Excessive Irrigation Research Articles

Projected impacts of climate change on global irrigation water withdrawals

Investigating processes causing water resource depletion risks is key to understanding past, present, and future excessive irrigation water withdrawal. Quantitative spatiotemporal analysis of the factors driving excessive irrigation water withdrawal is currently inadequate. Although multiple drivers typically contribute to this risk, we studied, for the first time, whether and how Actual Irrigation Water Withdrawals (AIWW) could affect global future water resources projection. Here, we used AIWW datasets from five CMIP6 climate models based on two Shared Socioeconomic Scenarios (SSP370 and 585) and a global hydrological model (H08) to compare the historical (1981–2014) with the future periods: 2041–2070 and 2071–2100. Results show that the temporal AIWW average variations have shown a statistically significant increase during 1981–2014 (p<0.05 and R2 = 0.98) ranging from 101.82 to 136.24 mm yr−1 (mean = 120.5 mm yr−1). Under SSP370 and SSP585, the global spatial AIWW average during 2041–2070 and 2071–2100 are 142.55 and 145.55, and 144.91 and 149.74 mm yr−1, respectively. Under SSP370 and SSP585, the average AIWW changes for 2041–2070 and 2071–2100 are projected to be 96.71, 97.55, 103.52, and 106.98 %, respectively. Under SSP370 and 585, the average global AIWW anomaly changes for 2041–2070 and 2071–2100 are also projected to be −96.86, −106.29, −97.72, and −111.48 %, respectively. Higher AIWW increases are mainly concentrated in India, South China, parts of the United States, parts of Europe, and parts of South African and Latin American countries. Substantiated with population increase, and higher food demand, an increased AIWW will further aggravate globally. Thus, exploring future AIWW changes is a key step forward that requires greater attention in irrigation research interventions helpful to inform societies to reduce future risks of water resource depletion. Adaptation policies targeting the future use of water for irrigation are crucial to lessen water resource depletion risk, suggesting the need for large-scale policy interventions.

Coupling effects of irrigation amount and fertilization rate on growth and bioactive components of four-year-old licorice (Glycyrrhiza uralensis Fisch) in arid regions of Xinjiang

Water scarcity, over-fertilization, and improper crop management practices severely limit the sustainable cultivation of licorice (Glycyrrhiza uralensis Fisch) in the arid regions of Xinjiang. To elucidate the impacts of integrated water and fertilizer management on the growth characteristics and bioactive components (glycyrrhizic acid and liquiritin) of four-year-old licorice plants, a comprehensive four-year field experiment was conducted from 2019 to 2022.The experiment included four irrigation levels (W1: 2500 m³/ha, W2: 4000 m³/ha, W3: 5500 m³/ha, W4: 7000 m³/ha) and four fertilization rates (F1: 305 kg/ha, F2: 610 kg/ha, F3: 915 kg/ha, F4: 1220 kg/ha), following a completely randomized design. Results indicated that both irrigation and fertilization significantly influenced plant height, root length, root weight, root diameter, leaf area index, and root-to-shoot ratio. The optimal growth characteristics were observed under the W2F2 treatment. The contents of glycyrrhizic acid and liquiritin varied significantly among different water and fertilizer treatments, with the highest levels observed under the W2F2 treatment. Excessive irrigation (W4) and over-fertilization (F4) led to a decrease in these bioactive components. A comprehensive evaluation of the growth characteristics and bioactive components revealed that the ideal irrigation and fertilization parameters were 4000 m³/ha and 610 kg/ha, respectively. These parameters optimized plant development and bioactive component accumulation while ensuring efficient resource use. This study provides scientific evidence for optimizing irrigation and fertilization strategies to enhance licorice yield in arid regions, thereby supporting sustainable agricultural practices and improving economic benefits.

Effect of Irrigation and Nitrogen Application at Early Tillering, Panicle Initiation and Flowering Stages on the Yield and Yield Attributes of Boro Rice

