Journal Description
Nitrogen
Nitrogen
is an international, peer-reviewed, open access journal on the whole field of nitrogen research published quarterly online by MDPI.
- Open Access—free to download, share and reuse content. Authors receive recognition for their contribution when the paper is reused.
- High Visibility: indexed within CAPlus / SciFinder, and many other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision provided to authors approximately 30 days after submission; acceptance to publication is undertaken in 4.5 days (median values for papers published in this journal in the second half of 2021).
- Recognition of Reviewers: APC discount vouchers, optional signed peer-review and reviewer names published annually in the journal.
Latest Articles
Increased Arctic NO3− Availability as a Hydrogeomorphic Consequence of Permafrost Degradation and Landscape Drying
Nitrogen 2022, 3(2), 314-332; https://doi.org/10.3390/nitrogen3020021 - 21 May 2022
Abstract
Climate-driven permafrost thaw alters the strongly coupled carbon and nitrogen cycles within the Arctic tundra, influencing the availability of limiting nutrients including nitrate (NO3−). Researchers have identified two primary mechanisms that increase nitrogen and NO3− availability within permafrost
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Climate-driven permafrost thaw alters the strongly coupled carbon and nitrogen cycles within the Arctic tundra, influencing the availability of limiting nutrients including nitrate (NO3−). Researchers have identified two primary mechanisms that increase nitrogen and NO3− availability within permafrost soils: (1) the ‘frozen feast’, where previously frozen organic material becomes available as it thaws, and (2) ‘shrubification’, where expansion of nitrogen-fixing shrubs promotes increased soil nitrogen. Through the synthesis of original and previously published observational data, and the application of multiple geospatial approaches, this study investigates and highlights a third mechanism that increases NO3− availability: the hydrogeomorphic evolution of polygonal permafrost landscapes. Permafrost thaw drives changes in microtopography, increasing the drainage of topographic highs, thus increasing oxic conditions that promote NO3− production and accumulation. We extrapolate relationships between NO3− and soil moisture in elevated topographic features within our study area and the broader Alaskan Coastal Plain and investigate potential changes in NO3− availability in response to possible hydrogeomorphic evolution scenarios of permafrost landscapes. These approximations indicate that such changes could increase Arctic tundra NO3− availability by ~250–1000%. Thus, hydrogeomorphic changes that accompany continued permafrost degradation in polygonal permafrost landscapes will substantially increase soil pore water NO3− availability and boost future fertilization and productivity in the Arctic.
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(This article belongs to the Special Issue Nitrogen Cycling in Permafrost Soils)
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Open AccessReview
Technologies for Biological and Bioelectrochemical Removal of Inorganic Nitrogen from Wastewater: A Review
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and
Nitrogen 2022, 3(2), 298-313; https://doi.org/10.3390/nitrogen3020020 - 14 May 2022
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Water contamination due to various nitrogenous pollutants generated from wastewater treatment plants is a crucial and ubiquitous environmental problem now-a-days. Nitrogen contaminated water has manifold detrimental effects on human health as well as aquatic life. Consequently, various biological treatment processes are employed to
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Water contamination due to various nitrogenous pollutants generated from wastewater treatment plants is a crucial and ubiquitous environmental problem now-a-days. Nitrogen contaminated water has manifold detrimental effects on human health as well as aquatic life. Consequently, various biological treatment processes are employed to transform the undesirable forms of nitrogen in wastewater to safer ones for subsequent discharge. In this review, an overview of various conventional biological treatment processes (viz. nitrification, denitrification, and anammox) have been presented along with recent novel bioelectrochemical methods (viz. microbial fuel cells and microbial electrolysis cells). Additionally, nitrogen is an indispensable nutrient necessary to produce artificial fertilizers by fixing dinitrogen gas from the atmosphere. Thus, this study also explored the potential capability of various nitrogen recovery processes from wastewater (like microalgae, cyanobacteria, struvite precipitation, stripping, and zeolites) that are used in industries. Further, the trade-offs, challenges posed by these processes have been dwelt on along with other biological processes like CANON, SHARON, OLAND, and others.
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Open AccessArticle
Effects of Nitrogen Fertilization on Weed Flora and Productivity of Soybean [Glycine max (L.) Merr.] Crop
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, , , , , , , , , and
Nitrogen 2022, 3(2), 284-297; https://doi.org/10.3390/nitrogen3020019 - 10 May 2022
Abstract
The literature suggests that nitrogen (N) fertilization increases yield in soybean. This study aimed to investigate the effects of N fertilization on: (i) The performance of soybean, and (ii) the weed flora. A two-year field experiment was carried out in Agrinio, Western Greece.
