Planting models and deficit irrigation strategies to improve radiation use efficiency, dry matter translocation and winter wheat productivity under semi-arid regions

The dry-land farming system of China relies on plastic film mulching and natural rainfall to mitigate damage caused by drought. However, the applications of deficit irrigation modes combined with the planting models can significantly increase production of wheat, dry matter translocation and radiation use efficiency (RUE) remains unidentified. Thus, in 2016-2018, we conducted field trials that implemented four deficit irrigation modes (IJF: irrigation at jointing and flowering stages; IF: irrigation at flowering stage; IJ: irrigation at jointing stage; NI: no irrigation) under two cultivation patterns (ridge furrow rainfall harvesting system (RF); traditional flat cultivation (TF)). The results indicated that the effects of RF system with deficit irrigation (IJF: 250 mm) could significantly increase the soil moisture, and thus enhanced LAI, I_n value, IPAR, RUE, and PAR capture ratio than that of TF-NI planting. This is due to decreased canopy light transmittance (LT), reflection and penetration ratio of PAR, as a result considerable improve the biomass translocation and grain yield. Owing to the very low soil water content after the seed-filling, the LAI, IPAR, and I_n value decreased during the seed-filling under water stress, ultimately affecting the dry matter translocation efficiency. While the IJF and IF treatments provided water for reproductive growth stage, therefore, the production of wheat and RUE were significantly maximum compared with IJ and NI irrigation mode. Under the RF system with IJF, IF, and IJ treatments the grain yield increased by 81.2%, 56.8%, 45.6% and 17.2%, then that of TF-NI treatment, respectively. The highest RUE (1.93 g MJ^-1), dry-matter translocation (154.2%) and seed yield (81.2%) were obtained in the RF-IJF treatment compared with TF-NI. Therefore, the RF-IJF treatment significantly improved the earlier development and rapid plant growth, which is a suitable planting model for increasing soil moisture, LAI, RUE, DMT, and winter wheat production.

Risk assessment for uptake and accumulation of pharmaceuticals by baby leaf lettuce irrigated with reclaimed water under commercial agricultural activities

The use of reclaimed water to irrigate agricultural crops has increased in recent years as a consequence of water shortage constituting a potential risk for human health. The main objective of this study was to evaluate the impact on the soil-plant system and determining the accumulation of carbamazepine (CBZ), diclofenac (DCF), ketoprofen (KTP) and naproxen (NPX) in the edible part of lettuce under commonly used agricultural practices in commercial production. For this purpose, red oak baby lettuce (Lactuca sativa L.) was irrigated with reclaimed water fortified with different concentrations of pharmaceuticals. The study was carried out in two different scenarios: soil and tray. The tray experiments were conducted with substrate and took place at three different seasons of the year. Lettuce tissue sampled from these experiments were analysed 3 times during the lettuce growing cycle (first, second and third harvest). The practices of first harvest regrowth were also evaluated. For all experiments, CBZ showed the highest accumulation in lettuce leaves of the pharmaceuticals tested, showing a correlation between irrigation exposure time and pharmaceutical uptake. Unexpectedly, DCF was the compound with the highest uptake levels after regrowth practices. Results suggested that pharmaceuticals uptake could be directly associated with the irrigation method and possible accumulation in soil and substrates, while concentration of pharmaceuticals in substrates were 10 times higher. Based on the concentration values detected in lettuce leaves, the risk assessment suggests that no compounds imply any risk to human health, except CBZ for those on vegetarian diets in the tray scenario. Although commercial agricultural practices are usually not considered with regards to risk reduction, in this experiment we demonstrated that climatic conditions are a key factor in pharmaceuticals uptake and different agricultural practices (soil cropping and drip irrigation) can limit the presence of pharmaceutical compounds in crops.

Wastewater irrigation: An opportunity for improving soil phosphorus availability; PHREEQC modeling and adsorption studies

Wastewater, an alternative supply of water and nutrients, is being allocated as a priority for human population sustainability in arid and semi-arid regions. This work proposes phosphorus (P), a vital growth-limiting nutrient, adsorption behavior in wastewater irrigated agricultural soils in comparison to non-irrigated soils using laboratory batch experiments. The adsorption mechanism was assessed using different adsorption isotherm models. Saturation indices were modeled, using the hydro-geochemical transport code PHREEQC and MINTEQ geochemical software. Phosphorus buffering parameters were also calculated based on the standard equations. The equilibrium data were well fitted with the Freundlich isotherm model. The physical adsorption mechanism was found based on the calculated isotherm parameters. The maximum adsorption capacity was two times more in non-wastewater irrigated soils than irrigated. Results highlighted the effectiveness of wastewater irrigation in P availability in soil. Based on the PHREEQC modeling data, precipitation of Pb and Zn mineral phases was probable in soils by wastewater influence. Meanwhile, the precipitation of stable calcium phases, that affect the P sorption and/or co-precipitation, in non-wastewater irrigated soils was highlighted in the PHREEQC calculations. The standard buffer capacity (SBC) was 43 and 64 L kg^-1 in wastewater irrigated soils and non-irrigated soils, respectively. Findings of the present study demonstrate the importance of wastewater reuse opportunities for agricultural application, especially soil P availability, and are helpful to minimize the environmental impacts of wastewater and solid waste.

Irrigation-facilitated low-density polyethylene microplastic vertical transport along soil profile: An empirical model developed by column experiment

The emerging issue of microplastic pollution of agricultural soils derives from the intensive utilization of plastic mulching film. Although surface runoff may transport microplastic off-site, infiltration may also facilitate microplastic transport from surface soil to deeper depths. Microplastic comprises a relatively new category of soil contaminants, whose transport in the soil has not yet been widely studied. In this study, we investigated microplastic transport from contaminated surface soil (50 g kg^-1) driven by irrigation, from permanent wilting point to saturation, and developed an empirical model to characterize the resulting accumulation of microplastic along soil profile. A soil column experiment was conducted under various treatments: the control, 1, 2 and 4 runs of irrigation. Soil samples were collected from inside and outside of soil cracks (if present) in each soil layer (0-2 cm (source layer), 2-5 cm, 5-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, 40-50 cm). The results showed that with increasing irrigation runs, microplastic in the source soil layer decreased, while microplastic contents in deeper soil depths increased significantly (p < 0.05), varying from 7.03 g kg^-1 in 2-5 cm to 0.29 g kg^-1 in 40-50 cm soil. The microplastic content detected in soil cracks was 1.3-17.8 times higher than that detected in the soil matrix at similar depths, indicating that the transported microplastic is prone to be enriched in soil cracks. In addition, the total amount of transported microplastic increased 1.5 times after four irrigation runs, and the variations were significantly observed especially at deeper soil depths. Based on correlation analyses, data-fitted empirical models that relate cumulative microplastic to the depth of soil layer and irrigation runs indicate that irrigation-facilitated microplastic transport could be well-characterized (R² >0.92). Further research is needed to develop an physical-based model in order to assess microplastic migration risks driven by irrigation and other agricultural management practices.

The trade-offs between resistance and resilience of forage stay robust with varied growth potentials under different soil water and salt stress

Water shortage and soil salinization are important factors restricting crop production worldwide. To conduct accurate yield prediction and reasonable crop layout, more attention should be paid to the performances of crop resistance and resilience under water and salt stress and their trade-off relationships. Here, we set different water (full irrigation, W0; moderate deficit irrigation, W1; and severe deficit irrigation, W2) and salt (S0, S1, S2, S3, S4, S5, and S6, representing 0 ‰, 1 ‰, 2 ‰, 3 ‰, 4 ‰, 5 ‰, and 6 ‰ salt in soil) treatments. Together with relevant studies, we analyzed the performances of forage resistance (Rt) and resilience (Rs) and their relationships under varied water and salt stress. The results indicated that logarithmic Rt (lg(Rt), the same as lg(Rs)) and the distribution of lg(Rs) were affected by water and salt stress, however, the relationships of lg(Rs)-lg(Rt) stayed stable with the constant slopes (k) and declined intercepts (m) as stress intensified. The physiological mechanisms and trade-offs for fixed species remained robust while the growth potentials varied under stress, which were closely related to stomatal regulations. Forage with larger |k| was suitable for fully irrigated regions to achieve higher yields, while regions with detrimental water and salt conditions should select cultivars with smaller |k| to ensure production. This study laid the groundwork for the estimation of the perennial forage adaptation and stability, and the method of long-term yield prediction and cultivar management under soil water and salt stress.

Residue and distribution of drip irrigation and spray application of two diamide pesticides in corn and dietary risk assessment for different consumer groups

BACKGROUND

As the use of diamide insecticides on corn continues to increase, there is growing concern about their residue levels on corn and dietary risks to populations. In this study, the distribution, dispersion and transfer efficiency of two diamide insecticides (tetrachlorantraniliprole (TCAP) and cyantraniliprole (CNAP)) in different parts of corn and soil were investigated in a 1-year field trial in Guangzhou and Lanzhou using two different application methods - spray and drip irrigation, respectively - and the dietary risk of the insecticides to different consumer populations was assessed under the two application methods.

RESULTS

The results showed that drip irrigation had a longer persistence period than spraying, and there was a hysteresis in the absorption distribution of the agent in different parts of corn, which was gradually transferred to the leaves after absorption from the roots. The average TE₁ (transfer efficiency) and TE₂ were 0.230-0.261 and 1.749-1.851 for TCAP and 0.168-0.187 and 2.363-2.815 for CNAP, respectively. At corn harvest, both TCAP and CNAP were below detectable levels in soil and corn. For different consumer populations, hazard quotients ranged from 0.001 to 0.066 for TCAP and from 0.003 to 0.568 for CNAP - both well below 100%.

