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Copyright of Journal of Soil Sciences & Agricultural Engineering is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Agricultural intensification has increased the use of chemical fertilizers, promoting plant growth and crop yield. Excessive use of nitrogen fertilizers leads to nutrient loss and low nitrogen use efficiency. Management of nitrogen fertilizer input requires close to real‐time information about the soil nitrate concentration. While there is extensive work developing nitrate ion sensing solutions for liquid media, few allow for in‐soil measurements. This study introduces inkjet‐printed potentiometric sensors, containing 2 electrodes, the reference electrode (RE) and the nitrate‐selective film‐encapsulated working electrode (WE). The interaction between the nitrate‐sensitive membrane and soil nitrate ions causes a change in potential across the RE and WE. Additionally, a hydrophilic Polyvinylidene Fluoride (PVDF) layer ensures the long‐term functionality of the sensor in wet soil environments by protecting it from charged soil particles while simultaneously allowing water to flow from the soil toward the sensor electrodes. The sensors are tested in sand and silt loam soil, demonstrating their versatility across soil types. The potential change can be related to the nitrate concentration in soil, with typical sensitivities of 45–55 mV decade−1. Overall, the use of the PVDF layer allows for direct sensing in moist soil environments, which is critical for developing soil nitrate sensors. [ABSTRACT FROM AUTHOR]

Abstract Great concern has long been raised about nitrate leaching in cropland due to its possible environmental side effects in ground water contamination. Here we employed two common techniques to measure nitrate leaching in tea plantation soils in subtropical China. Using drainage lysimeter as a reference method, the adaptability of estimating drainage and nitrate leaching by combining the water balance equation with the suction cup technique was investigated. Results showed that the final cumulative leachate volume for the calculated and measured method was 721.43 mm and 729.92 mm respectively during the study period. However, nitrate concentration exerted great influence in the estimation of nitrate leaching from the suction cup-based method. The cumulative nitrate leaching loss from the lysimeter and suction cup-based method was 47.45 kg ha−1 and 43.58 kg ha−1 under lysimeter nitrate concentrations ranging from 7 mg L−1 to 13 mg L−1, 156.28 kg ha−1 and 79.95 kg ha−1 under lysimeter nitrate concentrations exceeding 13 mg L−1. Therefore, the suction cup-based method could be an alternative way of monitoring nitrate leaching loss within a range of 7–13 mg L−1 of nitrate concentrations in leachate. Besides, lower results occurred in suction cup samplers due to lack of representative samples which mainly leached via preferential flow when in strong leaching events. Thus, it is advisable to increase sampling frequency under such special conditions. The results of this experiment can serve as a reference and guidance for the application of ceramic cups in monitoring nitrogen and other nutrient-ion leaching in tea plantation soils.

Nitrogen compounds, which are naturally present in the environment, are essential for the sustenance of life and for the growth of plants. However, to meet the needs of agricultural production and increase crop yields, they are often added in the form of fertilizers to the soil. These nitrogen compounds can then infiltrate deep soil layers, leach until they reach underground aquifers. Leaching of nitrates from soil is a serious environmental problem in modern agriculture as it can contaminate groundwater and degrade soil quality. Both nitrogen fertilization practices and irrigation methods contribute greatly to increased nitrate leaching. The present study aims to demonstrate the real impact of nitrate used in agriculture on groundwater comparing concentration of the chemical element between the soil and the aquifer at different depths. The case study involves a series of soil and groundwater sampling with the related analyses for the identification of nitrate concentrations. The sites considered as case of study have the same type of soil (lithology, texture) and the same land use (arable land with the same type of fertilization and irrigation). The experimentation carried out has shown that there is a correlation between the nitrate present in the soil and that present in the groundwater only for a limited distance from the emission point (

Nitrogen compounds, which are naturally present in the environment, are essential for the sustenance of life and for the growth of plants. However, to meet the needs of agricultural production and increase crop yields, they are often added in the form of fertilizers to the soil. These nitrogen compounds can then infiltrate deep soil layers, leach until they reach underground aquifers. Leaching of nitrates from soil is a serious environmental problem in modern agriculture as it can contaminate groundwater and degrade soil quality. Both nitrogen fertilization practices and irrigation methods contribute greatly to increased nitrate leaching. The present study aims to demonstrate the real impact of nitrate used in agriculture on groundwater comparing concentration of the chemical element between the soil and the aquifer at different depths. The case study involves a series of soil and groundwater sampling with the related analyses for the identification of nitrate concentrations. The sites considered as case of study have the same type of soil (lithology, texture) and the same land use (arable land with the same type of fertilization and irrigation). The experimentation carried out has shown that there is a correlation between the nitrate present in the soil and that present in the groundwater only for a limited distance from the emission point (<10m from the ground level), while for higher soil packages the correlation is absent as structures, such as vadose areas, intervene which intercept and accumulate nitrate leaching. This study demonstrate that a contamination of nitrate in the groundwater is correlated to the agricultural activities present in the impacting area only to a depth of 10 m and which therefore needs further investigation. [ABSTRACT FROM AUTHOR]

Abstract Urea is the most used fertilizer because of its significance on world food security but it is also the toughest fertilizer to manage. It is readily available to the plant and it is vulnerable to loss in various ways, causing environmental pollution and huge economic losses. Urea application requires a sound knowledge for its effective management, which will increase its availability to plants and reduce possible losses. Ammonia (NH3) and oxides of nitrogen (N) pollute the environment, and nitrate ( $${\text{NO}}_{3}^{ - }$$ NO 3 - ) leaching alters the aquatic ecosystem, which lowers the nitrogen use efficiency (NUE) of applied urea. Nitrate-contaminated drinking water causes human and animal health risks, whereas the emission of nitrous oxide (N2O) in the atmosphere is significant to ozone layer depletion and climate change. This review discusses the processes in the soil after urea application in the soil–plant system, which includes the loss mechanisms, and the significant factors affecting the N availability and losses. This review also shows that the judicial management of urea in soil–plant systems and maintaining the best management practices and technologies ensure sustainable agricultural development and decrease the risk of environmental contamination. Finally, the review summarizes the potential mechanisms of the applied urea in the soil with their mineralization and loss pathways and delivers the scientific reference to achieve sustainable crop production and reduce the risk of N losses. Graphical Abstract

Under the same perspective of the Sustainable Development Goal (SDG) 15.3 aiming to restore degraded land and soil, one of the current priorities of the new Common Agriculture Policy (CAP) is to overcome the serious environmental problems raised by intensive agriculture. Despite the steps forward guaranteed by new technologies and innovations (e.g., IoT, precision agriculture), the availability of real operational tools, which could help the member states fulfil the high requirements and expectations of the new CAP and SDGs, is still lacking. To fill this gap, in the H2020 LandSupport project, the web‐based best practice tool was developed to identify, on‐the‐fly, optimized agronomic solutions to help achieve land‐degradation neutrality. The tool's core is the ARMOSA process‐based model, which dynamically simulates the continuum soil–plant–atmosphere, combining several cropping systems, crops, nitrogen fertilization rates, tillage solutions, and crop residue management for specific regions of interest. It provides a synthetic "Best Practice index" to identify the optimized local solutions, which combines the production, nitrate leaching, and SOC_change, according to the end‐user dynamic requests. The tool was implemented for three case studies: Marchfeld Region in Austria, Zala County in Hungary, and Campania Region in Italy, which are representative of a variety of different pedoclimatic conditions. In the present work, we report three possible cases of use in supporting best practices aiming toward soil and water conservation: (i) crop production optimization; (ii) impact of management practices (i.e., cover crops) over soil carbon; (iii) lowering the impact of nitrate leaching. [ABSTRACT FROM AUTHOR]