The study aimed to evaluate the impact of irrigation scheduling and nitrogen splitting on the yield and yield attributes of boro rice, with particular emphasis on critical growth stages including early tillering, panicle initiation and flowering stages. The experiment was executed at the Agronomy Field Laboratory of the Department of Agronomy and Agricultural Extension, University of Rajshahi, from December 2022 to May 2023. The experiment setup was demonstrated using a split plot design, incorporating three replications. Two factors were determined for the experiment: the first included three different watering schedules aiming critical growth stages: early tillering (I1), early tillering and flowering (I2), and early tillering, panicle initiation and flowering panicle initiation (I3). The second factor was distinct nitrogen splitting techniques, which consisted of four levels: control (N0), 138 kg N ha-1 as basal (N1), 69 kg N ha-1 at early tillering and flowering stages (N2), and 46 kg N ha-1 at early tillering, panicle initiation and flowering stages (N3). The highest reading of chlorophyll content was noticed in I3 along with productive tillers (15.67), grains (115.25) and yield outcome (4.44 t ha-1). Regarding nitrogen application, the greatest chlorophyll content, number of functional tillers (13.32), productive grains (112.44) panicle-1 and grain yield (4.48 t ha-1) was recorded in treatment N3. Therefore, the research finding suggest that the application of water at early tillering, panicle initiation and flowering stages along with the application of 46 kg N ha-1 will be helpful to maximize the production of rice in drought prone areas. This approach not only maximizes yield but also helps to mitigate water wastages associated with excessive irrigation.

Irrigation Regime Optimization Plays a Critically Important Role in Plastic-Shed Vegetable Production to Mitigate Short-Term and Future N Leaching Pollution

In northern China, plastic-shed vegetable production significantly contributes to nitrogen (N)-induced groundwater eutrophication due to excessive fertilization and irrigation. However, the impact of optimized farming practices on N leaching has seldom been systematically examined. We conducted a four-season field study to evaluate the impacts of optimal farming measures on tomato yield, water percolation, N concentration in leachate, and total N (TN) leaching. The treatments included conventional fertilization and flood irrigation (CON), fertilization decreased by 20% and flood irrigation (OPT1) or drip fertigation (OPT2), fertilization decreased by 30% and drip fertigation (OPT3), and no fertilization with flood irrigation (CK). Compared with the CON treatment, the optimal treatments significantly reduced annual TN leaching by 9.92–50.7% without affecting tomato yield (57.1–98.2 t ha−1 for CON and 48.1–106 t ha−1 for three optimal treatments). Drip irrigation contributed 73.8–79.0% to the mitigation of TN leaching. The N originating from soil and irrigation water exhibited a similar contribution to TN leaching (45.4–58.6%) to that of fertilizer N. The daily TN leaching at the basal fertilization stage was much greater than that at the top-dressing stage, due to over-fertilization. Optimizing fertilization, particularly basal fertilization, in combination with drip irrigation could substantially reduce N leaching in plastic-shed vegetable production. Other optimal practices, such as decision support systems (DSSs) and fertilizer amendments, could also be investigated to further mitigate the N leaching.

Hydrogeochemical and isotopic investigations of groundwater in the reclaimed desert located between EL Nasr canal and Mariut Tableland, NW Coast, Egypt

A complete understanding of groundwater dynamics and its interaction with surface water under the impact of agricultural activities is vital for local agriculture, ecology, and residents of dry regions, which is not commonly recognized in arid areas. This research outlines the geochemical characteristics, recharge sources, and potential factors impacting groundwater quality in a new land reclamation located in the small basin of Abu Mina, which is part of the Western Nile Delta region.1 Thirty-one groundwater samples and two surface water samples were collected in 2021 to represent the Pleistocene aquifer and were subjected to multivariate statistical, hydrochemical, and stable isotope analyses. Data analysis demonstrates that Na+ > Ca2+ > Mg2+ > K+ and SO42– > Cl– > HCO3– > NO3– are the predominant cations and anions, respectively. Groundwater salinity ranged from 465.60 to 6455.18 mg/l, with slightly alkaline. Most of the water samples fall into one of three types of facies: Ca–Cl, Na–Cl, and Mixed Ca–Mg–Cl, in decreasing order. The meteoric genesis index (r2) indicates that deep meteoric water percolation dominates the Pleistocene aquifer. The aquiline diagrams, correlation matrix, and different ionic ratios indicate that evaporation, reverse ion exchange reactions, and the dissolution of carbonate and silicate minerals are the main processes governing groundwater chemistry. Factor analysis (FA) indicated that three factors explain groundwater hydrochemistry, accounting for 71.98% of the total variance. According to the rotating components matrix (F1–F3), the chemistry of the Quaternary aquifer is principally affected by evaporation, ion exchange reactions, and anthropogenic influences. Additionally, salinity increases due to the return flow of irrigation activities and mixing between old and recent water. The stable isotopes (δ18O and δ2H) indicate that the Quaternary aquifer receives groundwater recharge through the return flow of excess irrigation and canal seepage. Under desert reclamation conditions, groundwater salinization processes should be given special consideration. All groundwater samples are appropriate for agricultural irrigation based on the Sodium Adsorption Ratio (SAR), Permeability Index (PI), Percent Sodium (%Na), and Residual Sodium Carbonate (RSC).

