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Effects of Corn Silage and Alfalfa Hay on Production and Nitrogen Excretion in Lactating Dairy Cows
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Patterns of Leaf C, N, and P Stoichiometry in Populus euphratica Communities: A Local-Scale Study of Desert Riparian Zone in the Lower Heihe River, Northwest China
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Nitrogen Fertilizer Effects on Growth, Vegetation Indices, and Ammonia Volatilization in Korean Radish (Raphanus sativus L.)
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 for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within ESCI (Web of Science), Scopus, CAPlus / SciFinder, and other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 19.7 days after submission; acceptance to publication is undertaken in 3.3 days (median values for papers published in this journal in the first half of 2025).
- Journal Rank: CiteScore - Q2 (Agricultural and Biological Sciences (miscellaneous))
- Recognition of Reviewers: APC discount vouchers, optional signed peer-review and reviewer names published annually in the journal.
Impact Factor:
2.3 (2024);
5-Year Impact Factor:
2.1 (2024)
Latest Articles
Microbial Alliance of Paenibacillus sp. SPR11 and Bradyrhizobium yuanmingense PR3 Enhances Nitrogen Fixation, Yield, and Salinity Tolerance in Black Gram Under Saline, Nutrient-Depleted Soils
Nitrogen 2025, 6(3), 66; https://doi.org/10.3390/nitrogen6030066 - 7 Aug 2025
Abstract
Salinity is a major abiotic stress limiting black gram (Vigna mungo) productivity, particularly in arid and semi-arid regions. Saline soils negatively impact plant growth, nodulation, nitrogen fixation, and yield. This study evaluated the efficacy of co-inoculating salt-tolerant plant growth-promoting bacteria Paenibacillus
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Salinity is a major abiotic stress limiting black gram (Vigna mungo) productivity, particularly in arid and semi-arid regions. Saline soils negatively impact plant growth, nodulation, nitrogen fixation, and yield. This study evaluated the efficacy of co-inoculating salt-tolerant plant growth-promoting bacteria Paenibacillus sp. SPR11 and Bradyrhizobium yuanmingense PR3 on black gram performance under saline field conditions (EC: 8.87 dS m−1; pH: 8.37) with low organic carbon (0.6%) and nutrient deficiencies. In vitro assays demonstrated the biocontrol potential of SPR11, inhibiting Fusarium oxysporum and Macrophomina phaseolina by 76% and 62%, respectively. Germination assays and net house experiments under 300 mM NaCl stress showed that co-inoculation significantly improved physiological traits, including germination rate, root length (61.39%), shoot biomass (59.95%), and nitrogen fixation (52.4%) in nitrogen-free media. Field trials further revealed enhanced stress tolerance markers: chlorophyll content increased by 54.74%, proline by 50.89%, and antioxidant enzyme activities (SOD, CAT, PAL) were significantly upregulated. Electrolyte leakage was reduced by 55.77%, indicating improved membrane stability. Agronomic performance also improved, with co-inoculated plants showing increased root length (7.19%), grain yield (15.55 q ha−1; 77.04% over control), total biomass (26.73 q ha−1; 57.06%), and straw yield (8.18 q ha−1). Pod number, seed count, and seed weight were also enhanced. Nutrient analysis showed elevated uptake of nitrogen, phosphorus, potassium, and key micronutrients (Zn, Fe) in both grain and straw. To the best of our knowledge, this is the very first field-based report demonstrating the synergistic benefits of co-inoculating Paenibacillus sp. SPR11 and Bradyrhizobium yuanmingense PR3 in black gram under saline, nutrient-poor conditions without external nitrogen inputs. The results highlight a sustainable strategy to enhance legume productivity and resilience in salt-affected soils.
