Irrigation Water Use Efficiency Research Articles

Effects of Timing in Irrigation and Fertilization on Soil NO3−-N Distribution, Grain Yield and Water–Nitrogen Use Efficiency of Drip-Fertigated Winter Wheat in the North China Plain

In the North China Plain, drip irrigation is gradually used in winter wheat production, and the improper management of water and fertilizer aggravates the risk of crop instability and groundwater pollution. A lysimeter experiment with three levels of fertilization timing (T1 = beginning; T2 = middle; and T3 = end of the irrigation cycle) and two irrigation rates (W1 of 30 mm and W2 of 20 mm) was carried out to investigate the effects of irrigation rate and fertilization timing on the soil NO3−-N distribution, crop development, yield, and water–nitrogen usage efficiency of winter wheat. The results indicated that, under the condition of delayed fertilization timing (T2 and T3), the trend of NO3−-N migration to the edge of moist soil became more apparent. The treatments of irrigation rate and fertilization timing significantly affected the plant height, water–nitrogen utilization efficiency, aboveground biomass, grain yield, and leaf area index. The maximum grain yield of 7688.67 kg ha−1 was found at W1T2, which had a nitrogen partial factor productivity (NPFP) of 32.04 kg kg−1. Moreover, W1T2 did not result in a significant reduction in irrigation water use efficiency (IWUE) (4.27 kg m−3) in comparison with other treatments (4.00–5.43 kg m−3). Based on crop growth, N uptake, yield, IWUE, and NPFP, the irrigation rate of 30 mm combined with fertilization in the middle of the irrigation duration could be considered as suitable irrigation and nitrogen timing for drip-irrigated wheat.

Evaluating Effects of Regulated Deficit Irrigation under Mulched on Yield and Quality of Pumpkin in a Cold and Arid Climate

As the most effective irrigation method in arid and semi-arid regions, drip irrigation under mulch could general comprehension of the production efficiency of agricultural irrigation water, and reduce agriculture consumption of water resources. The paper has carried out an investigation over a two year period (2020–2021) in a semi-arid climate in the Hexi Oasis region of China, aiming at determining the influence of regulated deficit irrigation (RDI) under mulch on the growth, yield, water use efficiency (WUE), irrigation water use efficiency (IWUE) and quality of pumpkin at different growth stages. A total of nine treatments with three irrigation levels (75–85% field capacity, 65–75% field capacity, and 55–65% field capacity) have been used in four growing periods of pumpkin (seedling, vine extension, fruit expansion, and maturation stages). The results have shown that light water deficit treatment at the seedling stage had the highest water use efficiency (12.47 kg/m3) without significantly affecting yield (45,966.90 kg/ha), and improved pumpkin fruit quality. It was concluded that light water deficit at the seedling stage and adequate irrigation at other development stages was the optimal irrigation strategy for pumpkin growth. The results of this research provide theoretical and technical support for efficient water-saving plantation and industrialization of pumpkin in the Hexi Oasis.

Effects of Supplementary Irrigation and Nitrogen Fertilization on Characteristics of Sun Cured Tobacco in Semi-Arid Conditions

ABSTRACT Nitrogen and water should be applied at the right time and amount to obtain optimum crop yield in arid and semi-arid regions. The study was carried out in 2017–2018 to investigate the effects of different supplementary irrigation levels applied after harvests, and different nitrogen sources on water use efficiency (WUE), yield and quality characteristics of sun-cured tobacco. The study included five different nitrogen sources (N1: zero-nitrogen, N2: ammonium nitrate, N3: ammonium sulfate, N4: calcium ammonium nitrate, and N5: urea) and four different irrigation treatments (I0:No irrigation; I33:66% deficit, I66:33% deficit and I100:100% full irrigation). The effects of nitrogen sources and supplementary irrigation treatments on plant height, leaf number, leaf width, leaf height, yield, quality grade, sugars, nicotine, phenolics, WUE and irrigation water use efficiency (IWUE) were statistically significant. Seasonal crop evapotranspiration values ranged between 117.7 and 235.3 mm. The highest WUE 1.65 kg m−3 and IWUE: 10.48 kg m−3 were recorded in I33 treatment. Plant characteristics were different between nitrogen sources; however, the results did not indicate a prominent nitrogen form. The results for supplementary irrigation revealed that the I100 treatment in semi-arid conditions increased the sun-cured tobacco yield by 22% with acceptable quality improvements. The gross income increased 1705 $ ha−1 with the increase in tobacco yield and sale price per hectare.