Nitrate leaching, greenhouse gas emissions, and water loss are caused by conventional water and fertilizer management in vegetable fields. The Expert-N system is a useful tool for recommending the optimal nitrogen (N) fertilizer for vegetable cultivation. To clarify the fates of water and N in vegetable fields, an open-field vegetable cultivation experiment was conducted in Dongbeiwang, Beijing. This experiment tested two irrigation treatments (W1: conventional and W2: optimal) and three fertilizer treatments (N1: conventional, N2: optimal N rate by Expert-N system, and N3: 80% optimal N rate) on cauliflower (Brassica oleracea L.), amaranth (Amaranthus tricolor L.), and spinach (Spinacia oleracea L.). The EU-Rotate_N model was used to simulate the fates of water and N in the soil. The results indicated that the yields of amaranth and spinach showed no significant differences among all the treatments in 2000 and 2001. However, cauliflower yield under the W1N2 and W1N3 treatments obviously reduced in 2001. Compared with the W1 treatment, W2 reduced irrigation amount by 27.9–29.8%, water drainage by over 76%, increased water use efficiency by 5–17%, and irrigation water use efficiency by 29–45%. Nitrate leaching was one of the main pathways in this study, accounting for 8.4% of the total N input; compared to N1, the input of fertilizer N under the N2 and N3 treatments decreased by over 66.5%, consequently reducing gaseous N by 48–72% and increasing nitrogen use efficiency (NUE) by 17–37%. Additionally, compared with the W1 treatments, gaseous N loss under the W2 treatments was reduced by 18–26% and annual average NUEs increased by 22–29%. The highest annual average NUEs were under W2N3 (169.6 kg kg−1) in 2000 and W2N2 (188.0 kg kg−1) in 2001, respectively. We found that optimizing fertilizer management allowed subsequent crops to utilize residual N in the soil. Therefore, we suggest that the W2N3 management should be recommended to farmers to reduce water and N loss in vegetable production systems. [ABSTRACT FROM AUTHOR]

Urea is the most used fertilizer because of its significance on world food security but it is also the toughest fertilizer to manage. It is readily available to the plant and it is vulnerable to loss in various ways, causing environmental pollution and huge economic losses. Urea application requires a sound knowledge for its effective management, which will increase its availability to plants and reduce possible losses. Ammonia (NH3) and oxides of nitrogen (N) pollute the environment, and nitrate ( NO 3 - ) leaching alters the aquatic ecosystem, which lowers the nitrogen use efficiency (NUE) of applied urea. Nitrate-contaminated drinking water causes human and animal health risks, whereas the emission of nitrous oxide (N2O) in the atmosphere is significant to ozone layer depletion and climate change. This review discusses the processes in the soil after urea application in the soil–plant system, which includes the loss mechanisms, and the significant factors affecting the N availability and losses. This review also shows that the judicial management of urea in soil–plant systems and maintaining the best management practices and technologies ensure sustainable agricultural development and decrease the risk of environmental contamination. Finally, the review summarizes the potential mechanisms of the applied urea in the soil with their mineralization and loss pathways and delivers the scientific reference to achieve sustainable crop production and reduce the risk of N losses. [ABSTRACT FROM AUTHOR]

Copyright of Ingeniería del Agua is the property of Universidad Politecnica de Valencia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

IntroductionTo ensure higher productivity, fertilizers have been excessively applied to the fruit greenhouse soil yearly, thus resulting in the increasing risks of residual nitrate leaching in the North China Plain.MethodsIn this study, a water and solute transport HYDRUS-1D model was used to evaluate the effects of using sweet corn as a catch crop on deep water drainage and nitrate leaching in a sweet cherry greenhouse soil. A three-year (2019–2021) field experiment was conducted during the rainfall season from July to September in the post-harvest of sweet cherry, when the plastic cover was removed each year. In the experiment, the five treatments were designed. The three nitrate residue levels denoted by CKR, N1R, and N2R, represented nitrate residue amounts in the soil profile of three nitrogen fertilizer levels(0, 280 and 420kg ha-1) before the harvest of sweet cherry(March to June). Two other treatments with and without sweet corn as a catch crop based on the treatments of N1R and N2R were denoted by N1RC and N2RC, respectively. The data of both the spatial and temporal distribution of water and nitrate content during the rainy seasons of 2019, 2020 and 2021 in the field experiment were collected to calibrate and validate the model. ResultsThe simulated results have showed that using sweet corn as a catch crop increased the evapotranspiration rate, the upward flux of water and nitrate at a 100 cm soil depth reached a maximum of 1.5 mm d-1 and 1.0 kg N ha-1d-1, respectively, and the downward movement of water and nitrate leached to deeper soil layers was reduced. Compared with CKR, the treatments with catch crops (N1RC and N2RC) reduced the amount of water drainage by 16.4% -47.7% in the 0-180cm soil profile. The average amounts of nitrate leaching in the 1.8 m soil profile during the three-year experiment were 88.1, 113.3, and 58.2 kg N ha−1 for the treatment without catch crop (N1R and N2R) and 32.3, 54.8, and 31.4 kg N ha−1 for the treatment with catch crop (N1RC and N2RC), respectively. The treatments (N1RC and N2RC) with catch crops decreased the amount of nitrate leaching by 29.6%-69.1% compared with the treatments without catch crops (N1R and N2R).DiscussionSweet corn as summer catch crop can reduce nitrate leaching in the sweet cherry greenhouses. Our study has provided an effective method to reduce the risk of nitrate leaching for sweet cherry greenhouses in the North China Plain.

Integrating water and nitrogen (N) management is critical to addressing contemporary challenges in agricultural development. This research explored using multispectral sensors mounted on unmanned aerial vehicles (UAVs) to monitor N demand via the normalized difference red-edge (NDRE) vegetation index and consequently schedule fertigation. The experiment included eight treatments with four fertilizer levels under both excessive and full irrigation. The four fertilizer levels comprised: high reference treatment based on commercial lab soil tests, sensor-based treatment triggered by an NDRE saturation threshold of 0.95, deficit treatment with base rate at pre-plant and side-dress, and a control treatment without any N application. The performance of each treatment was evaluated through a comprehensive comparison of yield, water productivity (WP), and nitrogen use efficiency (NUE). The sufficiency index (SI) of sensor-based treatment plots reached a threshold of 0.95, allowing spatially variable adjustment of N application for optimal yield with reduced total N input. Reducing N fertilizer in sensor-based treatments resulted in a substantial reduction of 50 %-60 %, though it led to a yield loss up to 12 %. However, NUE parameters such as partial factor productivity, agronomic efficiency, recovery efficiency, and physiological efficiency improved with sensor-based treatments, alongside reduced N leaching. Combining sensor-based treatment with full irrigation demonstrated the best ecological return, showing relatively lower yield reduction but significant improvements in NUE and WP. Further research into economic returns, saturation threshold algorithms for SI, adaptability to diverse environments, and virtual saturation reference is recommended for the widespread adoption of UAV-based N split management among growers.