CONCLUSION

This study indicates that TCAP and CNAP applied by spray or drip irrigation are safe for long-term risk of human intake and also provides guidance for the use of both insecticides in agricultural production to control corn pests, especially in arid and semi-arid areas. © 2022 Society of Chemical Industry.

Multiparameter optimization system with DCNN in precision agriculture for advanced irrigation planning and scheduling based on soil moisture estimation

Agriculture is a distinct sector of a country's economy. In recent years, new patterns have evolved in the agricultural industry. In conjunction with sensor scaling down and precision agriculture, the field of remote sensor networks, such as the wireless sensor network (WSN), was developed. Its major purpose is to make horticultural operations simpler to identify, assess, and manage. This paper uses the proposed DCNN to predict soil moisture and plan irrigation for precision agriculture farmers to reduce water consumption used for cultivation and increase production yield by comparing water content during various stages of plant growth and integrating IoT applications into agriculture. It also optimizes the water level for future irrigation decisions to maintain crop growth and water stability. The data must be served and stored in the form of a grid view, according to Apriori and GRU (gated recurrent unit). Using numerous sensor and parameter modelling methodologies, this system assists in the prediction of irrigation planning based on irrigation needs. The predicted parameters include soil moisture, temperature, and humidity. This observed experimental data supports smart irrigation in crop production with a high yield and little water use. DCNN has a 98.5% experimental result accuracy rate and the MSE value is predicted in DCNN 99.25% of the time.

Soil Moisture Sensor Information Enhanced by Statistical Methods in a Reclaimed Water Irrigation Framework

Time series modeling and forecasting play important roles in many practical fields. A good understanding of soil water content and salinity variability and the proper prediction of variations in these variables in response to changes in climate conditions are essential to properly plan water resources and appropriately manage irrigation and fertilization tasks. This paper provides a 48-h forecast of soil water content and salinity in the peculiar context of irrigation with reclaimed water in semi-arid environments. The forecasting was performed based on (i) soil water content and salinity data from 50 cm beneath the soil surface with a time resolution of 15 min, (ii) hourly atmospheric data and (iii) daily irrigation amounts. Exploratory data analysis and data pre-processing phases were performed and then statistical models were constructed for time series forecasting based on the set of available data. The obtained prediction models showed good forecasting accuracy and good interpretability of the results.

Irrigation plays significantly different roles in influencing hydrological processes in two breadbasket regions

Agriculture is a major water user, especially in dry and drought-prone areas that rely on irrigation to support agricultural production. In recent years, the over-extraction of groundwater, exacerbated by climate change, population growth, and intensive agricultural irrigation, has led to a drop in water levels and influenced the hydrological cycle. Understanding changes in hydrological processes is essential for pursuing water sustainability. This study aims to estimate the amount and impact of irrigation on hydrological processes in two breadbasket regions, Jing-Jin-Ji (JJJ), China, and northern Texas (NTX), US. We used the Soil and Water Assessment Tool (SWAT) to explore spatiotemporal variations of irrigation from 2008 to 2013 and compared changes in hydrological processes caused by irrigation. The results indicated that deficit irrigation is more common in JJJ than in NTX and can reduce approximately 50 % of irrigation water use in areas with intensively irrigated cropland. The applied irrigation varies less over time in NTX but fluctuates in JJJ. Compared with NTX, the higher irrigation intensity in JJJ results in a more significant change in downstream peak streamflow of around 6 m³/s. Moreover, the difference in crop growing seasons can lead to different impacts of irrigation on hydrological processes. For example, the percentage change of surface runoff under real-world relative to the no-irrigation scenario was the greatest, around 40 %, in JJJ and NTX. However, the peak change occurred at different times, with the nearing maturity of winter wheat in May in JJJ and corn in August in NTX. The great potential to reduce groundwater extraction by adopting water conservation irrigation techniques calls for policies and regulations to help farmers shift towards more sustainable water management practices.

Multi-objective winter wheat irrigation strategies optimization based on coupling AquaCrop-OSPy and NSGA-III: A case study in Yangling, China

The contradiction between crop water requirements and water supplies in Guanzhong Plain of Northwest China restricts the production of local winter wheat. The optimization of irrigation strategies considering multiple-objectives is of great significance to alleviate water crisis and sustainability of winter wheat production. This paper considered three typical hydrological years (dry year, normal year, and wet year), and a simulation optimization model coupling AquaCrop and NSGA-III was developed using Python language. The multi-objective optimization problem considered four objectives: (1) maximize crop yield (Y), (2) minimize irrigation water (IW), (3) maximize irrigation water productivity (IWP), and (4) maximize water use efficiency (WUE). The TOPSIS-Entropy method was then adopted for decision-making based on the Pareto fronts which were generated by multi-objective optimization, thus facilitating the optimization of the irrigation strategies. The results show that AquaCrop model could accurately simulate the growth process of winter wheat in the study area, the relative error is acceptable. The R² of canopy cover (CC) is 0.75 and 0.61, and above ground biomass production (B) is 0.94 and 0.93, respectively. In the Pareto fronts, the difference between the maximum and minimum yield of winter wheat is 9.48 %, reflecting the diversity of multi-objective optimization results. According to the analysis results of this paper, the performance of different irrigation scenarios in each typical year varies greatly. The performance of the optimization in dry years is significantly better than that in normal years and wet years. The optimization of irrigation strategies and comparison of different scenarios play a positive role in improving the local water use efficiency, the winter wheat yield, as well as the sustainable development level of water resources.

A web-based GIS platform supporting innovative irrigation management techniques at farm-scale for the Mediterranean island of Crete

The aim of this paper is the creation of an integrated and free-access web platform for parcel irrigation water management on a large spatial scale (Water District of Crete, in Greece) in order to: a) accurately determine the irrigation needs of the main crops for Crete such as olives, citrus, avocados and vineyards, b) design strategies, for optimal adaptation of the agricultural sector in the context of climate change, and c) incorporate the dynamic integration of the above information through the creation of a digital platform. In the proposed decision-making system, essential factors are taken into account, such as real-time meteorological data, information about the type and spatial distribution of the agricultural parcels in Crete, algorithms for calculation crop evapotranspiration per development stage and age of the crops, satellite remote sensing techniques in combination with field surveys to depict accurate soil texture map for the whole island of Crete as well as sustainable cultivation practices for saving water per crop and parcel geomorphology. Based on the proposed decision-making system, users will have the opportunity in any specific location/farm in Crete to know the irrigation needs of the crops in real-time and obtain information about proper climate-water adaptation practices. The main novelty points of the proposed platform include the derivation of parcel-level soil texture data from Sentinel-2 satellite imagery and field samples, the comprehensiveness of the irrigation management information, the relatively low data requirements and the application interface simplicity provided to the end-user.

Estimation of regional farmland irrigation water requirements and water balance in Northeast China

Agricultural water use has long accounted for more than 70% of water consumption in Northeast China. Estimating farmland irrigation water requirements and water balance is essential to ensure safe agricultural water and promote rational development and utilization of regional water resources. In this study, based on the modified Penman-Monteith equation recommended by the Food and Agriculture Organization (FAO) and Geographic Information System (GIS) technology, the net crop irrigation water requirements for four main crops in Northeast China were calculated, and the spatiotemporal distribution characteristics were also analyzed. Additionally, regional farmland irrigation water requirements were estimated, water balance in a typical year was determined, and the dominant factors affecting farmland irrigation water requirements in different regions were analyzed. From 1986 to 2020, the net irrigation water requirements for four main crops all showed the temporal trend of no significant increase and the spatial distribution characteristic of being high in the west and low in the east. The farmland irrigation water requirement decreased, and the monthly average farmland irrigation water requirement peaked in July during 2010-2019. Compared with 2010, in 2019, the irrigation water requirement per cultivated land grid cell in 20 cities increased and that in 16 cities decreased. Most cities were facing varying degrees of water shortage. Precipitation had the greatest direct effect on the farmland irrigation water requirement in different regions. These results quantify the farmland irrigation water requirement and water balance in Northeast China, and provide a reference for water resources and related environmental governance.

The interacting effects of irrigation, sowing date and nitrogen on water status, protein and yield in pea (Pisum sativum L.)

Management for agronomic practices might improves growth and grain yield in pea. The main objective of this experiment was to assess the interacting effects of different irrigation regimes, sowing date and nitrogen fertilizer treatments on pea traits. We evaluated three irrigation regimes (50, 75, and 100% of the plant irrigation requirement), two sowing dates (February and March), and nitrogen [application of nitroregn (N1) and without nitrogen as control (N0)] in 2019 and 2020 under field conditions. Chlorphyll content, leaf area index, leaf water potential, grain yield and water productivity were higher in the late sowing (March) than in early sowing (February) treatment. Percentage of vegetation cover in late sowing (60%) was significantly higher than in early sowing (52.7%) treatment. Grain yield in 75% water requirement treatment was not significantly different from yield in full irrigation treatment. Application of nitrogen fertilizer significantly reduced grain yield, grain protein and seeds per pod whilst increased chlorophyll content only. The 100% irrigation requirement treatment showed higher evaporation form the soil in N0 than in 50% and 75% irrigation treatments in late sown pea. Leaf evapotranspiration (ET) was lower in 50% water requirement irrigation regime than in the other irrigation treatments. Water use efficiency (WUE) which was higher in the late than early sowing treatment did not differ between 50% and full irrigation treatments in N0. In conclusion, the results of the current study suggested that application of nitrogen fertilizer did not benefit pea growth and that management of irrigation regime in late sowing might improve grain yield in pea and save irrigation water in regions with limited water availability.

