Irrigation Amount Research Articles

A semi-centralized Multi-Agent RL framework for efficient irrigation scheduling

Efficient water management in agriculture is essential for addressing the growing freshwater scarcity crisis. Multi-Agent Reinforcement Learning (MARL) has emerged as a promising method for solving daily irrigation scheduling problems in spatially variable fields, where management zones are employed to account for field variability. To enhance the application of MARL to address daily irrigation scheduling in large-scale fields with significant spatial variation, this study proposes a Semi-Centralized MARL (SCMARL) framework. The SCMARL framework adopts a hierarchical structure, decomposing the daily irrigation scheduling problem into two levels of decision-making. At the top level, a centralized coordinator agent determines irrigation timing, which is modeled as a discrete variable, based on field-wide soil moisture data, crop conditions, and weather forecasts. At the lower level, decentralized local agents use local soil moisture, crop, and weather information to determine the appropriate irrigation amounts for each management zone. To address the issue of non-stationarity in this framework, a state augmentation technique is employed, wherein the coordinator’s decision is incorporated into the decision-making process of the local agents. The SCMARL framework, which leverages the Proximal Policy Optimization algorithm for training the agents, is evaluated on a large-scale field in Lethbridge, Canada, and compared with an existing MARL irrigation scheduling approach. The results demonstrate improved performance, achieving a 4.0% reduction in water use and a 6.3% increase in irrigation water use efficiency.

An Automatic Irrigation System Based on Hourly Cumulative Evapotranspiration for Reducing Agricultural Water Usage

This study investigates the development and application of an automatic irrigation system based on hourly cumulative evapotranspiration (ET) to optimize cabbage growth while reducing agricultural water usage. Traditional irrigation methods often result in inefficient water use due to reliance on human judgment or fixed schedules. To address this issue, the proposed system utilizes environmental data collected from a field sensor (FS), the Korea meteorological administration (KMA), and a virtual sensor based on a machine learning model (ML) to calculate the hourly ET and automate irrigation. The ET was calculated using the FAO 56 Penman–Monteith (P-M) ETo. Experiments were conducted to compare the effectiveness of different irrigation levels, ranging from 40, 60, 80, and 100% crop evapotranspiration (ETc), on plant growth and the irrigation water productivity (WPI). During the 46-day experimental period, cabbage growth and WPI were higher in the FS and KMA 60% ETc levels compared to other irrigation levels, with water usage of 8.90 and 9.07 L/plant, respectively. In the ML treatment, cabbage growth and WPI were higher in the 80% ETc level compared to other irrigation levels, with water usage of 8.93 L/plant. These results demonstrated that irrigation amounts of approximately 9 L/plant provided the optimal balance between plant growth and water conservation over 46 days. This system presents a promising solution for improving crop yield while conserving water resources in agricultural environments.

Yield and Sensorial and Nutritional Quality of Strawberry (Fragaria × ananassa Duch.) Fruits from Plants Grown Under Different Amounts of Irrigation in Soilless Cultivation.

Water scarcity is an ecological issue affecting over 10% of Europe. It is intensified by rising temperatures, leading to greater evaporation and reduced precipitation. Agriculture has been confirmed as the sector accounting for the highest water consumption globally, and it faces significant challenges relating to drought, impacting crop yields and food security. Sustainable practices, precision irrigation, and the development of drought-resistant crops are essential for the mitigation of this threat. Effective, innovative solutions are crucial for optimizing water use for intensive crops such as cultivated strawberries (Fragaria × ananassa). This study emphasizes the importance of identifying the genotypes most resilient to low water availability. Experimental trials involving reduced irrigation levels were set up to identify genotypes with a greater capacity to increase fruit quality and maintain fruit yield. Reduced water conditions positively influenced strawberry fruit quality, exhibiting improved citric acid, soluble solids, and color brightness linked to decreased water use, while firmness remained stable. Notably, the total phenolic content was most affected by stress, indicating strong antioxidant responses. With these interesting variations in fruit quality came a different response in plant yield. Plants belonging to the Lauretta and AN15,07,53 cultivars maintained a 98% fruit yield when grown under WS1 conditions. While the yield for the Francesca cultivar increased by 10% under the stressed WS1 conditions in comparison to the control conditions, water stress in the WS2 treatment caused a strong reduction in yield in all three genotypes. Overall, the findings emphasize the importance of identifying for each new cultivar the most appropriate water regime in order to amplify the quality of the fruit, thus maintaining high production standards and saving water.