Effect of irrigation regimes on nutrient uptake and nitrate leaching in maize (Zea mays L.) production at Birr-Farm, Upper Blue Nile, Ethiopia

Sustainably managed irrigation water is essential to agriculture. In order to identify the best irrigation strategies for maximizing agricultural productivity and environmental health, this study examines the effects of various irrigation depths on nutrient uptake, nitrate leaching, and maize yield. The study was carried out at Birfarm, in the Jabitehnan District, Amhara, Ethiopia, throughout the irrigation periods of 2022/23 and 2023/24. The experiment used a (RCBD) with three replications testing five application depths to apply irrigation (50 %, 75 %, 100 %, 125 % and 150 % ETc). ANOVA was performed to determine the influences of irrigation levels on nutrient uptake and nitrate leaching. Irrigation levels significantly impacted N, P and K uptake. Maximum nutrient uptake occurred at 150 % ETc with higher nutrient uptake observed in the second experimental season. Irrigation levels significantly affected nitrate leaching, with the highest leaching at 150 % ETc. Excessive irrigation increased nitrate leaching, aligning with findings from other studies. Maize yield, thousand grain weight (TGW) and above-ground biomass yield (ABY) were significantly influenced by irrigation depth. Optimal irrigation (100 % ETc) produced the maximum yield of 6.08 and 5.83 tha-1, the maximum thousand grain weight of 682.51 g and 685.12 g, and the highest above-ground biomass yield of 31.41 and 32.74 tha-1 in the second and first experiments, respectively, while excessive and deficit irrigation reduced yield. The study highlights the importance of optimizing irrigation depth for nutrient uptake, nitrate leaching and maize yield. While increased irrigation improved nutrient uptake and yield, excessive irrigation led to higher nitrate leaching, emphasizing the need for balanced irrigation practices to enhance productivity and environmental sustainability. Farmers should implement 100%ETc to enhance productivity, ensure efficient nutrient utilization, and protect the environment from the adverse effects of nitrate leaching.

Rational optimization of irrigation regimes for drip-irrigated cotton fields without mulch can alleviate the problem of residual film contamination in arid zones

The serious problem of residual film pollution in the arid region of northwestern China has a severe negative impact on both the farmland environment and the benefits of cotton planting. Drip irrigation without mulch (DIWM) has the potential to serve as an effective alternative to mulch drip irrigation and address the issue of residual film pollution. However, there are few studies on how to formulate a rational irrigation regime under DIWM conditions and achieve water savings and productivity gains. Consequently, from 2020 to 2021, we established three DIWM treatments: W4, W6, and W8. None of the treatments were irrigated at the seedling stage, and the irrigation regime was the same for all the treatments at the squaring stage (2 irrigations at an irrigation quota of 45 mm). From the initial flowering stage, the frequency of irrigation was once every 6 d, 8 d, and 12 d for W4, W6, and W8, respectively, and the corresponding total numbers of watering times were 8, 6, and 4, respectively. The irrigation amount was 69 mm at each time point during the flowering and boll-forming stages in all the treatments, and the final irrigation amount was 52.2 mm in W8. The total irrigation amounts were 366 mm, 504 mm and 625.2 mm for W4, W6 and W8, respectively. This study explored the spatiotemporal characteristics of soil moisture via sensors combined with the spatial grid method. Additionally, the growth indices, biomass accumulation, yield components, and water use efficiency (WUE) of cotton were assessed across various treatments. The results revealed that, in 2020 and 2021, the W8 treatment resulted in the highest soil water content (SWC) in the 70–110 cm soil layer and soil water consumption (WC) in the 10–110 cm layer, with the WC in the 10 cm layer being 20 % and 44 % greater than that in W6, respectively. The excessive total irrigation amount (IA) in the W8 treatment led to high vegetative growth of cotton, diminishing the positive impact on yield. Across both years, the WUE observed in the W6 treatment significantly exceeded that of W8, while the seed cotton yield demonstrated only marginal decreases of 5 % and 0.9 % compared with that of W8. The irrigation amount and average WC in the 10–40 cm soil layer were 19 % and 29 % lower in W6 than in W8, respectively, but the economic benefits were only 2 % lower than those in W8. There was a significant positive correlation between the SWC and WC in all the different soil layers, and the effect of the SWC on the WC gradually decreased with increasing soil depth. Overall, the irrigation regime employed in the W6 treatment within the arid zone, devoid of mulch cover, proves to be an effective water-saving strategy, ensuring a consistent cotton yield and enhancing WUE. This study serves as a reference for developing an efficient irrigation system tailored to the DIWM cotton industry in arid zones, contributing to the promotion of green and sustainable agricultural development in this region.