Improving footprint-based water use efficiency through planting structure optimization

Unreasonable utilization of water resources cause serious water shortage and associated pollution problems. Improving water use efficiency (WUE) is helpful for alleviating water scarcity and mitigating water pollution. However, due to the conflict between water saving and economic development as well as uncertain parameter information, it is challenging to improve WUE. To address these problems, a water-footprint-based interval fuzzy robust fractional programming (WF-IFRFP) model was developed through integrating water footprint (WF), interval parameter programming (IPP) and fuzzy robust optimization (FRP) into a fractional programming (FP) framework. The developed WF-IFRFP model improved upon traditional methods by being able to tackle interval numbers and fuzzy sets under different system-violation risks. The developed model was applied to a water management case in the northwest of Inner Mongolia, China. The results of WF assessment showed that the water consumption of crop growth increased, water, whereas that used for reducing total nitrogen concentration decreased from 2012 to 2016. Then, specific benefit- and risk-explicit plans for cropping pattern adjustments were generated. The results showed that the water supply-demand ratio from WF-IFRFP would be [5.1, 10.7] % higher than that in the benchmark year of 2016. To assess its performance and merits, the optimal results from the WF-IFRFP model were compared to four alternative models. These comparisons reveal that the WF-IFRFP model is beneficial for improving irrigation WUE.

Effect of potassium fertilization on roselle yield and yield components as well as IWUE under deficit irrigation regimes

This research aimed to investigate different levels of irrigation water and potassium fertilizer on the yield and yield components as well as qualitative properties and irrigation water use efficiency (IWUE) of Roselle (Hibiscus sabdariffa). For this purpose, in 2019 and 2020, a factorial experiment with a randomized complete block design (RCBD) with three replicates was conducted in a semi-dry region. The experimental treatments included three levels of potassium fertilizer 75 t ha−1 (K1), 112.5 t ha-1 (K2), and 150 t ha−1 (K3) (equivalent to 50, 75, and 100% of potassium fertilizer percentage) and four levels of irrigation water including I1 (40%), I2 (60%), I3 (80%), and I4 (100%) of the plant water requirement. At the end of the experiment, quantitative parameters including plant height, weight and number of capsules, dry yield, and IWUE were measured. Further, qualitative parameters such as level of anthocyanin, protein, carbohydrate, proline, chlorophyll a and b were also measured to investigate the effects of water stress and fertilizer stress on the quality of Roselle. Experimental results revealed that the simple effects of irrigation water and potassium fertilizer became significant at 1 and 5% probability levels on all of the measured parameters. The greatest dry yield (600.95 kg ha−1) was obtained from l3K3 treatment. The maximum IWUE was achieved in l2K3 treatment (0.058 kg m−3). However, no significant difference was observed in this regard between l2 and l3. Qualitatively, with the reduction of the depths of irrigation water up to 60% the plant water requirement and with decline in the potassium fertilizer consumption, the level of anthocyanin, protein, carbohydrate, and proline increased by 85.16%, 19.56%, 15.34%, and 28.35% respectively. However, the values of chlorophyll a and b dropped by 42.75 and 24.54% respectively. On the other hand, no significant difference was observed between K1 and K2 in this regard. Thus, considering the water status of the region and deficit of water resources, application of 80% water requirement (treatment l3) would save water consumption, and consuming 75% potassium content (K2 treatment) would enhance the quality and modify the damages resulting from drought stress in Roselle.