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

Lysimeters are often used in research concerning nutrient leachate all over the globe. However, due to factors such as Florida's high water table (a condition when the water level stays relatively close to the soil surface) in some production areas, the assessment and collection of leachate are not feasible. Another obstacle to the use of lysimeters in field research is the fact that several types of irrigation methods are used in Florida (e.g., subirrigation with seepage or drain-tile, overhead, microsprinkler, and drip irrigation) requiring different strategies for leachate assessment. This publication focuses on the use of crop models as alternatives to estimate nitrate leaching from cropping systems at a field scale. This publication's target audience is growers, extension agents, crop consultants, representatives of the fertilizer industry, state and local agencies, students, instructors, researchers, and interested Florida citizens.

Agricultural managed aquifer recharge (Ag-MAR, on-farm recharge), where farmland is flooded with excess surface water to intentionally recharge groundwater, has received increasing attention by policy makers and researchers in recent years. However, there remain concerns about the potential for Ag-MAR to exacerbate nitrate (NO3-) contamination of groundwater, and additional risks, such as greenhouse gas emissions and crop tolerance to prolonged flooding. Here, we conducted a large-scale, replicated winter groundwater recharge experiment to quantify the effect of Ag-MAR on soil N biogeochemical transformations, potential NO3- leaching to groundwater, soil physico-chemical conditions, and crop yield. The field experiment was conducted in two grapevine vineyards in the Central Valley of California, which were each flooded for 2 weeks and 4 weeks, respectively, with 1.31 and 1.32 m3 m-2 of water. Hydrologic, geochemical, and microbial results indicate that NO3- leaching from the first 1 m of the vadose zone was the dominant N loss pathway during flooding. Based on pore water sample and N2O emission data, denitrification played a lesser role in decreasing NO3- in the root zone but prolonged anoxic conditions resulted in a significant 29 % yield decrease in the 4-week flooded vineyard. The results from this research, combined with data from previous studies, are summarized in a new conceptual model for integrated water-N dynamics under Ag-MAR. The proposed model can be used to determine best Ag-MAR management practices.

Abstract Agricultural field experiments are costly and time-consuming, and often struggling to capture spatial and temporal variability. Mechanistic crop growth models offer a solution to understand intricate crop-soil-weather system, aiding farm-level management decisions throughout the growing season. The objective of this study was to calibrate and the Crop Environment Resource Synthesis CERES-Maize (DSSAT v 4.8) model to simulate crop growth, yield, and nitrogen dynamics in a long-term conservation agriculture (CA) based maize system. The model was also used to investigate the relationship between, temperature, nitrate and ammoniacal concentration in soil, and nitrogen uptake by the crop. Additionally, the study explored the impact of contrasting tillage practices and fertilizer nitrogen management options on maize yields. Using field data from 2019 and 2020, the DSSAT-CERES-Maize model was calibrated for plant growth stages, leaf area index-LAI, biomass, and yield. Data from 2021 were used to evaluate the model's performance. The treatments consisted of four nitrogen management options, viz., N0 (without nitrogen), N150 (150 kg N/ha through urea), GS (Green seeker-based urea application) and USG (urea super granules @150kg N/ha) in two contrasting tillage systems, i.e., CA-based zero tillage-ZT and conventional tillage-CT. The model accurately simulated maize cultivar’s anthesis and physiological maturity, with observed value falling within 5% of the model’s predictions range. LAI predictions by the model aligned well with measured values (RMSE 0.57 and nRMSE 10.33%), with a 14.6% prediction error at 60 days. The simulated grain yields generally matched with measured values (with prediction error ranging from 0 to 3%), except for plots without nitrogen application, where the model overestimated yields by 9–16%. The study also demonstrated the model's ability to accurately capture soil nitrate–N levels (RMSE 12.63 kg/ha and nRMSE 12.84%). The study concludes that the DSSAT-CERES-Maize model accurately assessed the impacts of tillage and nitrogen management practices on maize crop’s growth, yield, and soil nitrogen dynamics. By providing reliable simulations during the growing season, this modelling approach can facilitate better planning and more efficient resource management. Future research should focus on expanding the model's capabilities and improving its predictions further.

This paper presents the results of a study on the level of nitrate leaching from the 0–30 cm layer of grassland (GL) soil in the Lublin Voivodship during the winters of 2018/2019, 2019/2020 and 2020/2021. The amounts of leached nitrates were determined using the Burns model. For the calculations based on this model – directly and indirectly, the results determination of residual nitrate nitrogen, texture and organic matter in GL soils, obtained within the framework of agricultural monitoring of soils by the National Chemical and Agricultural Station (KSChR), and results of system meteorological measurements conducted by the Institute of Meteorology and Water Management – National Research Institute (IMGW-PIB) were used. The analysed soil samples were taken from 39 permanent control and measurement grassland sites. The research discovered in particular that: – the average leaching of nitrate nitrogen from GL mineral soil in the three analysed periods was 16.2 and 5.1 kg N∙ha–1 from organic soil; – on average, in autumn during the entire study period, 55.3% of NO3-N leached from the 0–30 cm layer of GL mineral soil, and 27.3% from organic soil; – among different agronomic categories of mineral soil, the highest leaching of NO3-N was recorded from medium soil (17.4 kg N∙ha–1) and the lowest from heavy soil (11.5 kg N∙ha–1); – individually determined values of NO3-N leaching from soil varied significantly from 0 to 68.5 kg N∙ha–1 for mineral soil and from 0.1 to 23.65 kg N∙ha–1 for organic soil.

Quantitative evaluation of the effects of diverse greenhouse vegetable production systems (GVPS) on vegetable yield, soil water consumption, and nitrogen (N) fates could provide a scientific basis for identifying optimum water and fertilizer management practices for GVPS. This research was conducted from 2013 to 2015 in a greenhouse vegetable field in Quzhou County, North China. Three production systems were designed: conventional (CON), integrated (INT), and organic (ORG) systems. The WHCNS-Veg model was employed for simulating vegetable growth, water dynamics, and fates of N, as well as water and N use efficiencies (WUE and NUE) for four continuous growing seasons. The simulation results revealed that nitrate leaching and gaseous N emissions constituted the predominant N loss within GVPS, which separately accounted for 11.5–59.4% and 6.0–21.1% of the N outputs. The order of vegetable yield, N uptake, WUE, and NUE under different production systems was ORG > INT > CON, while the order of nitrate leaching and gaseous N loss was CON > INT > ORG. Compared to CON, ORG exhibited a significant increase in yield, N uptake, WUE, and NUE by 24.6%, 24.2%, 26.1%, and 89.7%, respectively, alongside notable reductions in nitrate leaching and gaseous N loss by 67.7% and 63.2%, respectively. The ORG system should be recommended to local farmers. [ABSTRACT FROM AUTHOR]