Mitigating the accumulation of arsenic and cadmium in rice grain: A quantitative review of the role of water management

Arsenic exposure through rice consumption is a growing concern. Compared to Continuous Flooding (CF), irrigation practices that dry the soil at least once during the growing season [referred to here as Alternate Wetting and Drying (AWD)] can decrease As accumulation in grain; however, this can simultaneously increase grain Cd to potentially unsafe levels. We modelled grain As and Cd from field studies comparing AWD and CF to identify optimal AWD practices to minimize the accumulation of As and Cd in grain. The severity of soil drying during AWD drying event(s), quantified as soil water potential (SWP), was the main factor leading to a reduction in grain total As and inorganic As, compared to CF. However, lower SWP levels were necessary to decrease grain inorganic As, compared to total As. Therefore, if the goal is to decrease grain inorganic As, the soil needs to be dried further than it would for decreasing total As alone. The main factor driving grain Cd accumulation was when AWD was practiced during the season. Higher grain Cd levels were observed when AWD occurred during the early reproductive stage. Further, higher Cd levels were observed when AWD spanned multiple rice growth stages, compared to one stage. If Cd levels are concerning, the minimum trade-off between total As and Cd accumulation in rice grain occurred when AWD was implemented at a SWP of -47 kPa during one stage other than the early reproductive. While these results are not meant to be comprehensive of all the interactions affecting the As and Cd dynamics in rice systems, they can be used as a first guide for implementing AWD practices with the goal of minimizing the accumulation of As and Cd in rice grain.

Wastewater-derived organic contaminants in fresh produce: Dietary exposure and human health concerns

Irrigation with reclaimed wastewater is a growing practice aimed at conserving freshwater sources, especially in arid and semiarid regions. Despite the apparent advantages to water management, the practice of irrigation with reclaimed wastewater exposes the agroenvironment to contaminants of emerging concern (CECs). In this report, we estimated the unintentional dietary exposure of the Israeli population (2808 participants) to CECs from consumption of produce irrigated with reclaimed wastewater using detailed dietary data obtained from a National Health and Nutrition Survey (Rav Mabat adults; 2014-2016). Human health risk analyses were conducted based on acceptable daily intake (ADI) and threshold of toxicological concern (TTC) approaches. The highest unintentional exposure to wastewater-borne CECs was found to occur through the consumption of leafy vegetables. All analyzed CECs exhibited hazard quotients <1 for the mean- and high-exposure scenarios, indicating no human health concerns. However, for the extreme exposure scenario, the anticonvulsant agents lamotrigine and carbamazepine, and the carbamazepine metabolite epoxide-carbamazepine exhibited the highest exposure levels of 29,100, 27,200, and 19,500 ng/person (70 kg) per day, respectively. These exposure levels exceeded the TTC of lamotrigine and the metabolite epoxide-carbamazepine, and the ADI of carbamazepine, resulting in hazard quotients of 2.8, 1.1, and 1.9, respectively. According to the extreme estimated scenario, consumption of produce irrigated with reclaimed wastewater (leafy vegetables in particular) may pose a threat to human health. Minimizing irrigation of leafy vegetables using reclaimed wastewater and/or improving the quality of the reclaimed wastewater using an advanced treatment would significantly reduce human dietary exposure to CECs.

[Effects of deficit irrigation on seed production performance and water use efficiency of two native plant species in arid areas]

Scientific irrigation is of great significance to plant seed production. With two excellent native plant species in desert steppe, Agropyron mongolicum and Lespedeza potaninii, as the objects, and full irrigation as the control, we explored the effects of deficit irrigation in different growth stages on the seed production and water use efficiency (WUE) of those two species. The results showed that, compared with the control, soil water content of both species decreased under deficit irrigation. The decrease of soil water content of A. mongolicum mainly occurred in the 0-60 cm soil layer, while there was no obvious stratification for the reduction of soil water content of L. potaninii. There were significant differences in the yield components of A. mongolica under deficit irrigation. The seed yield of deficit irrigation at the flowering stage was the highest. There were significant differences in the numbers of fertile tillers, florets and pods of L. potaninii among treatments, but no significant difference in seed yield. There were positive correlations between seed yield of A. mongolicum and the numbers of fertile tillers (r=0.776) and spikelets (r=0.717). The racemes of L. potaninii was significantly negatively correlated with the number of fertile tillers (r=-0.685), and positively correlated with the number of florets (r=0.412). Compared with full irrigation, water consumption of seed production of the two native plant species was reduced under deficit irrigation, but water use efficiency was improved, with the strongest improvement at the flowering stage of A. mongolicum (32.9%) and at the branching stage of L. potaninii (27.4%). Therefore, proper deficit irrigation could improve water use efficiency of both plant species. From the perspective of water use efficiency and seed yield, deficit irrigation could be used for artificial breeding of A. mongolicum and L. potaninii seeds in arid area, with the suitable growth stage for deficit being the flowering and the branching stages, respectively.

Optimizing cropping pattern to improve the performance of irrigation network using system dynamics-Powell algorithm

One of the strategies for agricultural development is the optimal use of irrigation and drainage networks, which leads to higher productivity and economic benefits. In this regard, quantitative and qualitative studies of drainage water from networks are essential for efficient water management. In the present study, we develop a model using a system dynamics approach to simulate the cropping pattern of an irrigation and drainage network as well as the discharge and salinity of drainage water from network farms. We apply the Powell algorithm to optimize the economic profitability of cultivated crops by considering the salinity and discharge of drainage water from the fields. With three aims, i.e., (1) maximizing benefit-cost ratio, (2) minimizing drainage water salinity and discharge of network, and (3) economic and environmental considerations simultaneously, the optimization of cropping pattern within the Kosar irrigation and drainage network is performed. Results based on five consecutive years under different scenarios showed that some crops, such as watermelon, are not economically recommened for production due to high costs, water consumption, and low selling price causes environmental pollution. On the other hand, wheat, grain maize, silage maize, sorghum, and alfalfa have different conditions, and their production is suitable by considering all scenarios. By comparing with experimental data, we find that the proposed model is accurate to simulate and optimize the irrigation network and to detect its cropping pattern.

Deficit irrigation impacts on greenhouse gas emissions under drip-fertigated maize in the Great Plains of Colorado

Precise water and fertilizer application can increase crop water productivity and reduce agricultural contributions to greenhouse gas (GHG) emissions. Regulated deficit irrigation (DI) and drip fertigation control the amount, location, and timing of water and nutrient application. Yet, few studies have measured GHG emissions under these practices, especially for maize (Zea mays L.). The objective was to quantify N₂ O and CO₂ emission from DI and full irrigation (FI) within a drip-fertigated maize system in northeastern Colorado. During two growing seasons of measurement, treatments consisted of mild, moderate, and extreme DI and FI. Deficit irrigation was managed based on growth stage so that full evapotranspiration (ET) was met during the yield-sensitive reproductive stage, but less than full crop ET was applied during the late vegetative and maturation growth stages. In the first year, mild DI (90% ET) reduced N₂ O emissions by 50% compared with FI. In the second year, compared with FI, moderate DI (69-80% ET) reduced N₂ O emissions by 15%, and extreme DI (54-68% ET) reduced N₂ O emissions by 40%. Only extreme DI in the second year significantly reduced CO₂ emissions (by 30%) compared with FI. Mild DI reduced yield-scaled emissions in the first year, but moderate and extreme DI had similar yield-scaled emissions as FI in the second year. The surface drip fertigation resulted in total GHG emissions that were one-tenth of literature-based measurements from sprinkler-irrigated maize systems. This study illustrates the potential of DI and drip fertigation to reduce N₂ O and CO₂ emissions in irrigated cropping systems.

Metabolomics reveals primary response of wheat (Triticum aestivum) to irrigation with oilfield produced water

The reuse of oilfield produced water (PW) for agricultural irrigation has received increased attention for utility in drought-stricken regions. It was recently demonstrated that PW irrigation can affect physiological processes in food crops. However, metabolomic evaluations are important to further discern specific mechanisms of how PW may contribute as a plant-environmental stressor. Herein, the primary metabolic responses of wheat irrigated with PW and matching salinity controls were investigated. Non-targeted gas chromatography mass spectrometry (GC-MS) metabolomics was combined with multivariate analysis and revealed that PW irrigation altered the primary metabolic profiles of both wheat leaf and grain. Over 600 compounds (183 annotated metabolites) were detected that varied between controls (salinity control and tap water) and PW irrigated plants. While some of these changed metabolites are related to salinity stress, over half were found to be unique to PW. The primary metabolites exhibiting changes in abundance in leaf and grain tissues were amines/amino acids, organic acids, and saccharides. Metabolite pathway analysis revealed that amino acid metabolism, sugar metabolism, and nitrogen remobilization are all impacted by PW irrigation, independent of regular plant responses to salinity stress. These data, when combined with prior physiological studies, support a multi-faceted, physio-metabolic response of wheat to the unique stressor imposed by irrigation with PW.

