Reduce Irrigation Water Research Articles

The effect of deficit irrigation on yield and water use efficiency of lentil (Lens culinaris Medik.).

کم‌آبیاری یکی از گزینه‌های ایده‌آل برای کاهش تلفات آب و به تبع آن بهینه‌سازی کارایی مصرف آب در مناطق خشک است. به همین منظور، آزمایشی به صورت کرت‌های خرد شده در قالب طرح بلوک‌های کامل تصادفی در 4 تکرار در مزرعه تحقیقاتی مجتمع آموزش عالی سراوان انجام شد. فاکتور اصلی شامل چهار سطح ‌آبیاری (شامل 120، 100، 80 و 60 درصد) و فاکتور فرعی دو توده عدس (بلوچستان و کردستان) بود. به طور کلی، نتایج نشان داد که اثر کم‌آبیاری بر عملکرد دانه، عملکرد بیولوژیک، شاخص برداشت، تعداد غلاف در بوته، تعداد دانه در بوته و کارایی مصرف آب معنی‌دار بود. صرف‌نظر از توده عدس، با افزایش میزان مصرف آب، عملکرد افزایش پیدا کرد اما این افزایش در سطح 120 درصد نسبت به شاهد معنی‌دار نبود که این امر منجر به کاهش کارایی مصرف آب در تیمار 120 درصد گردید. تیمار 80 درصد با10 درصد کاهش عملکرد نسبت به تیمار شاهد (100 درصد)، دارای بیشترین کارایی مصرف اب بود. همچنین، بیشترین شاخص برداشت در تیمار 80 درصد (0.24) و توده بلوچستان بدست آمد. عملکرد بیولوژیک توده بلوچستان در تیمار 80 درصد نسبت به تیمار شاهد، 27 درصد کاهش یافت که در نهایت منجر به افزایش شاخص برداشت شد. بنابراین، با توجه به اینکه منطقه مورد نظر جزء اقلیم‌های خشک محسوب می‌شود می‌توان با 20 درصد کاهش آب آبیاری از منابع محدود آب حفاظت کرد.

Did water-saving irrigation protect water resources over the past 40 years? A global analysis based on water accounting framework

Water-saving technologies have long been seen as an effective method to reduce irrigation water use and alleviate regional water shortage. However, growing reports of more severe water shortage and increasing application of water-saving technologies across the world have necessitated reassessment of agricultural water-saving. This study develops a simple method based on satellite-based ET partitions to estimate water withdrawal, water consumption and return flow from the 1980s to 2010s, and quantifies water-savings across globe and four hot-spot irrigated areas at both field and regional scales based on water accounting framework. The results show that global irrigation water flows keep increasing from the 1980s to 2010s, with over 50% increase from the expansion in irrigated lands. While water-saving technologies are found mainly applied in originally old irrigated lands, traditional flooding irrigation is still dominant in newly-developed irrigated lands. Non-beneficial water consumption (soil evaporation) is effectively reduced by water-saving technologies, but return flow has increased at the same time. At field scale, water-saving technologies fail to save water because the accumulated increased return flow is more than the accumulated decreased non-beneficial water consumption. At regional scale, however, water is saved because the return flow percolated to fresh aquifers is seen as beneficial rather than loss. At the same time, the accumulated increase of beneficial water consumption (crop transpiration) exceeds regional water savings, which explains the paradox between wide application of water-saving technologies and more severe regional water shortage. This study provides key new evidence for the paradox of irrigation efficiency and helps reconsidering water-saving technologies and their impacts on regional water resources.

Impacts of alternate wetting and drying and delayed flood rice irrigation on growing season evapotranspiration