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The literature suggests that nitrogen (N) fertilization increases yield in soybean. This study aimed to investigate the effects of N fertilization on: (i) The performance of soybean, and (ii) the weed flora. A two-year field experiment was carried out in Agrinio, Western Greece. The experiment was set up in a randomized complete block design, with four organic fertilizer treatments and six replications. The four treatments included 0 kg N ha−1 (N0/unfertilized control) and the application of 80 kg N ha−1, 100 kg N ha−1, and 120 kg N ha−1. The application of 120 N kg ha−1 resulted in the most notable increment of plant height (22.6–24%), biomass (10–13%), LAI values (14–17%), and yield (10–12%) compared to the N0. Compared to the N0, total weed biomass was increased by 26–32%, 34–49%, and 55–57% in N80, N100, and N120, respectively. The values of the H (Shannon), Dmg (Margalef), and J (Pielou) indices were unaffected by the fertilization, hence they did not affect weed biodiversity. CRI (crop resistance index), on the contrary, was negatively affected by N fertilization and was significantly reduced. Overall, our results indicate that the application of 80 kg N ha−1 is more efficient, can effectively improve the soybean performance, and enhance its yield.
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(This article belongs to the Special Issue Nitrogen Metabolism: From Plant Cell to Field and Vice Versa)
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Open AccessArticle
Simulating Increased Permafrost Peatland Plant Productivity in Response to Belowground Fertilisation Using the JULES Land Surface Model
Nitrogen 2022, 3(2), 260-283; https://doi.org/10.3390/nitrogen3020018 - 05 May 2022
Abstract
Several experimental studies have shown that climate-warming-induced permafrost thaw releases previously unavailable nitrogen which can lower nitrogen limitation, increase plant productivity, and counteract some of the carbon released from thawing permafrost. The net effect of this belowground fertilisation effect remains debated and is
[...] Read more.
Several experimental studies have shown that climate-warming-induced permafrost thaw releases previously unavailable nitrogen which can lower nitrogen limitation, increase plant productivity, and counteract some of the carbon released from thawing permafrost. The net effect of this belowground fertilisation effect remains debated and is yet to be included in Earth System models. Here, we included the impact of thaw-related nitrogen fertilisation on vegetation in the Joint UK Land Environment Simulator (JULES) land surface model for the first time. We evaluated its ability to replicate a three-year belowground fertilisation experiment in which JULES was generally able to simulate belowground fertilisation in accordance with the observations. We also ran simulations under future climate to investigate how belowground nitrogen fertilisation affects the carbon cycle. These simulations indicate an increase in plant-available inorganic nitrogen at the thaw front by the end of the century with only the productivity of deep-rooting plants increasing in response. This suggests that deep-rooting species will have a competitive advantage under future climate warming. Our results also illustrate the capacity to simulate belowground nitrogen fertilisation at the thaw front in a global land surface model, leading towards a more complete representation of coupled carbon and nitrogen dynamics in the northern high latitudes.
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(This article belongs to the Special Issue Nitrogen Cycling in Permafrost Soils)
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Age-Related Changes in Water and Nitrogen Utilization in Crop Trees and Understory Vegetation in a Hinoki Cypress Plantation Forest in Kochi City, Southern Japan
Nitrogen 2022, 3(2), 247-259; https://doi.org/10.3390/nitrogen3020017 - 02 May 2022
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Age-related changes in water and nitrogen utilization of crop and understory vegetation in a hinoki cypress plantation forest were investigated from the age of 21 to 46 years in Kochi City, southern Japan. Nitrogen concentration in the leaf litter of hinoki cypress showed
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Age-related changes in water and nitrogen utilization of crop and understory vegetation in a hinoki cypress plantation forest were investigated from the age of 21 to 46 years in Kochi City, southern Japan. Nitrogen concentration in the leaf litter of hinoki cypress showed a decreasing trend with forest age. The leaf δ15N of hinoki cypress was related to a quadratic function and increased from the age of 21 to 26 years and then decreased to the age of 46 years. These results suggest that older hinoki cypress trees utilize soil nitrogen sources with lower δ15N values, and the competition for soil nitrogen with understory vegetation should be stronger. Carbon isotope discrimination (Δ13C) of hinoki cypress decreased from the age of 21 to 30 years and then increased to the age of 46 years. In contrast, the intrinsic water-use efficiency (iWUE) of hinoki cypress increased from the age of 21 to 36 years and then decreased to the age of 46 years. These findings suggest that hinoki cypress trees in the earlier time increased their iWUE by reducing stomatal opening. In the earlier time, the stomatal opening of understory vegetation increased due to higher soil water availability with decreasing stand density of crop trees. In the later time, the iWUE of hinoki cypress decreased due to lower photosynthetic capacity with nitrogen limitation. These results suggest that the increase in the iWUE of hinoki cypress in response to elevated atmospheric carbon dioxide levels should be smaller in the later time because of stronger competition with understory vegetation for soil nitrogen resources.