Background and aims: Organic farming has been viewed as a sustainable practice that can maintain yields and improve soil quality in greenhouse vegetable production. However, little attention has been given to the leaching of dissolved organic nitrogen (DON) due to excessive application of organic manure. The objectives of this study were to compare the characteristics of dissolved inorganic nitrogen (DIN) and DON leaching under different greenhouse vegetable production systems. Methods: A 2-year lysimeter field experiment was conducted with three different farming systems in North China, i.e. conventional (CON, 70% chemical fertilizer +30% organic manure), integrated (INT, 50% chemical fertilizer +50% organic manure) and organic (ORG, 100% organic manure). Results: The results indicated that vegetable yields under the ORG system were normally larger than the CON or INT. The amount of water drainage and dissolved total N (DTN, DIN + DON) leaching differed during two cropping seasons, with spring and summer seasons giving greater leaching than autumn and winter seasons. The total DIN leaching throughout four seasons of vegetable production under ORG was 176 kg N ha−1, which was much lower than that of CON (327 kg N ha−1) and INT (269 kg N ha−1). The DTN leaching under ORG (485 kg N ha−1) was also less than that of CON (528 kg N ha−1) and INT (521 kg N ha−1). However, the total DON leaching under the ORG was 309 kg N ha−1, far higher than the amounts for CON (202 kg N ha−1) and INT (252 kg N ha−1). The average DON leaching ratio (DON/DTN) under the ORG system was 63.7%, which was also much higher than that of the CON (38%) and INT (48%) systems. The increase in the proportion of organic manure in fertilizer types and over-irrigation were the main reasons for the increase in DTN leaching. Structural equation modeling analysis showed that the soil bulk density, saturated hydraulic conductivity and saturated soil water content were the most important factors influencing the DTN leaching. Conclusions: While the ORG system has many advantages, irrigation and fertilizer scheduling should be optimized under the ORG system in order to minimize DON leaching. [ABSTRACT FROM AUTHOR]

Background and Objectives: Nitrogen (N) plays a major role in maize growth and yield. Therefore, adequate supply of N is required for successful maize production. However, application of chemical nitrogen fertilizers is associated with some problems such as groundwater pollution, nitrogen enrichment of surface waters, and nitrate accumulation in agricultural products. Accordingly, nowadays a great attention has been paid to the slowrelease fertilizers. Nitrogen-enriched humic acids (NHAs) are considered as promising slow-release nitrogen fertilizers in agricultural systems. However, the effects of these types of fertilizers on plant growth and physiological characteristics have not been well understood. For this purpose, the present study investigates the effectiveness of NHAs on the morphological and physiological characteristics of maize as well as nitrogen loss through leaching. Methodology: The Nitrogen-enriched humic acids (NHAs) were prepared through the simple process of nitration, and from the reaction of nitric acid with humic acid (HA) extracted from leonardite of Yazd Golsang Kavir Company as an organic carbon source. Then, a greenhouse experiment in a completely randomized design (CRD) with three replications was conducted to determine the effects of 16 treatments, including control, urea (U1, U2 and U3), humic acid (HA1, HA2 and HA3), nitrogen-enriched humic acid (NHA1, NHA2 and NHA3), urea-humic acid (U1HA1, U2HA2 and U3HA3), and urea-nitrogen-enriched humic acid (U1NHA1, U2NHA2 and U3NHA3) on the morphological and physiological characteristics of maize plant (Single cross-704). The levels of treatments were determined as the quarter (50 mg N kg-1), half (100 mg N kg-1) and equal (200 mg N kg-1) to the maize fertilizer requirement. In the combined treatments of urea and HA or NHA, an equal fraction of the total nitrogen was considered. After the end of the experiment, using the standard methods, some characteristics including root length, leaf area, plant height, root volume, wet and dry weights of shoot and root, leaf chlorophyll index, concentrations of phosphorus, potassium, nitrogen and nitrate, and nitrate reductase activity in both shoot and root were determined. Moreover, during the experiment and on given days, the maize pots were leached and the obtained leachate was collected for the nitrate measurement. Findings: According to the results, the nitrogen content of the produced NHA (3.3%) was about two times higher than the HA (1.6%). In addition, the NHA had higher carboxyl and phenolic hydroxyl content than the HA. The FT-IR analysis showed the characteristic peaks of nitro (NO2) groups at wavenumbers of 1541 and 1336 cm-1 in the spectrum of NHA. Germination test indicated that the NHA was not toxic to the maize seeds. The results showed that the NHA treatments had a much better influence on the plant morphological characteristics than theHA treatments. This observation may be due to the negative effects of HA application at high dosages. In comparision, the UNHA treatments were only slightly more efficient than the urea treatments. Combining NHA with urea diminishes the adverse impacts of separate application of these two fertilizers. On average, leaf chlorophyll index and concentrations of total nitrogen, nitrate and nitrate reductase enzyme in shoot part of plants in the NHA treatments were 11.5, 17.0, 35.2 and 29.4% higher than the HA tratments. The nitrate reductase concentration in the roots was 40.4% lower than the shoots. However, the UNHA and urea treatments showed almost similar efficiency in improving physiological characteristics. The U3NHA3 or U3 treatments, i.e. the highest level of nitrogen, showed the highest efficiency which means the high nitrogen requirements of maize in pot experiments. Based on the results, the nitrogen supply to the maize plant increased the shoot concentration of potassium higher than that of phosphorus. Although the U3 treatment indicated the highest nitrogen and nitrate concentrations in both root and shoot, the highest nitrate leaching was also observed for this treatment. However, by using the U3NHA3 treatment, the mean concentration of nitrate in the leachate decreased by about 48.7% as compared to the U3 treatment. Conclusion: Findings of this research revealed that the combined fertilizer of UNHA can be a good alternative for urea. It could not only supply nitrogen for plants, but could improve plant vegetative growth, and in turn considerably reduce nitrate leaching, which has highly beneficial effects on nitrogen use efficiency as well as environmental issues. [ABSTRACT FROM AUTHOR]

Nitrate (NO3) leaching from agriculture represents the primary source of groundwater contamination and freshwater ecosystem degradation. At the field level, NO3 leaching is highly variable due to interactions among soil, weather and crop management factors, but the relative effects of these drivers have not been quantified on a global scale. Using a global database of 82 field studies in temperate rainfed cereal crops with 961 observations, our objectives were to (a) quantify the relative importance of environmental and management variables to identify key leverage points for NO3 mitigation and (b) determine associated changes in crop productivity and potential tradeoffs for high and low NO3 loss scenarios. Machine learning algorithms (XGboost) and feature importance analysis showed that the amount and intensity of rainfall explained the most variability in NO3 leaching (up to 24 kg N ha-1), followed by nitrogen (N) fertilizer rate and crop N removal. In contrast, other soil and management variables such as soil texture, crop type, tillage and N source, timing and placement had less importance. To reduce N losses from global agriculture under changing weather and climatic conditions, these results highlight the need for better targeting and increased adoption of science-based, locally adapted management practices for improving N use efficiency. Future policy discussions should support this transition through different instruments while also promoting more advanced weather prediction analytics, especially in areas susceptible to extreme climatic variation.