Characterization of soil salinization and its driving factors in a typical irrigation area of Northwest China

Salinization of irrigation areas is a global environmental challenge. The uncertainty in the distribution of salinization is increased by the complexity of the natural environment. This study adopted Yinchuan Plain as a typical irrigation area to study the relationship between soil salinity and the environment from the perspective of macro-environmental elements and micro-ion composition. A Geographic Weighted Regression model (GWR) was used to predict the risk of salinization in the Yinchuan Plain. The results showed obvious spatial variation in soil salinization in the Yinchuan Plain. Farmland accounted for the largest proportion of salinized land area, followed by woodland and "other" land use categories. The main characteristic ions in the salinized area of the Yinchuan Plain were SO₄^2-, K⁺+Na⁺and Cl^-. The rank of ions in terms of change rate with increasing soil salinity was: SO₄^2- > K⁺ + Na⁺ > Cl^- > Ca²⁺ > HCO₃^- > Mg²⁺ > CO₃^2-. However, the rank of ions in terms of their sensitivity to salinization was: HCO₃^- > Ca²⁺ > Mg²⁺ > SO₄^2- > Cl^- > K⁺ + Na⁺. On this basis, the geographical indicators of DEM and NDVI, groundwater indicators of groundwater depth and TDS, climate indicators of SPEI, as well as soil indicators of PH and organic matter were taken as the representative ecological drivers of salinization in irrigation areas. These environmental factors were found to control the distribution of salinization, whereas human activity affected the degree of change in salinization. The enrichment of SO₄^2- in the Yinchuan Plain was mainly related to agricultural activities (such as pesticides application and irrigation evaporation), and followed by phreatic evaporation. The salt ions carried by irrigation and rainfall further polluted phreatic water. In the end, the measures of optimizing drainage, combined irrigation, and improving planting layout were recommended for the effectively and economically controlling of salinization.

Life cycle assessment as decision support tool for water reuse in agriculture irrigation

This study presents a decision support tool that evaluates the environmental efficiency of water reclamation for agricultural irrigation, among other options. The developed tool is published as open source at https://doi.org/10.18167/DVN1/YLP1BA. The objective of this decision support tool is to facilitate the interpretation of the Life Cycle Assessment (LCA) results. This framework was applied to a representative case of reuse of reclaimed water for vine irrigation at the Murviel-Les-Montpellier experimental site (Hérault, France). It was then generalized through modeling assumptions to consider different reuse scenarios. To highlight situations in which the supply of recycled water for irrigation may or may not provide significant environmental benefits, three main parameters were varied: (i) tertiary treatment technologies, (ii) availability of conventional water sources, (iii) energy mix composition. The results show that the environmental impact of reclaimed water depends directly on the type of tertiary treatment technology and the location of the treatment plant in relation to the field and other water sources. The decision support tool has identified where wastewater reuse is clearly an environmentally beneficial source of irrigation among surface and groundwater sources (e.g., WWTP closer to field than river, groundwater too deep, tertiary treatment environmentally beneficial). However, there are many situations where the decision support process cannot distinguish between water reuse for agricultural irrigation and conventional water sources, especially when the nutrient content of treated municipal wastewater is insufficient to offset the negative effects of high energy requirements and chemicals of tertiary treatment.

Urban water as an alternative freshwater resource for matching irrigation demand in the Bengal delta

Rapid changes in climate patterns, population growth, urbanization, and rising economic activities have increased the pressure on the delta's freshwater availability. Bangladesh's coastal planes suffer from a shortage of good quality irrigation water, which is crucial for peri-urban agriculture and at the same time, a high volume of untreated wastewater is discharged into the surface water. This calls for a transition towards efficiently managing and (re)using available urban water resources for irrigation, which is addressed in this paper. A quantitative match between the irrigation demand and potential freshwater supply has been assessed considering different urban water generation scenarios. The FAO AquaCrop model has been used to calculate the irrigation water demand for Boro rice during the dry period. Results indicate that 7.4 million m³ of irrigation water is needed, whereas over 8.2 million m³ of urban water is being generated during the dry season. Simultaneously, mismatches between irrigation demand and alternative water supply mainly occurred in February and March, which could be resolved with water storage capacities. However, to make urban water reuse a reality, the water management policy needs to change to facilitate the construction of required infrastructures for collection, treatment, and storage. The proposed method helps realize the urban water's hidden potential to sustain agricultural activities in the delta areas.

Development of Smart Weighing Lysimeter for Measuring Evapotranspiration and Developing Crop Coefficient for Greenhouse Chrysanthemum

The management of water resources is a priority problem in agriculture, especially in areas with a limited water supply. The determination of crop water requirements and crop coefficient (K_c) of agricultural crops helps to create an appropriate irrigation schedule for the effective management of irrigation water. A portable smart weighing lysimeter (1000 × 1000 mm and 600 mm depth) was developed at CPCT, IARI, New Delhi for real-time measurement of Crop Coefficient (K_c) and water requirement of chrysanthemum crop and bulk data storage. The paper discusses the assembly, structural and operational design of the portable smart weighting lysimeter. The performance characteristics of the developed lysimeter were evaluated under different load conditions. The K_c values of the chrysanthemum crop obtained from the lysimeter installed inside the greenhouse were K_c ini. 0.43 and 0.38, K_c mid-1.27 and 1.25, and K_c end-0.67 and 0.59 for the years 2019-2020 and 2020-2021, respectively, which apprehensively corroborated with the FAO 56 paper for determination of crop coefficient. The K_c values decreased progressively at the late-season stage because of the maturity and aging of the leaves. The lysimeter's edge temperature was somewhat higher, whereas the center temperature closely matched the field temperature. The temperature difference between the center and the edge increased as the ambient temperature rose. The developed smart lysimeter system has unique applications due to its real-time measurement, portable attribute, and ability to produce accurate results for determining crop water use and crop coefficient for greenhouse chrysanthemum crops.

A comprehensive method to increase yield and narrow the yield gap of winter wheat for sustainable intensification

BACKGROUND

The agricultural production system is facing increasing demand pressure and environmental pressure. Green and efficient production methods are urgently needed in order to further enhance the yield of winter wheat and reduce the negative impact on the environment. Here, we analyzed the potential yield and yield gap of winter wheat in Shandong Province of China from 1981 to 2009. Meanwhile, we specified the effects of sowing time, irrigation and fertilization scheme, and variety characteristics on winter wheat.

RESULTS

In the past 29 years, the yield gap in most areas of Shandong has become smaller, because the actual yield has increased and the potential yield has changed little under the background of climate change. In addition, it is found that delaying sowing date is beneficial to increase yield by helping winter wheat avoid adverse climate conditions. Also, an irrigation amount of 240 mm and nitrogen application amount of 180-210 kg ha^-1 are best to maintain high yield, high resource utilization rate and low environmental pollution in this area. These suggested levels are lower than those currently used by many local farmers. Wheat varieties with longer grain-filling period and photoperiod response, higher grain-filling rate and grain weight were more adaptable to climate change.

CONCLUSION

Improving agronomic management measures can significantly increase the yield of winter wheat and narrow the yield gap. This study can provide valuable information for improving the production potential of winter wheat, and for reducing the damage of agricultural activities to the environment. © 2022 Society of Chemical Industry.

Moisture movement, soil salt migration, and nitrogen transformation under different irrigation conditions: Field experimental research

Irrigation and fertilizer application can lead to significant changes in groundwater quality. In this study, a field irrigation experiment was carried out from April 9 to 23, 2021 under irrigation and fertigation conditions to understand the mechanisms of moisture movement, soil salt migration, and nitrogen transformation in the soil profile. Continuous in-situ monitoring and sampling of soil and irrigation water, as well as stable isotopes, chemical parameters, and soluble salt analyses, were performed in this research. The results showed that the time cost by the irrigation water in the vadose zone was about 5 h. The infiltrated irrigation water was accompanied by high concentrations of soluble salts, leached from the soil layers of 20-80 cm and 100-150 cm, which is associated with the leaching of Na⁺, Cl^-, SO₄^2-, and Ca²⁺ and the dissolution of minerals such as gypsum and halite. Furthermore, the variations in nitrogen concentrations (NH₄⁺ and NO₃^-) in the soil profile suggested that fertilizer application was the main source of NO₃^- in the soil and groundwater, while irrigation was the biggest driving force for nitrogen transport and transformation in soil. The application of urea fertilizer can increase the content of ammonium nitrogen at the soil layer of 0-80 cm. This nitrogen form can be subsequently transformed to nitrate nitrogen during the water transport to the groundwater. The current study provides a strong scientific basis for the protection and management of groundwater and soil quality in agricultural areas.

Quantification of human adenovirus in irrigation water-soil-crop continuum: are consumers of wastewater-irrigated vegetables at risk?

Because of health concerns regarding the presence of enteric viruses in wastewater effluents, this study was designed to investigate the occurrence of human adenovirus (HAdV) in the irrigation water-soil-crop continuum. Viral particles were extracted from wastewater and wastewater- or water-irrigated soil and crop samples and analyzed using real-time PCR. Concentration of fecal indicator bacteria (FIB) were also determined. Quantitative microbial risk assessment was performed to determine the HAdV illness risk associated with the consumption of wastewater-irrigated vegetables. HAdV-F was detected in 74% of wastewater effluent samples with a mean concentration of 38 Genomic Copy (GC)/mL. HAdV was also detected in wastewater-irrigated soil (2 × 102 GC/g) and crop (< 10 GC/g) samples, with no statistically significant difference in concentrations between wastewater- and freshwater-irrigated samples. The results showed no correlation between concentrations of FIB and HAdV in the analyzed samples. Mean probability of illness risk from consumption of wastewater-irrigated vegetables was 4 × 10-1 per person per year (pppy) which was about two orders of magnitude higher than the proposed value by WHO (10-3 pppy) for safe reuse of wastewater. This finding suggests that the wastewater reuse for irrigation of vegetables eaten raw could pose a threat to human health with respect to the risk of viral illness, signifying stricter management of wastewater reuse. However, because of uncertainties in the QMRA model, particularly the ratio of infectious to non-infectious virus particles, more data is required to validate the predicted risk. This information is especially important in arid and semi-arid regions where high temperatures, UV radiation intensity, and desiccation can efficiently inactivate microorganisms in the environment.