As rice production is water intensive, establishing an accurate field–scale water budget is paramount for sustainable use of local water resources. This study’s goal was to quantify and characterize half-hourly and seasonal evapotranspiration (ET) in two commercial, zero–grade rice fields in the U.S. Mid–South over three growing seasons. During each growing season, irrigation regimes for the studied fields differed between alternate wetting and drying (AWD) and delayed flooding (DF). The 2015 growing season enabled a direct comparison of the effects of AWD and DF on ET, while during the 2016 and 2017 seasons both fields were simultaneously under AWD and DF, respectively. The DF method is the region’s most common irrigation practice, and it prescribes a continuous flood to be maintained for the majority of the growing season after the plants have reached the 5-leaf growth stage (40–50 days after planting). In contrast, after holding this initial flooding for 3 weeks, AWD allows for field drying to promote the capture of seasonal rains to reduce irrigation water withdrawal and associated water pumping costs. In this study, ET was estimated using gap–filled eddy covariance observations and two variations of the Penman–Monteith equation. These methods determined growing season ET values between 560 mm and 636 mm. This study found that there were no significant differences in cumulative ET or yield when comparing AWD to DF practices. Furthermore, AWD elicited no change in ET during periods of drying when compared to DF. By this metric, AWD did not induce drought stress within the plants. We conclude that the main benefit of the AWD practice is to take advantage of seasonal rainfall to offset pumping costs and pressure on irrigation water requirements while maintaining yields comparable to conventional irrigation practices.

Nexus Between Smallholder Irrigation Farming and Farmers’ Livelihood Outcomes in Ghana’s Guinea Savannah

The aim of the study was to relate small-scale irrigation farming and farmers’ livelihood outcomes using the poorest District in the Upper West Region of Ghana. The livelihood implications of rural farmers remain inconclusive across the literature. Mixed methods and primary data consisting of key informant interviews, household questionnaires and personal observation were used for the study. Data were obtained from 120 farmers drawn from 173 farming households living in four (4) small-scale irrigation dams’ communities. The results revealed a significant source of supplementary income and household food is provided by smallholder irrigation farming. The results further revealed that farmers employ a plethora of technologies including the use of mulch to stem soil moisture loss, livestock manure and chemical fertilizers to remedy soil productivity decline as well as hand-dug wells to supplement the reduction in irrigation water. However, the results revealed that irrigable land is not accessible to non-land owning ethnic groups. Access to irrigable land should be the number one consideration in siting irrigation facilities in Ghana.

Reducing sugarcane irrigation demand through planting date adjustment in Alagoas State, Brazil

ABSTRACT Sugarcane is both an important crop for the Brazilian Northeast economy, which faces severe water scarcity, and a water-intensive crop. Thus, it is important to develop irrigation strategies to reduce irrigation water demand in the region. This study aims to determine the sugarcane planting date that results in the maximum rainwater availability to the crop in the growing cycle. The crop effective precipitation was estimated from a soil water balance performed during three planting cycles of sugarcane, cultivar ‘RB 92579’. The crop was planted under subsurface drip irrigation in five months: October, November, December, January, and February, corresponding to the dry season period of the region. The experiment was conducted at the Açúcar e Álcool Coruripe Mill, located in the Coruripe municipality, State of Alagoas, Brazil, during the years 2012 to 2016. For all planting dates and growing cycles studied, the average effective rainy precipitation was equal to 30% of the total rainfall under irrigated conditions and 54.5% without considering the irrigation component in the soil water balance. November was the planting date that resulted in the minimum irrigation depth for the sugarcane growing cycle, with the potential irrigation water saving ranging from 5 to 129 mm.

Effect of controlled soil drying on the grain yield and nutritional quality of rice

AbstractControlled soil drying can substantially enhance water use efficiency by reducing irrigation water. However, grain quality traits are yet to be studied under such an irrigation regime, particularly on nutritional quality and heavy metal residues. This study investigated these issues by using two varieties Yongyou 2640 (YY‐2) and Nanjing 9108 (NJ‐9). Rice (Oryza sativa L.) was grown in the field under controlled soil drying (SD) and continuous flooding irrigation (FI). The results showed that, compared with FI, SD increased grain yield and nutritional quality simultaneously for both NJ‐9 and YY‐2. When compared with NJ‐9, YY‐2 had greater grain and protein yield, higher concentrations of As and Cd, and higher photosynthetic rate and transpiration rate when plants were rewatered. Although the relative content of protein and essential amino acids decreased in the SD regime, the absolute content (protein yield and amino acid yield) was increased. Besides, SD improved protein components and essential amino acid score (AAS) and decreased residues of As. The results demonstrated that SD improved photosynthetic characteristics and increased grain abscisic acid levels of inferior grains during soil drying. The results suggest that the adoption of SD may exert a synergistic effect on both grain yield and grain quality.

