Effects of brackish water irrigation with different exogenous salt concentrations on the growth and rhizosphere salinity of Lycium barbarum.

To investigate the effects of different typical exogenous salt concentrations on total soil salinity and the growth of Lycium barbarum under brackish water irrigation, and to determine the salinity threshold of irrigated brackish water that is conducive to the normal growth of Lycium barbarum while mitigating soil salinity accumulation. Four typical exogenous salts (NaCl, CaCl2, NaHCO3, Na2SO4) were selected and set at four concentrations (0.1, 0.5, 2.0, 4.0 g L-1) to conduct a field crossover experiments in the downstream region of the Hetao Irrigation District. The results showed that in the same fertility period, the growth rates of new branches, ground diameter, and crown width first increased and then decreased with rising concentrations of NaCl, CaCl2, and Na2SO4, but showed an inverse relationship with NaHCO3 concentrations. Furthermore, increasing salt concentrations linearly reduced the yield of dry fruits from Lycium barbarum and led to a notable accumulation of total soil salts. Utilizing an experimental research approach, a comprehensive analysis of involving multiple growth indices, stable yield, and soil salinity control of Lycium barbarum revealed that optimal growth occurs at salt concentrations of 0.1-0.5 g L-1 for different water quality areas within the irrigation area; using the method of path analysis identified the total soil salt and crown width as the primary direct and indirect factors influencing the yield of Lycium barbarum. The results of this study provide scientific basis and significant theoretical support for the safe and rational utilization of brackish water and cultivation of Lycium barbarum in typical regions with varying saline water qualities of Hetao irrigation area.

Evaluating the need and feasibility of micro-irrigation systems for sustainable irrigation.

Irrigation is crucial for sustainable agriculture and improving farm yields, but a significant gap exists between the irrigation potential created and its actual utilization. This gap is due to losses in canal conveyance and the inefficiency of conventional irrigation methods within canal command areas. Most modernization efforts in India focus on implementing micro-irrigation for tube well systems, addressing the problem of water table decline experienced in many districts. With this context, the present study examines the command area of Gadarjudda minor of the Upper Ganga Canal in Haridwar district, Uttarakhand, India, to assess the present state of the canal by conducting on-site surveys and feasibility of micro-irrigation by evaluating the viability of replacing minor canals with a gravity flow piped irrigation network. The evaluation involves assessing the current canal status, designing the gravity flow piped irrigation network, and conducting a social survey to determine farmers' willingness, awareness, and purchasing capacity toward adoptin of micro-irrigation systems on their farms. The study identifies high conveyance loss and poor maintenance in conventional irrigation methods, highlighting the importance of micro-irrigation in the study area. The profile of the minor canal is adequate to support gravity flow in the pipe network, with velocity and pressure head within permissible limits. A social survey revealed that 85% of farmers are willing to adopt micro-irrigation, but low purchasing capacity (36%) hampers its adoption. The study concludes that micro-irrigation is viable in the Gadarjudda minor canal command area as long as a piped irrigation network is implemented and farmers receive government subsidies and proper training.

Analytical derivation of optimal irrigation water depth for efficient irrigation scheduling.

Optimal irrigation water depth is a crucial parameter in irrigation engineering, often referred to as root zone depth. It is typically assumed to lie between 1 and 1.5 m below the ground surface, depending on the crop and soil types as well as the practitioner's skill and experience. This approach can lead to inefficient irrigation scheduling. Coupling Richards' equation with the Soil Conservation Service Curve Number (SCS-CN) concept and using the three-phase diagram of soil column widely used in geotechnical engineering, this paper suggests an analytical expression for optimal irrigation water depth providing the maximum storage capacity of a soil depending on its hydraulic/storage properties. The results for winter wheat crop in different hydrologic soil groups show that the use of the proposed concept can lead to savings of 71.79% and 57.69% of irrigation water in sandy soils (HSG-A) compared to that used in traditional irrigation considering lump-sum 1.5 m and 1 m optimal irrigation water depths, respectively. In the case of silty loam soils (HSG-C), these savings can assume 52.42% and 28.62%, respectively. The proposed relation can also be of great help in volumetric assessment of field capacity, moisture content, maximum water storage capacity (of different agricultural soils), and avoiding the issue of waterlogging that may arise from over-irrigation and thus is useful in efficient irrigation scheduling as well as in sustainable agricultural water management.