Effects of biogas slurry drip irrigation on growth performance of Brassica chinensis L. and soil nutrient dynamics

The optimal amount of biogas slurry was determined to improve both the yield of Brassica chinensis L. (BL) and soil quality. An experiment was set up with six sets of drip irrigation gradients (1:3 mix of biogas and water) of 12 (BS-1), 15 (BS-2), 18 (BS-3), 21 (BS-4), 24 (BS-5), and 27 (BS-6) L. Each treatment was repeated three times and irrigated eight times. The radius of drip irrigation was 1.2 m, and the dripping speed was 2 L/h. The highest plant height, fresh weight, dry weight, soluble sugar content, and protein content of 25.2 cm, 16.7 g, 1.10 g, 0.61 g/100 g, and 1.90 mg/g, respectively, were obtained under the BS-5 treatment. Soil total nitrogen, available phosphorus, and organic matter content under the BS-4 treatment increased 5.29%, 230.75%, and 1.00%, respectively, compared with those before drip irrigation treatment. The soil available potassium content was highest under the BS-3 treatment and had increased 20.4% compared with that before drip irrigation treatment. The most remarkable influence on the yield and quality of BL was observed when the drip irrigation amount was 24 L. Drip irrigation with 21 L of biogas slurry is conducive to improving soil physical and chemical properties.

Deficit Irrigation and an IoT-Based System for Improving Yield and Water Use Efficiency of Winter Wheat Grown Under Semi-Arid Conditions

In the context of water restriction, the adoption of innovative technology and water saving strategies is crucial to sustainable agriculture production. Thus, we sought to emphasize the contribution of precision irrigation based on Internet of Things (IoT) technology and smart sensors for optimizing irrigation water use. The effects of different drip irrigation regimes on total dry matter (TDM), grain yield (GY) and water use efficiency (WUE) of winter wheat grown on clay-loam soil under semi-arid conditions of Tunisia have been assessed for three consecutive growing seasons. The trial included fully irrigated (FI) treatment (100% of crop evapotranspiration (ETc)), two deficit irrigation treatments (DI1, DI2 corresponding to 75 and 60% of ETc, respectively) and rainfed treatment DI3, replicated three each. The results showed that TDM and GY increase with increasing irrigation amount. At harvest, the highest TDM and GY values were recorded under FI and DI1. Reducing irrigation amount by 40% (DI2) resulted in a significant grain yield reduction, quantified as 52.7, 45.7, 30.4%, respectively, for the three cropping seasons. Across all growing seasons and treatments, WUETDM values ranged between 4.11 and 6.32 Kg m−3. The highest values were achieved under rainfed treatment. However, no significant difference was observed between irrigated treatments, in particular, during 2022–2023 and 2023–2024. In terms of WUEGY, no significant difference was observed between the FI and DI1 treatments, while significant reductions were registered under DI2 and DI3. The adoption of deficit irrigation at 75% ETc based on smart tensiometers can be used as an effective strategy to optimize water use in winter wheat without compromising yield.

Effect of irrigation regime on yield component and water use efficiency of tomato at Ataye irrigation scheme, Ataye Ethiopia

The importance of an irrigation regime is that it enables the irrigator to apply the exact amount of water to achieve optimum production and minimize adverse environmental impact. In the study area, the amount of irrigation and the frequency of application are not well determined, and the farmers are unaware of how much water and when to apply for tomato crops. Therefore, the objective of this study is to quantify the effects of irrigation regimes on yield and yield components of tomatoes in lowland areas of Ethiopia. The treatments were factorial combinations of five irrigation depths (50, 75, 100, 125, and 150 % of ETc) and three irrigation intervals and laid out in a randomized complete block design with three replications. The collected data were analyzed using R-software and significant treatment means separated using the least significant difference at 5 %. According to the findings, irrigation level and frequency had a significant (P< 0.05) effect on marketable fruit yield, water use efficiency, and plant height of tomatoes. The highest and lowest yields were 54.49 t/ha and 37.89 t/ha respectively. The optimum yield (48.5 t/ha) and water use efficiency (10.79kgm-3) were obtained from 75% ETc before the 3-day interval. Therefore, for the study area and similar agro-ecologies, tomatoes can be irrigated with 376.72 mm net irrigation depth with 33.64 mm and 5-day interval, 60.54 mm and 9-das interval, 94.18 mm and 14-day interval, 94.18 mm and 14-days interval, and 94.18 mm and 14-days irrigation interval at initial, development one, development two, mid and late stages of tomatoes crop respectively and saving 3127.33 m3 water to irrigate an additional 0.59 ha to achieve a yield of 29.00 t/ha for the user without a high yield penalty.