Interactive effect of soil mulching and irrigation regime on yield, irrigation water use efficiency and ‎weeds of trickle–irrigated onion

ABSTRACT Reducing the water loss sources, i.e. soil evaporation and weeds presence, is an essential act for keeping well soil moisture to crop growth, especially under drought conditions. Therefore, two–year field trials were conducted for seeking the best compatible practice between irrigation regime and weed control method in onion onion. Three irrigation water regimes (60%, 80% and 100% of the crop water requirements, CWR) and seven weed control practices (rice, wheat and peanut straws as soil mulches as well as oxadiargyl, oxyfluorfen, weeding, and unweeded) were applied. Findings revealed that the application of 60% of CWR either with peanut straw mulch or weeding recorded the maximum reduction in weed biomass. In plots mulched by peanut straw irrigation with 80% of CWR produced acceptable marketable bulb yield, NPK contents, flavonoids content and economic returns closing irrigation by 100% of CWR. In conclusion, the rate of water loss from soil surface through evaporation was much lower in case of mulch treatment than non–mulched one. Thus, mulch not only keeps weeds out but also maintains soil moisture. This allows the opportunity to reduce irrigation water by 20% (80% of CWR) with gaining acceptable yield, saving water and raising benefit/cost ratio.

Leaching Fraction-based Microirrigation Schedule Reduced Water Use but Not N and P Loss during Production of a Container-grown Shrub

Irrigation that decreases the leaching fraction (LF; leachate/water applied) has been shown to reduce fertilizer N and P leaching during the production of sprinkler-irrigated, container-grown plants; however, little research involving outdoor production of microirrigated plants in large containers has been conducted. Two microirrigation schedules based on routine leaching fraction testing were compared to determine their effects on water use and leaching losses of N and P during the production of Dwarf Burford holly in 36-cm-diameter (trade #7) containers. Applied irrigation water and leachate were collected continuously and sampled weekly during the 12-month experiment. An irrigation schedule adjusted once every 1 to 3 weeks to a target LF of 20% resulted in the application of 36% less water (383 vs. 597 L/plant) and 43% less leachate (255 vs. 445 L/plant) than a schedule adjusted to a target LF of 40%; plant growth was unaffected (P > 0.05). Irrigation schedules had no effect (P > 0.05) on cumulative N and P leaching losses, which were attributed in large part to rain. Average leaching losses of N and P were 15.2 and 2.2 g per container (210 and 30 kg·ha−1·year−1), respectively. Both N and P leaching losses represented 35% of the 43.5 g N and 6.3 g P applied per container in two controlled-release fertilizer applications. The results support the best management practice of scheduling irrigation based on routine LF testing to reduce irrigation water use but not reduce N and P leaching.

Reducing N2O emissions with enhanced efficiency nitrogen fertilizers (EENFs) in a high-yielding spring maize system.

Enhanced efficiency nitrogen fertilizers (EENFs), including nitrification inhibitors (NIs) and slow-release fertilizer (SRF), are considered promising approaches for mitigating nitrous oxide (N2O) emissions while improving crop yield. This study investigated the combined application of EENFs with improved water and fertilizer management in an intensively irrigated spring maize rotation over five years in Northwestern China. High-frequency measurements of N2O fluxes were made throughout each year (both during crop growth and the fallow season) in five treatments: no N fertilizer as a control (CK), conventional N fertilization and irrigation (Con), optimum N fertilization and irrigation (Opt, 33% reduction in N fertilizer and 25% reduction of irrigation water), optimum N fertilization and irrigation with nitrification inhibitor (Opt+NI), and optimum N fertilization and irrigation with slow-release fertilizer (Opt-SRF). Annual mean cumulative N2O emissions reached 0.31±0.07, 3.66±0.19, 1.87±0.16, 1.23±0.13, and 1.61±0.16kg N2O-N ha-1 for CK, Con, Opt, Opt+NI, and Opt-SRF, respectively, with annual mean nitrogen use efficiency (NUE) of 36, 54, 61 and 59% for Con, Opt, Opt+NI, and Opt-SRF, respectively. The Opt, Opt+NI and Opt-SRF treatments significantly reduced cumulative N2O emissions by 49%, 66%, and 56% (P<0.05), respectively, and increased NUE by 51%, 70%, and 66% (P<0.05), respectively, relative to Con. However, mean above-ground N uptake (288-309kgN ha-1) and mean grain yields (12.7-12.8Mgha-1) did not differ significantly between the Con, Opt, Opt+NI, and Opt-SRF treatments during the five-year study. High N2O emissions mainly occurred within a few days of fertilization with irrigation, which could have been produced by microbially-mediated nitrifier or nitrifier denitrification processes. The fallow seasons had significantly lower cumulative N2O emissions, which were mainly attributed to the low temperature, low N inputs of crop residues, and low soil moisture conditions. Our study clearly indicated that the combined application of EENFs with optimum N fertilization and irrigation management can reduce environmental impacts while maintaining high crop yields in dryland regions such as Northwest China.