The Root Zone Water Quality Model (RZWQM) is a one-dimensional process-based model used for simulating major physical, chemical, and biological processes in agricultural systems. To date, the model has not been applied to potato production systems for simulating nitrate leaching. In this study, 35 datasets collected between 2009 and 2016 at a field under a three-year potato (potato–barley–red clover) rotation in Prince Edward Island (PEI), Canada, have been employed for calibrating and validating the water, nitrogen (N) cycling, and plant growth routines of RZWQM and for subsequently estimating nitrate leaching. The model fitness, evaluated using univariate and bivariate indicators, was rated as high for most of the parameters tested. As a result of the combined influence of higher infiltration and reduced plant uptake, the model showed that the highest leaching at the rotation level occurred between September and December. A secondary leaching period occurred in spring, when residual soil nitrate was mobilized by increased percolation due to snowmelt. Most of the nitrate leaching occurred during the potato year (89.9 kg NO3–N ha−1 y−1), while leaching for barley and red clover years had comparable values (28.6 and 29.7 kg NO3–N ha−1 y−1, respectively). The low N use efficiency of the entire rotation (i.e., 30.2%), combined with the high NO3–N concentration in leachate (i.e., 34.9 mg NO3–N L−1 for potato and 16.3 mg NO3–N L−1 for the complete rotation), suggest that significant efforts are required for adapting management practices to ensure sustainability of potato production systems. [ABSTRACT FROM AUTHOR]

This study presents the projected future evolution of water resource balance and nitrate pollution under various climate change scenarios and climatic models using a holistic approach. The study area is Almyros Basin and its aquifer system, located in Central Greece, Thessaly, Greece. Almyros Basin is a coastal agricultural basin and faces the exacerbation of water deficit and groundwater nitrate pollution. Using an Integrated Modeling System (IMS), which consists of the surface hydrology model (UTHBAL), the nitrate leachate model (REPIC, an R-ArcGIS-based EPIC model), the groundwater hydrology model (MODFLOW), and the nitrates' advection, dispersion, and transport model (MT3MDS), the projected values of the variables of water quantity and quality are simulated. Nineteen climatic models from the Med-CORDEX database were bias-corrected with the Quantile Empirical Mapping method and employed to capture the variability in the simulated surface and groundwater water balance and nitrate dynamics. The findings indicate that future precipitation, runoff, and groundwater recharge will decrease while temperature and potential evapotranspiration will increase. Climate change will lead to reduced nitrogen leaching, lower groundwater levels, and persistent nitrate pollution; however, it will be accompanied by high variability and uncertainty, as simulations of IMS under multiple climatic models indicate. [ABSTRACT FROM AUTHOR]

Biochar is promoted as a means of improving soil fertility. Yet, few experiments have investigated its potential to improve nitrogen (N) use efficiency for high‐yielding maize production in the U.S. Midwest. We tested the hypothesis that biochar application increases inorganic soil N availability during maize growth, leading to higher grain yields and N recovery efficiency while reducing the risk of N leaching following harvest. Four N fertilizer rates (0, 90, 179, and 269 kg ha−1 as urea ammonium nitrate [UAN] solution) were applied with or without biochar (10 Mg ha−1) before planting in a two‐year field study. Inorganic soil N concentration was measured during the growing season (0–15 cm), and deep soil cores were obtained following harvest (0–90 cm). Results show that biochar did not affect maize yield, crop N uptake, or N recovery efficiency (by the difference method) across N rates, and there was no biochar by N rate interaction. While biochar lowered soil inorganic N concentrations on several sampling dates, this did not translate into seasonal differences in cumulative soil N availability, although grain yields in the unfertilized control were ~10% lower with biochar, suggesting net N immobilization. Biochar partially reduced the risk of N leaching following harvest by decreasing soil N concentrations at 30–60 cm, but mean concentrations for 0–90 cm were not different. Compared to previous work highlighting the benefits of biochar in arid climates with low soil fertility, we found no evidence of increased crop yield, NRE, or reduced risk of N leaching on Mollisols in a temperate climate. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study on the level of nitrate leaching from the 0-30 cm layer of grassland (GL) soil in the Lublin Voivodship during the winters of 2018/2019, 2019/2020 and 2020/2021. The amounts of leached nitrates were determined using the Burns model. For the calculations based on this model - directly and indirectly, the results determination of residual nitrate nitrogen, texture and organic matter in GL soils, obtained within the framework of agricultural monitoring of soils by the National Chemical and Agricultural Station (KSChR), and results of system meteorological measurements conducted by the Institute of Meteorology and Water Management - National Research Institute (IMGW-PIB) were used. The analysed soil samples were taken from 39 permanent control and measurement grassland sites. The research discovered in particular that: - the average leaching of nitrate nitrogen from GL mineral soil in the three analysed periods was 16.2 and 5.1 kg N·ha-1 from organic soil; - on average, in autumn during the entire study period, 55.3% of NO3-N leached from the 0-30 cm layer of GL mineral soil, and 27.3% from organic soil; - among different agronomic categories of mineral soil, the highest leaching of NO3-N was recorded from medium soil (17.4 kg N·ha-1) and the lowest from heavy soil (11.5 kg N·ha-1); - individually determined values of NO3-N leaching from soil varied significantly from 0 to 68.5 kg N·ha-1 for mineral soil and from 0.1 to 23.65 kg N·ha-1 for organic soil. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Conflicts over water use and the high demand for food and biofuels have motivated the use of wastewater in irrigated agriculture. The study aimed to evaluate the nitrogen losses through nitrate leaching and nitrous oxide emission for sugarcane first ratoon irrigated by subsurface drip (SDI) with fresh water and treated domestic sewage (TDS) and traditional crop management under rainfed conditions. Therefore, the following treatments were implemented: T1—non-irrigated and topdressing fertilization; T2—irrigated with TDS, with fertigation; T3—irrigated with TDS, without fertigation; T4—irrigated with fresh water, with fertigation; T5—irrigated with fresh water, without fertigation. The nitrogen (N) fertilizer applied corresponded to 120 kg ha−1 to all treatments, with broadcast fertilization for nonirrigated cropping and, for the irrigated plots, it was performed by supplementing the concentration of the nutrients in the TDS and freshwater. All the fertigated treatments had lower leaching losses than nonirrigated treatment with topdressing fertilization, the total N loss for nonirrigated plots differed significantly from irrigated treatments, with a total loss of 16.36 kg N ha−1. The application of TDS by SDI to meet the needs for water and nutrients resulted in a decrease of N losses by NO3− leaching and N2O emissions, compared with traditional sugarcane cultivation under non-irrigated with topdressing fertilization (total of 16.36 kg ha−1 for T1), being the nitrate leaching the main factor that contributed to the N loss with a loss of 71% for T1 (11.50 kg ha−1). Irrigation with TDS, in addition to providing nutrients and water for sugarcane cultivation, can help minimize nitrogen contamination compared to conventional management methods through SDI systems. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