Molasses-based waste water irrigation: a friend or foe for carrot (Daucus carota L.) growth, yield and nutritional quality.

Management of molasses-based wastewater generated in yeast and sugar industries is a major environmental concern due to its high chemical oxygen demand and other recalcitrant substances. Several strategies have been used to reduce the inland discharge of wastewater but the results are not satisfactory due to high operating cost. However, reuse of molasses-based wastewater irrigation in agriculture has been a major interest nowadays to reduce the freshwater consumption. Thus, it is crucial to monitor the impacts of molasses-based waste water irrigation on growth, metabolism, yield and nutritional quality of crops for safer consumer's health. In present study, carrot seeds of a local cultivar (T-29) were germinated on filter paper in Petri dishes under controlled conditions. The germinated seeds were then transplanted into pots and irrigated with three different treatments normal water (T0), diluted molasses-based wastewater (T1), and untreated molasses-based wastewater (T2), in six replicates. Results revealed that carrot irrigated with untreated molasses-based waste water had exhibited significant reductions in growth, yield, physiology, metabolism, and nutritional contents. Additionally, accumulation of Cd and Pb contents in carrot roots irrigated with untreated molasses-based waste water exceed the permissible limits suggested by WHO and their consumption may cause health risks. While, diluted molasses-based waste water irrigation positively enhanced the growth, yield of carrot plants without affecting the nutritional quality. This strategy is cost effective, appeared as most appropriate alternative mean to reduce the freshwater consumption in water deficit regions of the world.

Evaluation of crop water stress index of wheat by using machine learning models.

The Crop Water Stress Index (CWSI), a pivotal indicator derived from canopy temperature, plays a crucial role in irrigation scheduling for water conservation in agriculture. This study focuses on determining CWSI (by empirical method) for wheat crops in the semi-arid region of western Uttar Pradesh, India, subjected to varying irrigation treatments across two cropping seasons (2021-2022 and 2022-2023). The aim is to investigate further the potential of four machine learning (ML) models-support vector regression (SVR), random forest regression (RFR), artificial neural network (ANN), and multiple linear regression (MLR) to predict CWSI. The ML models were assessed based on determination coefficient (R2), mean absolute error (MAE), and root mean square error (RMSE) under diverse scenarios created from eight distinct input combinations of six variables: air temperature (Ta), canopy temperature (Tc), vapor pressure deficit (VPD), net solar radiation (Rn), wind speed (U), and soil moisture depletion (SD). SVR emerges as the top-performing model, showcasing superior results over ANN, RFR, and MLR. The most effective input combination for SVR includes Tc, Ta, VPD, Rn, and U (R2 = 0.997, MAE = 0.901%, RMSE = 2.223%). Meanwhile, both ANN and MLR achieve optimal results with input combinations involving Tc, Ta, VPD, Rn, U, and SD (R2 = 0.992, MAE = 2.031%, RMSE = 3.705%; R2 = 0.759, MAE = 13.95%, RMSE = 19.98%, respectively). For RFR, the ideal input combination comprises Tc, Ta, VPD, and U (R2 = 0.951, MAE = 5.023%, RMSE = 9.012%). The study highlights the considerable promise of ML models in predicting CWSI, proposing their future application in integration into an irrigation decision support system (IDSS) for crop stress mitigation and efficient water management in agriculture.