Determining effects of foliar boron applications on yield and fruit quality of apricot trees for reducing water stress

Aims: The research was carried out to determine the effects of different boron doses on yield, yield components and quality on 5-6 years old apricot trees of Mogador variety, which were exposed to water stress in the Amik Plain in 2019. Methods and Results: The factorial experimental design was conducted on apricot trees of Mogador variety, using four doses of foliar boron (ppm) (0-B0, 150-B150, 225-B225 and 300-B300 ppm) and four irrigation levels (100%-I100, 75%-I75, 50%-I50 and 25%-I25 of available water holding capacity) in four replications. Each replication consisted of two apricot trees. The quantity of irrigation water applied in the experiment ranged from 179 to 742 mm, while the evapotranspiration varied between 295 and 832 mm during the irrigation season. Irrigation water use efficiency (IWUE) and water use efficiency (WUE) varied between 3.51-5.18 kg m-3 and 2.89-4.17 kg m-3, respectively. Boron doses did not cause significant differences in WUE and IWUE values. Each unit increase in crop water use caused an average yield increase of 16.8 kg ha-1. Relative to the full irrigation (I100), fruit weight decreased by 13 and 3% in I25 and I50, respectively, but increased by 2% in I75. Relative to the control group (B0), fruit weight increased by 2, 4, and 2% with B150, B225, and B300, respectively. Average fruit size varied between 47.40 (I75) and 42.99 mm (I25); total soluble solids (TSS) between 16.13 (I100) and 12.65 (I25); and pH between 3.16 (I100) and 3.30 (I50). The increased boron dose did not cause a significant difference in fruit size and width. The leaf boron content increased up to the B225 dose and tended to decrease at the B300 dose.Conclusions: Boron element provides an increase in yield in deficit irrigation conditions, the yield increase is higher in fully irrigated apricot trees. In full irrigation treatment (I100), the B225 treatment was more effective on the yield.Significance and Impact of the Study: The boron element is an important element that causes an increase in photosynthesis by light adsorption. There is not a lot of research investigating the effects of nutrient elements to relieve the negative effect of water stress in orchards. This research is important in terms of revealing the effects of the element boron in water stress conditions.

Effects of film mulching on the physiological and morphological parameters and yield of cucumber under insufficient drip irrigation

AbstractA comprehensive study was conducted to analyse the influence of film mulching on the soil water content (SWC), plant physiological and morphological parameters, yield and irrigation water use efficiency (IWUE) of cucumber grown in a greenhouse. The experiment was designed to set the film mulching (M1) and non‐film mulching (M0) applications under two irrigation levels (T1: sufficient irrigation; T2: insufficient irrigation). Thus, four treatments, i.e. T1M1, T1M0, T2M1 and T2M0 were set. The response of plant growth, physiology characteristics, yield and SWC under the designed treatments was analysed based on the data from two planting years (2019 and 2020). Applying film mulching effectively improved the SWC by approximately 10%. The cucumber plant height, stem diameter and leaf area index (LAI) under the T2M1 treatment increased by 38.0–63.1, 16.5–24.9 and 84.0–89.4%, respectively, compared to the T2M0 treatment. The maximum yield was found in the T1M1 treatment, which increased by 24.2–27.5% compared to T1M0. Film mulching increased cucumber yield by 18.0–24.7% compared to non‐film mulching. It was also observed that film mulching under insufficient drip irrigation had a positive influence on plant morphological parameters (photosynthetic rate and stomatal conductance). Among the four treatments, the maximum photosynthetic rate (= 20.69 μmol m−2 s−1) and stomatal conductance (= 0.47 μmol m−2 s−1) were found in the T2M1 treatment. The sap flow rate under the T2M1 treatment was close to that under the T1M0 treatment, while the largest variation in the sap flow rate occurred under the T1M1 treatment, and the smallest variation occurred under the T2M0 treatment. It can be concluded that the effect of the film mulching technique on cucumber yield and IWUE was significant under insufficient drip irrigation.

Comprehensive Evaluation on the Yield, Quality, and Water-Nitrogen Use Efficiency of Mountain Apple Under Surge-Root Irrigation in the Loess Plateau Based on the Improved TOPSIS Method