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(This article belongs to the Special Issue Microbial Interactions with Plants: Advancing Nitrogen Fixation, Uptake, and Utilization)
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Open AccessReview
Harnessing Legume Productivity in Tropical Farming Systems by Addressing Challenges Posed by Legume Diseases
by
Catherine Hazel Aguilar, David Pires, Cris Cortaga, Reynaldo Peja, Jr., Maria Angela Cruz, Joanne Langres, Mark Christian Felipe Redillas, Leny Galvez and Mark Angelo Balendres
Nitrogen 2025, 6(3), 65; https://doi.org/10.3390/nitrogen6030065 - 5 Aug 2025
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Legumes are among the most important crops globally, serving as a major food source for protein and oil. In tropical regions, the cultivation of legumes has expanded significantly due to the increasing demand for food, plant-based products, and sustainable agriculture practices. However, tropical
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Legumes are among the most important crops globally, serving as a major food source for protein and oil. In tropical regions, the cultivation of legumes has expanded significantly due to the increasing demand for food, plant-based products, and sustainable agriculture practices. However, tropical environments pose unique challenges, including high temperatures, erratic rainfall, soil infertility, and a high incidence of pests and diseases. Indeed, legumes are vulnerable to infections caused by bacteria, fungi, oomycetes, viruses, and nematodes. This review highlights the importance of legumes in tropical farming and discusses major diseases affecting productivity and their impact on the economy, environment, and lives of smallholder legume farmers. We emphasize the use of legume genetic resources and breeding, and biotechnology innovations to foster resistance and address the challenges posed by pathogens in legumes. However, an integrated approach that includes other cultivation techniques (e.g., crop rotation, rational fertilization, deep plowing) remains important for the prevention and control of diseases in legume crops. Finally, we highlight the contributions of plant genetic resources to smallholder resilience and food security.
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Open AccessArticle
Fertilization Promotes the Recovery of Plant Productivity but Decreases Biodiversity in a Khorchin Degraded Grassland
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Lina Zheng, Wei Zhao, Shaobo Gao, Ruizhen Wang, Haoran Yan and Mingjiu Wang
Nitrogen 2025, 6(3), 64; https://doi.org/10.3390/nitrogen6030064 - 4 Aug 2025
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Fertilization is a critical measure for vegetation restoration and ecological reconstruction in degraded grasslands. However, little is known about the long-term effects of different combinations of nitrogen (N), phosphorus (P), potassium (K) on plant and microbial communities in degraded grasslands. This study conducted
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Fertilization is a critical measure for vegetation restoration and ecological reconstruction in degraded grasslands. However, little is known about the long-term effects of different combinations of nitrogen (N), phosphorus (P), potassium (K) on plant and microbial communities in degraded grasslands. This study conducted a four-year (2017–2020) N, P, K addition experiment in the Khorchin Grassland, a degraded typical grassland located in Zhalute Banner, Tongliao City, Inner Mongolia, to investigate the effects of fertilization treatment on plant functional groups and microbial communities after grazing exclusion. Our results showed that the addition of P, NP, and NPK compound fertilizers significantly increased aboveground biomass of the plant community, which is mainly related to the improvement of nutrient availability to promote the growth of specific plant functional groups, especially annual and biennial plants and perennial bunchgrasses. However, the addition of N, P, and NP fertilizers significantly reduced the species diversity of the plant community. At the same time, the addition of N, P, and NP fertilizers and the application of N and NP significantly reduced fungal species diversity but had no significant effect on soil bacteria. Our study provides new insights into the relationships between different types of fertilization and plant community productivity and biodiversity in degraded grasslands over four years of fertilization, which is critical for evaluating the effect of fertilization on the restoration of degraded grassland.
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Open AccessArticle
Assessing Controlled Traffic Farming as a Precision Agriculture Strategy for Minimising N2O Losses
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Bawatharani Raveendrakumaran, Miles Grafton, Paramsothy Jeyakumar, Peter Bishop and Clive Davies
Nitrogen 2025, 6(3), 63; https://doi.org/10.3390/nitrogen6030063 - 4 Aug 2025
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Intensive vegetable farming emits high nitrous oxide (N2O) due to traffic-induced compaction, highlighting the need for preventing nitrogen (N) losses through better traffic management. This study examined the effects of Controlled Traffic Farming (CTF) and Random Traffic Farming (RTF) on N
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Intensive vegetable farming emits high nitrous oxide (N2O) due to traffic-induced compaction, highlighting the need for preventing nitrogen (N) losses through better traffic management. This study examined the effects of Controlled Traffic Farming (CTF) and Random Traffic Farming (RTF) on N2O emissions using intact soil cores (diameter: 18.7 cm; depth: 25 cm) collected from a vegetable production system in Pukekohe, New Zealand. Soil cores from CTF beds, CTF tramlines, and RTF plots were analysed under fertilised (140 kg N/ha) and unfertilised conditions. N2O fluxes were monitored over 58 days using gas chambers. The fertilised RTF system significantly (p < 0.05) increased N2O emissions (5.4 kg N2O–N/ha) compared to the unfertilised RTF system (1.53 kg N2O–N/ha). The emission from fertilised RTF was 46% higher than the maximum N2O emissions (3.7 kg N2O–N/ha) reported under New Zealand pasture conditions. The fertilised CTF system showed a 31.6% reduction in N2O emissions compared to fertilised RTF and did not differ significantly from unfertilised CTF. In general, CTF has demonstrated some resilience against fertiliser-induced N2O emissions, indicating the need for further investigation into its role as a greenhouse gas mitigation strategy.