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The shortage of water resources and the irrational application of nitrogen fertilizer restrict the synergistic enhancement of yield and water- and fertilizer-use efficiencies of wheat in the Huang-Huai-Hai region. In this study, we conducted an experiment following two-factor split zone design with three irrigation levels and four nitrogen application rates. The relative water content of the 0-40 cm soil layer was supplemented to 65% (W1), 75% (W2), and 85% (W3) of field water capacity at the jointing and anthesis stages of wheat. The rates of nitrogen application were 0 (N0), 150 (N1), 180 (N2), and 210 (N3) kg·hm-2. We analyzed the effects of these different managements on post-anthesis photosynthetic matter production, yield, and water- and nitrogen-use efficiencies. The results showed that yield first increased with increases in the levels of irrigation and nitrogen application, peaking under the W2N2 treatment (9103.53 kg·hm-2). However, further increases in water and nitrogen input did not have further enhancement of wheat yield. Under the same nitrogen application condition, compared with W1 treatment, the canopy light interception rate, chlorophyll relative content and actual photochemical efficiency after anthesis increased by 4.5%-6.0%, 19.7%-28.2%, and 7.5%-9.8% in response to the W2 treatment, respectively, without any difference between the W2 and W3 irrigation levels. At the same irrigation level, post-anthesis dry matter accumulation in repose to the N2 treatment increased by 80.1%-88.9% and 16.7%-22.2% compared with N0 and N1 treatments, respectively, without significant difference between the N2 and N3 treatments. Both the irrigation water-use efficiency (IWUE) and the nitrogen partial factor productivity declined with increases in the levels of irrigation and nitrogen application. Under the W1, W2, and W3 treatments, the values obtained for IWUE were 16.23, 11.01, and 7.91 kg·hm-2·m-3, respectively, whereas in response to the N1, N2, and N3 treatments, N partial factor productivity was 50.8%, 48.4%, and 42.5%, respectively. In all, based on soil moisture measurements and assessments of wheat yield and water- and nitrogen-use efficiencies, the optimal water and nitrogen management strategy for enhancing wheat yield in the Huang-Huai-Hai region is supplementation of water content of 0-40 cm soil layer at the jointing and anthesis stages to 75% field capacity combined with the application of 180 kg·hm-2 nitrogen (W2N2). This approach could achieve high yield and efficiency and promote conservation of water and fertilizer.

Grapevine varieties show different sensitivities to flavonoid alterations caused by high temperatures under two irrigation conditions.

This study aimed to assess the response of four red grapevine (Vitis vinifera L.) varieties to elevated temperature, drought and their combination, focusing on the concentration and profile of grape flavonoids. Fruit-bearing cuttings of Tempranillo, Cabernet Sauvignon, Merlot and Grenache grew in greenhouses under, either ambient temperature (T) or ambient temperature + 4 °C (T+4). Plants also received either full irrigation (FI, substrate field capacity) or deficit irrigation (DI, 50 % substrate field capacity). In general, T+4 decreased the concentration of anthocyanins, but DI mitigated this effect. T+4 and DI increased the abundance of methylated anthocyanins and flavonols with additive effects. Grapes under T+4 had higher abundance of acylated anthocyanins, while DI increased the proportion of tri-hydroxylated anthocyanins and flavonols. The impact of interacting elevated temperature and drought on grape composition was genotype dependent. In terms of anthocyanin concentration and profile, Tempranillo was the most affected variety, whereas Grenache was less sensitive.

Effects of wide-range precision sowing and row spacing on water consumption and grain yield of wheat.

The mechanism for water-saving and high-yield of wide-range precision sowing technology remains unclear. We investigated the impact of wide-range precision sowing on the physiological characteristics of root system, water consumption, and grain yield of wheat 'Jimai 22' during the growing seasons of 2017-2019. We set up two planting modes: wide precision sowing and conventional strip sowing, and three row spacings of 20 cm, 25 cm, and 30 cm under water-saving cultivation with supplemental irrigation to examine the effects of planting modes on root biomass and senescence characteristics of wheat, water utilization characteristics, interplant evaporation, grain yield, and water utilization efficiency. The results showed that the 25 cm treatment (K25) led to an increase in root weight density, root soluble protein content, and root activity by 7.2%-23.9%, 8.7%-25.1%, 10.7%-29.9%, and 7.3%-27.6%, 8.0%-38.5%, 15.2%-32.7%, respectively, compared to the other treatments. At the same row spacing, the wide-range precision sowing treatment showed a significantly higher soil water storage consumption and proportion to total water consumption compared to the conventional strip-tillage treatment. Additionally, irrigation and interplant evaporation were lower in the wide-range precision sowing treatment. The K25 treatment exhibited significantly higher water consumption and modal coefficient of water consumption from flowering to ripening than other treatments. Furthermore, it had significantly higher seed yield, water utilization efficiency, and irrigation utilization efficiency than the other treatments. We found that a 25 cm spacing in the lower rows and density of 180-270 plants·m-2 was the water-saving and high-yielding planting pattern of wide-range precision sowing wheat in Huang-Huai-Hai region.

Moderate alternate wetting and drying irrigation enhances drought-resistance abilities by improving structural mesophyll conductance of water-saving and drought-resistant rice under severe drought.