Groundwater level prediction for excessive agricultural irrigation to achieve SDGs: Vulnerability assessment using field-based empirical method

Excessive over-drafting and unsystematic management of groundwater brings different geo-environmental problems; thus precise prediction of groundwater (GW) status in large scale becomes prime concern for efficient GW management. This present study primarily focused on estimating the current groundwater status of agro-rich Murshidabad district using a GIS-based empirical approach including trend analysis of groundwater depth (2001–2021) by using Modified Mann Kendall test (MMKT) and Sen's slope estimator; the most prominent water level fluctuation (WLF) method employed in the estimation of groundwater recharge scenario of the last three decades. The groundwater recharge potential zone (GWRPZ) also delineated through widely used logistic regression (LR) method. The current research depicts that eight CD Blocks and twenty-five CD Blocks out of twenty-six CD Blocks are facing notable declining trend in groundwater depth in pre-monsoon and post-monsoon period accordingly, with a 95% confidence level; the lowering down of groundwater recharge (GWR) also alarming, the recharge amount in 2001, 2011 and 2021 was 210958.70 ham, 240168.80 ham and 201921.90 ham respectively due to variability in rainfall; the predicted GWRPZ shows that 674 (12.6%) Km2 and 1392 Km2 (26.02%) come under very high and high recharge zone which is predominantly found in the eastern and south-eastern part of this study region, validated through most reliable method Receiver Operating Characteristics (ROC) and Area Under Curve (AUC) with 0.954 value. Unsystematic over-drafting of groundwater and intense cropping intensity are severely responsible for this alarming condition. Thus, sustainable groundwater management is essential to fulfil SDG-6 by ensuring SDG-2 and policymakers and planners will be benefited from this study in formulating the proper mitigation measures for this agronomic Murshidabad district.

Effects of water and fertilizer regulation on soil microbial community, fruit nutrients, and saponin content of Panax notoginseng: A three years field experiment

In pursuit of maximum yield and economic benefits of Panax notoginseng, farmers usually apply excessive fertilizer and irrigation. Which easily induce the decline of Panax notoginseng quality, fertilizer and water use efficiencies and soil health. From 2021–2023, a field experiment was conducted in Dali Village, Luxi County, Honghe Prefecture, Yunnan Province, to study the response of soil microbial community, root nutrient content, and ginsenoside content of Panax notoginseng to different water and fertilizer regulation. The experiment including three irrigation levels (F1: 120 mm, F2: 240 mm, and F3: 360 mm) four fertilization rates(F1: 48 kg ha−1, F2: 72 kg ha−1, F2: 96 kg ha−1, and 120 kg ha−1),and a CK treatment (no fertilizer and no irrigation) The results showed that the average N, P, and K contents across all treatments were greater in 2023 than those in 2021 and 2022. W3F4 treatment significantly increased N absorption. W2F4 treatment significantly increased P and K absorption. W2F4 treatment significantly increased the Panax notoginseng yield, and W3F2 treatment significantly increased the saponin content. The Panax notoginseng yield ranged from 1165 to 3006 kg∙ha−1, with a maximum average yield in 2023. The Re content averaged 81.5 % in 2023 over 2021, and the highest Re content in W3F2 treatment in 2023 was 108.54 mg∙g−1. In 2023, W2F3 treatment had the highest R1 content of 15.34 mg∙g−1, W2F3 treatment had the highest content of Rg1 of 44.65 mg∙g−1, and W3F2 treatment had the highest Rb1 content of 52.52 mg∙g−1. From 2021–2023, the total number of unique OTUs in W1F1 was the largest, out followed by W3F2, W3F4, and W3F1. The treatment that significantly increased the bacterial Chao1 index was W3F1 and W2F2 in 2021, W3F3, W2F1, W2F1 and W2F3 in 2022, and W2F3 and W2F4 in 2023. The Shannon nor Simpson indices were not varied significantly from CK. At the phylum level, W1F3 in 2021 and W3F1 in 2022 and 2023 improved the relative abundance of Proteobacteria, Acidobacteriota At the genus level, W1F1 in 2021 and 2023 improved the relative abundance of Vicinamibacteraceae_norank and Vicinamibacterales_norank. LEfSe analysis of soil microbial communities showed the most divergent species in 2021 with W3F2, W1F1 in 2022, and W2F1 in 2023. Different water and fertilizer treatments affected the total OTU number of bacterial communities and changed the bacterial community structure. W3F1 and W2F3 treatments significantly increased soil bacterial diversity, and soil microbial diversity regulated plants N as well as R1 and Rg1 content, and the quality of Panax notoginseng is related to microbial diversity. N, P, K, and R1 had a significant positive correlation with microbial community diversity (P<0.05). The W1F1 treatment communities were relatively abundant, and the community species showed high similarity in W3F1 and W2F3.