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Open AccessArticle
Untangling the Toxicity Dilemma of the Orbetello Lagoon Sediments in Paracentrotus lividus Bioassay: Trace Metals vs. Ammonium
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Davide Sartori, Simona Macchia, Giorgio Tranchida, Paolo Altemura, Vincenzo Tancredi, Alice Scuderi, Maria Elena Piccione, Stefano Ferrari and Andrea Gaion
Nitrogen 2025, 6(3), 62; https://doi.org/10.3390/nitrogen6030062 - 28 Jul 2025
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This study assesses sediment toxicity in the historically contaminated Orbetello Lagoon (southern Tuscany) using Paracentrotus lividus embryo development bioassays. Elutriates from 15 sites were analysed for trace metals, organic matter, and ammonium. Despite elevated mercury concentrations, toxicity did not consistently correlate with metal
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This study assesses sediment toxicity in the historically contaminated Orbetello Lagoon (southern Tuscany) using Paracentrotus lividus embryo development bioassays. Elutriates from 15 sites were analysed for trace metals, organic matter, and ammonium. Despite elevated mercury concentrations, toxicity did not consistently correlate with metal levels. Instead, Principal Component Analysis (PCA) identified ammonium as a key driver of developmental toxicity, suggesting that it significantly influences both biological effects and metal bioavailability. These results demonstrate that ammonium, often overlooked, can confound sediment toxicity assessments and should be integrated into risk evaluation frameworks for coastal systems affected by legacy pollution.
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Open AccessArticle
Effect of Biochar-Coated Urea on Soil Nitrogen, Plant Uptake, and Sweet Corn Yield in Sandy Soil
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Sa’adah Shofiati, Gabryna Auliya Nugroho, Zaenal Kusuma and Syahrul Kurniawan
Nitrogen 2025, 6(3), 61; https://doi.org/10.3390/nitrogen6030061 - 28 Jul 2025
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The low nitrogen-use efficiency (NUE) in sandy soils, due to high porosity and poor nutrient retention, necessitates proper management in fertilization. This study aims to evaluate the effect of biochar-coated urea (BCU) with different coating thicknesses and nitrogen doses on soil nitrogen content,
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The low nitrogen-use efficiency (NUE) in sandy soils, due to high porosity and poor nutrient retention, necessitates proper management in fertilization. This study aims to evaluate the effect of biochar-coated urea (BCU) with different coating thicknesses and nitrogen doses on soil nitrogen content, nitrogen uptake, NUE, growth, and yield of sweet corn in sandy soil. The experiment used a factorial randomized block design with two factors, including biochar coating thicknesses (i.e., 14% and 29%) and fertilization doses (i.e., 50%, 100%, 150%, 200%, and 250%). The results showed that the 29% biochar coating thickness led to 9.9–21.3% higher plant height, N uptake, and N-use efficiency, but it led to 22.8% lower yield, as compared to the 14% biochar coating thickness. Additionally, the application of BCU doses of 100% and 150% (~161 and 241.5 kg N/ha) led to 9.2–97.3% higher maize growth, yield, N uptake, and NEU as compared to the other doses (i.e., 50%, 100%, 250%). This study confirmed that the combination of a 29% biochar coating thickness with 150% of the recommended BCU dose (~241.5 kg N/ha) was the best combination, resulting in the highest N uptake, growth, and yield of maize.
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Open AccessArticle
Nitrogen Fertilization and Glomus Mycorrhizal Inoculation Enhance Growth and Secondary Metabolite Accumulation in Hyssop (Hyssopus officinalis L.)