While soil nitrogen (N) losses under drip irrigation water and fertilizer management have become a key issue in global environmental N pollution, no current systematic review of this issue exists in the literature. Drawn from the Web of Science Core Collection database, 290 related articles were identified as research subjects (1991–2022). To reveal the basic characteristics, research power, hotspots and future perspectives of this research field, an in-depth bibliometrics analysis and graphical knowledge display were undertaken by using CiteSpace software. By analyzing the evolution process of keywords, greenhouse gases, water use efficiency and crop yield have been research hotspots of this field in recent years. Irrigation systems, soil moisture, fertigation and N losses have always been the core research topics. The focus on N losses pathways has gradually shifted from nitrate (NO3-) leaching alone to comprehensive consideration of multiple losses pathways including NO3- leaching, and emissions of N2O, NH3 and NO. The corresponding water and fertilizer management strategies have gradually shifted from concentrating on water and fertilizer application amounts to diversified management methods involving combinations of amounts, methods and types. Moreover, the development and widespread application of new water and fertilizer management technologies and exogenous additives have further enriched the research direction of soil N losses under drip irrigation water and fertilizer management. Future research still needs to explore how to balance high crop yields and minimize environmental impacts, which will provide effective strategies for controlling agricultural non-point source pollution and mitigating global warming.

High emissions of nitrogen to the environment are one of the major drawbacks of modern agriculture. Subsurface drip fertigation (SDF) is a technology to apply fertilizer in small amounts continuously and directly into the root zone with the potential of mitigating deep percolation losses when accurately managed. Our study was established to analyze possible benefits of SDF, i.e. nitrate losses reduction without decrease in yield, as alternative to the conventional application of nitrogen fertilizer. In this five-year field study, effects of SDF on red cabbage (Brassica oleracea) growth, yield, root distribution and nitrogen uptake were evaluated. The experiments took place in northern Germany. Application of fertilizer in a solution with water was managed to match the needs of crops and placed directly in the root zone through permanently buried driplines. The outcomes of crop growth under SDF were compared with a control crop receiving fertilizer at one or two dates by surface broadcasting. Yield and agronomic nitrogen use efficiency were higher for crops grown under SDF. Total dry mass increase was especially high under dry conditions (34%) but as well under wet conditions with efficient management (20%). Head dry mass of crops grown under SDF had a stronger reaction to the available nitrogen than crops under conventional application, with values of 0.19 and 0.1 Mg ha-1 per kg N ha-1 respectively. Moreover, SDF treatment resulted on average ca. 14 kg ha−1 higher nitrogen uptake. In SDF plots, yield formation and nitrogen uptake was higher for plants grown directly above drip lines. Effect of the distance to nitrogen source was supported with numerical simulations. The root structure showed different distributions for the two treatments, particularly in years with low rainfall. Overall, the results showed the potential of SDF to effectively control nitrogen supply, thereby increasing yield formation of marketable plant organs.

Nitrate leaching from soil is a major environmental issue in modern agriculture as it can contaminate groundwater and degrade soil quality. Both nitrogen fertilization practices and irrigation methods contribute greatly to increased nitrate leaching. Researchers have developed quantitative models to predict nitrate leaching based on these farming techniques. This article examines new literature focusing on such models, particularly regarding salty soils used for maize cultivation. The study investigated the effects of nitrogen application rates and irrigation intervals on soil and groundwater properties in clay soils in Egypt. Results showed that nitrogen fertilization and irrigation frequency significantly impacted the water table depth, groundwater salt content, soil moisture levels, soil nitrogen availability, and groundwater nitrate levels. Correlations were discovered between nitrogen application, irrigation schedules, and various soil and groundwater parameters. The research emphasizes managing nitrogen rates and irrigation timings to maximize soil moisture while minimizing nitrate leaching during maize production. Proper agricultural management techniques are needed to reduce groundwater nitrate pollution risks. The review contributes to more sustainable farming practices.

Nitrate contamination in surface and groundwater remains a widespread problem in agricultural watersheds is primarily associated to high levels of percolation or leakage from fertilized soil, which allows easy infiltration from soil into groundwater. This study was aimed to predict canopy water content to determine the nitrate contamination index resulting from nitrogen fertilizer loss in surface and groundwater. The study used Geographically Weighted Regression (GWR) model using MODIS 006 MOD13Q1-EVI Earth observation data, crop information and rainfall data. Satellite data collection was synchronized with regional crop calendars and calibrated to plant biomass. The average plant biomass during observed plant growth stages was between 0.19 kg/m2 at the minimum and 0.57 kg/m2 at the maximum. These values are based on the growth stages of crops and provide a solid basis for monitoring and validating crop water productivity data. The simulation results were validated with a high correlation coefficient (R2 = 0.996, P

Excessive application of water and nitrogen fertilizer during farmland management practices leads to serious groundwater nitrate pollution. A field experiment was conducted during the spring maize growth period in Alxa, Inner Mongolia, China. The soil Water Heat Carbon Nitrogen Simulator (WHCNS) model was calibrated by the ensemble smoother method (ES(DL)) based on the field experiment. Then dynamics of soil water content, soil water percolation flux, soil nitrate concentration and soil nitrate leaching flux were simulated with the calibrated WHCNS model under different water and nitrogen fertilization treatments within the vadose zone. The main conclusions are as follows: ES(DL) is feasible for the calibration of the WHCNS model. RMSE_Maximum a posteriori (RMSE_MAP) of soil water content are 0.0301 cm3 cm−3 and 0.0302 cm3 cm−3 for model calibration and model validation, respectively. RMSE_MAP of soil nitrate concentration are 5.49 mg N kg−1 and 3.86 mg N kg−1 for model calibration and model validation, respectively. Both average soil nitrate concentration and average nitrate leaching flux increase with increasing irrigation amount under the same nitrogen fertilization level for the depths of 1.2 m and 1.8 m. However, average soil nitrate concentration decreased and leaching flux increased with increasing irrigation amount under the same nitrogen fertilization level for the depths of 10 m and 20 m. The study of nitrate dynamics in the deep vadose zone contributes to better understand the procedure of nitrate pollution in groundwater caused by excessive water and nitrogen application.

Growing public concern over agricultural nitrogen (N) pollution is now reflected in consumers’ food choices and shareholders’ resolutions, causing rapid changes in global food supply chains. Nitrate (NO3) leaching represents the primary N source for groundwater contamination and freshwater ecosystem degradation. However, simplified science-based indicators are still lacking to facilitate improved N management practices at the farm-level. We conducted a global analysis of published field studies to evaluate N balance (N inputs minus N outputs) as a robust predictor for NO3 losses. Using 82 studies (1110 observations) for rainfed cereal crops in temperate regions, we 1) quantified the response of NO3 losses to changes in N balance for major rainfed cereal crops while accounting for environmental and management variables; and 2) assessed the feasibility of improving water quality through lower N balance under different scenarios using the case study of maize (Zea mays L.) data from the US Corn Belt. Observations were grouped in studies from the US and non-US regions. Results show that NO3 losses increased exponentially as N balance increases for both the US and non-US regions, though they were 60% higher in the US at a given N balance. Scenario analysis revealed that reducing the N rate from the agronomic optimum to the lower point within the economic optimum N rate range decreased NO3 losses by 13% without impacting economic returns. The case study for maize showed that improvements in N use efficiency that increase grain yield at a given fertilizer rate can substantially reduce N balance and mitigate NO3 losses. This study provides an evidence-based foundation for food supply chain companies to mitigate global NO3 pollution, specifically by using the generalized relationships presented here to track progress in NO3 leaching mitigation. To further resolve uncertainties and improve region-specific estimates for NO3 losses, we propose a tiered monitoring and assessment framework similar to the IPCC (Intergovernmental Panel on Climate Change) methodology for N2O emissions, widely implemented in science and used for policy.