Development and Evaluation of a Variable-Rate Irrigation Management Method in the Mississippi Delta

HighlightsWe developed and evaluated a variable-rate irrigation (VRI) management method for five crop years in the Mississippi Delta.VRI management significantly reduced irrigation water use in comparison with uniform-rate irrigation (URI). There was no significant difference in grain yield and irrigation water productivity between VRI and URI management.Soil apparent electrical conductivity (ECa) was used to delineate irrigation management zones and generate VRI prescriptions.Sensor-measured soil water content was used in irrigation scheduling.Abstract. Variable-rate irrigation (VRI) allows producers to site-specifically apply irrigation water at variable rates within a field to account for the temporal and spatial variability in soil and plant characteristics. Developing practical VRI methods and documenting the benefits of VRI application are critical to accelerate the adoption of VRI technologies. Using apparent soil electrical conductivity (ECa) and soil moisture sensors, a VRI method was developed and evaluated with corn and soybean for five crop years in the Mississippi Delta. Soil ECa of the study fields was mapped and used to delineate VRI management zones and create VRI prescriptions. Irrigation was scheduled using soil volumetric water content measured by soil moisture sensors. A center pivot VRI system was employed to deliver irrigation water according to the VRI prescription. Grain yield, irrigation water use, and irrigation water productivity in the VRI treatment were determined and compared with that in a uniform-rate irrigation (URI) treatment. Results showed that the grain yield and irrigation water productivity between the VRI and URI treatments were not statistically different with both corn and soybean crops. The VRI management significantly reduced the amount of irrigation water by 22% in corn and by 11% in soybean (p = 0.05). Adoption of VRI management could improve irrigation water use efficiency in the Mississippi Delta. Keywords: Soil electrical conductivity, Soil moisture sensor, Variable rate irrigation, Water management.

Nitrification and Denitrification Processes in Rice (Oryza Sativa), with an Emphasis on Reduced Water Irrigation Regimes in USA

The nitrogen cycle is the basis for understanding nitrogen dynamics in soil fertility and ecosystem health. Nitrification and denitrification are key nitrogen cycle components that influence nitrogen uptake in food crops, thus critical to food security. Rice (Oryza sativa) is comparatively unique in that the nitrification-denitrification sequence is a perceived loss of available nitrogen for plant uptake and the production of nitrous oxide (N2O) has severe implications in climate change. This review focuses on recent research involving nitrification and denitrification, with an emphasis on rice. The review also focuses on the emerging irrigation strategies associated with furrow irrigation and alternating wetting-drying irrigation. With growing global interest in reducing irrigation water application, new research paradigms are emerging to perfect these reduced water applications systems to guarantee food security and farm profitability.

Performance of Drip Irrigation at Werer, Middle Awash, Ethiopia

Agriculture is the main contributor of the Ethiopian economy as it accounts for about 55% of the GDP, 60% of the foreign exchange earnings and provides livelihood to 85% of the population. The field experiments were conducted to evaluate the performance of drip irrigation systems werer agricultural research station, middle awash, Ethiopia. Middle awash is largest irrigated part of the country. It is well gifted with the land, sunshine and highly fortune in available water resources. Drip irrigation has greater water economy over other systems in arid and semi-arid regions characterized by high evaporation rates and it has the potential to increase yields of crops even with reduced irrigation water application. The performance of drip irrigation system was evaluated on the basis of parameters like emitter flow variation (q_var), distribution uniformity (DU), application uniformity (Ea), coefficient of variation (CV), statistical uniformity (SU) and Christiansen uniformity coefficient (UCC). High values of uniformity coefficient and uniformity of distribution are attributed to the effect land levelling. The hydraulic performance of drip irrigation result shows the emitter flow variation (0.07%), emission uniformity (92.2%), coefficient of variation (0.07%), Christiansen uniformity coefficient (90.8) and application efficiency of (85%).