by
Saeid Hazrati, Marzieh Mohammadi, Saeed Mollaei, Mostafa Ebadi, Giuseppe Pignata and Silvana Nicola
Nitrogen 2025, 6(3), 60; https://doi.org/10.3390/nitrogen6030060 - 26 Jul 2025
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Nitrogen (N) availability often limits primary productivity in terrestrial ecosystems, and arbuscular mycorrhizal fungi (AMF) can enhance plant N acquisition. This study investigated the interactive effects of N fertilization and AMF inoculation on N uptake, plant performance and phenolic acid content in Hyssopus
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Nitrogen (N) availability often limits primary productivity in terrestrial ecosystems, and arbuscular mycorrhizal fungi (AMF) can enhance plant N acquisition. This study investigated the interactive effects of N fertilization and AMF inoculation on N uptake, plant performance and phenolic acid content in Hyssopus officinalis L., with the aim of promoting sustainable N management in H. officinalis cultivation. A factorial randomized complete block design was employed to evaluate four AMF inoculation strategies (no inoculation, root inoculation, soil inoculation and combined root–soil inoculation) across three N application rates (0, 0.5 and 1,1 g N pot−1 (7 L)) in a controlled greenhouse environment. Combined root and soil AMF inoculation alongside moderate N fertilization (0.5 mg N pot−1) optimized N use efficiency, maximizing plant biomass and bioactive compound production. Compared to non-inoculated controls, this treatment combination increased N uptake by 30%, phosphorus uptake by 24% and potassium uptake by 22%. AMF colonization increased chlorophyll content and total phenolic compounds under moderate N supply. However, excessive N application (1 g N pot−1) reduced AMF effectiveness and secondary metabolite accumulation. Notably, AMF inoculation without N fertilization yielded the highest levels of anthocyanin and salicylic acid, indicating differential N-dependent regulation of specific biosynthetic pathways. The interaction between AMF and N demonstrated that moderate N fertilization (0.5 g N pot−1) combined with dual inoculation strategies can reduce total N input requirements by 50%, while maintaining optimal plant performance. These findings provide practical insights for developing N-efficient cultivation protocols in medicinal plant production systems, contributing to sustainable agricultural practices that minimize environmental N losses.
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Open AccessArticle
Soybean (Glycine Max L.) Grain Yield Response to Inoculation with Novel Bradyrhizobia Strains Across Different Soil Fertility Conditions in Zimbabwe
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Akinson Tumbure, Grace Kanonge, Collis S. Mukungurutse, Cathrine Mushangwe, Tonny P. Tauro and Mazvita S. Chiduwa
Nitrogen 2025, 6(3), 59; https://doi.org/10.3390/nitrogen6030059 - 23 Jul 2025
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The agronomic effectiveness of biofertilizers is influenced by strain origin, genetic identity, crop genotype, soil type, and environmental conditions. For best results, both the plant and rhizobia strain must be adapted to the common harsh soil conditions in the tropics. While plant varieties
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The agronomic effectiveness of biofertilizers is influenced by strain origin, genetic identity, crop genotype, soil type, and environmental conditions. For best results, both the plant and rhizobia strain must be adapted to the common harsh soil conditions in the tropics. While plant varieties have changed over the years, complementary research on new strains effectiveness under varying soil fertility conditions has lagged in southern Africa. Seven field experiments were established in the main soybean-producing areas of Zimbabwe in the north, central, and north–east regions to evaluate agronomic benefits of new rhizobia strains against the current exotic commercial strain (MAR1491). One site was irrigated (site 3), and the other six sites were rainfed (sites 1, 2, 4, 5, 6, and 7). While trends in inoculation response varied from site to site due to site conditions, inoculation with the strains NAZ15, NAZ25, and NAK128 consistently yielded high grain yields, which were similar to the current commercial strain MAR1491 and to application of mineral fertilizer (51.75 and 100 kg N ha−1). Grain yield levels were generally below 2 t ha−1 for sites 2, 3, and 5 and above 2 t ha−1 for sites 1, 4, and 6, while for the irrigated site 3, they ranged upwards of 3 t ha−1. When irrigated, all strains except NAK9 performed similarly in terms of grain yields and aboveground N uptake. Further testing on the inclusion of the indigenous strains NAZ15, NAZ25, and NAK128 in multi-strain commercial inoculant production targeting application in regions and soils where they excel beyond the current exotic strain MAR1491 is recommended.