Evaluating dynamic soil quality by the soil management assessment framework (SMAF) in the watershed scale in a semi-arid Mediterranean ecosystem in Turkey

Soil is an indispensable and important natural resource and it is necessary to manage and monitor soil quality with appropriate methods in order to ensure the sustainability of the soil. The aim of this study is to determine the current state of soil quality in different land uses where soil functions change. This study was carried out in the Karasu river watershed with an area of 19,178 ha where Entisols soil order is dominant, located Andırın, Kahramanmaraş. The Soil Management Assessment Framework (SMAF) method and Principal Component Analysis (PCA) was used to assess the dynamic soil quality in watershed scale. In the evaluation of soil quality, random samples were taken from a total of 360 topsoil layers (0−30) according to land use and physiography. Soil indicators such as bulk density, aggregate stability, total organic carbon, pH, electrical conductivity, available phosphorus (P), potassium (K), available water amount and water-filled pore volume were selected to create the minimum data set (MDS). The results showed that the productivity, environmental protection, waste recycling quality scores and general soil quality index of forest lands are higher than agricultural lands. According to expert opinion, general soil quality scores were found to be 0.86 in forest land, 0.78 in crop land and 0.83 in grassland, while in PCA, general soil quality scores were calculated as 0.85 in forest land, 0.79 in crop land and 0.78 in grassland. Contribution level of soil functions to management targets was observed in water relations function the most. The contribution levels of the water relations function to the productivity, environmental protection and waste recycling management targets are 0.38, 0.32 and 0.34 in forest lands, 0.42, 0.33 and 0.35 in croplands, respectively; It was showed that 0.40, 0.33 and 0.36 in grasslands. Contribution rates of productivity, environmental protection and waste recycling management targets to soil quality were 30%, 37% and 33%, respectively, in forest lands; 29%, 37% and 34% in crop lands; It has been determined as 30%, 36% and 34% in the grasslands. Negative effects such as heavy rainfall in the watershed, wrong agricultural practices (excessive fertilization and irrigation, improper tillage, and crop selection, etc.) and excessive grazing have led to soil degradation and erosion, reducing the soil function capacity of agricultural lands and meadows. In order to increase the functional capacity of the soil, a soil management approach aimed at protection, improvement and sustainability must be adopted and implemented.

Nitrogen rate is more important than irrigation rate in mitigating nitrogen leaching in flood-irrigated maize: A 6-year lysimeter experiment

Excessive nitrogen (N) fertilization and irrigation prevail in irrigated agriculture worldwide. However, little information is available that systematically evaluates grain yield, plant N uptake, residual soil NO3−-N (RSN), and N leaching under different irrigation–N regimes in an irrigated maize production system. To address such agronomic and environmental issues, a 6-year in situ lysimeter field trial was conducted in the Hetao Irrigation District of China with five treatments: 1) conventional irrigation (3,900 m3/ha) and local farmer fertilizer N rate (490 kg ha−1) (CON); 2) conventional irrigation and the recommended fertilizer N rate (420 kg ha−1) (RN); 3) deficit irrigation (2,730 m3/ha) and the recommended fertilizer N rate (SRN); 4) deficit irrigation and the recommended fertilizer N rate (with ∼ 10 % organic fertilizer N substitution) (SMN); and 5) conventional irrigation and controlled-release N fertilizer (270 kg ha−1) (CRF). Maize yield was not significantly different across treatments in 2015–2020. Averaged across years, SMN, SRN, and CRF significantly increased plant N uptake compared with that in CON by 28.84 %, 19.15 %, and 17.53 %, respectively. Residual soil NO3−-N at 0–90 cm was ranked as SRN > CON ≈ SMN > RN > CRF, whereas cumulative N in leachate from 2015–2020 (Nloss) in CON was 86.2 % to 187.1 % higher than that in other treatments. The Nloss in SRN was equivalent to that in RN and SMN, but Nloss in SMN decreased significantly compared with that in RN, indicating additive benefits of deficit irrigation and organic input on reducing N leaching. Structural equation modelling revealed that irrigation had greater effects on plant N uptake than those of fertilization, whereas N rate had a greater total effect on N leaching than that of irrigation. Overall, rampant excessive irrigation and N fertilization by farmers can be substantially reduced while maintaining grain yield and mitigating N leaching loss, with further benefits gained by applying controlled-release N fertilizer and manure in irrigated maize production.