Leaf senescence characteristics and economic benefits of rice under alternate wetting and drying irrigation and blended use of polymer-coated and common urea.

Water-saving irrigation and the mixed application of controlled-release nitrogen fertilizer (CRNF) and common urea (CU; with a higher nitrogen release rate) have shown promise in improving rice yield with high resource use efficiency. However, the physiological mechanism underlying this effect remains largely unknown. This study involved a field experiment on rice in Jingzhou City, Central China, in 2020 and 2021. Two irrigation regimes were employed [alternate wetting and drying irrigation (AWD) and conventional flood irrigation (CI)], with three nitrogen (N) compounding modes [00% CU (N1), 60% CRNF + 40% CU (N2), and 100% CRNF (N3)] with an equal N rate of 240kg ha-1. The results indicated a significant interactive effect of watering regimes and N compounding modes on net photosynthetic rate (P n), leaf area index (LAI), and SPAD values; activities of superoxide dismutase (SOD), peroxidases (POD), catalase (CAT), glutamine synthetase (GS), glutamine 2-oxoglutarate amidotransferase (GOGAT), and nitrate reductase (NR); and the contents of malondialdehyde (MDA) and soluble protein in rice leaves. Compared with N1, N2 and N3 increased the P n, LAI, and SPAD values; activities of SOD, POD, CAT, NR, GS, and GOGAT; and soluble protein content but decreased MDA content in the post-growth (heading and maturity) stages by 8.7%-31.2% under the two irrigation regimes. Compared to CI (traditional irrigation), AWD had higher P n, LAI, and SPAD values; activities of SOD, POD, CAT, NR, GS, and GOGAT; and soluble protein content (increased by 12.1%-38.0%, and lower MDA content (reduced by 13.1%-27.6%) irrespective of N compounding modes. This suggested that AWD combined with N2 and N3 could delay the leaf senescence of rice, thus achieving a larger grain yield. Moreover, AWD significantly decreased water costs (irrigation amount) and labor costs (irrigation frequency), thus increasing total income. N2 decreased fertilizer costs with a higher or comparable total income compared with N3. Therefore, the AWDN2 treatment achieved the highest net income (13,907.1 CNY ha-1 in 2020 and 14,085.7 CNY ha-1 in 2021). AWD interacted with 60% CRNF + 40% (N2) to delay leaf senescence by improving photosynthesis, antioxidant defense system, osmoregulation, and N assimilation, contributing to high grain yield and net income in rice.

Assessment of maize evapotranspiration, water requirements and productivity using weather data in Coimbatore’s semiarid climate

Accurately estimating crop water use is crucial for efficient water management in conservation agriculture, especially in Coimbatore's semiarid climate. This study assessed maize water use and productivity over three growing seasons (2023-2024) at AC&RI, Coimbatore. Irrigation applied each season varied between 500.8mm and 554.1 mm, averaging 535.8 mm, while total water supply ranged from 810.6 to 985.3 mm. Actual evapotranspiration (ETa) was estimated using locally developed crop coefficient curves (Lkc) and FAO crop coefficients. Water productivity for maize was calculated based on these estimates. Daily ETa for maize ranged from 0.9mm to 8.2 mm. Other than the different seasons, ETa varied from 342.6 to 372 mm, averaging 355.6 mm with the Lkc curve. By FAO Kc, ETa ranged from 400.8mm to 479.1 mm, with an average of 444.2 mm. The irrigation requirement ranged from 579.6mm to 672.7 mm, with an average of 629.5 mm using LKc. Using FAO Kc, the range was 637.8mm to 762.9 mm, with an average of 718 mm. Crop water use efficiency (CWUE) ranged from 0.8 and 0.9 kg/m³, with an average of 0.9 kg/m³. The evapotranspiration water use efficiency (ETWUE) ranged from 2.0 to 2.1 kg/m³, with an average of 2.1 kg/m³. The irrigation water use efficiency (IWUE) varied across seasons, averaging 1.4 kg/m³. Strong correlations were observed between CWUE, IWUE, and the amount of seasonal irrigation (R² = 0.98 and 0.99, respectively). CWUE and ETWUE strongly correlated with IWUE (R² = 0.98 and 0.75, respectively). These findings suggest that maize irrigation in Coimbatore's semiarid regions should be tailored to local conditions to enhance water productivity.