Water-saving and drought-resistant rice (WDR) coupled with alternate wetting and drying irrigation (AWDI) possesses a high photosynthetic potential due to higher mesophyll conductance (gm) under drought conditions. However, the physiological and structural contributions to the gm of leaves and their mechanisms in WDR under AWDI are still unclear. In this study, WDR (Hanyou 73) and drought-sensitive rice (Huiliangyou 898) were selected as materials. Three irrigation patterns were established from transplanting to the heading stage, including conventional flooding irrigation (W1), moderate AWDI (W2), and severe AWDI (W3). A severe drought with a soil water potential of -50 kPa was applied for a week at the heading stage across all treatments and cultivars. The results revealed that severe drought reduced gas exchange parameters and gm but enhanced antioxidant enzyme activities and malondialdehyde content in the three treatments and both cultivars. The maximal photosynthetic rate (Amax) of HY73 in the W2 treatment was greater than that in the other combinations of cultivars and irrigation patterns. The contribution of leaf structure (54%) to gm (gm-S, structural gm) was higher than that of leaf physiology (46%) to gm (gm-P, physiological gm) in the W2 treatment of Hanyou 73. Additionally, gm-S was significantly and linearly positively correlated with gm under severe drought. Moreover, both the initial and apparent quantum efficiencies were significantly and positively with gm in rice plants (p < 0.05). These results suggest that the improvements in photosynthesis and yield in the WDR combined with moderate AWDI can mainly be attributed to the enhancement of gm-S under severe drought conditions. Quantum efficiency may be a potential factor in regulating photosynthesis by cooperating with the gm of rice plants under severe drought conditions.

Optimized irrigation and fertilization can mitigate negative CO2 impacts on seed yield and vigor of hybrid maize.

Seed yield and vigor of hybrid maize determine the planting, yield, and quality of maize, and consequently affect food, nutrition, and livelihood security; however, the response of seed yield and vigor to climate change is still unclear. We established an optimization-simulation framework consisting of a water­nitrogen crop production function, a seed vigor and a gridded process-based model to optimize irrigation and nitrogen fertilization management, and used it to evaluate seed yield and vigor in major seed production locations of China, the USA, and Mexico. This framework could reflect the influence of water and nitrogen inputs at different stages on seed yield and vigor considering the spatio-temporal variability of climate and soil properties. Projected seed yield and vigor decreased by 5.8-9.0 % without adaptation by the 2050s, due to the 1.3-5.8 % decrease in seed number and seed protein concentration. Seed yield was positively correlated with CO2 and negatively correlated with temperature, while seed vigor depended on the response of components of seed vigor to climatic factors. Under optimized management, the direct positive effects of temperature on seed protein concentration and CO2 on seed number were strengthened, and the direct negative effects of temperature on seed number and CO2 on seed protein concentration were weakened, which mitigated the reductions in both seed yield and vigor. Elevated CO2 was projected to exacerbate the 2.6 % seed vigor reduction and mitigate the 2.9 % seed yield loss without adaptation, while optimized management could increase seed yield by 4.1 % and mitigate the 2.2 % seed vigor reduction in the Hexi Corridor of China, and decrease the seed yield and vigor reduction by 2.4-5.8 % in the USA and Mexico. Optimized management can strengthen the positive and mitigate the negative effects of climate change on irrigated hybrid maize and inform high-yield and high-quality seed production globally.

Impact of long-term irrigation practices on distribution and speciation of arsenic in agricultural soil.