Assessing the impacts of canal rehabilitation and lining on groundwater conditions

ABSTRACT The Nile Delta aquifer stands as Egypt’s second primary freshwater source following the Nile River. Its replenishment deriveed from various sources, including the Nile branches, the surface irrigation networks, and the infiltration of excess irrigation water. The expanded demand for irrigation water causes water shortages at the canal tails of some irrigation canals across Egypt. Farmers have resorted to addressing this issue by illegally excavating shallow wells, employing them in times when surface water is inaccessible. Among the national action plans to improve water availability at canal tails is the lining of distributary canals. However, this intervention potentially obstructs the natural replenishment source of the Nile Delta aquifer, consequently contributing to the deterioration of groundwater quality. Hence, this research aims to evaluate the impacts of lining distributary canals on groundwater status through numerical modeling. Utilizing the MODFLOW package, the study determines the natural infiltration rates from the canals into the adjoining groundwater system. Two prevalent hydrological conditions in Egypt were selected for numerical modeling. The first case study focuses on a Canal, located in Qalyoubia governorate, represents the semi-confined aquifer conditions prevalent in the Nile Delta. The second case study is a Canal, situated in Sharqia governorate, represents the phreatic aquifer conditions present in the Nile Delta. Piezometers were implemented to determine the groundwater levels and for the calibration process. The calibrated models were employed to simulate the expected impacts of canal lining for each case and contrasted with pre-lining infiltration rates. Findings indicate that while canal lining effectively reduces water seepage into shallow groundwater in sandy soils, it is of little avail in clayey top soils. The research recommends implementing integrated water resource management to mitigate the possible impacts of lining. It also suggests prioritizing regular maintenance practices for canal linings, especially in areas with sandy soils.

A Cheap and Basic Solar-Powered Smart Irrigation System Proposal for Medium and Small-Scale Farming

Nowadays, the need for water consumption for agricultural production is increasing. Economical use of water has become mandatory both to increase agricultural product yield and to eliminate the damage caused by excessive irrigation to the soil. Preferred instead of traditional irrigation, Drip irrigation, sprinkler irrigation, and pivot irrigation systems are now being replaced by “Smart Irrigation Systems” that save more water. In this study, a basic solar energy-supported mobile phone-controlled smart irrigation system, recommended for medium and small-scale agricultural enterprises, is proposed. In the study, the basic elements that make up the system, their approximate prices and circuit connection ways are shown. In the study, the cost, water, energy consumption, and payback periods of smart irrigation systems with traditional drip, sprinkler, and pivot irrigation methods were compared. As a result, although the initial investment cost in smart irrigation systems seems relatively high, it offers significant advantages in terms of resource efficiency and environmental sustainability. It is a fact that modern irrigation systems will make important contributions to national economies in the long term by increasing agricultural production and saving energy and water.

The cost of mismanaging crop heat stress with irrigation: Evidence from the mid-south USA

Field level data from a voluntary water use reporting program in the Delta region of Mississippi (MS), USA, provides empirical evidence that crop growers increase the amount of groundwater pumped for irrigation during periods of high temperature (degree days above 32 C). Regression analysis reveals that growers apply excess irrigation to cope with high temperature conditions while growing season evapotranspiration and precipitation are not significant factors in their decision of how much irrigation to apply. The existing literature indicates that excess water does not alleviate the harmful effect of extreme heat, making the excess irrigation wasteful and costly. Additional degree days above 32 C are associated with a 4.6 mm increase in irrigation depth (46 m3ha−1). This result may be partially explained by the fact that most farmers use visual cues (such as leaf folding which correlate with air temperature) to initiate irrigation events regardless of soil moisture contents. To quantify the impact of this mismatch, we estimate that shifting the underlying sensitivity in the farmers’ minds by 1 C would reduce groundwater pumpage by 800862 mega liters across the Delta region of Mississippi, USA. The monetary cost of mismanaging heat stress with excessive irrigation is estimated at a minimum of over US$33 million per year. We further identify two additional possible distortions affecting the demand for irrigation groundwater: (i) overestimated benefits from irrigation; and (ii) underestimated groundwater pumping cost. The policy implication is that more efforts and incentives should be placed for programs that affect the producers’ water management mindset, such as "Master Irrigator" programs that will reduce or eliminate the identified groundwater distortions and optimize benefits from irrigation.

Root Zone Water Management Effects on Soil Hydrothermal Properties and Sweet Potato Yield.