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Open AccessArticle
Response of Dittany Cultivation to an Organic Fertilization on Nitrogen and Phosphorus Content, Uptake and Use Efficiency
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Aikaterini Molla, Anastasia Fountouli, Christina Emmanouil, Evaggelia Chatzikirou and Elpiniki Skoufogianni
Nitrogen 2025, 6(3), 58; https://doi.org/10.3390/nitrogen6030058 - 16 Jul 2025
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The growing negative environmental effects associated with chemical fertilizers have led to the promotion of organic fertilizers in agriculture. The purpose of this study was to evaluate the impacts of organic fertilization on nitrogen and phosphorus content, uptake and use efficiency in Origanum
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The growing negative environmental effects associated with chemical fertilizers have led to the promotion of organic fertilizers in agriculture. The purpose of this study was to evaluate the impacts of organic fertilization on nitrogen and phosphorus content, uptake and use efficiency in Origanum dictamnus (Dittany) cultivation. With this aim, a randomized complete blocks field experiment was carried out in Istron Kalou Xoriou (Agios Nikolaos—Crete). The study included three fertilization treatments (N0: 0 kg/ha−1, N1: 1250 kg/ha−1 and N2: 2500 kg/ha−1). Throughout the growing period, measurements were taken for the plant’s content, uptake and efficiency indices of total nitrogen (TN) and phosphorus (P). The findings indicated that the fertilization doses affect nutrient uptake and efficiency. The highest values of TN and P were recorded 60 days after transplants. N1 treatment showed the greatest improvement in nitrogen use efficiency, while phosphorus use efficiency reached its maximum level under N2 treatment. That research can contribute to achieving an in-depth insight of organic fertilization practices for aromatic and medicinal plants such as Dittany, promoting a sustainable agricultural strategy and enhancing product quality.
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Open AccessCommunication
Differential N2O-Producing Activity of Soil Fungi Across Agricultural Systems: High in Vegetable Fields and Vineyards, Low in Paddies
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Shutan Ma, Jintao Zhang, Ting Wu, Yuqing Miao, Hua Fang, Haitao Wang, Huayuan Niu and Lan Ma
Nitrogen 2025, 6(3), 57; https://doi.org/10.3390/nitrogen6030057 - 11 Jul 2025
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The substrate-induced respiration-inhibition (SIRIN) method has been used to estimate fungi-derived N2O emissions, but its contribution to soil N2O emissions remains unclear. There is a need to quantify the fungal fraction of N2O production more precisely. Here,
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The substrate-induced respiration-inhibition (SIRIN) method has been used to estimate fungi-derived N2O emissions, but its contribution to soil N2O emissions remains unclear. There is a need to quantify the fungal fraction of N2O production more precisely. Here, using isotopocule analysis, we assessed the relative contribution of fungi to soil N2O production potential under denitrifying conditions, where key limiting factors of denitrification (soil moisture, soil NO3−, and electron donor) were removed. The result showed that the ratio of fungi-derived N2O emissions (RF) was 0.83~4.28% in paddy soils, 13.80~23.21% in vineyard soils, and 15.34~65.94% in vegetable field soils, respectively. This indicated that the bacteria were the dominator of soil N2O production potential in most cases, but fungal pathways could be significant in vegetable field soils. The experiment with bactericide addition showed that inhibitors could affect non-target microorganisms in the SIRIN method. Our further analyses suggest that it is worth to explore the effect of soil organic carbon and microbial synergies on fungi-derived N2O emissions.
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Open AccessArticle
Unraveling Carbon and Nitrogen Dynamics in Cattle Manure: New Insights from Litterbag Incubation
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Thierry Morvan, Françoise Watteau and Paul Robin
Nitrogen 2025, 6(3), 56; https://doi.org/10.3390/nitrogen6030056 - 11 Jul 2025
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Management of livestock manure is a major concern due to its environmental impacts; consequently, laboratory-based incubations aim to quantify the C and N mineralization of organic matter (OM) to assess its potential to supply OM to soils. However, they can be limited by
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Management of livestock manure is a major concern due to its environmental impacts; consequently, laboratory-based incubations aim to quantify the C and N mineralization of organic matter (OM) to assess its potential to supply OM to soils. However, they can be limited by methodological constraints, notably the drying process of organic products. While litterbag experiments allow in situ decomposition of OM to be monitored, they often focus only on mass loss on a dry matter basis, which may overestimate biodegradation rates. To address these limitations, we designed an experiment that combined the measurement of material fluxes with the characterization of OM using transmission electron microscopy. Raw and dried farmyard cattle manure were incorporated into the soil and incubated in litterbags (200 µm mesh) for 301 days. The results demonstrated that drying significantly altered the biochemical composition of the cattle manure and influenced its microbial dynamics at the beginning of the incubation. However, this alteration did not influence the C mineralization rate at the end of incubation. Biodegradation alone could not explain C losses from litterbags after day 112 of incubation, which supports the assertion that physical and biological processes transferred large amounts of matter from the litterbags to the soil. These results highlight the importance of conditioning samples before laboratory incubations.