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Open AccessReview
Communicating Nitrogen Loss Mechanisms for Improving Nitrogen Use Efficiency Management, Focused on Global Wheat
Nitrogen 2022, 3(2), 213-246; https://doi.org/10.3390/nitrogen3020016 - 28 Apr 2022
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Nitrogen (N) losses are a major environmental issue. Globally, crop N fertilizer applications are excessive, and N use efficiency (NUE) is low. N loss represents a significant economic loss to the farmer. NUE is difficult to quantify in real time because of the
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Nitrogen (N) losses are a major environmental issue. Globally, crop N fertilizer applications are excessive, and N use efficiency (NUE) is low. N loss represents a significant economic loss to the farmer. NUE is difficult to quantify in real time because of the multiple chemical–biological–physical factors interacting. While there is much scientific understanding of N interactions in the plant–soil system, there is little formal expression of scientific knowledge in farm practice. The objective of this study was to clearly define the factors controlling NUE in wheat production, focusing on N inputs, flows, transformations, and outputs from the plant–soil system. A series of focus groups were conducted with professional agronomists and industry experts, and their technical information was considered alongside a structured literature review. To express this understanding, clear graphical representations are provided in the text. The analysis of the NUE processes revealed 16 management interventions which could be prioritized to increase farm nitrogen use efficiency. These management interventions were grouped into three categories—inputs, flow between pools, and outputs—and include management options through the range of application errors, fertilizer input choice, root development, pests and disease, soil structure, harvesting and storage errors, and soil resources of water, micronutrients, carbon, nitrogen, and pH. It was noted that technical solutions such as fertilizer formulation and managing organic matter require significant supply chain upgrades. It was also noted that farm-scale decision support would be best managed using a risk/probability-based recommender system rather than generic guidelines.
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Open AccessArticle
An Original Experimental Design to Quantify and Model Net Mineralization of Organic Nitrogen in the Field
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, , , , , and
Nitrogen 2022, 3(2), 197-212; https://doi.org/10.3390/nitrogen3020015 - 15 Apr 2022
Abstract
Improving the assessment and prediction of soil organic nitrogen (N) mineralization is essential: it contributes significantly to the N nutrition of crops and remains a major economic and environmental challenge. Consequently, a network of 137 fields was established in Brittany, France, to represent
[...] Read more.
Improving the assessment and prediction of soil organic nitrogen (N) mineralization is essential: it contributes significantly to the N nutrition of crops and remains a major economic and environmental challenge. Consequently, a network of 137 fields was established in Brittany, France, to represent the wide diversity of soils and cultivation practices in this region. The experimental design was developed to measure net N mineralization for three consecutive years, in order to improve the accuracy of measuring it. Net N mineralization was quantified by the mineral N mass balance, which was estimated from March to October for a maize crop with no N fertilization. The effect of climate on mineralization was considered by calculating normalized time (ndays) and, then, calculating the N mineralization rate (Vn) as the ratio of the mineral N mass balance to normalized time. Strict screening of the experimental data, using agronomic and statistical criteria, resulted in the selection of a subset of 67 fields for data analysis. Mean Vn was relatively high (0.99 kg N ha−1 nday−1) over the period and varied greatly, from 0.62 to 1.46 kg N ha−1 nday−1 for the 10th and 90th percentiles, respectively. The upper soil layer (0–30 cm) was sampled to estimate its physical and chemical properties, particulate organic matter carbon and N fractions (POM-C and POM-N, respectively), soil microbial biomass (SMB), and extractable organic N (EON) determined in a phosphate borate extractant. The strongest correlations between Vn and these variables were observed with EON (r = 0.47), SMB (r = 0.45), POM-N (r = 0.43), and, to a lesser extent, the soil N stock (r = 0.31). Vn was also strongly correlated with a cropping system indicator (r = 0.39). A modeling approach, using generalized additive models, was used to identify and rank the variables with the greatest ability to predict net N mineralization.