Microbial Network Complexity Helps to Reduce the Deep Migration of Chemical Fertilizer Nitrogen Under the Combined Application of Varying Irrigation Amounts and Multiple Nitrogen Sources

The deep migration of soil nitrogen (N) poses a significant risk of N leaching, contributing to non-point-source pollution. This study examines the influence of microbial networks on the deep migration of chemical fertilizer N under varying irrigation management and multiple N fertilizer sources. A soil column experiment with eight treatments was conducted, utilizing 15N isotope labeling and metagenomic sequencing technology. The findings revealed that reduced irrigation significantly curbs the deep migration of chemical fertilizer N, and straw returning also mitigates this migration under conventional irrigation. Microbial network complexity and stability were markedly higher under reduced irrigation compared to conventional practices. Notably, network node count, average degree, and modularity exhibited significant negative correlations with the deep migration of chemical fertilizer N. The network topology indices, including node count, average clustering coefficient, average degree, modularity, and edge count, were found to be relatively more important for the deep migration of chemical fertilizer N. In conclusion, microbial networks play an important role in reducing the deep migration of chemical fertilizer N.

Effects of Irrigation Methods on Growth and Water Productivity in Bell Pepper Cultivation in Northern South Korea

Although the bell pepper (Capsicum annuum L.) is sensitive to water stress, little information is available on proper irrigation management methods for bell pepper cultivation in the northern South Korean climate. We compared the effects of different irrigation methods on crop growth and water productivity in two bell pepper varieties (Maldonado and Nagano) at different irrigation durations (ending 3 h before sunset and ending 4 h before sunset) and irrigation quantities (placing two, three, and four drippers capable of irrigating at 2 L·h−1) over approximately 280 days by performing in-depth analysis of various growth indicators. The plant height of Maldonado increased as the irrigation amount increased in all irrigation treatments of T1 and T2. In Nagano, there was no significant difference in plant height between D3 and D4. Overall, the irrigation treatments produced a higher difference in yield in Maldonado plants than in Nagano plants. WP tended to increase inversely to reduction in irrigation quantity in Groups 1 (May–June) and 4 (November–December) of both varieties, and response to irrigation stop time varied among the varieties. We inferred that the optimal irrigation method for bell pepper cultivation in northern South Korea is to supply irrigation at the D3 level and adjust the irrigation end time according to the variety and crop strength.

Optimizing Terminal Water Management in Irrigation District Using Water Balance and Genetic Algorithm

Water delivery management in China’s irrigation districts has traditionally prioritized the main canal system, often overlooking the water-saving potential of the final canals and field irrigation, which offer substantial opportunities to enhance water use efficiency and conserve agricultural water resources. This study summarizes and defines the integrated water management of final canals and field irrigation as terminal water management. An optimization method was developed to improve terminal water management, which includes optimizing irrigation quotas based on water balance and scheduling final canal water delivery to minimize seepage losses. A genetic algorithm was employed to solve the problem. The method was applied to the Hongjin irrigation district in Jiangsu Province, China. In 2020, paddy water management was observed, revealing that the irrigation amount for organic and traditional rice was 1113 mm and 956 mm, respectively. Conventional irrigation and water delivery practices have led to extensive drainage, significant rainwater wastage, and inefficient water use. The optimized irrigation quotas for organic and traditional rice resulted in water savings of 302.5 mm and 325.9 mm, respectively, compared to the 2020 monitored data. An irrigation event in early August during a 75% hydrological frequency year was selected as an example. With conventional scheduling, optimized final canal water delivery scheduling reduced the seepage losses from 6.3% to 4.6%, shortened the irrigation time from 17 h to 14 h, and stabilized canal flow rates. The proposed optimization method is a valuable tool for enhancing terminal water management and supporting better irrigation decisions in irrigation districts.