Reclaimed water reuse system on water quality, growth of irrigated crops, and impact of ecology: case study in Taiwan

In rapidly urbanized regions, the development of sustainable and resilient urban agriculture is essential to reduce environmental pollution and ensure reusable resources. The purpose of this study was to design, implement, and analyze the effects of reclaimed water reuse systems on crop growth, water purification, and ecology. A simulated experimental field near the side of Li Tse Lake at MingDao University in Changhua County, Taiwan, was chosen as the research field. A reclaimed water reuse system was established to collect domestic sewage discharged from the student dormitory, and a soil filter bed and plants in the system were used to purify the sewage, so as to detect its effects on water quality, soil, plant growth, and ecology throughout the year. According to the results, the water purified by the reclaimed water reuse system met the agricultural irrigation water quality criteria. While the soil filter bed showed that the purified water was alkaline and had low electrical conductivity, this did not affect plant growth. In the reclaimed water reuse system, the cultivation of fruiting and leafy vegetables increased the habitats of a number of organisms, and a total of 49 families of arthropods in 13 orders were found. This study showed that the reclaimed water reuse system could not only purify water and promote water reuse but also improve the ecology and develop the potential for food production.

Optimization of water and land allocation in salinity and deficit- irrigation conditions at farm level in Qazvin plain

Improper extraction of water from resources especially in arid and semi-arid regions leads to a decrease in the quality of water and soil resources. In such areas, management activities such as increasing water productivity in agricultural sector would be a key step towards sustainable development. Therefore, water resources management to improve the allocation of limited water supplies is essential. In this study, a non-linear programming optimization model have been combined with a AquaCrop model to determine the optimal water and land allocation considering the quality issues of both water and soil resources with focusing on enhancing agriculture water productivity. For this purpose, the spatial variations of chemical and physical properties of soil in the Qazvin plain were taken into account. The soil of study site was divided into three salinity classes, and three weather conditions were identified by Standardized Precipitation Index (SPI). Moreover, five irrigation strategies were modeled under each weather condition. To understand the response of major crops under cultivation to water and salinity, the AquaCrop model was calibrated and validated (2005–2020) and utilized in the objective function. Accordingly, the production functions of the different products were obtained, and the cultivation area as well as amount of water consumption of the crops were optimized by using the target functions of maximum net income and maximum water use efficiency. The results showed that the model is capable of simulating crop yield in salinity and water deficit conditions. The coefficient of determination (R²) for barley, wheat and maize was equal to 0.86, 0.92, and 0.96, respectively. Findings reveal that total irrigation water could be reduced by 20% on average without profit reduction when compared to the profit of the present situation. Total economic profit could be increased by 18% on average through the optimization of water allocation and cropping pattern with the same water supply amount as that of the current situation. Also, the water productivity increased between 12 to 30% under these conditions. Therefore, the proposed model can efficiently optimize the amount of irrigation water and cultivation area on a regional scale considering salinity conditions.

Risk regulation of water allocation in irrigation areas under changing water supply and demand conditions

The uncertainty of the hydrological environment and unbalanced water resource allocation result in a high risk of irrigation water shortages in regional agriculture, which seriously affects the sustainable development of agricultural systems. In this paper, we propose a risk regulation based modeling approach for the optimal allocation of agricultural water resources in a complex stochastic environment. The approach includes a conditional value-at-risk (CVaR) model, two-stage stochastic programming (TSP) model, two-dimensional joint distribution probability (JP) model, fractal criteria, and a multiple forms of chance-constrained programming (CCP) model. The model can weigh the contradiction between the intended target and associated penalties attributed to unknown hydrological events, measure the risk between system benefits and expected losses in agricultural water allocation at different confidence levels, and address the randomness in the objective function and constraints (including the left end term, right end term, and left and right end terms). To verify the applicability of the method, it is applied to the Jinxi Irrigation District in China to optimize the allocation and risk regulation of limited water resources under the variable runoff conditions of the Songhua River and crop water demands in the irrigation area. By adjusting parameters such as risk preference and probability of violation, the risk of water shortages in the irrigation area can be regulated, and the multidimensional impacts of different water allocation schemes on agricultural economic benefits, social benefits, ecology and environment can be determined. The case study reveals that the CTSP-CCJP method is sensitive, applicable to complex and uncertain environments and important for the efficient use of agricultural water resources and risk reduction.

Assessment of heavy metals accumulation in agricultural soil, vegetables and associated health risks

Industrialization plays a vital role in the development of a country's economy. However, it also adversely affects the environment by discharging various unwanted and harmful substances such as heavy metals into the surface and subsurface aquifers. The current research work investigates the identification, characterization, and evaluation of specific heavy metals in industrial wastewater (IWW) and different composite samples of soil and vegetables (onion, pumpkin, lady finger, and green pepper) collected from selected agricultural fields irrigated with canals fed IWW in Mingora city of Swat (Pakistan). Obtained results were compared with the tube well water irrigated soil and vegetables grown in it. Heavy metals accumulation was tested through wet digestion method and atomic absorption spectrophotometry (AAS). The metal transfer factor (MTF) of heavy metals from soil to vegetables was also determined along with the health index (HI) to assess the potential health risk of the metals towards consumers using Monte Carlo simulation technique. Analysis of water samples showed that the concentration in mg l-1 of heavy metals in IWW follows the trend Fe (6.72) > Cr (0.537) > Pb (0.393) > Co (0.204) > Mn (0.125) > Ni (0.121). Analysis of the soil samples irrigated with IWW followed the order of Fe (47.27) > Pb (2.92) > Cr (2.90) >Ni (1.02) > Mn (0.90) > Co (0.68) and Fe (17.12) > Pb (2.12) > Cr (2.03) >Ni (0.76) > Co (0.49) > Mn (0.23) irrigated with TWW. Heavy metals concentration values found in soil irrigated with IWW were higher than the soil irrigated with TWW. Similar trends were found for agricultural produces grown on soil irrigated with IWW and found higher than the normal allowable WHO limits, indicating higher possibilities of health risks if continuously consumed. MTF values were found higher than 1 for ladyfinger and green pepper for Pb intake and pumpkin for Mn intake. The current study suggests the continuous monitoring of soil, irrigation water and agricultural products to prevent heavy metals concentration beyond allowable limits, in the food chain. Thus, concrete preventive measures must be taken to reduce heavy metal accumulation through wastewater irrigation to protect both human and animal health in the study area of Mingora Swat Pakistan.

Non-target and suspect-screening analyses of hydroponic soybeans and passive samplers exposed to different watershed irrigation sources

Water scarcity increases the likelihood of irrigating food crops with municipal wastewater that may pose potential dietary risks of regulated and non-regulated organic chemical uptake to edible plant tissues. Only a few studies have used high resolution mass spectrometry (HRMS) to assess the uptake of chemicals of concern into food crops. This study used non-target and suspect-screening analyses to compare total chemical features, tentatively identified chemicals (TICs), and EPA ToxCast chemicals in soybean plants and passive samplers exposed to five different irrigation sources that were collected from an agricultural watershed during mild drought conditions. Secondary-treated municipal wastewater effluent, two surface waters, two ground waters, and deionized municipal tap water were used for two hydroponic experiments: soybean roots and shoots and Composite Integrative Passive Samplers (CIPS) harvested after fourteen days of exposure and soybeans after fifty-six days. CIPS were sealed in separate glass amber jars to evaluate their efficacy to mimic chemical features, TICs, and ToxCast chemical uptake in plant roots, shoots, and beans. Total soybean biomass and water use were greatest for tap water, municipal wastewater, and surface water downstream of the municipal wastewater facility relative to groundwater samples and surface water collected upstream of the wastewater facility. ToxCast chemicals were ubiquitous across watershed irrigation sources in abundance, chemical use category, and number. Wastewater-exposed soybeans had the fewest extractable TICs in plant tissues of all irrigation sources. More ToxCast chemicals were identified in CIPS than extracted from irrigation sources by solid phase extraction. ToxCast chemicals in beans and CIPS were similar in number, chemical use category, and log Kow range. CIPS appear to serve as a useful surrogate for ToxCast chemical uptake in beans, the edible food product.