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(This article belongs to the Special Issue Soil Nitrogen Supply: Linking Plant Available N to Ecosystems Functions and Productivity)
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Open AccessArticle
Autumn Tillage Reduces the Effect of Plant Cover on Topsoil Nitrogen Leaching
Nitrogen 2022, 3(2), 186-196; https://doi.org/10.3390/nitrogen3020014 - 13 Apr 2022
Abstract
Keeping cover crops to reduce nitrogen leaching often conflicts with timing tillage operations before the soil becomes un-trafficable during winter, while leaving cover crops in the field until spring raises concerns over pre-emptive competition with the following crop. Therefore, farmers may resort to
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Keeping cover crops to reduce nitrogen leaching often conflicts with timing tillage operations before the soil becomes un-trafficable during winter, while leaving cover crops in the field until spring raises concerns over pre-emptive competition with the following crop. Therefore, farmers may resort to tilling their fields in autumn after letting cover crops remain in the fields for only a short period of time. We explore the effects of this practice in a laboratory lysimeter setting by analyzing the leaching of nitrate from intact topsoil cores. Cores were extracted from no-till (NT) plots and plots tilled in autumn (AuT), in areas kept bare (B) and with volunteer winter rye plant cover (V) after harvest. Nitrate breakthrough curves show that V significantly reduced N leaching by 61% relative to B in NT, but did not have a significant effect in AuT. Dissection of leached cores and undisturbed reference cores indicated a significant removal of mineral N from the soil during the lysimeter experiment for all treatments except V in NT. This indicates that volunteer cover removed a crucial amount of leachable N and suggests that tillage counteracted the effect of V in AuT, likely due to a combination of reduced uptake and re-mineralization of N in cover crop residue.
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(This article belongs to the Special Issue Soil Nitrogen Supply: Linking Plant Available N to Ecosystems Functions and Productivity)
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Open AccessReview
Efficiency and Management of Nitrogen Fertilization in Sugar Beet as Spring Crop: A Review
by
, , , , , , and
Nitrogen 2022, 3(2), 170-185; https://doi.org/10.3390/nitrogen3020013 - 12 Apr 2022
Abstract
Sugar beet fertilization is a very complex agrotechnical measure for farmers. The main reason is that technological quality is equally important as sugar beet yield, but the increment of the root yield does not follow the root quality. Technological quality implies the concentration
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Sugar beet fertilization is a very complex agrotechnical measure for farmers. The main reason is that technological quality is equally important as sugar beet yield, but the increment of the root yield does not follow the root quality. Technological quality implies the concentration of sucrose in the root and the possibility of its extraction in the production of white table sugar. The great variability of agroecological factors that directly affect root yield and quality are possible good agrotechnics, primarily by minimizing fertilization. It should be considered that for sugar beet, the status of a single plant available nutrient in the soil is more important than the total amounts of nutrients in the soil. Soil analysis will show us the amount of free nutrients, the degree of soil acidity and the status of individual elements in the soil so that farmers can make a compensation plan. An estimate of the mineralizing ability of the soil, the N min, is very important in determining the amount of mineral nitrogen that the plant can absorb for high root yield and good technological quality. The amount of N needed by the sugar beet crop to be grown is an important factor, and it will always will be in the focus for the producers, especially from the aspect of trying to reduce the N input in agricultural production to preserve soils and their biodiversity but also to establish high yields and quality.
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(This article belongs to the Special Issue Alternatives to Mineral Nitrogen Fertilizers in Agriculture: State of the Art, Challenges and Future Prospects)
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Open AccessArticle
Degradation of N-(n-butyl) Thiophosphoric Triamide (NBPT) with and without Nitrification Inhibitor in Soils
Nitrogen 2022, 3(2), 161-169; https://doi.org/10.3390/nitrogen3020012 - 02 Apr 2022
Abstract
Recent studies have shown that nitrification inhibitor (NI) impairs the efficacy of urease inhibitor, N-(n-butyl) thiophosphoric triamide (NBPT), in reducing ammonia volatilization and urea hydrolysis rate. A laboratory study was conducted to evaluate the influence of NI (specifically 3,4-dimethyl pyrazole
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Recent studies have shown that nitrification inhibitor (NI) impairs the efficacy of urease inhibitor, N-(n-butyl) thiophosphoric triamide (NBPT), in reducing ammonia volatilization and urea hydrolysis rate. A laboratory study was conducted to evaluate the influence of NI (specifically 3,4-dimethyl pyrazole phosphate) on the degradation of NBPT in six soils. Soils were amended with either NBPT (10 mg NBPT kg−1 soil) or NBPT plus NI (DI; 10 mg NBPT + 2.5 mg NI kg−1 soil), incubated at 21 °C, and destructively sampled eight times during a 14-day incubation period. The degradation of NBPT in soil was quantified by measuring NBPT concentration with high-performance liquid chromatography-mass spectrometry, and the degradation rate constant was modeled with an exponential decay function. The study showed that the persistence of NBPT in soil was not influenced by the presence of NI, as the NBPT degradation rate constant across soils was 0.5 d−1 with either NBPT or DI. In contrast, the degradation rate constant was significantly dependent on soils, with values ranging from 0.4 to 1.7 d−1. Soil pH was the most important variable affecting the persistence of NBPT in soils. The half-life of NBPT was 0.4 d in acidic soil and 1.3 to 2.1 d in neutral to alkaline soils. The faster degradation of NBPT in acidic soils may explain its reduced efficacy in such soils.