To better understand the impact of long-term irrigation practices on arsenic (As) accumulation in agricultural soils, 100 soil samples from depths of 0-20 cm were collected from the Datong basin, where the As-contaminated groundwater has been used for irrigation for several decades. Soil samples were analyzed for major elements, trace elements, and As, Fe speciation. Results reveal As content ranging from 4.00 to 14.5 mg/kg, an average of 10.2 ± 2.05 mg/kg, consistent with surveys conducted in 1998 and 2007. Arsenic speciation ranked in descending order as follows: As associated with silicate minerals (AsSi, 29.70 ± 7.53 %) > amorphous Fe-minerals associated As (AsFeox1, 26.40 ± 3.27 %) > crystalline Fe-minerals associated As (AsFeox2, 24.02 ± 4.60 %) > strongly adsorbed As (AsSorb, 14.29 ± 2.81 %) > As combined with carbonates and Fe-carbonates (AsCar, 2.30 ± 0.44 %) > weakly adsorbed As (AsDiss, 2.59 ± 1.00 %). The anomalous negative correlation between As and Fe content reflects the primary influence of soil provenance. Evidence from major element compositions and rare earth element patterns indicates that total As and Fe contents in soils are controlled by parent materials, exhibiting distinct north-south differences (As: higher levels in the north, lower levels in the south; Fe: higher levels in the south, lower levels in the north). Evidence from the Chemical Index of Alteration (CIA) and As/Ti ratio suggests that chemical weathering has led to As enrichment in the central basin. Notably, relationships such as AsDiss/Ti, AsSorb/Ti with CIA and total Fe content indicate significant influences of irrigation practices on adsorbed As (both weakly and strongly adsorbed) contents, showing a pattern of higher levels in the central basin and lower levels in the Piedmont. However, total As content remained stable after long-term irrigation, potentially due to the re-release of accumulated As via geochemical pathways during non-irrigated periods. These findings demonstrate that the soil systems can naturally remediate exogenous As contamination induced by irrigation practices. Quantitative assessment of the balance between As enrichment and re-release in soil systems is crucial for preventing soil As contamination, highlighting strategies like water-saving techniques and fallow periods to manage As contamination in agricultural areas using As-contaminated groundwater for irrigation.

Investigating the synergy of rapidly synthesized iron oxide predecessor and plasma-gaseous species for dye-removal to reuse water in irrigation.

This study explores a novel and sustainable approach to reusing textile wastewater for irrigation. This is investigated by degrading Evans blue dye, a model azo dye, in wastewater by combining iron oxide predecessor (IOP) catalyst with gaseous species generated by multi-electrode cylindrical plasma device (MCPD). Analysis of IOP-plasma gaseous species revealed the generation of different types of reactive oxygen species in solution which were responsible for degradation of model dye. Key factors influencing the degradation process were studied by performing optimization experiments that resulted in rates of up to 0.008 L mg-1 min-1, more than twice as fast as using plasma gas treatment alone. These studies included mechanistic response of MCPD generated gaseous species with the IOP. In particular, reusability testing of IOP affirmed the robustness and performance efficiency up to three cycles. Finally, toxicity analysis revealed not only reduced negative effects on plant growth by the treated wastewater, but also it can used as minerals to plants. These findings highlight the feasibility of the IOP-MCPD system as a sustainable and eco-friendly solution to reduce scarcity of water in irrigation by treating textile effluent.

Potential of land degradation index for soil salinity mapping in irrigated agricultural land in a semi-arid region using Landsat-OLI and Sentinel-MSI data.

Irrigated agricultural lands in arid and semi-arid regions are prone to soil degradation. Remote sensing technology has proven useful for mapping and monitoring the extent of this issue. To accurately discern soil salinity, it is essential to choose appropriate spectral wavelengths. This study evaluated the potential of the land degradation index (LDI) using the visible and near infrared (VNIR) and the short wavelength infrared (SWIR) spectral bands compared to that of soil salinity indices by integrating only the VNIR wavelengths. Landsat-OLI and Sentinel-MSI data, acquired 2 weeks apart, were rigorously preprocessed and used. This research was conducted over irrigated agricultural land in Morocco, which is well known for its semi-arid climate and moderately saline soil. Furthermore, a field soil survey was conducted and 42 samples with variable electrical conductivity (EC) were collected for index calibration and validation of the results. The results showed that the visual analysis of the derived maps based on the examined indices exhibited a clear spatial pattern of gradual soil salinity changes extending from the elevated upstream plateau to the downstream of the plain, which limits agricultural activities in the southwestern sector of the study area. The results of this study show that LDI is effective in identifying soil salinity, as indicated by a coefficient of determination (R2) of 0.75 when using Sentinel-MSI and 0.72 with Landsat-OLI. The R2 value of 0.89 and root mean square error (RMSE) of 0.87 dS/m for soil salinity maps generated from LDI with Sentinel-MSI demonstrate high accuracy. In contrast, the R2 value of 0.83 and RMSE of 1.24 dS/m for maps produced from Landsat-OLI indicate lower accuracy. These findings indicate that high-resolution Sentinel-MSI data significantly improved the prediction of salinity-affected soils. Furthermore, this study highlights the benefits of using VNIR and SWIR bands for precise soil salinity mapping.