The purpose of this study was to know the controlling effects of water and nitrogen coupling on the yield, quality, and water-nitrogen utilization effectiveness of mountain apples under surge-root irrigation in the Loess Plateau. In order to optimize the water and nitrogen irrigation systems of superior quality and high yield, 7 years was selected for the mountain apple test material. The trial was designed with four tiers of irrigation, i.e., full irrigation (FI: 85–100% θf, where θf is the field capacity), light deficit irrigation (DIL: 70–85% θf), moderate deficit irrigation (DIM: 55–70% θf), and severe deficit irrigation (DIS: 40–55% θf) and three tiers of nitrogen, i.e., high nitrogen (NH: 600 kg ha–1), medium nitrogen (NM: 400 kg ha–1), and low nitrogen (NL: 200 kg ha–1). The subjective weight attained by the analytic hierarchy methods and the objective weight achieved by the enhanced coefficient of variation method were examined to find the comprehensive weight based on the notion of game hypothesis. Then, the weighted technique for order of preference by similarity to the ideal solution (TOPSIS) process was utilized to comprehensively assess the yield, quality, and water-nitrogen use efficiency of the apples, and a binary quadratic regression model was created between the comprehensive evaluation index and water-nitrogen inputs. The results showed that the effects of irrigation and nitrogen levels on the fruit yield, irrigation water use efficiency (IWUE), total water use efficiency (TWUE), nitrogen partial factor productivity (NPFP), and quality of mountain apples were significant (P < 0.05). The apple yield and TWUE first improved and then diminished with an escalating quantity of water-nitrogen inputs, the IWUE diminished with a boost in the irrigation quantity, the NPFP dwindled when the nitrogen amount was increased. The best water and nitrogen inputs for apple yield, quality, or water-nitrogen use efficiency were dissimilar. The best comprehensive evaluation index was DILNM treatment, and the worst comprehensive evaluation index was DISNL treatment, based on the TOPSIS system. The interval of irrigation and nitrogen attained from the mathematic model ranged in 95–115 mm and 470–575 kg ha–1, respectively. The outcome of this study may perhaps offer a theoretical basis for the scientific research of surge-root irrigation and the managing of mountain apple tree irrigation and fertilization in the Loess Plateau, China.

Soil-plant water dynamics, yield, quality and profitability of spring sweet corn under variable irrigation scheduling, crop establishment and moisture conservation practices

Spring sweet corn as a short duration cash crop is gaining popularity in northern India owing to increasing demand in urban and peri-urban regions. Under hot dry climate and minimal rainfall, irrigation is the major yield contributing factor for attaining superior quality cobs and higher economic returns. The study aimed at examining the effect of irrigation scheduling (I) (IW/CPE 1.0, 1.2, 1.4), sowing methods (S) (flat and furrow) and moisture conservation practices (M) (no-residue, rice straw mulch 6.0 t ha −1 and rice straw biochar 3.0 t ha −1 ) on spring sown sweet corn yield, quality, profitability and water use efficiency in the Tarai region (sandy loam soil texture) of Uttarakhand, India. The experiment was conducted in split factorial design (Main I x S, Sub M) with 18 treatment combinations and three replications. Results indicated that the combination IW/CPE 1.4 +furrow+mulch being at par with IW/CPE 1.4 +furrow+biochar were superior in terms of dehusked cob yield which was ~42% higher over IW/CPE 1.0 +flat+control. Application of biochar 6 t ha −1 and straw mulch 3 t ha −1 increased dehusked cob yield of sweet corn by ~6–9% over control (no-residue) during both years. Among irrigation schedules, IW/CPE 1.0 obtained highest irrigation water use efficiency (IWUE) followed by IW/CPE 1.2. Mulch and biochar being on par recorded 7–10% higher IWUE over no-residue control. Likewise, furrow sowing increased IWUE by 39–44% over flat method with ~25% higher water savings. Average soil moisture content under mulch and biochar was 25% and 12% higher respectively over no-residue. Maximum net returns was obtained under the combination IW/CPE 1.4 +furrow+mulch (1672 USD ha −1 ) which was 69% higher over IW/CPE 1.0 +flat+no-residue. Sweet corn quality parameters viz., total soluble solids and non-reducing sugar was significantly higher under IW/CPE 1.0 and 1.2 in comparison to 1.4, as well as under furrow sowing over flat sowing. Therefore, although maximum yield and profitability of sweet corn was obtained under irrigation schedule IW/CPE 1.4, the treatment combination of IW/CPE 1.2 with furrow sowing and mulch/biochar application may be adopted for attaining superior quality parameters and improved water use efficiency of sweet corn. • Irrigation scheduled at IW/CPE 1.4 & 1.2 increased sweet corn yield over IW/CPE 1.0. • IW/CPE 1.2 improved irrigation water use efficiency (IWUE) by 7% over IW/CPE 1.4. • Furrow sowing had 4–8% and 39–44% higher cob yield and IWUE resp. than flat sowing. • Mulch 6 t ha −1 & biochar 3 t ha −1 observed 7–10% higher IWUE of sweet corn over control. • Virtual water of sweet corn was lowest with IW/CPE 1.0, furrow and mulch.