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Open AccessArticle
Reducing Nitrogen Input Increases the Efficacy of Soil Nitrogen Utilization by Regulating Cotton–Arbuscular Mycorrhizal Fungi–Soil Nitrogen Interactions
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Hushan Wang, Yunzhu He, Zihui Shen, Mengjuan Liu, Wangfeng Zhang and Xiaozhen Pu
Nitrogen 2025, 6(3), 55; https://doi.org/10.3390/nitrogen6030055 - 3 Jul 2025
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Crops and arbuscular mycorrhizal (AM) fungi can enhance nitrogen (N) transformation and utilization efficiency in the soil, and this effect is regulated by soil N application rates. However, it remains unclear whether the N utilization efficiency of cotton can be improved through the
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Crops and arbuscular mycorrhizal (AM) fungi can enhance nitrogen (N) transformation and utilization efficiency in the soil, and this effect is regulated by soil N application rates. However, it remains unclear whether the N utilization efficiency of cotton can be improved through the symbiosis of cotton with AM fungi under reduced N application rates. Therefore, we conducted 15N labeling experiments using a compartmentalized culture system with Gossypium hirsutum L. as the experimental plant. We established three N treatments (0.15 g·kg−1, 0.10 g·kg−1 and 0 g·kg−1) to investigate the effects of different fertilization rates on N utilization, soil N priming effects, and differences in N accumulation in various parts of cotton plants within the soil–AM fungi–cotton system. The results indicate that under reduced N application, symbiosis between cotton and AM fungi increased the N fertilizer utilization efficiency and the soil N priming effect. Specifically, reducing the fertilization dosage from 0.15 g·kg−1 to 0.10 g·kg−1 increased the N fertilizer utilization efficiency and soil N priming effect by 8.87% and 11.67%, respectively, and decreased the N loss rate by 7.02%. The symbiosis between cotton and AM fungi after N reduction significantly increased N accumulation in the roots and leaves. Moreover, the N fertilizer content accounted for 5.89% of the total N content in roots. Overall, when N application was reduced, symbiosis with AM fungi effectively promoted the rhizosphere N priming effect, which reconciled the conflict in N nutrient allocation within cotton and thus enabled the efficient utilization of soil N.
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Open AccessEditorial
Alternatives to Mineral Nitrogen Fertilizers in Agriculture: State of the Art, Challenges and Future Prospects
by
Germán Tortosa
Nitrogen 2025, 6(3), 54; https://doi.org/10.3390/nitrogen6030054 - 2 Jul 2025
Abstract
Despite being one of the most abundant elements in the biosphere, nitrogen remains a limiting factor in agricultural systems [...]
Full article
(This article belongs to the Special Issue Alternatives to Mineral Nitrogen Fertilizers in Agriculture: State of the Art, Challenges and Future Prospects)
Open AccessArticle
What Is the Maximum Nitrogen Dose for the Fertilization of BRS Tamani?
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Anna Beatriz Oliveira Moura, Lucas Gimenes Mota, Luis Carlos Oliveira Borges, Eduarda Caroline Kichel Cuff, Sidney dos Santos Silva, Camila Fernandes Domingues Duarte, Carla Heloisa Avelino Cabral and Carlos Eduardo Avelino Cabral
Nitrogen 2025, 6(3), 53; https://doi.org/10.3390/nitrogen6030053 - 1 Jul 2025
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This study aimed to determine the optimal nitrogen (N) fertilization rate per regrowth cycle for Megathyrsus maximus cv. BRS Tamani by evaluating its effects on forage production, nutrient uptake, bromatological composition, and in vitro degradation kinetics. A randomized complete block design with five
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This study aimed to determine the optimal nitrogen (N) fertilization rate per regrowth cycle for Megathyrsus maximus cv. BRS Tamani by evaluating its effects on forage production, nutrient uptake, bromatological composition, and in vitro degradation kinetics. A randomized complete block design with five N doses (0, 40, 80, 120, and 160 kg N ha−1) and seven replications was conducted over two rainy seasons. From December 2019 to April 2020, canopy height and light interception were measured weekly. When canopy height reached 95% of light interception the grass was harvest and productive and morphological structure were measured. Nitrogen fertilization increased forage mass and yield up to the dose of 40 kg N ha−1, resulting in 1959 and 9798 kg DM ha−1, respectively, while nitrogen use efficiency declined at higher doses. Weed mass was decreased at 0 kg ha−1, and chlorophyll index increased with the N dose. Nitrogen and potassium were the most extracted nutrients, with nitrogen uptake being highest at 80 kg ha−1. Fertilization elevated the levels of crude protein, NDIP, cell content, and cell wall-bound protein, while ash content decreased. In vitro fermentation showed a reduced gas volume at higher N doses and improved degradation and digestibility up to 40 kg ha−1. Nitrogen fertilization enhanced the forage yield and quality of BRS Tamani, with 40 kg ha−1 maximizing efficiency and digestibility.