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(This article belongs to the Special Issue Soil Nitrogen Supply: Linking Plant Available N to Ecosystems Functions and Productivity)
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Open AccessArticle
Simulated Cropping Season Effects on N Mineralization from Accumulated No-Till Crop Residues
Nitrogen 2022, 3(2), 149-160; https://doi.org/10.3390/nitrogen3020011 - 31 Mar 2022
Abstract
The adoption of no-till management practices has increased in the United States over the last decade. In the state of North Dakota, approximately 5.7 million hectares of cropland is managed under no-till or conservation tillage management practices. Even though conservation tillage is known
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The adoption of no-till management practices has increased in the United States over the last decade. In the state of North Dakota, approximately 5.7 million hectares of cropland is managed under no-till or conservation tillage management practices. Even though conservation tillage is known for building soil health, increasing soil organic matter, capturing soil moisture, and reducing wind and water erosion, it also presents a unique best management practice since an increased mass of crop residue remains on the soil surface. Producers are concerned about whether plant needs are being met by nitrogen fertilizer that is currently being applied based on current North Dakota recommendations for long-term no-till systems. A Forman clay loam soil (fine-loamy, mixed, superactive, frigid Calcic Argiudolls) was used in this study, as it represented glacial till soils of the region. We examined whether N mineralization from surface-applied crop residue would result in similar or different results when compared to crop residue mixed into the soil. Soil freeze-thaw contribution to soil N mineralization was also evaluated. Six residue treatments with different C/N ratios including corn (Zea mays L.), soybean (Glycine max L.), forage radish (Raphanus sativus L.), winter pea (Pisum sativum L.), spring wheat (Triticum aestivum L.), and winter wheat (Triticum aestivum L.) were used. Five 10–14-week cycles with a three-week freeze period between each cycle at 0 ºC were evaluated for NO3-N production. Crop residues with a narrow C/N ratio contributed to greater instances of N mineralization during each incubation cycle, and the accumulation of crop residues with a wide C/N ratio over each incubation cycle following the first incubation did not offset the immobilization trends observed in the first incubation. A change in N mineralized in the untreated control soil during the last two incubation cycles may have been caused by freeze-thaw effects or a shift in microbial population due to a lack of fresh C inputs.
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(This article belongs to the Special Issue Soil Nitrogen Supply: Linking Plant Available N to Ecosystems Functions and Productivity)
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Open AccessArticle
Effects of Drainage Water Management in a Corn–Soy Rotation on Soil N2O and CH4 Fluxes
by
, , , , , , , and
Nitrogen 2022, 3(1), 128-148; https://doi.org/10.3390/nitrogen3010010 - 17 Mar 2022
Abstract
Drainage water management (DWM), also known as controlled drainage, is a best management practice (BMP) deployed on drainage ditches with demonstrated success at reducing dissolved nitrogen export from agricultural fields. By slowing discharge from agricultural ditches, subsequent anaerobic soil conditions provide an environment
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Drainage water management (DWM), also known as controlled drainage, is a best management practice (BMP) deployed on drainage ditches with demonstrated success at reducing dissolved nitrogen export from agricultural fields. By slowing discharge from agricultural ditches, subsequent anaerobic soil conditions provide an environment for nitrate to be reduced via denitrification. Despite this success, incomplete denitrification might increase nitrous oxide (N2O) emissions and more reducing conditions might increase methanogenesis, resulting in increased methane (CH4) emissions. These two gases, N2O and CH4, are potent greenhouse gases (GHG) and N2O also depletes stratospheric ozone. This potential pollution swapping of nitrate reduction for GHG production could negatively impact the desirability of this BMP. We conducted three years of static chamber measurements of GHG emissions from the soil surface in farm plots with and without DWM in a corn–soybean rotation on the Delmarva Peninsula. We found that DWM raised the water table at the drainage ditch edge, but had no statistically significant effect on water-filled pore space in the field soil surface. Nor did we find a significant effect of DWM on GHG emissions. These findings are encouraging and suggest that, at least for this farm site, DWM can be used to remove nitrate without a significant tradeoff of increased GHG emissions.