Direct comparisons of four irrigation systems on a commercial rice farm: Irrigation water use efficiencies and water dynamics

This two-year field study compared the industry-standard rice (Oryza sativa L.) irrigation practice, a continuous-flood delivered using cascade distribution (CASC), to two related levee-based systems (multiple-inlet rice flood distribution (MIRI) and MIRI plus alternate wetting-drying flood management (AWD)) and one furrow-irrigated with end-blocking (ROW) system. Seasonal applied irrigation, soil volumetric water holding content, water depth, grain yield and irrigation water use efficiency (IWUE) were determined for sixteen 16-ha commercial rice fields sown using the same hybrid each year. Also, runoff from one field for each system was measured each year. Average seasonal irrigation applications were 824 ± 197 mm for CASC, 641 ± 165 mm for MIRI, 696 ± 181 mm for AWD and 631 ± 125 mm for ROW. Although a minimum of two AWD dry-down cycles were performed each year and runoff was the least from MIRI (5% runoff) and AWD (3% runoff), ROW (13% runoff) was the only system to receive less irrigation (p = 0.0314) than CASC (14% runoff). In terms of grain yield, only the ROW fields, with an average yield of 8890 ± 417 kg ha−1, differed (p = 0.0107) from CASC (9991 ± 751 kg ha−1). This reduction in ROW yield was due primarily to herbicide injury in 2018 and resulted in average irrigation water use efficiency (IWUE) values that were not different between irrigation treatments (p > 0.05). Taken together, ROW with end-blocking (a) proved to be a more consistent method of water conservation than MIRI and AWD under field conditions complicated by variable soil textures, and (b) lends itself to automation as the ROW fields were irrigated regularly, on a three-to-four-day schedule, rather than depending on human judgement to decide when to irrigate as was required for CASC, MIRI and AWD.

Irrigation efficiency optimization at multiple stakeholders’ levels based on remote sensing data and energy water balance modelling

The agricultural sector, the largest and least efficient water user, is facing important challenges in sustaining food production and careful water use. The objective of this study is to improve farm and irrigation district water use efficiency by developing an operational procedure for smart irrigation and optimizing the exact water use and relative water productivity. The SIM (smart irrigation monitoring and forecasting) optimization irrigation strategy, based on soil moisture (SM) and crop stress thresholds, was implemented in the Chiese (North Italy) and Capitanata (South Italy) Irrigation Consortia. The system is based on the energy–water balance model FEST-EWB (Flashflood Event-based Spatially distributed rainfall runoff Transformation Energy–Water Balance model), which was pixelwise calibrated with remotely sensed land surface temperature (LST), with mean areal absolute errors of approximately 3 °C, and then validated against local measured SM and latent heat flux (LE) with RMSE values of approximately 0.07 and 40 Wm−2, respectively. The effect of the optimization strategy was evaluated on the reductions in irrigation volume and on the different timing, from approximately 500 mm over the crop season in the Capitanata area to approximately 1000 mm in the Chiese district, as well as on cumulated drainage and ET fluxes. The irrigation water use efficiency (IWUE) indicator appears to be higher when applying the SIM strategy than when applying the traditional irrigation strategy: greater than 35% for the tomato fields in southern Italy and 80% for maize fields in northern Italy.

An Economic Analysis of the Efficiency of Irrigation Water Use in the Production of the Most Important Water-consuming Crops in Egypt

An Economic Analysis of the Efficiency of Irrigation Water Use in the Production of the Most Important Water-consuming Crops in Egypt

Biochar effects on soil properties, water movement and irrigation water use efficiency of cultivated land in Qinghai-Tibet Plateau