Searching for “Win-Win” solutions for food-water-GHG emissions tradeoffs across irrigation regimes of paddy rice in China

Paddy rice cultivation is an important source of agricultural greenhouse gas emissions in China. The traditional flooded paddy rice fields not only use large amounts of irrigation water, but also produce significant methane (CH4) emissions. To balance food security with environmental impacts of rice production, many water-saving irrigations technologies have been tested in the field to increase the drainage period during the rice growth cycle. However, whether these management solutions can be implemented at the regional scale needs to be further explored. Because it is too time-consuming and resource-intensive for field experiments to be carried out across large areas, we opt to assess the regional impacts of alternative irrigation schemes via computer modeling, by coupling the well-known DSSAT and DNDC models, which have been extensively validated in China. Irrigation methods tested include the traditional Continuous Flooding (CF), Midseason Drainage (MD) and Alternate Wetting and Drying (AWD). Simulation results show that compared with CF, water-saving irrigation methods can significantly reduce the CH4 emission from paddy rice field, with slight or no loss in expected rice yields. AWD had the greatest effect in reducing irrigation water amounts and CH4 emission. Compared with CF, CH4 emission under the AWD were 60% - 71% lower in Northeast China sites and 34% - 65% lower in South China sites. At the same time, compared to CF, irrigation water use in AWD was reduced by 23% - 34% in northeast China sites and by 18% - 50% in south China sites. Our results suggest that policies that support expansion of AWD in paddy rice cultivation across China can lead to a “win-win” for the food-water-GHG emissions tradeoffs, and offer a viable solution for policy makers and stakeholders in China.

Environmental Mitigation Through Irrigation Management in Sugar Beet Production

This study assessed the greenhouse gas (GHG) emissions of sugar beet production under different irrigation and fertilizing strategies. This manuscript is an evaluation of the on production inputs used in a research carried previous on sugar beet and its conversion into GHG emissions equivalent. This paper evaluated the potential for environmental mitigation, including the reduction of total GHG emissions from agricultural inputs in sugar beet production by managing irrigation and nitrogen fertilizing. In this context, the nine treatments based on three different irrigations (full irrigation, conventional deficit irrigation, partial root drying irrigation) and three nitrogen fertilizing strategies (full nitrogen, partial deficit nitrogen, moderate deficit nitrogen) were assessed. The results of evaluation showed that DI-N 1 strategy can reduce irrigation water and nitrogen use up to 25% compared to control treatment (FI-N). In addition, this strategy saved 25% of electricity consumption use for irrigation. The analyse of pollution in this study led to very important findings: more environment-friendly irrigation and fertilization practices by using less water and nitrogen have a considerable potential for environmental mitigation in sugar beet production

Crop and Residue Management Improves Productivity and Profitability of Rice–Maize System in Salt-Affected Rainfed Lowlands of East India

This study was conducted over 3 years in a salt-affected coastal rainfed lowland ecosystem. Farmers most commonly grow tall rice varieties in the wet season to cope with flash and/or stagnant floods, leading to large amounts of rice residue production. Most of the land remains fallow during the dry season because of increased salinity and scarcity of freshwater for irrigation. The study aims to provide options for increasing cropping intensity through management of crop residues (CR) and soil salinity, conservation of soil moisture, and reduction in production cost. The rice–maize rotation was assessed with rice as the main plot as (1) puddled transplanted rice (PTR) with CR of both rice and maize removed, (2) PTR and 40% CR of both crops retained, (3) dry direct-seeded rice (DSR) with CR of both crops removed, and (4) DSR with 40% CR of both crops retained. Maize in the dry season was supplied with different N levels as sub-plots—control (0 kg N ha−1), 80, 120, and 160 kg N ha−1. DSR, when combined with CR retention (DSR + R), reduced soil salinity. The increase in rice grain yield with CR retention (observed in second and third years) and crop establishment (higher in DSR versus PTR in the third year) was 16 and 24%, respectively. The cost of production increased by 17% (USD 605 ha−1) in PTR compared with DSR (USD 518 ha−1). CR retention reduced irrigation water requirement by 37% and N requirement by 40 kg ha−1 for hybrid maize. When CR was removed (−R), the N requirement for hybrid maize increased to 160 kg N ha−1 compared to when it was partially (40%) retained, where the requirement was 120 kg ha−1 with similar yields. Available N was highest under DSR + R (314 kg ha−1) and lowest under PTR − R (169 kg ha−1), and it also increased with increasing N application up to 120 kg ha−1 (+R) and 160 kg ha−1 (−R). The results of the study hold promise for increasing cropping intensity and farmers’ incomes, with broader implications for increasing productivity on about 2.95 million hectares currently under a rice–fallow system in eastern India, and in coastal areas affected by similar conditions in South and Southeast Asia.