Increased anaerobic conditions promote the denitrifying nitrogen removal potential and limit anammox substrate acquisition within paddy irrigation and drainage units.

Microbial nitrogen (N) removal is crucial for purifying surface water quality in paddy irrigation and drainage units (IDUs). However, the spatiotemporal microbial N removal potential characteristics within these IDUs and the effects of changing anaerobic conditions on this potential remain insufficiently studied. In this study, we investigated the microbial N removal potential of conventional rice-wheat rotation and anaerobically enhanced rice-crayfish rotation IDUs using field measurements, isotope tracing techniques, and quantitative PCR. Our findings reveal that paddy fields were identified as hotspots for anammox activity, contributing to 76.0 %-97.4 % of the total anammox N removal potential in the IDU, while denitrification processes in ditches accounted for 43.5 %-77.4 % of the IDU's denitrification potential. During the rice transplanting period, the anammox N removal potential peaked, representing 35.8 % and 71.8 % of the total anammox N removal potential of the paddy fields in rice-wheat and rice-crayfish IDUs, respectively. An increase in anaerobic conditions diminished the anammox N removal potential while amplifying denitrification capabilities. The N removal potential in paddy fields decreased with increasing depth, contrasting with the relative stability in ditches. Spatiotemporal fluctuations in N removal potentials within these units are influenced by Fe2+ concentration, carbon and N content, WFPS, and pH levels. This study provides a scientific basis for improving nitrogen removal and water quality treatment in IDUs.

The food-water-climate nexus of green infrastructure: Examining ecosystem services trade-offs of peri-urban agriculture.

Emission reduction, heat mitigation, and improved access to water and food provision are increasingly critical challenges for urban areas in the context of global climate change adaptation and mitigation. The revival of local agricultural production is often lauded as a potential nature-based solution. However, an expansion of peri-urban agriculture (peri-UA) may entail significant ecosystem trade-offs. This study explores the impacts on the food-water-climate nexus of different scenarios of peri-urban agricultural expansion in a semi-arid, Mediterranean climate, addressing local food provision, freshwater use, local temperature regulation, global climate change mitigation, and the trade-offs thereof. We estimate food provision and irrigation water requirements based on a georeferenced urban metabolism approach along with atmospheric and biosphere models to examine four land-use scenarios in the Metropolitan Area of Barcelona. Our study reveals that a 31 % (+17.27 km2) and 115 % (+64.25 km2) increase in the current peri-UA in the AMB, results in an increase in local food production of 24 % (+16,503 tons year-1) and 86 % (+58,940 tons year-1), and irrigation water requirements by 10.0 % (+3.2 hm3) and 43.5 % (+14.1 hm3), respectively. The expansion of irrigated peri-UA potentially reduces near-surface temperatures by 0.7 °C, albeit temperature reductions in the densest urban areas are minimal. Since the additional peri-UA is achieved by replacing natural non-forested and forest areas, the simulations predict reductions in the net ecosystem productivity of up to 18.5 % and total carbon stocks by 3.3 %. This integrated approach combining urban metabolism and atmospheric modelling to determine the trade-offs appears to be a promising tool for informing land-use decision-making in the context of urban climate adaptation and mitigation.

Reuse of straw in the form of hydrochar: Balancing the carbon budget and rice production under different irrigation management.

Hydrochar is proposed as a climate-friendly organic fertilizer, but its potential impact on greenhouse gas (GHG) emissions in paddy cultivation is not fully understood. This two-year study compared the impact of exogenous organic carbon (EOC) application (rice straw and hydrochar) on GHG emissions, the net ecosystem carbon budget (NECB), net global warming potential (net GWP), and GHG emission intensity (GHGI) in a rice pot experiment using either flooding irrigation (FI) or controlled irrigation (CI). Compared with FI, CI increased ecosystem respiration by 23 - 44 % and N2O emissions by 85 - 137 % but decreased CH4 emissions by 30 - 58 % (p < 0.05). Since CH4 contributed more to net GWP than N2O, CI reduced net GWP by 16 - 220 %. EOC amendment increased crop yield by 5 - 9 % (p < 0.05). Compared with CK, hydrochar application increased initial GHG emission, net GWP and GHGI in the first year, while in the second year, there was no significant difference in net GWP and GHGI between CI-hydrochar and CK. Compared with straw addition, hydrochar amendment reduced net GWP and GHGI by 20 - 66 % and 21 - 66 %; and exhibited a lower net CO2 emission when considering the energy input during the hydrochar production. These findings suggest that integrated CI-hydrochar practices would be a sustainable and eco-friendly way for organic waste management in rice production as it holds potential to enhance the NECB and SOC sequestration of rice production, while also offsetting the extra carbon emissions from organic inputs.