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Open AccessArticle
Multi-Class Machine Learning to Quantify the Impact of Nitrogen Management Practices on Grassland Biomass
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Sebastian Raubitzek, Margarita Hartlieb, Philip König, Judith Hinderling and Kevin Mallinger
Nitrogen 2025, 6(3), 52; https://doi.org/10.3390/nitrogen6030052 - 30 Jun 2025
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Grassland biomass yield reflects a complex interaction of management intensity and environmental factors, yet quantifying the relative role of practices such as mowing and fertilization remains challenging. In this study, we introduce a multi-class machine learning framework to predict above-ground biomass on 150
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Grassland biomass yield reflects a complex interaction of management intensity and environmental factors, yet quantifying the relative role of practices such as mowing and fertilization remains challenging. In this study, we introduce a multi-class machine learning framework to predict above-ground biomass on 150 permanent grassland plots across eight years (2009–2016) in Germany’s Biodiversity Exploratories and to evaluate the influence of key management variables. Following rigorous data cleaning, imputation of missing nitrogen values, feature standardization, and encoding of categorical practices, we trained CatBoost classifiers optimized via Bayesian hyperparameter search and mitigated class imbalance with ADASYN oversampling. We assessed model performance under binary, three-class, four-class, and five-class quantile-based categorizations, achieving test accuracies of 0.76, 0.57, 0.42, and 0.38, respectively. Across all schemes, mowing frequency and mineral nitrogen input emerged as the dominant predictors, while secondary variables such as drainage and conditioner use contributed as well. These results demonstrate that broad biomass categories can be forecast reliably from standardized management records, whereas finer distinctions necessitate additional environmental information or automated sensing to capture nonlinear effects and reduce reporting bias. This work shows both the potential and the limits of machine learning for informing sustainable grassland management and explainability thereof. Frequent mowing and higher mineral nitrogen inputs explained most of the predictable variation, enabling a 76% accurate separation of low and high biomass categories. Predictive accuracy fell below 60% for finer class resolutions, indicating that management records alone are insufficient for detailed yield forecasts without complementary environmental data.
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Open AccessArticle
High-Power Closed-Loop Pilot System for Nitric Acid Production Using Inductively Coupled Microwave Plasma
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Ian McKinney, Qi Rao, Elizaveta Grushnikova, Kenshin Ushiroda, Tommy Kesler, Stephen Dvorak and Jovan Jevtic
Nitrogen 2025, 6(3), 51; https://doi.org/10.3390/nitrogen6030051 - 28 Jun 2025
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This work presents the characterization of a large-scale pilot plant for nitric acid production that employs atmospheric-pressure plasma in a closed-loop configuration. The primary objective here is to evaluate the scientific and practical feasibility of using high-power Cerawave™ plasma torch technology, manufactured by
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This work presents the characterization of a large-scale pilot plant for nitric acid production that employs atmospheric-pressure plasma in a closed-loop configuration. The primary objective here is to evaluate the scientific and practical feasibility of using high-power Cerawave™ plasma torch technology, manufactured by Radom Corporation, to enhance the rate of nitric acid production of plasma-assisted nitrogen fixation systems, while achieving specific energy consumption (SEC) comparable to that of smaller-scale setups reported in the literature. We provide a comprehensive overview of the components of the pilot plant, its operational strategy, and the analytical models underlying its processes. Preliminary system optimization results are discussed alongside the outcomes from a controlled batch run. After 30.9 h of operation at 50 kW plasma power, the system produced 198.9 L of nitric acid with a concentration of 28.6% by weight, corresponding to overall SEC of approximately 5.3 MJ/mol. This SEC could be improved to 3.7 MJ/mol using absorption columns with greater than 90% absorption efficiency. Additionally, around 60% of the plasma power was recovered as usable process heat via a heat exchanger. These results demonstrate that plasma-based nitrogen fixation is scientifically and technically viable at higher production scales while maintaining competitive specific energy consumption using microwave plasma.