Simulating water and salt changes in the root zone of salt-alkali fragrant pear and the selection of the optimal surface drip irrigation mode.

Faced with the increasingly serious problem of water scarcity, developing precise irrigation strategies for crops in saline alkali land can effectively reduce the negative effects of low water resource utilization. Using a model to simulate the dynamic changes in soil water and salt environment in the root zone of fragrant pear trees in saline alkali land, and verifying them from a production practice perspective with comprehensive benefits as the goal, can optimize the irrigation amount and irrigation technology elements of saline alkali fruit trees, broaden the comprehensive evaluation perspective of decision-makers, and have important significance for improving the yield and production efficiency of forestry and fruit industry in arid and semi-arid areas worldwide. In this study, a two-year field experiment based on three irrigation levels (3000, 3750, and 4500 m3·ha-1) and four emitter discharge rates (1, 2, 3, and 4 L·h-1) was conducted in Xinjiang, China. The root zone soil water content (SWC) and soil salinity content (SSC) dynamics were simulated during the fertility period of fragrant pear using the numerical model HYDRUS-2D and field data. The results showed that the R2, root mean squared error (RMSE), and Nash-Sutcliffe efficiency coefficient (NSE) of the HYDRUS-2D simulated soil water content (SWC) (soil salinity content SSC) reached 0.89-0.97 (0.91-0.97), 0.02-0.16 cm3·cm-3 (0.22-1.54 g·kg-1), and 0.76-0.95 (0.68-0.96), respectively, indicating the strong performance of the model. A positive correlation was observed between the irrigation amount and soil infiltration depth. Moderately increasing irrigation amount could effectively leach soil salinity at a depth of 80-100 cm and maintain a water and salt environment in the main root zone of 0-80 cm, benefiting the growth and development of the main root system of fragrant pear, as well as the yield and quality of above-ground fruits. The irrigation amount and emitter discharge were optimized and quantified based on multi-objective optimization methods, normalization processing, and spatial analysis methods to maximize yield, fruit weight, soluble solids, and net profits. When the yield, fruit weight, soluble solids, and net profits simultaneously reached 90% of their maximum value, the irrigation amount and emitter discharge ranges were 4274-4297 m3·ha-1 and 3.79-3.88 L·h-1, respectively. Our study provides new insights into regulating soil water and salt environmental factors in the saline fragrant pear root zone and assessing the impact of soil water and salt management under precision irrigation strategies, and profoundly influences decision-making for irrigation of forest fruits in saline arid zones based on a production practice perspective.

Evaluation of the Relationship Between Rainwater Harvesting and Landscape Plant Water Consumption

If rainwater is not used, it is considered waste and ends up as surface water in underground resources or flows into oceans. In view of dwindling water resources, rainwater should not only flow as surface water but should be reused to conserve groundwater and mains water. To achieve this, rainwater must be collected and solutions produced on site. When we look at water consumption rates, we realize that a large amount of water is significantly used for the irrigation of landscaped areas. In addition, the water requirements of plants are often not known and water is wasted through unconscious irrigation. This study aims to provide the right amount of irrigation by showing the water requirements of plants according to their species. At the same time, it aims to provide the right amount of irrigation by showing the water requirements of plants according to their species. These two main objectives are aimed at learn the needs of plants and at the same time ensuring efficient water use. In this study, it is aimed to contribute to the water cycle by reusing rainwater. Various roofing and paving materials were identified in the study area. The amount of rainwater to be collected from the different materials within the study area was calculated using the Rational Method and the water consumption of each plant was calculated using the CropWat 8.0 program. In conclusion, the amount of rainwater collected on the entire campus was calculated as 494,000 m3per year and the amount of irrigation water required by the plants was 54,530 m3per year. This data shows that the amount of rainwater collected corresponds to the water consumption of the landscape plants. The rainwater harvested on campus is fed into tanks. The rainwater collected on the campus is channelled into tanks. The volume of the tanks was calculated. In addition to the stored rainwater, solutions were developed on-site using sustainable methods for the remaining rainwater. Plants with low or medium water requirements are recommended for use in new landscape areas.