Effect of bio-fertilizers and seaweed extract on growth and yield of wheat (Triticum aestivum L.) under different irrigation regimes: Two-year field study.

Wheat productivity is constrained by genetic, agronomic, and climate factors, though it is an important crop for food production worldwide. The present study evaluated the effect of bio-fertilizer consortia and seaweed extracts on the growth and yield of two wheat varieties under different irrigation regimes in a field study. This experiment was conducted in a split-split plot based on a randomized complete block design with four replications in 2018 and 2019. Irrigation treatments were the main factor, wheat variety (Sardari and Sirvan) the sub-factor, and bio-fertilizers the sub-sub-factors. The results showed that irrigation regimes significantly improved leaf width, number of leaves, fresh weight of roots and shoots, osmotic potential, leaf water content, and number of stomata respectively by 57.53, 38.59, 106.65, 135.29, 87.92, 14.22 and 13.77, 88.02 and 96.11 percent compared to dry-land conditions. Applying one- and two-times irrigation increased grain yield by 51% and 79%, respectively, and the response varied in wheat varieties. Sardari variety due to having smaller leaf dimensions (Leaf length and width) and lower fresh and dry weight of roots and shoots, as well as lower leaf and tissue water content, had lower grain yield than the Sirvan variety. All the bio-fertilizers positively impacted the growth and yield of both varieties. However, the highest average grain yield in the first and second years of the experiment (with an average of 5226.25 and 4923.33 kg/ha, respectively) were found under the combined application of Mycorrhiza + Nitrozist and Phosphozist + Seaweed extract. The results of the present study underscore the importance of irrigation regimes and consortia of bio-fertilizers for improving grain yield. This study also highlighted the resilience of the studied wheat varieties and bio-fertilizers to projected climate changes. These findings could provide insights into adaptive strategies for mitigating the impact of climate change on wheat production.

Impacts of aquaculture wastewater irrigation on soil health, nutrient availability, and date palm fruit quality.

Water scarcity and droughts are among the most challenging issues worldwide, particularly in arid and semi-arid regions like Saudi Arabia. Date palm (Phoenix dactylifera L.), a major crop in Saudi Arabia, is being significantly affected by water scarcity, soil salinity, and desertification. Alternative water sources are needed to conserve freshwater resources and increase date palm production in Saudi Arabia. On the other hand, Saudi Arabia has a significant number of aquaculture farms that generate substantial amounts of wastewater, which can be utilized as an alternative source of irrigation. Therefore, this study aimed to assess the potential of aquaculture wastewater as an alternative irrigation source for date palm orchards. Aquaculture wastewater was collected from 12 different farms (Al-Kharj, Al-Muzahmiya, and Al-Qassim regions, Saudi Arabia) and its quality was analyzed. The impacts of aquaculture wastewater irrigation on soil quality, nutrient availability, nutrient status of date palm trees, and dates fruit quality were assessed in comparison to source water (freshwater) irrigation at Al-Kharj, Al-Muzahmiya, and Al-Qassim regions. The water quality analyses showed higher salinity (EC = 3.31 dSm-1) in farm Q3, while all other farms demonstrated no salinity, sodicity, or alkalinity hazards. Moreover, the aquaculture wastewater irrigation increased soil available P, K, NO3--N, and NH4+-N by 49.31%, 21.11%, 33.62%, and 52.31%, respectively, compared to source water irrigation. On average, date palm fruit weight, length, and moisture contents increased by 26%, 23%, and 43% under aquaculture wastewater irrigation compared to source water irrigation. Further, P, K, Fe, Cu, and Zn contents in date palm leaf were increased by 19.35%, 34.17%, 37.36%, 38.24%, and 45.29%, respectively, under aquaculture wastewater irrigation compared to source water irrigation. Overall, aquaculture wastewater irrigation significantly enhanced date palm plant growth, date palm fruit quality, and soil available nutrients compared to freshwater irrigation. It was concluded that aquaculture wastewater can be used as an effective irrigation source for date palm farms as it enhances soil nutrient availability, date palm growth, and date fruit yield and quality. The findings of this study suggest that aquaculture wastewater could be a viable alternative for conserving freshwater resources and increase date palm production in Saudi Arabia.