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(This article belongs to the Special Issue Alternatives to Mineral Nitrogen Fertilizers in Agriculture: State of the Art, Challenges and Future Prospects)
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Spatial Variability in Inorganic Soil Nitrogen Production in a Mixed-Vegetation Urban Landscape
by
and
Nitrogen 2022, 3(1), 118-127; https://doi.org/10.3390/nitrogen3010009 - 11 Mar 2022
Abstract
Urban landscapes are not homogeneous, and small-scale variations in plant community or management inputs can give rise to a large range of environmental conditions. In this paper, we investigated the small-scale variability of soil nitrogen (N) properties in a single urban landscape that
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Urban landscapes are not homogeneous, and small-scale variations in plant community or management inputs can give rise to a large range of environmental conditions. In this paper, we investigated the small-scale variability of soil nitrogen (N) properties in a single urban landscape that has distinctly different patches or types of cover. We specifically measured soil net N mineralization, nitrification, and exchangeable forms of inorganic N for patches with traditional turfgrass versus patches with common turfgrass alternatives such as ornamental grasses, groundcovers, and mulches. All soil N properties were variable among landscape patches, showing that soil N processing can vary on scales of a few meters. Notably, both mineralization and nitrification were the highest in a patch covered with perennial peanut, but exchangeable nitrate (NO3−) was low for the same soil, indicating that soils under perennial peanut may be producing high levels of inorganic N but that the produced N does not stay in the soil, possibly leaching to underlying groundwater. We recommend future studies on the mechanisms that drive the variable N properties seen under distinct urban landscape patches, with special emphasis on potential patterns in N losses for mixed-vegetation landscapes.
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(This article belongs to the Special Issue Soil Nitrogen Supply: Linking Plant Available N to Ecosystems Functions and Productivity)
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Open AccessReview
Review on Detection Methods of Nitrogen Species in Air, Soil and Water
by
and
Nitrogen 2022, 3(1), 101-117; https://doi.org/10.3390/nitrogen3010008 - 04 Mar 2022
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Nitrogen species present in the atmosphere, soil, and water play a vital role in ecosystem stability. Reactive nitrogen gases are key air quality indicators and are responsible for atmospheric ozone layer depletion. Soil nitrogen species are one of the primary macronutrients for plant
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Nitrogen species present in the atmosphere, soil, and water play a vital role in ecosystem stability. Reactive nitrogen gases are key air quality indicators and are responsible for atmospheric ozone layer depletion. Soil nitrogen species are one of the primary macronutrients for plant growth. Species of nitrogen in water are essential indicators of water quality, and they play an important role in aquatic environment monitoring. Anthropogenic activities have highly impacted the natural balance of the nitrogen species. Therefore, it is critical to monitor nitrogen concentrations in different environments continuously. Various methods have been explored to measure the concentration of nitrogen species in the air, soil, and water. Here, we review the recent advancements in optical and electrochemical sensing methods for measuring nitrogen concentration in the air, soil, and water. We have discussed the advantages and disadvantages of the existing methods and the future prospects. This will serve as a reference for researchers working with environment pollution and precision agriculture.
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Open AccessArticle
Biochar Applied with Inorganic Nitrogen Improves Soil Carbon, Nitrate and Ammonium Content of a Sandy Loam Temperate Soil
by
, , , , and
Nitrogen 2022, 3(1), 90-100; https://doi.org/10.3390/nitrogen3010007 - 23 Feb 2022
Abstract
Biochar is suggested to improve soil properties. However, its combination with inorganic nitrogen (N) fertilizer in temperate soils is not well understood. This study compared the effect of fertilizer N-biochar-combinations (NBC) and fertilizer-N (FN) on total soil N (TSN), soil organic carbon (SOC),
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Biochar is suggested to improve soil properties. However, its combination with inorganic nitrogen (N) fertilizer in temperate soils is not well understood. This study compared the effect of fertilizer N-biochar-combinations (NBC) and fertilizer-N (FN) on total soil N (TSN), soil organic carbon (SOC), soil nitrate (NO3−–N), and ammonium (NH4+–N). Soil samples were taken from experiments at Efaw and Lake Carl Blackwell (LCB), Oklahoma, USA with ten treatments consisting of three N rates (50, 100, and 150 kg N ha−1) and three biochar rates (5, 10, and 15 t ha−1). Results at Efaw showed greater TSN and SOC under NBC compared to FN by 3 and 21%, respectively. No percentage difference was observed for NH4+–N while NO3−–N was lower by 7%. At LCB, TSN, SOC, NO3−–N, and NH4+–N were higher under NBC by 5, 18, 24, and 10%, respectively, compared to FN. Whereas application of biochar improved SOC at both sites, NO3−–N and NH4+–N were only significant at LCB site with a sandy loam soil but not at Efaw with silty clay loam. Therefore, biochar applied in combination with inorganic N can improve N availability with potential to increase crop N uptake on coarse textured soils.
