying worldwide with the claimed objective to secure food production while alleviating the pressure on water resources. However, there is a persisting and widespread questioning about the actual impact when implementing the techniques in the real-world context, particularly in smallholder farms. We propose a framework to support an integrated assessment of the impact on farm holding performance resulting from the conversion towards a new irrigation technique. It is implemented for a 4030 ha agricultural district in the Triffa plain of NE Morocco where increasing number of farms are changing surface to drip irrigation. The indicators within the framework are calculated using survey data from a sample of 25 farm holdings collected in 2012 and 2013. The survey data are enriched with institutional data and data estimated from hydrologic modeling. The results indicate that, in the study area, farmers engaging with drip irrigation are mainly motivated by social factors, while most environmental and economic indicators are signaling a neutral or undesirable effect resulting from the conversion to drip irrigation. These results question the relevance of the water use reduction objective underlying the ongoing national plan “Plan Maroc Vert” (PMV) that aims converting up to 50% of irrigated agricultural land in drip irrigation, and call for a stronger appropriation of this water-saving objective by the farm holders. However, limited data availability and quality did not allow to firmly demonstrate the robustness of the findings. This severe data constraint revealed the difficulty to assess the socio-eco and environmental impact of such irrigation plan in the study area, and highlights the need for a data collection, centralization, and sharing effort. Conditioned to a strong reduction in data uncertainty, the framework methodology proposed in this study can serve as a practical reference for other studies seeking for an integrated assessment of irrigation management changes.

High-input of water and nitrogen (N) fertilizers in intensive greenhouse vegetable production regions in China has successfully increased crop productivity in the past decades, but at a significant environmental cost and resource consumption. It is essential to choose best management practice (BMP) to meet multiple goals, such as keeping greenhouse vegetable yield stable, improving nitrogen use efficiency (NUE), and reducing the nitrogen pollution issue. However, the bottleneck is the capacity of predicting the simultaneous effects of different management practice scenarios on multiple goals and choosing BMP among scenarios. The object of this study was to identify BMP of water and N fertilizer for greenhouse summer cucumber in North China Plain using calibrated and validated EU-Rotate_N model. The data used to calibrate and validate the model were collected from a typical greenhouse summer cucumber field with four different water and N fertilizer treatments within the target domain region. A total of 240 varied scenarios of water use and fertilizer application were set up and then simulated by the model. An osculating value method was used to evaluate combinations of irrigation and fertilizer practices. Agronomic indices (yield, WUE and NUE), environmental indices (nitrate leaching and gaseous N loss), and economic index (value to cost ratio) were selected as the evaluation indices to identify the BMP. The results showed that cucumber yield increased to maximum value as water input reached to about 277 mm, then kept constant or even decreased under lower N fertilizer rates. Nitrogen started to lose as nitrate leaching when irrigation increased to 300–400 mm, and then nitrate leaching increased with irrigation increasing. The effects of water input on gaseous nitrogen loss were not significant. Regardless of N fertilizer rates, irrigating about 300 mm water can obtain the maximum NUE. Cucumber yield increased to maximum values as N fertilizer input reached to about 313 and 310 kg N ha−1 for furrow and drip irrigation, then was not affected by N fertilizer increase. The BMPs under furrow irrigation condition were to irrigate 300 mm with 300 kg N ha-1 and 250 mm with 300 kg N ha-1 under drip irrigation condition for greenhouse cucumber in the study area, respectively. Adopting the current BMPs, the applied nitrogen and irrigation water were at about 55 and 40% lower rates, respectively, than the current conventional use. Our study indicated that the EU-Rotate_N model combined with Osculating value method can be helpful to assess multi-goal effects of management alternatives and identify BMP.

The North China Plain (NCP) is the main wheat production area in China; however, irrigation water and nitrogen fertilizer use in this area is relatively inefficient, and must be optimized to attain higher yield and resource use efficiency for winter wheat. In this study, a four-year field experiment was conducted during the 2012–2016 growing seasons. Under quota irrigation conditions, an experiment with various micro-sprinkling frequencies (S2, irrigation at jointing and anthesis; S3, irrigation at jointing, booting and filling; and S4, irrigation at jointing, booting, anthesis and filling) was conducted in 2012–2014. In 2014–2016, different nitrogen application rates (150, 195, and 240 kg N ha−1; denoted as S4N1, S4N2, and S4N3, respectively) under the S4 condition were tested. The local traditional flood irrigation pattern was designated as the control (CK) in 2012–2016. The grain yield, leaf area index of the population (LAI), flag leaf senescence during gain filling, accumulation and distribution of dry matter and nitrogen, and water and nitrogen use characteristics were investigated. The results showed that, no significant difference was observed in grain yield between the CK and S2, whereas S4 and S3 showed increased grain yields of 5.7–22.2% and 4.6–19.1%, respectively, compared with the CK. The increase of yield in micro-sprinkling treatments was mainly due to a significant increase in the 1000-grain weight. With increasing irrigation frequency, the LAI at the filling stage improved significantly; the flag leaf chlorophyll content decreased slowly; and the total dry matter accumulation, dry matter after anthesis, and its contribution to grain yield increased significantly. Meanwhile, the total water consumption of S4 (N2) decreased significantly, and the water use efficiency increased by 10.0–27.8% compared with the CK. In addition, micro-sprinkling irrigation with frequent application of a small amount of water with optimized nitrogen application (S4N2) yielded the highest nitrogen fertilizer use efficiency. Water consumption and nitrogen accumulation during grain filling were significantly increased in S4, which could explain the higher yield and resource use efficiency of S4. Overall, a suitable micro-sprinkling irrigation frequency (S4) and nitrogen application (195 kg N ha−1) can achieve higher grain yields and resource use efficiencies in the NCP.