Field and Modeling Study on Manual and Automatic Irrigation Scheduling under Deficit Irrigation of Greenhouse Cucumber

The primary goal of all those working in the field of sustainable water management, particularly in the arid and semi-arid zones, is to increase irrigation efficiency, reduce irrigation water losses, and improve water productivity for all crops. This study assessed the automatic irrigation scheduling and irrigation management on the growth, yield, and water productivity of cucumber under greenhouse conditions. A field experiment was conducted using cucumber grown in aplastic greenhouse during the winter of 2017/18 and 2018/19 at the research farm station of the National Research Centre (NRC), El-Noubaria Region, Behaira Governorate, Egypt. In a split-plot experiment, two different methods to control irrigation scheduling (manual control (MC) and automatic control (AC)) were used in the main plots and three deficit irrigation treatments (100% of full irrigation (FI), 80% of FI, and 60% of FI). Through the obtained results, it was found that the use of the automatic control of the irrigation schedule led to an improvement in the productivity and quality characteristics of the cucumber crop. Automatic irrigation control created healthy conditions for the plant roots located under the least water stress. This led to an increase in nitrogen uptake at the ages of 3, 5, 7, and 9 weeks after planting in addition to improving the total leaf area and the chlorophyll content of leaves, which consequently had a greater effect on increasing yield and water productivity of cucumber. Although the highest values of cucumber productivity were obtained with irrigation at 100% of FI, there were no significant differences between 100% FI and 80% of FI, therefore it is preferable to irrigate at 80% of FI, and this means saving 20% of irrigation water that can be used to irrigate other areas. The SALTMED model simulating all of the following evaluation criteria performed well for soil moisture content and N-uptake as well as the leaves area, the yield, and water productivity of cucumber for all treatments for the two growing seasons 2017/18 and 2018/19, with the overall R2 of 0.882, 0.903, 0.975, 0.907, and 0.933, respectively.

Impact of participatory irrigation management on mulched drip irrigation technology adoption in rural Xinjiang, China

Abstract Reforms in irrigation management can make important contributions to reducing irrigation water scarcity. This paper attempts to examine the role of participatory irrigation management (PIM) in farmers’ mulched drip irrigation technology adoption decisions. It is based on a comparative analysis between government-promoted mulched drip irrigation technology (GMDIT) and localized self-governed mulched drip irrigation technology (LMDIT) in rural Xinjiang, China. Data from a survey conducted in 2017 across 739 households covering 1763 plots in Awati County in Xinjiang were used to estimate a nested logit model. The results indicate that PIM induces farmers to switch from traditional flood irrigation technology to GMDIT but does not promote the adoption of LMDIT. We conclude that promoting PIM can make an important contribution to more sustainable water use in this drought-prone area but that the self-governance of localized irrigation systems requires more attention by local governments.