Nitrate leaching, greenhouse gas emissions, and water loss are caused by conventional water and fertilizer management in vegetable fields. The Expert-N system is a useful tool for recommending the optimal nitrogen (N) fertilizer for vegetable cultivation. To clarify the fates of water and N in vegetable fields, an open-field vegetable cultivation experiment was conducted in Dongbeiwang, Beijing. This experiment tested two irrigation treatments (W1: conventional and W2: optimal) and three fertilizer treatments (N1: conventional, N2: optimal N rate by Expert-N system, and N3: 80% optimal N rate) on cauliflower (Brassica oleracea L.), amaranth (Amaranthus tricolor L.), and spinach (Spinacia oleracea L.). The EU-Rotate_N model was used to simulate the fates of water and N in the soil. The results indicated that the yields of amaranth and spinach showed no significant differences among all the treatments in 2000 and 2001. However, cauliflower yield under the W1N2 and W1N3 treatments obviously reduced in 2001. Compared with the W1 treatment, W2 reduced irrigation amount by 27.9–29.8%, water drainage by over 76%, increased water use efficiency by 5–17%, and irrigation water use efficiency by 29–45%. Nitrate leaching was one of the main pathways in this study, accounting for 8.4% of the total N input; compared to N1, the input of fertilizer N under the N2 and N3 treatments decreased by over 66.5%, consequently reducing gaseous N by 48–72% and increasing nitrogen use efficiency (NUE) by 17–37%. Additionally, compared with the W1 treatments, gaseous N loss under the W2 treatments was reduced by 18–26% and annual average NUEs increased by 22–29%. The highest annual average NUEs were under W2N3 (169.6 kg kg−1) in 2000 and W2N2 (188.0 kg kg−1) in 2001, respectively. We found that optimizing fertilizer management allowed subsequent crops to utilize residual N in the soil. Therefore, we suggest that the W2N3 management should be recommended to farmers to reduce water and N loss in vegetable production systems.

Abstract Nanofertilizers could promote nutrient efficiency with slow release compared to conventional fertilizers (CF). Most of the applied nitrogen is lost on the soil by leaching, due to the rapid release behavior of CF. Clays can function as a nanosized porous structure to retain and slowly release nutrients. The objective of this study was to evaluate a nitrogenous nanocomposite (NCN) and its effect on leaching and N content of lettuce (Lactuca sativa). The treatments applied were: 100% conventional fertilizer, 100% nitrogenous nanocomposite and the mixture in percentage of CF/NCN 25/75, 50/50, 75/25 and 25/0, 50/0 75/0% on columns of soil with lettuce for 45 days. Leachates at the end of the cycle increased in treatments with NCN. Treatments with NCN have higher N content in the leaf. In regard to biomass growth, leaf area, leaf N, drained variables, electrical conductivity and NO3 − content, it was possible to show that the doses of 50 and 75% of NCN match the characteristics of the crop compared to the control, which allows us to use lower doses than those recommended with CFs.

Introduction Savory is considered one of the most important medicinal plants, which is used in various food and medical industries. Nitrogen (N) plays a major role on the growth and yield of medicinal plants. Therefore, an adequate supply of N is required for successful production of savory. However, the application of chemical N fertilizers is associated with many obstacles such as groundwater ‎pollution, N enrichment of surface waters, and drop in the quality of plants. ‎Accordingly, nowadays, great attention has been paid to organic fertilizers. In this regard, humic acid-based fertilizers have shown promising results. Humic acids (HAs) could be converted into nitrohumic acids (NHAs) through the nitration process, in which nitro groups (NO2) are located on the aromatic rings. This process increases the N content of the HA. Thus, ‎‎NHAs can be used as organic N fertilizers in the cultivation of medicinal plants whose organic production is a priority. However, the ‎effects of these types of fertilizers on plant growth and physiological characteristics have not been well ‎understood. Accordingly, the present study for the first time investigates the effectiveness of NHA on the ‎morphological and physiological characteristics of savory, as well as N loss through leaching.‎ Materials and Methods In the current study, HA was initially extracted from leonardite (purchased from Yazd Golsang Kavir Company) as a rich source of HA. Then, NHA was prepared through the nitration process using nitric acid (50% by volume). After that, using FT-IR (Fourier transform infrared spectroscopy) and CHNS analysis the extracted HA and NHA were characterized, and their N content was determined. Afterward a ‎greenhouse experiment in a completely randomized design (CRD) with three replications was conducted ‎to determine the effects of 16 treatments, including control (without urea, HA and NHA), urea (U1, U2 and U3), humic acid ‎‎(HA1, HA2 and HA3), nitrohumic acid (NHA1, NHA2 and NHA3), urea-humic acid (U1HA1, U2HA2‎ and U3HA3), and urea-nitrohumic acid (U1NHA1, U2NHA2 and U3NHA3) on the morphological ‎and physiological characteristics of savory plant. The treatment levels were ‎determined as 40, 80, and 120 mg N kg-1 for the first, second and third level of the treatments, respectively. In the combined treatments of urea and HA or NHA, an equal fraction of the total nitrogen (N) was applied. At the end of the experiment, standard methods were used to assess various characteristics, including root length, leaf area, plant height, root volume, wet and dry weights of shoot and root, leaf chlorophyll index, concentrations of phosphorus, potassium, nitrogen, nitrate, and nitrate reductase in both the shoot and root. Additionally, leaching was conducted on specific days during the experiment, and the leachate was collected for nitrate measurement. Results and Discussion The results showed that using the nitration process, some characteristics of the NHA such as total acidity, the content of carboxylic and phenolic groups as well as N content improved as compared to the initial HA. Moreover, the results indicated that most of the morphological and physiological ‎traits of savory plants, including leaf area, plant height, root length, fresh and dry weights of root and shoot as well as chlorophyll index, and the concentration of nitrogen, phosphorous, potassium, nitrate and nitrate reductase enzyme were significantly higher in the NHA treatments than those of HA. In addition, the highest shoot dry weight was obtained in the combined treatments of U3NHA3 and U3HA3 as well as in the U3 treatment alone. The average rate of nitrate concentration increase in the U treatments was 1.77 times higher than the UNHA treatments. According to the results, U3 treatment indicated the highest nitrate loss which by using the U3NHA3 treatment, the mean concentration of nitrate ‎in the leachate decreased by about 40.5% as compared to the U3 treatment.‎ Conclusion The findings of this research revealed that most of the morphological and physiological ‎traits of savory plant showed better responses to the combined treatments of U3NHA3 and U3HA3 as well as to the U3 treatment alone. However, with regard to the lower accumulation of nitrate in the shoot of savory as well as to the lower nitrate leaching, the combined treatments were preferred. Accordingly, NHA can be ‎a alternative nitrogen source in increasing the yield and growth indicators of savory. However, the reasons behind the fact of the better performance of combined nitrogen treatments than the individual ones require more research in the future.