Precise partial root-zone irrigation technique and potassium-zinc fertigation management improve maize physio-biochemical responses, yield, and water use in arid climate.

BACKGROUND: To optimize irrigation water use and productivity, understanding the interactions between plants, irrigation techniques, and fertilization practices is crucial. Therefore, the experiment aims to assess the effectiveness of two application methods of potassium humate combined with chelated zinc under partial root-zone drip irrigation techniques on maize nutrient uptake, yield, and irrigation water use efficiency across two irrigation levels. METHODS: Open-field experiments were carried out in two summer seasons of 2021 and 2022 under alternate and fixed partial root-zone drip irrigation techniques to investigate their impacts at two irrigation levels and applied foliar and soil applications of potassium humate or chelated zinc in a sole and combinations on maize. RESULTS: Deficit irrigation significantly increased hydrogen peroxide levels and decreased proline, antioxidant enzymes, carbohydrate, chlorophyll (a + b), and nutrient uptake in both partial root-zone techniques. The implementation of combined soil application of potassium humate and chelated zinc under drought conditions on maize led to varying impacts on antioxidant enzymes and nutritional status, depending on the type of partial root-zone technique. Meanwhile, the results showed that fixed partial root-zone irrigation diminished the negative effects of drought stress by enhancing phosphorus uptake (53.8%), potassium uptake (59.2%), proline (74.4%) and catalase (75%); compared to the control. These enhancements may contribute to improving the defense system of maize plants in such conditions. On the other hand, the same previous treatments under alternate partial root zone modified the defense mechanism of plants and improved the contents of peroxidase, superoxide dismutase, and the uptake of magnesium, zinc, and iron by 81.3%, 82.3%, 85.1%, 56.9%, and 80.2%, respectively. CONCLUSIONS: Adopting 75% of the irrigation requirements and treating maize plants with the soil application of 3 g l-1 potassium humate combined with 1.25 kg ha-1 chelated zinc under alternate partial root-zone technique, resulted in the maximum root length, leaf water content, chlorophyll content, yield, and irrigation water use efficiency.

Effect of drought stress on morpho-physiological characteristics, nutritive value, and water-use efficiency of sorghum [Sorghum bicolor (L.) Moench] varieties under various irrigation systems.

Addressing water scarcity and the need for high-quality forage in arid regions necessitates the development of efficient irrigation techniques. This study assesses the impact of various irrigation methods on the performance and irrigation water-use efficiency (IWUE) of sorghum cultivars under water-deficit conditions in a semi-arid region of Iran during the 2019 and 2020 cropping seasons. Three irrigation methods-variable alternate furrow irrigation (AFI), fixed alternate furrow irrigation (FFI), and conventional furrow irrigation (CFI)-were evaluated alongside three levels of drought stress (severe stress: I50, moderate stress: I75, and full irrigation: I100) and two sorghum cultivars. The results indicated that increasing drought stress, as well as the transition from CFI to AFI and FFI, led to reductions in metabolizable energy yield (MEY), plant height, cellulose, hemicellulose, and lignin. Conversely, there were increases in leaf-to-stem ratio, digestible organic matter, metabolizable energy content, crude protein content, and IWUE for metabolizable energy production (IWUEME). The highest MEY (211.68 GJ ha-1) was recorded under CFI×I100, albeit at the expense of maximum water consumption (7261 m3 ha-1). Meanwhile, the AFI×I50 and FFI×I50 treatments exhibited the highest IWUEME (44.46 MJ m-3) and metabolizable energy content (8.736 MJ kg-1), respectively, while conserving over 60% of water. Hybrid Speedfeed outperformed in forage yield and IWUEME, while cultivar Pegah excelled in forage quality. Transitioning from CFI to AFI or FFI resulted in decreased forage yield but improved forage quality and IWUEME. Principal component analysis revealed that leaf-to-stem ratio and plant height serve as effective indicators for assessing the nutritive value and forage yield of sorghum, respectively. Considering the overall results, cultivating the hybrid Speedfeed under AFI×I75 conditions is recommended for optimal water utilization, achieving satisfactory forage yield and quality, and enhancing IWUE.