Optimizing drip irrigation to enhance winter wheat performance: yield, economic benefits, and water use efficiency

ABSTRACT Drip irrigation is beneficial for improving crop yield and water use efficiency (WUE); however, it is rarely used for winter wheat production in semi-humid and drought-prone areas. To evaluate the optimal drip irrigation amount, a 4-year field experiment was conducted to investigate the effects of applying different water amounts (RF: rainfed; DI1, DI2, and DI3: 60, 120, and 180 mm of drip irrigation; FI3: 180 mm of traditional flood irrigation) on available soil water storage (ASWS), agronomic and physiological characteristics, yield, net income, and WUE of winter wheat in the Guanzhong Plain of China. The results showed that DI2 treatment performed the best among five treatments, which was attributed to the improvement of ASWS consumption in the 1–2 m soil layer, leaf area index, chlorophyll content, and net photosynthetic rate. The four-year average grain yield, net income, and WUE of DI2-treated winter wheat increased by 15.4%, 18.4%, and 25.5%, respectively, compared with FI3. Regression analysis indicated the optimal drip irrigation amounts were 163 and 137 mm in dry and normal years, respectively, and can be considered as a guideline for economical irrigation strategy for winter wheat production in semi-humid and drought-prone areas.

Melatonin-Mediated Modulation of Grapevine Resistance Physiology, Endogenous Hormonal Dynamics, and Fruit Quality Under Varying Irrigation Amounts.

Grapevine, as a globally significant economic fruit tree, is highly sensitive to water stress, which not only damages its growth but also affects the formation of fruit quality. Melatonin (MT), acting as a signaling molecule, plays a crucial role in plant stress responses. However, the regulatory mechanisms of MT on grape leaf physiological characteristics and fruit quality under different irrigation amounts have not been fully elucidated. In this experiment, grape leaves were treated with a 150 μmol·L-1 MT solution at 0, 30, 60, and 90 days after flowering under different irrigation amounts (360, 300, 240, and 180 mm). It was found that MT significantly increased the contents of osmotic adjustment substances in leaves, reduced the level of reactive oxygen species, enhanced the activity of antioxidant enzymes, and promoted the metabolism of the ascorbic acid-glutathione cycle, thereby improving the antioxidant capacity of grapes and effectively alleviating the damage caused by a water deficit. At the same time, MT also maintains the dynamic balance of endogenous hormones by upregulating and downregulating the expression levels of related genes, thereby improving fruit quality. In summary, this study reveals the potential application value of MT in enhancing the drought resistance and fruit quality of grapes.

Effect of drip irrigation and boron application on enhancing seed production of sainfoin (Onobrychis viciifolia) in Northwest China

Sainfoin has gained considerable attention in the forage, medicinal, and food industries due to its exceptional nutritional profile and rich bioactive compounds. However, knowledge of agricultural practices for its seed production, particularly in arid and semiarid regions, remains limited. We conducted a three-year field experiment from 2021 to 2023 to evaluate the effects of four irrigation frequencies (2, 3, 4, and 5 applications of 50mm each) and four boron concentrations (0, 0.3%, 0.6% and 0.9%) on seed yield, quality, water use efficiency (WUE) and economic benefits in sainfoin. Our findings revealed a negative parabolic relationship between seed yield and both irrigation amount and boron concentration. The highest yields were achieved with four irrigations (200mm) combined with a 0.6% boron application, resulting in seed yield of 696.69kg/hm2 in 2021, 1200.94kg/hm2 in 2022, and 1687.91kg/hm2 in 2023. This optimal combination also exhibited superior WUE and economic benefits compared to other treatments. Higher irrigation frequency increased seed dimensions (length, width, and height), but it had a negative impact on both germination percentage and speed. The impact of boron on seed quality varied with irrigation levels. All yield components, except for 1000-seeds weight, showed significant positive correlations with seed yield (P < 0.001). A structural equation model indicated that the number of reproductive branches per plant was the most significant contributor to seed yield. Our findings enhance the understanding of the mechanisms underlying seed yield responses to irrigation and boron application in sainfoin, offering valuable insights for agronomic practices aimed at improving seed yield in sainfoin and similar crops.