Abstract Biochar is promoted as a means of improving soil fertility. Yet, few experiments have investigated its potential to improve nitrogen (N) use efficiency for high‐yielding maize production in the U.S. Midwest. We tested the hypothesis that biochar application increases inorganic soil N availability during maize growth, leading to higher grain yields and N recovery efficiency while reducing the risk of N leaching following harvest. Four N fertilizer rates (0, 90, 179, and 269 kg ha−1 as urea ammonium nitrate [UAN] solution) were applied with or without biochar (10 Mg ha−1) before planting in a two‐year field study. Inorganic soil N concentration was measured during the growing season (0–15 cm), and deep soil cores were obtained following harvest (0–90 cm). Results show that biochar did not affect maize yield, crop N uptake, or N recovery efficiency (by the difference method) across N rates, and there was no biochar by N rate interaction. While biochar lowered soil inorganic N concentrations on several sampling dates, this did not translate into seasonal differences in cumulative soil N availability, although grain yields in the unfertilized control were ~10% lower with biochar, suggesting net N immobilization. Biochar partially reduced the risk of N leaching following harvest by decreasing soil N concentrations at 30–60 cm, but mean concentrations for 0–90 cm were not different. Compared to previous work highlighting the benefits of biochar in arid climates with low soil fertility, we found no evidence of increased crop yield, NRE, or reduced risk of N leaching on Mollisols in a temperate climate.

Biosolid applications based on crop nitrogen (N) demand have been widely adopted to attenuate nitrate leaching. However, due to the dependence of N supply on the mineralization rate and the early release of the majority of the mineralizable N, there are concerns about a compromise in crop yield and groundwater. A two-year field lysimeter study was conducted to verify whether higher nitrate leaching from biosolid at the early growth stage would compromise maize yield compared to a two-split inorganic N fertilizer application. Four treatments (biosolid + humid rainfall, inorganic fertilizer + humid rainfall, biosolid + subhumid rainfall, inorganic fertilizer + subhumid rainfall) replicated three times were randomly allocated to 12 lysimeters. Overall, the cumulative nitrate leaching from biosolid application was comparable to inorganic fertilization. Nitrate leaching at the early (V0–V14) growth stage of maize from biosolid was lower than inorganic fertilizer, except in the second year under humid rainfall. However, nitrate leaching did not compromise maize yield. Thus, biosolid application based on crop and site specificity can replace inorganic fertilizer in maize cultivation. Further studies may need to ascertain the findings in the humid agro-ecological zone because of the high soil N residue observed under biosolid-humid rainfall treatment.

Aims: Nitrate (NO3−) leaching from forest ecosystems can differ depending on the plant species because of differences in nitrogen (N) retention capacities. Moso bamboo, a fast-growth species, expands into adjacent forests worldwide, potentially leading to increased N retention and subsequently reduced NO3− leaching. Accordingly, this study aims to compare NO3− leaching and potential factors between Moso bamboo and neighboring forest. Methods: We measured NO3− concentrations in soil solutions at a Moso bamboo site (BF) and an adjacent Japanese cedar plantation (CF). We also evaluated soil nitrification and plant N uptake by the in situ depletion method. Results: The NO3− concentration in the soil solution below the root zone (50 cm) was lower in BF (48 ± 8 µmol L−1) than in CF (305 ± 16 µmol L−1). The NO3− concentration in the soil solution was significantly higher for surface soil (0–5 cm) (111 ± 11 µmol L−1) than for soil below the root zone in BF, but not significantly different between these two layers in CF (357 ± 25 µmol L−1), indicating high N retention in BF. The net nitrification rates and root NO3− uptake rates were higher in BF than in CF, indicating that plant N uptake could be the main contributors to the low NO3− leaching. Conclusions: Bamboo invasion has the potential to mitigate forest NO3− leaching due to its high N uptake. Our findings highlight the importance of vegetation with higher N uptake in enhancing N retention under elevated atmospheric N deposition. [ABSTRACT FROM AUTHOR]

This study tested prescribed management practices to reduce nitrogen (N) leaching by 20% while maintaining or improving profitability relative to an existing farm management baseline (Control). N leaching and profitability were estimated for a South Canterbury case study dairy farm using Overseer® Nutrient Budgets and FARMAX Dairy. Three practices were used: (1) reducing N in cows’ diets through low-N feed (fodder beet), (2) recapturing N from soils through catch crops (oats) and (3) diluting urinary N by including plantain in cows’ diet. While most treatments reduced N leaching, significant management inputs were required to achieve a 20% reduction from the Control. Plantain was identified as the key forage for reducing N leaching from the milking platform. Fodder beet and oats had little impact, due to the small area cropped on the milking platform and low dietary substitution. However, they increased profitability relative to the Control. Only one scenario, employing all three forages with biannual direct drilling of plantain, achieved the target, reducing N leaching by 27% and increasing profitability by 2% compared with the Control. The implications of this modelling study for real-life application are that a combination of measures will be needed to achieve large environmental and economic targets. [ABSTRACT FROM AUTHOR]

A suitable nitrogen (N) application rate (NAR) and ideal planting period could improve upland rice productivity, enhance the soil water utilization, and reduce N losses. This study was conducted for the assessment and application of the EPIC model to simulate upland rice productivity, soil water, and N dynamics under different NARs and planting windows (PWs). The nitrogen treatments were 30 (N30), 60 (N60), and 90 (N90) kg N ha−1 with a control (no N applied −N0). Planting was performed as early (PW1), moderately delayed (PW2), and delayed (PW3) between September and December of each growing season. The NAR and PW impacted upland rice productivity and the EPIC model predicted grain yield, aboveground biomass, and harvest index for all NARs in all PWs with a normalized good–excellent root mean square error (RMSEn) of 7.4–9.4%, 9.9–12.2%, and 2.3–12.4% and d-index range of 0.90–0.98, 0.87–0.94, and 0.89–0.91 for the grain yield, aboveground biomass, and harvest index, respectively. For grain and total plant N uptake, RMSEn ranged fair to excellent with values ranging from 10.3 to 22.8% and from 6.9 to 28.1%, and a d-index of 0.87–0.97 and 0.73–0.99, respectively. Evapotranspiration was slightly underestimated for all NARs at all PWs in both seasons with excellent RMSEn ranging from 2.0 to 3.1% and a d-index ranging from 0.65 to 0.97. A comparison of N and water balance components indicated that PW was the major factor impacting N and water losses as compared to NAR. There was a good agreement between simulated and observed soil water contents, and the model was able to estimate fluctuations in soil water contents. An adjustment in the planting window would be necessary for improved upland rice productivity, enhanced N, and soil water utilization to reduce N and soil water losses. Our results indicated that a well-calibrated EPIC model has the potential to identify suitable N and seasonal planting management options. [ABSTRACT FROM AUTHOR]