Biochar, has recently, been widely used as a potential soil additive to improve the quality of cultivated land. However, the effect of biochar on irrigation water use efficiency (IWUE) remains unclear in the Qinghai-Tibet Plateau (QTP). Therefore, the purpose of this study was to explore the effects of biochar on the soil properties, water infiltration, and irrigation water efficiency of QTP cultivated land. A column experiment with four biochar application levels (0, 3, 6, and 9 kg·m−2 denoted CK, BC1, BC2, and BC3, respectively) was conducted to explore the biochar effect on the soil water infiltration process. The soil bulk density (γ), saturated water content (θs), soil water retention curve (SWRC), specific water capacity C(h), and saturated hydraulic conductivity (Ks) were measured after the trial. The effects of biochar application level, biochar application depth, irrigation water depth, and initial soil moisture on water loss and IWUE were then simulated by HYDRUS-2D. The results showed that biochar slowed the process of soil water infiltration by changing the soil physical properties and hydraulic properties, reducing the water loss by 5%–15.02%, effectively alleviating the waste of irrigation water, and therefore increasing IWUE by 2%–9.43%. Water loss and IWUE were significantly associated with the biochar application depth and level. Additionally, a biochar level of 6 kg·m−2 showed the best effect for ameliorating the QTP's cultivated soil. These results provide a novel approach for reducing water loss and enhancing the irrigation water use efficiency of QTP cultivated soil.

Optimizing Irrigation Strategies to Improve Water Use Efficiency of Cotton in Northwest China Using RZWQM2

Irrigated cotton (Gossypium hirsutum L.) is produced mainly in Northwest China, where groundwater is heavily used. To alleviate water scarcity and increase regional economic benefits, a four-year (2016–2019) field experiment was conducted in Qira Oasis, Xingjiang Province, to evaluate irrigation water use efficiency (IWUE) in cotton production using the Root Zone Water Quality Model (RZWQM2), that was calibrated and validated using volumetric soil water content (θ), soil temperature (Tsoil°) and plant transpiration (T), along with cotton growth and yield data collected from full and deficit irrigation experimental plots managed with a newly developed Decision Support System for Irrigation Scheduling (DSSIS). In the validation phase, RZWQM2 adequately simulated (S) topsoil θ and Tsoil°, as well as cotton growth (average index of agreement (IOA) &gt; 0.76). Relative root mean squared error (RRMSE) and percent bias (PBIAS) of cotton seed yield were 8% and 2.5%, respectively, during calibration, and 20% and −10.3% during validation. The cotton crop’s (M) T was well S (−18% &lt; PBIAS &lt; 14% and IOA &gt; 0.95) for both full and deficit irrigation fields. The validated RZWQM2 model was subsequently run with seven irrigation scenarios with 850 to 350 mm water (Irr850, Irr750, Irr700, Irr650, Irr550, Irr450, and Irr350) and long-term (1990–2019) weather data to determine the best IWUE. Simulation results showed that the Irr650 treatment generated the greatest cotton seed yield (4.09 Mg ha−1) and net income (US $3165 ha−1), while the Irr550 treatment achieved the greatest IWUE (6.53 kg ha−1 mm−1) and net water production (0.94 $ m−3). These results provided farmers guidelines to adopt deficit irrigation strategies.

Optimization of the Regulated Deficit Irrigation Strategy for Greenhouse Tomato Based on the Fuzzy Borda Model

It is of great significance to explore the strategy of regulated deficit irrigation (RDI) under mulched drip irrigation to stabilize tomato yield and improve quality and efficiency. This experimental study was conducted on a drip-irrigated greenhouse in two consecutive years (2020 and 2021). Three deficit levels were set for the flowering and fruit development stage (Stage I), and three were set for the fruit-ripening stage (Stage II). As a combination evaluation method, the fuzzy Borda model was used to optimize the RDI strategy of greenhouse tomato. The results showed that the net photosynthetic rate, stomatal conductance, transpiration rate, and total shoot biomass of tomato decreased with an increase in the water deficit, while the intercellular CO2 concentration had an opposite trend. The mild and moderate water deficit at Stage I reduced tomato yield by 16–24% and 30–40% compared to full irrigation. The water deficit at Stage II was able to improve various quality parameters and the water-use efficiency of tomato; the irrigation water-use efficiency (32.8–33.9 kg/m3) and leaf water-use efficiency (3.2–3.6 μmol/mmol) were the highest when the soil water content was 70–90% θf (field capacity) at Stage I and 40–60% θf at Stage II (T3). Based on the fuzzy Borda combination evaluation model, T3 was determined as the treatment with stable yield, high quality, and efficient irrigation under the experimental conditions. The irrigation regime was as follows: irrigating 20–25 mm in the transplanting stage, no irrigation in the seedling stage, irrigating 193.2–220.8 mm at Stage I, and then irrigating 27.6 mm at Stage II.