Sufficient soil moisture is required to ensure the successful transplantation of sweet potato seedlings. Thus, reasonable water management is essential for achieving high quality and yield in sweet potato production. We conducted field experiments in northern China, planted on 18 May and harvested on 18 October 2021, at the Nancun Experimental Base of Qingdao Agricultural University. Three water management treatments were tested for sweet potato seedlings after transplanting: hole irrigation (W1), optimized drip irrigation (W2), and traditional drip irrigation (W3). The variation characteristics of soil volumetric water content, soil temperature, and soil CO2 concentration in the root zone were monitored in situ for 0-50 days. The agronomy, root morphology, photosynthetic parameters, 13C accumulation, yield, and yield components of sweet potato were determined. The results showed that soil VWC was maintained at 22-25% and 27-32% in the hole irrigation and combined drip irrigation treatments, respectively, from 0 to 30 days after transplanting. However, there was no significant difference between the traditional (W3) and optimized (W2) drip irrigation systems. From 30 to 50 days after transplanting, the VWC decreased significantly in all treatments, with significant differences among all treatments. Soil CO2 concentrations were positively correlated with VWC from 0 to 30 days after transplanting but gradually increased from 30 to 50 days, with significant differences among treatments. Soil temperature varied with fluctuations in air temperature, with no significant differences among treatments. Sweet potato survival rates were significantly lower in the hole irrigation treatments than in the drip irrigation treatments, with no significant difference between W2 and W3. The aboveground biomass, photosynthetic parameters, and leaf area index were significantly higher under drip irrigation than under hole irrigation, and values were higher in W3 than in W2. However, the total root length, root volume, and 13C partitioning rate were higher in W2 than in W3. These findings suggest that excessive drip irrigation can lead to an imbalance in sweet potato reservoir sources. Compared with W1, the W2 and W3 treatments exhibited significant yield increases of 42.98% and 36.49%, respectively. The W2 treatment had the lowest sweet potato deformity rate.

Transient anterior subcapsular vacuolar lens opacities after Tanito microhook trabeculotomy: report of six cases

ObjectiveTo present six cases exhibiting transient anterior subcapsular vacuolar lens opacities following early postoperative Tanito microhook trabeculotomy (TMH) performed by the same surgeon.MethodsSix patients who underwent lens-sparing TMH at Meizankai Shimizu Eye Clinic from November 2021 to May 2023, and developed anterior subcapsular vacuolar lens opacities postoperatively were reviewed. Detailed records of surgeries, follow-up findings were collected and reported.ResultsIn all six cases, anterior vacuolar subcapsular lens opacities were observed on the day after surgery, gradually decreasing without affecting visual acuity or contrast sensitivity. In all cases, without any specific interventions, the opacities disappeared by 21 months postoperatively.ConclusionAnterior subcapsular cataracts, characterized by a vacuolar appearance and transient existence, should be recognized as an early complication of ab interno glaucoma surgery, possibly linked to use of distributed ophthalmic viscosurgical devices and excessive anterior chamber irrigation leading to traumatic cataracts on the lens surface.

Late-Season Irrigation Influences French Fry Color

Given the increasing challenges of water scarcity and the stringent quality requirements of the frozen potato-processing industry, this multi-year research trial aimed to determine whether reduced late-season irrigation on potatoes could improve French fry color. The study was conducted near Othello, WA, and was comprised of five irrigation levels: 40%, 60%, 80%, 100%, and 120% of modeled evapotranspiration (ET), and five potato cultivars: Alturas, Clearwater Russet, Ranger Russet, Russet Burbank, and Umatilla Russet. Irrigation treatments started 100 to 105 days after planting (DAP), approximately 1500 day degrees (at or near peak canopy growth), and ended at vine kill, 150 to 155 DAP. Fry color was assessed following storage durations of 45 and 90 days after harvest from three storage temperatures of 4.4 °C, 6.7 °C, and 8.9 °C, using a photovolt reflectometer, measuring percent light reflectance, in which higher values represented lighter fries. The study found that reducing late-season irrigation generally improved overall fry color. Fry color improvements were observed in four potato cultivars grown with 20% to 40% less irrigation than the control (100% ET); Ranger Russet exhibited no improvement. Reducing late-season irrigation by more than 40% resulted in darker fries for Clearwater Russet, Russet Burbank, and Umatilla Russet when tubers were stored at 4.4 °C and 6.7 °C. Excess irrigation, greater than 100% ET, generally darkened fries in Alturas, Clearwater Russet, Russet Burbank, and Umatilla Russet. These findings provide valuable guidelines for potato growers, indicating that while reducing late-season irrigation can enhance fry color, the effects may depend on a combination of cultivar, irrigation level, and storage temperature.