Improving Irrigation Water Use Efficiency and Maximizing Vegetable Yields with Drip Irrigation and Poly-Mulching: A Climate-Smart Approach

Water management is a significant aspect of sustainable vegetable farming, especially in water-scarce regions. This, in addition to weed infestations, limits vegetable yields, which negatively affect food security in developing regions, particularly East Africa, where livelihoods chiefly depend on rain-fed agriculture. Vegetable farming, especially tomato cultivation, requires more water. By promoting mulching, a soil water conservation tool, we can control surface evaporation (E), which, together with irrigation, enhances effective water use and vegetable yields. The experiments for this study were conducted at the Tokyo University of Agriculture, Japan, to evaluate the influences of different irrigation conditions and poly-mulching on weed control, tomato yields, and water use efficiency. The study was conducted from May to September 2018 on a 30 m2 plot in an open-ended greenhouse using drip irrigation for tomato cultivation. Three predetermined irrigation conditions of 4, 3, and 2 mm/day were applied on black poly-mulched and bare ridges. Data on soil conditions—soil temperature, as well as meteorological variables, including solar radiation and temperature—were measured using thermocouple sensors and micro-hobo weather stations, respectively, during the tomato cultivation, while yield components—growth, yield, water productivity, and sugar content—were determined after harvest. The results of a two-way ANOVA show that irrigation conditions with poly-mulching reduced the weed biomass significantly, and improved yields and water use efficiency compared to the irrigation conditions on bare ridges. The application of 4, 3, and 2 mm/day irrigation with poly-mulching significantly reduced the weed biomass by 5% compared to the same irrigation conditions on bare ridges. Similarly, 4 and 3 mm/day irrigation conditions with poly-mulching significantly increased the tomato yield by 5% compared to 2 mm/day on bare ridges. The bigger roots were concentrated and widely distributed at the shallow soil depth (0–20 cm) of the ridges with high irrigation amounts, while the small and thin roots were in deeper soil layers (30–45 cm). This study provides scientific knowledge on the application of predetermined irrigation conditions that can be (i) integrated into irrigation scheduling and (ii) adopted for regions facing water scarcity and limited or no in situ meteorological data, to improve water use efficiency for vegetable cultivation.

Responses of soil water supply during the wheat growing season to agricultural management practice in Northern China: A meta-analysis

Context or problemAchieving efficient use of water resources is crucial for ensuring food security in the face of the problems posed by water scarcity and the growing demand for food. Wheat is one of the major crops in the north of China, improving the soil water supply (ΔSWS) through effective agricultural management practices during the wheat growing season is a key strategy to reduce water crises. Objective or research questionThere is much uncertainty regarding the effects of different agricultural management practices (eg. fertilizer practice, mulching practice, irrigation practice, soil amendment or straw returning and tillage practice) on ΔSWS for wheat production. MethodsThis meta-analysis was based on 2523 comparisons in 274 publications from 1999 to 2021 to evaluate the effects of agricultural management practices on ΔSWS during the wheat-growing season in Northern China. ResultsIrrigation and soil amendment practices reduced ΔSWS by 76.95 % and 50.63 %, whereas the wheat yield increased by 21.22 % and 8.86 %, respectively. Fertilizer, tillage, and mulching practices increased ΔSWS by 70.41 %, 32.83 %, 24.6 % and improved wheat yield by 31.1 %, 9.41 %, and 16.26 %, respectively. The effects of different drivers on soil water availability under different agricultural management practices were quantified using linear regression analysis. Irrigation management increased ΔSWS capacity under higher mean annual precipitation, and lower seasonal precipitation, seasonal average temperature, soil pH, seasonal relative humidity, irrigation amounts. Fertilizer practice significantly increased ΔSWS capacity at higher seasonal wind speeds and irrigation amounts. Tillage practice had the best effect on enhancing ΔSWS capacity below 5 °C and lower relative humidity. When the N application less than 210 kg/hm2, seasonal wind speed > 1.31 m/s, seasonal sunshine duration > 900 h, higher seasonal relative humidity and seasonal average temperature conditions, mulching was the best practice to improve ΔSWS capacity. ConclusionsAppropriate agricultural management practices combined with key factors can maximize improve ΔSWS capacity. Implications or significanceThe results provide a reference for fully exploiting ΔSWS capacity using appropriate agricultural management practices under different environment conditions, thereby improving water use efficiency for wheat production in Northern China.