A fixed-mix stochastic fractional programming method for optimizing agricultural irrigation and hydropower generation in Central Asia

In this study, a fixed-mix stochastic fractional programming (FSFP) method is developed for balancing the water-allocation conflict between upstream hydropower generation and downstream agricultural irrigation. FSFP has advantages in dealing with ratio-objective problem under uncertainty, reflecting the dynamic and stochastic characteristics over a long-term planning context, as well as analyzing interrelationships between system efficiency and violation risk of water-allocation target. Then, FSFP is firstly applied to Tuyamuyun reservoir in the lower reach of Amu Darya River basin (Central Asia), where multiple scenarios based on different hydropower-generation targets and inflow levels are examined for identifying the complex relationship between hydropower generation and crop irrigation. Major findings and managerial insights can be summarized as: (i) with the reduction of reservoir inflow, water allocation for downstream agricultural irrigation would decrease by 30.4% once the minimum demand is satisfied, and hydropower generation should be higher priority for pursuing higher marginal benefit; (ii) with the shrinking water supply and rising hydropower-generation target, cotton planting should be firstly restrained due to its high water demand and grape planting is encouraged; (iii) under extreme water scarcity (i.e., low and very-low inflow levels), low-level hydropower generation target (i.e., α = 0.45) is desired for meeting the food requirement in the study basin; (iv) for alleviating the water shortage during dry seasons, it is recommended that water storage should be conducted in autumn and winter, and water release for crop irrigation should be implemented during spring and summer. These findings can help managers identify sustainable water-allocation schemes for agricultural irrigation and hydropower generation against water shortage, environmental destruction and energy insecurity in arid regions.

Irrigation and phosphorous fertilization management to minimize rice grain arsenic content

This research sought to minimize inorganic arsenic levels in polished rice grain by using different irrigation and phosphorous fertilization practices while also maintaining crop yield and water productivity. Two experiments were conducted during seasons 2018-2019 and 2019-2020 using a split-plot design with three blocks, five irrigation treatments (main-plots) and two phosphorous levels (sub-plots). Irrigation treatments consisted of a traditional continuous flood (CF) control and four alternatives irrigation techniques with one or two drying events during the irrigation cycle. The phosphorous fertilization levels investigated were an unfertilized control (0 kg P₂O₅ ha^-1) and the recommended fertilization level of 50 kg P₂O₅ ha^-1. Soil pH and redox potentials were measured in each treatment. Strategically-timed, low severity drying events were effective at achieving aerobic soil conditions, resulting in Eh values over 50 mV. The alternative irrigation treatment with two drying events, implemented at panicle initiation and full flowering, was the most effective in reducing inorganic arsenic in grain without affecting grain yield or the amount of irrigation water applied. This irrigation technique could be considered as an alternative management to the traditional continuous flooded to reach minimal inorganic arsenic accumulation in grain in order to attend special quality standards or specific market requirements. Accumulated inorganic arsenic in grain was below international maximum levels in all analyzed samples, with an average value of 0.084 mg kg^-1.

Fate of contaminants of emerging concern in the reclaimed wastewater-soil-plant continuum

Reclaimed wastewater irrigation, a common agricultural practice in water-scarce regions, chronically exposes the agricultural environment to a wide range of contaminants of emerging concern (CECs) including pharmaceuticals and personal care products. Here we provide new data and insights into the processes governing the translocation of CECs in the irrigation water-soil-plant continuum based on a comprehensive dataset from 445 commercial fields irrigated with reclaimed wastewater. We report on CEC exposures in irrigation water, soils, and edible produce (leafy greens, carrots, potatoes, bananas, tomatoes, avocados, and citrus fruits). Our data show that CEC concentrations in irrigation water and their physiochemical properties (mainly charge and lipophilicity) are the main factors governing their translocation and accumulation in the soil-plant continuum. CECs exhibiting the highest detection frequency in plants (lamotrigine, venlafaxine, and carbamazepine) showed a reduction in their leaf accumulation factor with increasing soil organic matter content. The higher soil organic matter likely reduced the available CEC concentration in the soil solution due to soil-CEC interactions, leading to reduced uptake. Interestingly, the concentration of carbamazepine in the leaves showed a saturation-like trend when plotted against its concentration in the soils. This probably resulted from steady-state conditions when uptake equals in-planta decomposition. Our data indicate that due to continuous reclaimed wastewater irrigation, the soil acts as a sink for CECs. CECs in the soil reservoir can be desorbed into the soil solution during the rainy season and be taken up by rain-fed crops.

Effect of long-term saline mulched drip irrigation on soil-groundwater environment in arid Northwest China

Water shortage and soil salinization are the two main factors that are limiting the sustainability of agriculture in arid and semi-arid areas. The mulched drip irrigation (MDI) with brackish groundwater is widely used in the arid areas of Northwest China. In this study, field experiments were carried out to study the effect of long-term MDI with brackish groundwater on the soil and groundwater environment. It was found that the groundwater level decreased in the Peacock river watershed steadily from 2008 to 2019, resulted from escalating groundwater exploitation due to the expanding agricultural irrigation area and increasing irrigation water demand. The decline of groundwater level reduced the evaporation of phreatic surface (ET_g) and groundwater recharge from MDI (R_g). The ET_g and R_g would be very small, where ET_g tended to be zero and R_g would decrease to a constant value, while the water table depth was larger than 3 m. In addition, MDI had little effect on the soil moisture content (SMC) during the MDI period while the groundwater level was shallow (less than 1.9 m), and it increased SMC gradually as the cycle of irrigations increased while the groundwater level was deep (greater than 4.2 m). MDI reduced the concentration of soluble salt ions (Na⁺, K⁺ and Cl^-) and increased the concentration of Ca²⁺ and SO₄^2- in the soil. The accumulation of Ca²⁺ and SO₄^2- in bare soil was more serious than that in the mulched land. The SMC, soil ions concentrations, soil salinity and the total dissolved solids of groundwater decreased significantly with the decrease of the groundwater level, and the salinization degree of the soil and groundwater tended to be weak in the field experimental site. However, groundwater level dropped too much caused by increasing agricultural irrigation would be harmful to the sustainable ecological environment.

Sustainable agricultural water management incorporating inexact programming and salinization-related grey water footprint

In arid and semi-arid regions, improper irrigation activities not only exacerbate water shortages, but also lead to environmental pollution such as soil salinization that hinders crop growth and agricultural sustainability. There has been a lack of agricultural water management tools that could support agricultural water management with salinization-related grey water footprints being considered and associated uncertainties being addressed. In this study, salinization-related grey water footprints were measured through accounting for relationships among irrigation, soil salinity, evapotranspiration and crop yield, and then incorporated into an agricultural water management model for supporting environmentally sound irrigation decisions. Such an agricultural water management model was also characterized by a newly proposed generalized fuzzy interval fractional programming (GFIFP) method that could address ratio problems of two objectives and dual uncertainties. The developed methodology coupling the GFIFP method and grey water footprints was applied to an irrigation region in northwestern China where water scarcity and soil salinization hindered local development. Five credibility levels corresponding to decision makers' varied satisfactory degrees over water availability, and nine weight coefficients of possibility and necessity measures were considered. Results showed that, in order to reduce negative environmental impacts while increasing economic benefits, more irrigation water should be allocated to wheat and sunflower rather than corn. When the credibility level is 0.5 and weight coefficient is 0.9, the system efficiency would be the highest. Compared to the benchmark year of 2018, this scenario would generate [0.330, 6.647] billion yuan more benefits and [16.0, 133.9] million m³ less grey water footprints. Compared to three conventional approaches, GFIFP could provide decisions with more flexibility and less environmental impacts. The developed approach could also be applied to agricultural water management problems in other areas aiming at reducing grey water footprints and enhancing environmental benefits under uncertainty.

Water resource use and driving forces analysis for crop production in China coupling irrigation and water footprint paradigms

The crop water relationship quantification is conducive to decision-making for regional food safety and resource conservation. However, irrigation water and crop water footprint (CWF) was observed separately in previous studies, which leads to incomplete evaluation of water resource occupation in agricultural system. The crop water resource use (WRU), combining WF and irrigation water accounting, in 31 provinces of China from 1999 to 2018 was estimated in current paper. The driving forces of WRU were analyzed using the logarithmic mean divisia index (LMDI) model, based on its spatial and temporal patterns demonstration. The results showed that national WRU increased from 1051.6 Gm³ in 1999 to 1676.4 Gm³ in 2018, with an average annual growth rate of 2.48%. The provinces with high WRU were mainly distributed in North China and Northeast China. Hebei, Shandong, and Henan jointly contributed 28.9% of the national WRU. In addition, economic level was the largest contributor to promote the growth of WRU, and water use intensity was the most important contributor to inhibit the growth of WRU. Economic level, resource endowment, and population size had a promoting effect on WRU in Northeast, Northwest, North China, and Southeast provinces, while water use intensity, irrigation technique, and urbanization degree showed inhibitory effect in Northeast, Northwest, and Southwest provinces. It is meaningful to combine water footprint and irrigation water use for agricultural water management and conservation. The arid North China Plain should adopt water-saving irrigation and rainwater recycling technologies to control WRU, and the Northeast granary should reduce WRU by strengthening water pollution prevention and improving water resources scheduling to ensure food security and sustainable use of water resources.

Accumulation and human health risk assessment of nitrate in vegetables irrigated with different irrigation water sources- transfer evaluation of nitrate from soil to vegetables

The present study aimed to investigate the rate of accumulation, human health risk assessment, and nitrate-related transfer factor in vegetables irrigated with different sources, including treated wastewater effluent (TWE) of Kermanshah wastewater treatment plant, Gharasoo river water (RW) of Kermanshah, and well water with chemical fertilizer (WWF). For this purpose, three different types of vegetables, including basil, coriander, and radish, was cultivated, and each of them was irrigated by the three irrigation sources mentioned above. Finally, the amount of nitrate in different sources of irrigation, soil (before growing vegetables and after harvesting vegetables), and the mentioned vegetables was measured. Based on the study results, it can be concluded that the water of the Gharasoo River (RW), compared to the other two irrigation sources, causes more nitrate accumulation in the soil and vegetables grown in it. The highest transmission factor was related to basil vegetables irrigated with WWF. The results showed that the average daily intake of nitrate through the consumption of vegetables grown in Kermanshah with any irrigation water is less than the allowable amount, so the consumption of such vegetables is not dangerous to consumers' health. Therefore, it is suggested that the best irrigation source for vegetable cultivation in Kermanshah is TWE, provided that all of its physical, chemical and microbial parameters meet the standards for reuse in agriculture irrigation. Thus, the use of treated wastewater reduces the need for farmers to use chemical and organic fertilizers and cost-effectiveness, high frequency, and high availability.