Effect of potassium fertilization on water productivity, irrigation water use efficiency, and grain quality under direct seeded rice-wheat cropping system

A two-year field investigation was conducted to find out the right time, method, rate and source of potassium (K) fertilization for maximizing nutrient and water use efficiency and quality in a basmati rice-wheat cropping system. The split application of a recommended dose of K (RDK = 60 kg K2O ha−1) as half basal (B) and remaining half at panicle/ear initiation (PI/EI) stages significantly increased the system water productivity (SWP) (0.60 kg ha−1mm−1) and system irrigation water use efficiency (SIWUE) (1.26 kg ha−1mm−1) by 9.1% and 7.1% respectively over basal application of entire RDK. Likewise, in basmati rice, the split application of 100% RDK increased the water productivity (WP) and irrigation water use efficiency (IWUE) by 10.9% and 10.6% respectively over basal dressing of 100% RDK. The split application of RDK and supplementation of K through foliar spray besides basal K application increased the nitrogen, phosphorus and potassium concentration in grain and straw of both the crops. With respect to grain quality, the split application of 100% RDK increased the protein content by 2.3% in basmati rice, and 2.8% in wheat over basal application of 100% RDK. Similarly, the split application of RDK increased the hulling, milling and head rice recovery percentage of basmati rice by 1.3%, 6.6% and 3.3% respectively over basal application of RDK. The root length and dry weight of wheat was increased by 6.9% and 21% by split application of RDK over basal dressing of same dose of K.

Soil Aeration and Plastic Film Mulching Increase the Yield Potential and Quality of Tomato (Solanum lycopersicum)

Soil aeration and plastic film mulching have been reported to accelerate plant growth and increase fruit yield by improving the rhizosphere soil–air environment. The aim of this study was to investigate plant growth, fruit yield, irrigation water-use efficiency (IWUE) and fruit quality in response to a micro/nano-bubble aeration (MNBA) system and a subsurface artificial air layer aeration system (SAALA) under different treatments. The results indicated that both MNBA and SAALA positively influenced the plant dry weight, fruit yield, IWUE and fruit quality. In comparison with the no aeration treatment, the MNBA treatment increased the dry matter accumulation, fruit yield, IWUE, lycopene content and soluble protein content by 7.1%, 9.0%, 7.1%, 6.2% and 16.2%, respectively. Plastic film mulching (PFM) significantly improved the total dry weight, fruit yield and IWUE during both seasons. The increased yield in response to soil aeration during autumn was significantly greater than that during spring, and the yield increase in response to PFM was significantly greater in spring than in autumn. Moreover, the nutrition indices in response to both soil aeration and PFM were more significant during spring than autumn. Taking into account costs, efficiency and benefits, the optimal treatment was the MNBA and full (F) PFM combination.

Evaluation of water use efficiency and optimal irrigation quantity of spring maize in Hetao Irrigation District using the Noah-MP Land Surface Model

Hetao Irrigation District (HID), one of the main grain-producing areas in China, is facing the severe challenge of agricultural water shortages. Improving water use efficiency (WUE) is the most appropriate way to achieve sustainable agricultural development and obtain high returns. However, farmers knew little about efficient irrigation strategies for flood-irrigated fields in the HID. In this study, the Noah-MP Land Surface Model (LSM) with dynamic crop and irrigation schemes is used to jointly simulate the maize yield and irrigation amount in the HID from 2003 to 2012. A sensitivity test for ten sets of irrigation setup with different soil moisture (SM) triggering thresholds (CRI=0–1) is conducted, and the corresponding WUE and irrigation water use efficiency (IWUE) are evaluated and analyzed. In addition, irrigation at different crop growth stages affects total irrigation amounts and crop yield. The results show that under rain-fed conditions, the severe SM deficit during the growing season significantly decreases the maize yield in the HID, with almost no harvest in dry years. With traditional flood irrigation, the irrigation amount per unit area exceeds 1000 mm, leading to low WUE and IWUE, while more than 18–25% of irrigation water is wasted as runoff. With the increase of irrigation intensity, both WUE and IWUE show a significant diminishing marginal effect, usually occurring when SM is greater than 0.24–0.27 m3/m3. The optimal WUE is obtained near CRI= 0.6, while the worst WUE is obtained at CRI= 1. In a normal year, efficient irrigation amount is about 390–480 mm, 53–63% less than that in flood irrigation. In this scenario, most irrigation water becomes SM and transpiration, and less than 5% becomes runoff. With effective irrigation in the reproductive stage, only a small amount of irrigation is needed to promote yield formation. Fully considering the maize yield, WUE, ecosystems, and the available water resources in the HID, the recommended irrigation amount is about 600–650 mm to achieve the optimal maize yield and WUE.