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(This article belongs to the Special Issue Soil Nitrogen Supply: Linking Plant Available N to Ecosystems Functions and Productivity)
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Open AccessArticle
Negligible Response of Transpiration to Late-Summer Nitrogen Fertilization in Japanese Oak (Quercus crispula)
Nitrogen 2022, 3(1), 76-89; https://doi.org/10.3390/nitrogen3010006 - 03 Feb 2022
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Increased atmospheric nitrogen (N) deposition, caused by anthropogenic activities, has various effects on forest ecosystems. Some reports have investigated the responses in tree transpiration to N addition, but few studies have measured the short-term response of mature tree transpiration to N fertilization. This
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Increased atmospheric nitrogen (N) deposition, caused by anthropogenic activities, has various effects on forest ecosystems. Some reports have investigated the responses in tree transpiration to N addition, but few studies have measured the short-term response of mature tree transpiration to N fertilization. This study aimed to clarify the short-term transpiration response in 27-year-old deciduous hardwood trees to an increase in N availability. We established two plot types (control and N-fertilized plots) in Quercus crispula plantation stands in Hokkaido, Northern Japan. We measured sap flow density (SFD; cm3 m−2 s−1) using a thermal dissipation method for three months during the growing season. In the N-fertilized plot, we added 50 kg N ha−1 yr−1 of ammonium nitrate (NH4NO3) to the forest floor in the middle of the measurement periods. For daily mean SFD, we did not find a significant difference between the control and the N-fertilized plots. Leaf N contents did not differ between treatments, implying a negligible difference in physiological responses and transpiration rates. The slight difference between treatments could be because the trees had already foliated before applying the N fertilizer to our deciduous hardwood trees. The present results indicate that the potential increase in N deposition during the growing season does not immediately alter tree transpiration.
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Open AccessEditorial
Acknowledgment to Reviewers of Nitrogen in 2021
Nitrogen 2022, 3(1), 74-75; https://doi.org/10.3390/nitrogen3010005 - 28 Jan 2022
Abstract
Rigorous peer-reviews are the basis of high-quality academic publishing [...]
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Combination of Inorganic Nitrogen and Organic Soil Amendment Improves Nitrogen Use Efficiency While Reducing Nitrogen Runoff
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, , , , , and
Nitrogen 2022, 3(1), 58-73; https://doi.org/10.3390/nitrogen3010004 - 20 Jan 2022
Abstract
Improved nitrogen fertiliser management and increased nitrogen use efficiency (NUE) can be achieved by synchronising nitrogen (N) availability with plant uptake requirements. Organic materials in conjunction with inorganic fertilisers provide a strategy for supplying plant-available N over the growing season and reducing N
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Improved nitrogen fertiliser management and increased nitrogen use efficiency (NUE) can be achieved by synchronising nitrogen (N) availability with plant uptake requirements. Organic materials in conjunction with inorganic fertilisers provide a strategy for supplying plant-available N over the growing season and reducing N loss. This study investigated whether a combined application of inorganic N with an organic soil amendment could improve nitrogen use efficiency by reducing N loss in runoff. Nitrogen runoff from a ryegrass (Lolium multiflorum) cover was investigated using a rainfall simulator. Nitrogen was applied at low, medium and high (50, 75 and 100 kg/ha) rates as either (NH4)2SO4 or in combination with a poultry manure-based organic material. We showed that the NUE in the combination (58–75%) was two-fold greater than in (NH4)2SO4 (24–42%). Furthermore, this combination also resulted in a two-fold lower N runoff compared with the inorganic fertiliser alone. This effect was attributed to the slower rate of N release from the organic amendment relative to the inorganic fertiliser. Here, we demonstrated that the combined use of inorganic and organic N substrates can reduce nutrient losses in surface runoff due to a better synchronisation of N availability with plant uptake requirements.