Drip irrigation affects soil bacteria primarily through available nitrogen and soil fungi mainly via available nutrients.

The issue of water scarcity is a global concern. Water-saving irrigation has long been a topic of interest among agricultural researchers. In this study, changes in soil microbial community structure and diversity under different periods of drip irrigation were analyzed using the Illumina HiSeq high-throughput sequencing platform and 16S rRNA gene sequence amplification. Six treatments were established based on varying drip irrigation amounts: maintaining the drip irrigation amount at 320 mm without any increase (CK), increasing by 72 mm during different growth stages: from the sowing stage to the jointing stage (J), from the jointing stage to the big trumpet stage (B), from the big trumpet stage to the tasseling stage (T), from the tasseling stage to the grain filling stage (G), and from the grain filling stage to the maturity stage (M). Compared to CK, the T treatment significantly increased the Chao index of soil bacteria by 2.95%. The main bacterial phyla included Proteobacteria, Acidobacteria, blastomonas, Actinobacteria, Chloromycetes, and Bacteroidetes, while ascomycetes, basidiomycetes, chytridomycetes, and mortieromycetes were the main fungal phyla across different periods of drip irrigation. Zoopagales, Amtridomyces, and Trichomyces were absent in the G, T, and M treatments, respectively. The content of soil-available potassium in the T treatment was higher than that in other treatments, whereas the content of soil-available nutrients in the B treatment was the lowest. Overall, the T treatment had the highest content of available nutrients. Redundancy analysis showed that available nitrogen was the main soil chemical property affecting soil bacterial community structure, while soil-available nutrients were the main soil chemical property affecting the fungal community structure. Thus, the T treatment was effective in enhancing soil microbial community structure and increasing soil-available nutrients.

Improving the Microenvironmental of Spring Soybean Culture and Increasing the Yield by Optimization of Water and Nitrogen

Optimizing water and nitrogen management is an effective measure to reduce nitrogen fertilizer loss and environmental pollution risks. This study aims to quantify the impacts of different water and nitrogen management strategies on the soil microenvironment and yield of spring soybeans in southern Xinjiang. In this study, two irrigation quotas were established: W1—36 mm (low water) and W2—45 mm (high water). Three nitrogen application gradients were established: low nitrogen (150 kg·hm−2, N1), medium nitrogen (225 kg·hm−2, N2), and high nitrogen (300 k kg·hm−2, N3). The analysis focused on soil physicochemical properties, enzyme activities, microbial community diversity, soybean yield, and soybean quality changes. The results indicate that the activities of nitrate reductase and urease, as well as total nitrogen content, increased with higher irrigation and nitrogen application rates. The W2N3 treatment significantly increased 0.15 to 4.39, 0.18 to 1.04, and 0.31 to 1.73 times. (p &lt; 0.05). Alkaline protease and sucrase activities increased with higher irrigation amounts, while their response to nitrogen application exhibited an initial increase followed by a decrease. The W2N2 treatment significantly increased by 0.10 to 0.34 and 0.07 to 1.46 times (p &lt; 0.05). Irrigation significantly affected the soil bacterial community structure, while the coupling effects of water and nitrogen notably influenced soil bacterial abundance (p &lt; 0.05). Increases in irrigation and nitrogen application enhanced bacterial diversity and species abundance. Partial least squares path analysis indicated that water–nitrogen coupling directly influenced the soil microenvironment and indirectly produced positive effects on soybean yield and quality. An irrigation quota of 4500 m3 hm−2 and a nitrogen application rate of 300 kg·hm−2 can ensure soybean yield while enhancing soil microbial abundance. The findings provide insights into the response mechanisms of soil microbial communities in spring soybeans to water–nitrogen management, clarify the relationship between soil microenvironments and the yield and quality of spring soybeans, and identify optimal irrigation and fertilization strategies for high quality and yield. This research offers a theoretical basis and technical support for soybean cultivation in southern Xinjiang.