Biochars reduce irrigation water sodium adsorption ratio

Irrigation water quality plays a vital role in sustaining crop productivity and feeding a growing world population. In many countries, continued agricultural water reuse can lead to greater water-soluble salt concentrations, and in particular Na; finding means by which irrigation water Na, and thus sodium adsorption ratios (SAR), can be reduced would reduce the rate at which soil sodification occurs. Four biochars, containing a variety of organic functional groups and electrochemistries, were examined for their potential to sorb and remove Na from simulated irrigation water, and subsequently reduce water SAR. Two batch experiments examined the role that wheat straw biochar, lodgepole pine biochar, Kentucky bluegrass biochar, and hemp biochar played in terms of sorbing sodium over time or application rate. Of the four biochars examined, hemp biochar had the lowest oxidation–reduction potential (ORP; ~ 0–100 mV), sorbed the greatest Na amount (up to 923 mg kg−1), and released Ca and Mg (up to 115 and 63 mg kg−1, respectively) into solution, all of which led to a significant reduction in water SAR (from 8.8 to 7.3; 17% decrease). Sodium sorption onto hemp biochar better fit a Langmuir versus a Freundlich isotherm, yet followed a pseudo-second-order model better than a pseudo-first-order kinetic model. The data suggest that Na ions formed a monolayer on the hemp biochar surface, influenced by associations with π electrons, but given time the Na ions may diffuse into biochar pores or more slowly interact with biochar-borne π electrons. Hemp biochar shows promise in reducing the SAR of Na-impacted waters. Future investigations should focus on additional laboratory, greenhouse, and field trials with hemp biochar and other biochars designed to have similar or superior properties for sorbing excess irrigation water Na and improving crop growth.

Application of high‐voltage discharges for disinfection and activation of irrigation water*

AbstractTo prevent the development of plant diseases, irrigation water needs to be disinfected. The commonly applied cleaning methods do not allow the possibility of activation and enrichment of irrigation water with nutrients. The target of this study is to develop an environmentally friendly method for disinfecting and activating irrigation water by treatment with high‐voltage discharges in an electro‐hydraulic installation. The study used the following materials and equipment: a high‐voltage installation with an electro‐hydraulic spark gap, an EnSURE luminometer (Hygiena) to measure the level of hygiene of water and its solutions, AquaSnap Total (AQ100X) test tubes (Hygiena) to determine the total amount of adenosine triphosphate (ATP) in water, and an ITAN ionomer (Tomanalit) for measuring nitrogen compounds in water. Experimentally the following optimal parameters and technological conditions were determined and substantiated to reduce irrigation water pollution from 1210 RLU to 73 RLU and increase water content of nitrogen compounds from 1.2 mg L‐1 to 8.4 mg L‐1: an operating voltage of 19.9 kV, a capacity 0.145 μF, and a number of discharges of 2860 pcs. Water disinfected with high‐voltage discharges will be useful for agricultural irrigation since it can serve as a nitrogen fertilizer, which does not have any harmful effect on the environment.

Verification of the Efficiency of Alternate Furrow Irrigation on Amount of Water Productivity and Yield of Onion at Sekota Woreda

Efficient water use becomes an important issue in recent years because of the lack of available water resources in some areas is increasing and a serious problem. Globally and more particularly in developing Countries, changing water availability and quality is a complex problem, and management options are not easy. Therefore Partial rootzone drying is a practice of using irrigation to alternately wet and dry (at least) two spatially prescribed parts of the plant root system to simultaneously maintain plant water status at maximum water potential and control vegetative growth for seasonal plant development. The experiment was conducted on the 2017/2018 irrigation season at the irrigation scheme of Sekota woreda. Three irrigation methods alternating furrow irrigation (AFI), conventional furrow irrigation (CFI), and fixed furrow irrigation were verified on separate plots. The design of the experiment was RCBD with four farmers as replications. Each irrigation method was used a 75% amount of irrigation water for five days irrigation interval for verified irrigated onion. The results show that total irrigation water applied in the AFI and FFI treatment was roughly half (3038 m3) that applied to the CFI treatment (6078 m3). There was a significant reduction in irrigation water used with the AFI but a non-significant reduction on the onion yield production. The AFI water productivity was astatically significantly different from FFI and CFI. The water productivity obtained 4.05 kg m-3 with AFI and 3.16 kg m-3 with FFI which was nearly double the 2.15 kg m-3 with CFI. Alternate furrow irrigation (AFI) is gaining interest as a means of saving water while minimizing loss in crop production. In the AFI system, the total water used was half of the CFI system. Rather than using 6076 m3/ha of water for 1 hectare in the CFI system, it is possible to double the irrigated area to 2 hectares in the AFI system. The onion needs a high amount of irrigation water during the development stage, but in the FFI system, as half of the root stays dry throughout the growth period, continuous stress significantly reduces fresh bulb yield.