Effects of diverse irrigation with wastewater in soil and plants: assessing the risk of metal to the animal food chain

In District Jhang, farmers use municipal wastewater to irrigate fodder crops as an alternative source to the deficient availability of fresh water. Therefore, the present study selected the three irrigation sources in District Jhang (canal water, ground water and municipal wastewater) to study the iron (Fe) concentration in the soil, fodder crops and ultimately their transfer into the animal body. Analysed Fe concentration varied as 16.40-27.53 mg/kg in soil samples, 19.72-30.34 mg/kg in fodder crops and 2.49-5.11 mg/kg in animals. Analysed Fe concentration in soil was higher on the wastewater irrigation site while canal water-irrigated fodder crop Zea mays exhibit the higher Fe concentration. In animal samples, higher Fe concentration was observed in the cow blood (4.09 mg/l), cow hairs (3.39 mg/kg) and cow faeces (5.11 mg/kg). Results of pollution load index (0.288-0.484 mg/kg) and enrichment factor (0.112-0.197 mg/kg) indicated that Fe concentration was minimally dispersed and enriched in these sites. Health risk and daily intake values were observed between the 0.029-0.059 and 0.042-0.084 mg/kg/day. Bio-concentration factor (0.834-1.47 mg/kg) for Fe which was greater than 1 explains that Fe contamination was transferred from the soil to fodder tissues and may raise health issues in the grazing animals if they are continuously exposed to these contaminated forages. Wastewater irrigation in study area has increased the Fe content in soil-plant environment that is a risking factor for animal and human health. Hence, this study recommended that wastewater should be treated prior to their irrigation on agricultural lands.

[Effects of brackish water irrigation on grain quality characteristics and yield of winter wheat]

Brackish water resource is widely distributed in the North China Plain, which has not been effectively utilized. Using brackish water for irrigation can alleviate water resource conflict in the well-irrigated area and solve the problem of groundwater over-exploitation of the North China Plain. A long-term experiment (since 2006) was conducted to investigate the effects of brackish water irrigation on the quality and yield of winter wheat in the North China Plain. There were five salinity degrees of irrigation water, i.e. 1, 2, 4, 6, and 8 g·L^-1, respectively. The results showed that higher salinity degree of irrigation water (4-8 g·L^-1) significantly increased water absorption, development time, sedimentation, wet gluten content, and protein content, but decreased the stabilization time, flour yield, and gluten index. There was no significant difference between the treatments of 1 g·L^-1 and 2 g·L^-1 on grain yield and yield components, but the treatment of 2 g·L^-1 significantly improved grain quality, including water absorption, development time, sedimentation, wet gluten, and protein content. Higher salinity degree of irrigation water (4-8 g·L^-1) treatments significantly decreased spike number (44.0%-60.7%) and grain yield (35.6%-64.7%), compared with 1 g·L^-1 treatment. Results of principal component analysis showed that 2 g·L^-1 treatment had the best overall effect with no significant decrease in grain yield and quality of grain. This study could provide theoretical basis and technical support for use of brackish water in the North China Plain.

[Effects of saline-water furrow irrigation on the stability of soil water-stable aggregates in cotton field]

It is of great importance to explore the effects of saline-water furrow irrigation on soil water-stable aggregates for safe and efficient utilization of saline water resources. We conducted a long-term cotton experiment with six levels of saline-water furrow irrigation (1, 2, 4, 6, 8, 10 g·L^-1) since 2006 and analyzed the variations of soil salinity and water-stable aggregates in the 10th and 15th years under saline irrigation. The results showed that soil salinity in the 0-30 cm layer at the ditch increased with increasing salinity level of irrigation water. There were significant differences between the 6, 8, 10 g·L^-1 and 1 g·L^-1 treatments. Soil salinity in each treatment increased gradually with increasing soil depth. Saline-water furrow irrigation tended to reduce the stability of soil water-stable aggregates. When the salinity level of the irrigation water was ≥6 g·L^-1, the mass fraction of macroaggregates (&gt;0.25 mm), the mean weight diameter and geometric mean diameter of water-stable aggregates significantly decreased. In contrast, the fractal dimension and mean weight specific surface area increased significantly. The stability of soil water-stable aggregates decreased with soil depth in all treatments. Under the condition of saline-water furrow irrigation for several years, there was no accumulation of soil salinity and instability of water-stable aggregates in the 0-30 cm soil layer at the ditch with each passing year. With the irrigation scheduling of this study, saline-water furrow irrigation with salinity ≤4 g·L^-1 did not affect soil salinity and water-stable aggregate stability of cotton field in this area.

Growth and productivity assessments of peanut under different irrigation water management practices using CSM-CROPGRO-Peanut model in Eastern Mediterranean of Turkey

Irrigation water scheduling is crucial to make the most efficient use of ever-decreasing water. As excessive irrigation decreases yield, while imprecise application also causes various environmental issues. Therefore, efficient management of irrigation frequency and irrigation level is necessary to sustain productivity under limited water conditions. The objective of the current study is to assess the water productivity at various irrigation regimes during peanut crop growing seasons (2014 and 2015) in Eastern Mediterranean, Turkey. The field experiments were conducted with treatments consisting of three irrigation frequencies (IF) (IF₁: 25 mm; IF₂: 50 mm; and IF₃: 75 mm of cumulative pan evaporation (CPE)), and four irrigation water levels (WL₁ = 0.50, WL₂ = 0.75, WL₃ = 1.0, and WL₄ = 1.25). WL₁, WL₂, WL₃, and WL₄ treatments received 50, 75, 100, and 125 of cumulative pan evaporation. The CSM-CROPGRO-Peanut model was calibrated with experimental data in 2014 and evaluated with second-year experimental data (2015). The model simulated seed yield and final biomass (dry matter) reasonably well with low normalized root mean square error (RMSE_n) in various irrigation intervals. The model simulated reasonably well for days to anthesis (RMSE = 2.53, d-stat = 0.96, and r² = 0.90), days to physiological maturity (RMSE = 2.55), seed yield (RMSE = 1504), and tops biomass dry weight at maturity (RMSE = 3716). Simulation results indicated good agreement between measured and simulated soil water content (SWC) with low RMSE_n values (4.0 to 16.8% in 2014 and 4.3 to 18.2% in 2015). Further results showed that IF₂I₁₂₅ irrigation regime produced the highest seed yield. Generally, model evaluation performed reasonably well for all studied parameters with both years' experimental data. Results also showed that the crop model would be a precision agriculture tool for the extrapolation of the allocation of irrigation water resources and decision management under current and future climate.

The effects of reclaimed water irrigation on the soil characteristics and microbial populations of plant rhizosphere

In this paper, the effects of irrigation with different water qualities on the soil characteristics of 8 kinds of garden plants were analyzed. The results showed that soil pH (ranging at 7.76-8.73) had no significant difference in different soils compared with the contrast treatment. Under the reclaimed water irrigation, the content of soil total salinity, chloride ions, and water soluble sodium in soil of most plants was averagely 160.3%, 83.3%, and 67.5% higher than that of tap water, respectively. The influences of reclaimed water irrigation on soil nutrients were changed with the types of plants. The content of soil organic matter and the available potassium showed no significant differences in most plants. Compared with the tap water irrigation, the content of alkaline nitrogen in 5 plants increased (averagely 25.8%) after 5-year irrigation with reclaimed water. In terms of soil microorganism, the increase of soil microbial population, including bacteria, fungus and actinomycetes, has been promoted by different levels of reclaimed water irrigation, which is closely related with soil nutrients.

Soil Water Content Prediction Using Electrical Resistivity Tomography (ERT) in Mediterranean Tree Orchard Soils

Water scarcity in arid and semiarid regions poses problems for agricultural systems, awakening special interest in the development of deficit irrigation strategies to improve water conservation. Toward this purpose, farmers and technicians must monitor soil water and soluble nutrient contents in real time using simple, rapid and economical techniques through time and space. Thus, this study aimed to achieve the following: (i) create a model that predicts water and soluble nutrient contents in soil profiles using electrical resistivity tomography (ERT); and (ii) apply the model to different woody crops under different irrigation regimes (full irrigation and regulated deficit irrigation (RDI)) to assess the efficiency of the model. Simple nonlinear regression analysis was carried out on water content and on different ion contents using electrical resistivity data as the dependent variable. A predictive model for soil water content was calibrated and validated with the datasets based on exponential decay of a three-parameter equation. Nonetheless, no accurate model was achieved to predict any soluble nutrient. Electrical resistivity images were replaced by soil water images after application of the predictive model for all studied crops. They showed that under RDI situations, soil profiles became drier at depth while plant roots seemed to uptake more water, contributing to reductions in soil water content by the creation of desiccation bulbs. Therefore, the use of ERT combined with application of the validated predictive model could be a sustainable strategy to monitor soil water evolution in soil profiles under irrigated fields, facilitating land irrigation management.