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(This article belongs to the Special Issue Soil Nitrogen Supply: Linking Plant Available N to Ecosystems Functions and Productivity)
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Identifying Sustainable Nitrogen Management Practices for Tea Plantations
Nitrogen 2022, 3(1), 43-57; https://doi.org/10.3390/nitrogen3010003 - 14 Jan 2022
Abstract
Tea (Camellia sinensis L.) is the most widely consumed beverage in the world. It is mostly grown in the tropics with a heavy dependence on mineral nitrogen (N) fertilisers to maintain high yields while minimising the areas under cultivation. However, N is
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Tea (Camellia sinensis L.) is the most widely consumed beverage in the world. It is mostly grown in the tropics with a heavy dependence on mineral nitrogen (N) fertilisers to maintain high yields while minimising the areas under cultivation. However, N is often applied in excess of crop requirements, resulting in substantial adverse environmental impacts. We conducted a systematic literature review, synthesising the findings from 48 studies to assess the impacts of excessive N application on soil health, and identify sustainable, alternative forms of N management. High N applications lead to soil acidification, N leaching to surface and groundwater, and the emission of greenhouse gases including nitrous oxide (N2O). We identified a range of alternative N management practices, the use of organic fertilisers, a mixture of organic and inorganic fertilisers, controlled release fertilisers, nitrification inhibitors and soil amendments including biochar. While many practices result in reduced N loading or mitigate some adverse impacts, major trade-offs include lower yields, and in some instances increased N2O emissions. Practices are also frequently trialled in isolation, meaning there may be a missed opportunity from assessing synergistic effects. Moreover, adoption rates of alternatives are low due to a lack of knowledge amongst farmers, and/or financial barriers. The use of site-specific management practices which incorporate local factors (for example climate, tea variety, irrigation requirements, site slope, and fertiliser type) are therefore recommended to improve sustainable N management practices in the long term.
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(This article belongs to the Special Issue Alternatives to Mineral Nitrogen Fertilizers in Agriculture: State of the Art, Challenges and Future Prospects)
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Nutrient Availability for Lactuca sativa Cultivated in an Amended Peatland: An Ionic Exchange Study
Nitrogen 2022, 3(1), 26-42; https://doi.org/10.3390/nitrogen3010002 - 14 Jan 2022
Abstract
Few conservation strategies have been applied to cultivated peatland. This field study over one growth cycle of Lactuca sativa examined the effect of plant-based, high-C/N-ratio amendments in a real farming situation on peatland. Plant Root Simulator (PRS®) probes were used directly
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Few conservation strategies have been applied to cultivated peatland. This field study over one growth cycle of Lactuca sativa examined the effect of plant-based, high-C/N-ratio amendments in a real farming situation on peatland. Plant Root Simulator (PRS®) probes were used directly in the field to assess the impacts of incorporating Miscanthus x giganteus straw and Salix miyabeana chips on nutrient availability for lettuce. The results showed that lettuce yield decreased by 35% in the miscanthus straw treatment and by 14% in the willow chip treatment. In addition, the nitrogen flux rate was severely reduced during crop growth (75% reduction) and the plant N uptake index was much lower in the amended treatments than in the control. The phosphorus supply rate was also significantly lower (24% reduction) in the willow treatment. The influence of sampling zone was significant as well, with most macro-nutrients being depleted in the root zone and most micro-nutrients being mobilized. Additional work is needed to optimize the proposed conservation strategy and investigate the effects of consecutive years of soil amendment on different vegetable crops and in different types of cultivated peatlands to confirm and generalize the findings of this study. Future field studies should also explore the long-term carbon dynamics under plant-based, high-C/N-ratio amendments to determine if they can offset annual C losses.
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(This article belongs to the Special Issue Soil Nitrogen Supply: Linking Plant Available N to Ecosystems Functions and Productivity)
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Nitrogen
Nitrogen Metabolism: From Plant Cell to Field and Vice Versa
Guest Editor: Marouane BaslamDeadline: 1 June 2022
Special Issue in
Nitrogen
The Role of Soil Nitrogen Cycling and Its Impacts in Managed Terrestrial Ecosystems: A Shift with Environmental Changes
Guest Editors: Chengrong Chen, Johnvie GoloranDeadline: 1 August 2022
Special Issue in
Nitrogen
Microbial Nitrogen Cycling
Guest Editor: Rosa María Martínez-EspinosaDeadline: 15 October 2022
Special Issue in
Nitrogen
Alternatives to Mineral Nitrogen Fertilizers in Agriculture: State of the Art, Challenges and Future Prospects
Guest Editor: Germán TortosaDeadline: 31 October 2022