Effects of intercropping and regulated deficit irrigation on the yield, water and land resource utilization, and economic benefits of forage maize in arid region of Northwest China

Intercropping has been widely recognized to have great advantages in terms of increasing yield, controlling pests and diseases, and saving land, particularly in developing countries. Regulated deficit irrigation reduces water consumption and improves water productivity (WP). However, it is unclear whether the combination of intercropping and deficit irrigation could improve crop yield and WP simultaneously. In this experiment, three planting modes, including forage maize (Zea mays L.) monoculture (M), lablab bean (Lablab purpureus L.) monoculture (L), and maize-lablab bean intercropping (ML) were used. Six irrigation modes were set for each planting mode, including severe water deficit (W1), late water deficit (W2), alternate water deficit (W3), late moderate water deficit (W4), early moderate water deficit (W5), and full irrigation (W6). Results showed that compared with M, the ML treatment significantly increased the fresh forage yield (9.8%–17.0%), hay yield (9.5%–13.1%), crude protein yield (22.9%–25.9%), and WP (7.8%–8.7%). The W5 treatment achieved similar fresh forage yield, hay yield, and crude protein yield as that of the W6 treatment but reduced irrigation water by 25% and increased the WP (21.9%–24.8%). Intercropping achieved a high-water equivalence ratio (WER;1.52–1.81) and land equivalence ratio (LER;1.56–1.84), indicating its advantages over monocultures. The W6 treatment had the lowest WER and LER, suggesting that excessive irrigation can reduce the efficiency of utilizing land and water resource in maze-based forage production. Among all treatments, ML–W5 achieved the highest net income and output to input ratio. Overall, intercropping of forage maize and lablab bean with moderate deficit irrigation at an early stage could be used as a high-yield and efficient forage production system in the arid areas of northwest China.

Dune soil nitrogen leaching for Chinese-yam cultivation: Impact of microbe-decomposable slow-release fertilizer

Chinese yam production is thriving in Aomori Prefecture, a cold and snowy region in Japan. Recently, there has been an increasing risk of nitrogen leaching in Chinese-yam fields, which consist of sandy soil, due to localized torrential rain. The relationships between the type of fertilizer used for Chinese-yam cultivation, the amount of nitrogen (N) leaching, and the timing of leaching remain unknown. Therefore, this study aimed to fill this knowledge gap by investigating the effects of different fertilizers (fast-acting and/or slow-release fertilizer) and irrigation practices (conventional and/or excessive irrigation) in order to mitigate the detrimental impact of nitrogen leaching on groundwater quality. An enhanced mathematical model and the spatiotemporal dynamics of inorganic nitrogen concentration in soil pore water were evaluated the negative impact of nitrogen leaching on the groundwater environment was evaluated. The results showed that the combined use of slow-release fertilizers could significantly reduce nitrate-nitrogen concentration in soil-water, especially during the harvest season. This study demonstrated that cultivating Chinese yam with a fertilizer application system that includes the use of slow-release fertilizer can diminish the negative impact of nitrogen leaching on the groundwater environment, contributing to our understanding of sustainable agricultural practices in regions facing similar environmental challenges. Therefore, our findings represent an important advancement providing new approaches to maintaining productivity while mitigating the adverse impacts on groundwater environments, as well as offering guidelines for agricultural practices in regions facing similar environmental challenges.

Investigating the Impact of Large Lakes on Local Precipitation: Case Study of Lake Urmia, Iran

Large lakes face considerable challenges due to human activities and climate change, impacting local weather conditions and ecosystem sustainability. Lake Urmia, Iran’s largest lake and the world’s second-largest saltwater lake, has undergone a substantial reduction in water levels, primarily due to drought, climate change, and excessive irrigation. This study focuses on the potential repercussions on local climate conditions, particularly investigating the impact of moisture sources, evaporation from lake surfaces, and evapotranspiration from agricultural activities, on local convection rainfall. The prevailing westerly winds in the basin suggest a hypothesis that this moisture is transported eastward within the basin, potentially leading to local precipitation as it ascends to higher altitudes near the eastern basin border. To validate this hypothesis, climate data from 1986 to 2017 from the Sarab meteorological station (east of the lake basin, influenced by local precipitation) and Saqez meteorological station (south of the basin, unaffected by local precipitation) were analyzed. The impact of lake water level reduction was assessed by categorizing data into periods of normal lake conditions (1986–1995) and water level reduction (1996–2017). Additionally, the MSWEP global precipitation product was used to examine the precipitation distribution in the entire basin over the entire period and sub-periods. The findings indicate Lake Urmia’s significant influence on convective rainfall in the eastern basin, especially during the summer. Despite decreasing lake levels from 1996 to 2017, convective rainfall in the eastern basin increased during the summer, suggesting intensified agricultural irrigation, particularly in hot seasons.