Deficit drip irrigation based on crop evapotranspiration and precipitation forecast improves water- use efficiency and grain yield of summer maize

BACKGROUND

Limited and erratic precipitation with inefficient irrigation scheduling often leads to an unstable crop yield and low water-use efficiency (WUE) in semi-arid and semi-humid regions. A 2-year field experiment was conducted to evaluate the effect of three irrigation strategies (conventional irrigation (CK), full-drip irrigation (FI), based on crop evapotranspiration and precipitation forecast, and deficit drip irrigation (DI) (75% FI)) on photosynthetic characteristics, leaf-to-air temperature difference (∆T), grain yield, and the WUE of summer maize.

RESULTS

The results showed that the daily average net photosynthetic rate (Pn) of DI and FI increased by 25.4% and 25.8% at jointing stage in 2018, and 26.3% and 26.5% at grain-filling stage in 2019 compared with CK, respectively. At jointing stage in 2018 and grain-filling stage in 2019, the transpiration rate (Tr) of DI was significantly lower than that of FI (P < 0.05) but there was insignificant difference in Pn value (P > 0.05). The ∆T between 12:00-14:00 of DI and FI was significantly lower than that of CK at jointing stage in 2018 and grain-filling stage in 2019 (P < 0.05). The 2-year average grain yields of DI and FI were 11.4 and 11.5 t ha^-1 , which increased by 32.4% and 32.8% compared with CK, respectively. The WUE of DI was 2.82 kg m^-3 , which was 17.9% and 33.8% higher than that of FI and CK, respectively.

CONCLUSION

Deficit drip irrigation based on crop evapotranspiration and precipitation forecast improves crop WUE and maintains high grain yields in semi-arid and semi-humid regions. © 2021 Society of Chemical Industry.

Exploration of water-nitrogen coupling effects in paddy field based on ORYZA (v3) model

BACKGROUND

Nitrogen and water are two major factors in rice production. Due to the lack of ample evidence and much uncertainty in field experiments, the coupling effects of water and nitrogen in paddy fields have remained debatable over recent years.

RESULTS

A fine-calibrated ORYZA (v3) model was applied to simulate rice growth and development under different nitrogen (N) rates and irrigation regimes for a double rice-cropping system in South China. We designed a numerical experiment of 504 treatments, consisting of seven nitrogen rates (0-300 kg ha^-1 ), eight irrigation thresholds (30-100%, presented as the percentage of saturated soil water content) and nine irrigation quotas (20-100 mm), and each treatment was simulated for 30 years. Yield varied greatly with different water-nitrogen conditions, particularly in the scenario of frequently alternate wetting and drying irrigation and low-N rates. The coupling effects had a negligible influence on water input and water loss, which were found to be sensitive only to the irrigation regime and rainfall distribution. Based on the results, the N fertilizer for early rice growing in the wet season is suggested as 150-200 kg ha^-1 , and 200-250 kg ha^-1 for late rice growing in the dry season. The irrigating threshold and irrigation quota for early rice are suggested as lower than 70% and 30-40 mm, respectively, and, for late rice, 70-80% and 40-60 mm.

CONCLUSION

Remarkable water-nitrogen coupling effects were found in the paddy field, and integrative water-nitrogen management strategies were suggested for both early rice and late rice in South China. © 2021 Society of Chemical Industry.

Conservation tillage improves productivity of sunflower (Helianthus annuus L.) under reduced irrigation on sandy loam soil

Sunflower production is significantly lower in arid and semi-arid regions due to various crop management problem. Conservation of tillage provides the most excellent opportunity to reduce degradation of soil reserves and increase soil productivity. The main objective of this study was to investigate the combined effects of conservation tillage and drought stress on growth and productivity of different sunflower hybrids. Experimental treatments included two sunflower hybrids ('NK-Senji' and 'S-278'), two drought stress treatments (i.e., well-watered and drought stress at flowering and grain filling stages) and three tillage practices (i.e., conservation, minimum and deep tillage). The results indicated that morphological and physiological parameters, and yield-related traits were significantly (P≤0.05) affected by all individual factors; however, their interactive effects were non-significant. Among sunflower hybrids, 'NK-Senji' performed better for morphological, physiological, and yield-related traits than 'S-278'. Similarly, conservation tillage observed better traits compared to the rest of the tillage practices included in the study. Nonetheless, conservation tillage improved growth and yield-related traits of hybrid 'NK-Senji' under drought stress. Hence, it is concluded that conservation tillage can improve the productivity of sunflower under low moisture availability. Therefore, conservation tillage could be suggested in the areas of lower water ability to improve sunflower production. Nonetheless, sunflower hybrids or varieties need thorough testing for their adaptability to conservation tillage and low moisture availability before making recommendations.

Soil bacterial microbiota predetermines rice yield in reclaiming saline-sodic soils leached with brackish ice

BACKGROUND

Saline-sodic lands threaten the food supply and ecological security in the western Songnen Plain of northeast China, and the gypsum is commonly adopted for restoration. However, the dynamics of soil bacterial community and the correlation with crop yield during restoring processes remain poorly understood. Here, we elucidated the soil chemical properties and bacterial communities and their associations with rice yield under different flue gas desulphurization gypsum (FGDG) application rates combined with brackish ice leaching.

RESULTS

The increased application rate of FGDG generally improved soil reclamation effects, as indicated by soil chemical properties, bacterial diversity, and rice yield. Compared with fresh ice irrigation, the rice yield in brackish ice treatment increased by 15.84%, and the soil alkalinity and sodium adsorption ratio (SAR) decreased by 35.19% and 10.30%, respectively. The bacterial alpha diversity significantly correlated and predicted rice yield as early as brackish ice melt, suggesting the bacterial diversity was a sensitive indicator in predicting rice yield. Meanwhile, the bacterial communities in the control possessed a high abundance of oligotrophic Firmicutes, while eutrophic bacterial taxa (e.g. Proteobacteria) were enriched after brackish water irrigation and FGDG application. Moreover, we also established a Random Forest model and identified a bacterial consortium that explained an 80.0% variance of rice yield.

CONCLUSION

Together, our results highlight the reclaiming effect of brackish ice in the saline-sodic field and demonstrate the sensitivity and importance of the soil bacterial community in predicting crop yield, which would provide essential knowledge on the soil quality indication and bio-fertilizer development for soil reclamation. © 2021 Society of Chemical Industry.

Modelling the effect of changing transplanting date on consumptive water footprints for paddy under the system of rice intensification

BACKGROUND

Consumptive water footprint (CWF) is a comprehensive measure of water consumption by paddy and can be used to assess the impact on freshwater volume. The seasonal water consumption and water footprints of paddy under any irrigation practice vary with changing the transplanting dates. The present study aimed to investigate the impact of shifting transplanting dates on CWFs of paddy under the system of rice intensification (SRI) using a crop model. A medium-duration variety (IR-36) was cultivated during kharif (monsoon) and rabi (non-monsoon) seasons of 2015/16 and 2016/17. The field data were used to calibrate and validate the crop model, Agricultural Production Systems Simulator (APSIM)-Oryza, as well as simulate paddy yield, evapotranspiration and consumptive water footprints (CWFs) under different transplanting dates.

RESULTS

The APSIM-Oryza simulated grain yield was found to be closely matched with the observed yield during both calibration (r²  = 0.98, root-mean-square error < 300 kg ha^-1 ) and validation (r²  = 0.88, root-mean-square error < 400 kg ha^-1 ). The seasonal water savings in SRI practice was 18-21% compared to conventional, with an effect of a 20-30% improvement in the yield. The early transplanting on 1 July in kharif and 15 December in rabi can produce maximum grain yields of 4.55 and 5.15 t ha^-1 , respectively, with a minimum CWF of 1064 and 855 m³ t^-1 under SRI for the study region.

CONCLUSION

The comparison of yield and CWF scenarios under different transplanting dates revealed the superiority of early transplanting in terms of yield improvement with the least irrigation requirement and CWF under SRI. © 2021 Society of Chemical Industry.

Effect of potassium fertilizer on the growth, physiological parameters, and water status of Brassica juncea cultivars under different irrigation regimes

Abiotic stress, especially a lack of water, can significantly reduce crop yields. In this study, we evaluated the physiological and biochemical effects of potassium sulfate (K2SO4) fertilizer and varied irrigation regimes on the economically significant oilseed crop, Brassica juncea L, under open field conditions. Two cultivars (RH-725 and RH-749) of B. juncea were used in a randomized complete block design experiment with three replicates. Irrigation regimes consisted of a control (double irrigation: once at the 50% flowering and another at 50% fruiting stages), early irrigation (at 50% flowering only), late irrigation (at 50% fruiting only) and stress (no irrigation). The K2SO4 applications were: control (K0, no fertilization); K1, 10 kg ha-1; and K2, 20 kg ha-1. We measured growth via fresh and dry plant weight, plant height, root length, and leaf area. All the growth parameters were higher in RH-749. The physiological attributes, including the membrane stability index and relative water content, were higher at the 50% flowering stage in RH-749. The amount of antioxidant enzymes (catalase (CAT), guaiacol peroxidase (POX), ascorbate peroxidase (APX), and superoxide dismutase (SOD)) was enhanced when both plants were fertilized during water stress. All of these enzymes had higher activity in RH-749. The total chlorophyll content and photosynthesis rate were considerably higher in RH-749, which leaked fewer electrolytes and maintained a less destructive osmotic potential under limited water conditions. The results indicated that it is water-stress tolerant when given a high concentration of K2SO4, which alleviated the adverse effects of water stress on growth and physiology.