Maximizing soybean productivity and profitability by transitioning from flood to furrow irrigation on clay‐textured soils

AbstractThe type of irrigation delivery system used in the mid‐southern United States can have an effect on crop–water relationships and withdrawal from the Mississippi River Valley Alluvial Aquifer. This study was conducted to determine whether converting from flood irrigation to an optimized furrow irrigation delivery system improves soybean [Glycine max (L.) Merr.] grain yield, net returns, and irrigation water use efficiency (IWUE). The effects of flood and optimized furrow irrigation on soybean grain yield, net returns above specified costs, irrigation water applied, and IWUE were investigated from 2016 to 2018 on 24 paired fields with the same soil type, cultivar, planting date, and management practices in the Delta region of Mississippi. Transitioning from flood irrigation to an optimized furrow irrigation system increased soybean grain yield by 7% and net returns above specified costs by 18% but had no effect on consumptive water use or IWUE. Our data indicate that mid‐southern US soybean producers should convert from flood to optimized furrow irrigation systems to maximize soybean grain yield and net returns; however, switching between irrigation delivery systems will have no effect on aquifer decline

Mechanism of water savings and pollution reduction in paddy fields of three typical areas in southern China

Field irrigation and drainage regulation and fertilization application could affect water utilization and pollution transportation in a paddy field. In this study, representative rice-producing areas of Zhejiang Province in southern China were selected to study the effects of different field water level control (conventional irrigation and drainage W0, controlled irrigation and drainage W1 and W2) and different fertilization methods (2 times of fertilization F2 and three times of fertilization F3) on water irrigation quantity and consumption of rice, rice growth, water utilization, and pollution reduction. Results showed that field water level control had a great effect on irrigation quota in growing period rather than that in soaking period, and irrigation quota for W0 was 37.0%-71.7% higher than that for W1 and W2 in the whole growth period of rice. Although the upper limit of rain storage was greatly increased by W1 and W2, on the contrary, the yield under W1 and W2 was 0.4%-2.1% higher than that under W0. Water consumption, water leakage, and evapotranspiration were 16.63%-34.4%, 39.97%-60.8%, and 9.40%-31.53% lower under W1 and W2 than those under W0, respectively, while it showed no significant changes under W1 and W2. Rainfall use rate and WUEI (water use efficiency of irrigation) under W1 and W2 had been significantly improved by 8.20%-129.58% and 31.58%-201.61% compared to W0. The contribution of nitrogen and phosphorus loss from surface water accounted for 90% and the total pollution load of total nitrogen (TN), NO3−-N, NH4+-N and chemical oxygen demand (COD) were 20.0%-63.4%, 21.8%-66.3%, 21.5%-63.8%, and 21.4%-46.5% lower for W1 and W2 than that for W0, respectively. Meanwhile, compared to F2, dispersed fertilization (F3) was beneficial to increase the yield and decrease pollutant load. Additionally, the path of IRA→NH4+-N→COD and IRA→WCA→WUEI presented partial remediation effect, and the effect size was 23.6% and 38.1%, respectively, the path of IRA→WUEI→WUEET presented a full remediation effect, and the path of IRA→WCA→WUEET presented suppression effect. Keywords: controlled irrigation and drainage, water consumption, water use efficiency, non-point source pollution, structural equation mode DOI: 10.25165/j.ijabe.20221501.6092 Citation: Xiao M H, Li Y Y, Jia Y, Wang J W. Mechanism of water savings and pollution reduction in paddy fields of three typical areas in southern China. Int J Agric & Biol Eng, 2022; 15(1): 199–207.