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Open AccessArticle
Insights into Pyrite-Based Autotrophic Denitrification: Impacts of the Initial Addition of Organic Co-Substrates at a Low Concentration
by
Baokun Xu, Lihong Zhang, Niannian Yuan, Yujiang Xiong and Haolong Fu
Nitrogen 2025, 6(3), 50; https://doi.org/10.3390/nitrogen6030050 - 28 Jun 2025
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Pyrite-based autotrophic denitrification is an effective method for nitrate removal. However, pyrite does not exist alone and is inevitably accompanied by the presence of organic matter in nature, and thus the influence of organic co-substrates on pyrite-based denitrification should be taken into consideration.
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Pyrite-based autotrophic denitrification is an effective method for nitrate removal. However, pyrite does not exist alone and is inevitably accompanied by the presence of organic matter in nature, and thus the influence of organic co-substrates on pyrite-based denitrification should be taken into consideration. Even in a circumstance where no addition of an exogenous organic carbon source is implemented, the introduction of pyrite into groundwater and sediment is capable of stimulating both autotrophic and heterotrophic denitrifying bacteria. In this study, the impact of the initial addition of organic co-substrates on the performance and dynamics of bacterial communities in pyrite-based denitrification processes was evaluated under low-concentration conditions. The findings suggest that the initial addition of organic co-substrates at low concentrations (6–48 mg L−1) could enhance the efficiency of pyrite-based autotrophic denitrification. In contrast, the competitive effects of organic co-substrates became positive with increasing additions of initial organic co-substrates. When an organic co-substrate was added at an initial concentration of 96 mg L−1, the competition between heterotrophic denitrification and pyrite-based autotrophic denitrification was found to be more pronounced than their promotion role as the majority of nitrate was consumed by heterotrophic denitrification. Thiobacillus was the most dominant bacterium in the denitrification system, where pyrite served as the sole electron donor. At the same time, the addition of organic co-substrate under low initial concentration, led to a different microorganism composition.
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Open AccessArticle
Partial Substitution of Synthetic Nitrogen with Organic Nitrogen Enhances Soil Fertility, Photosynthesis, and Root Growth of Grapevine Seedlings
by
Feng Han, Binxian Jiang, Wenyu Wang, Shuang Wu, Jinggui Wu, Yan Ma and Xiaochi Ma
Nitrogen 2025, 6(3), 49; https://doi.org/10.3390/nitrogen6030049 - 25 Jun 2025
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The overuse of synthetic nitrogen fertilizer in vineyards degrades soil quality and poses environmental risks. Partial substitution of synthetic nitrogen with organic alternatives may enhance grapevine performance and soil sustainability, depending on the substitution rate. This study evaluated the effects of replacing synthetic
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The overuse of synthetic nitrogen fertilizer in vineyards degrades soil quality and poses environmental risks. Partial substitution of synthetic nitrogen with organic alternatives may enhance grapevine performance and soil sustainability, depending on the substitution rate. This study evaluated the effects of replacing synthetic nitrogen with composted spent mushroom substrate at five different rates (0%, 25%, 50%, 75%, and 100%, denoted as NOS, OS-25, OS-50, OS-75, and OS-100, respectively) and a control with no nitrogen fertilization applied (CK), on soil fertility, root growth, and photosynthetic performance in grapevine seedlings. Compared to CK, nitrogen fertilization and organic substitution significantly increased soil electrical conductivity, organic matter, and macronutrient contents, but had no significant effect on soil pH. Organic substitution markedly improved leaf photosynthetic capacity in the summer, with the highest rates observed under OS-25, exceeding CK and NOS by 32.98–63.19% and 13.93–27.38%, respectively. Root growth was also significantly enhanced by organic substitution, with OS-25 exhibiting the best performance. Fine roots in the 0.0–0.5 mm diameter class were dominant, accounting for 56.88–63.06% of total root length and 96.22–97.31% of total root tip count. Increasing substitution rates beyond 25% yielded no further improvements in photosynthesis or root growth. Mantel test analysis indicated strong positive correlations between soil fertility parameters (e.g., alkali-hydrolyzable nitrogen, available phosphorous and potassium) and both photosynthetic efficiency and root growth. These findings suggest that an appropriate substitution rate (i.e., 25%) of organic nitrogen using spent mushroom substrate effectively improves soil fertility, simultaneously optimizing photosynthetic capacity and root growth of grapevine seedlings.
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Open AccessArticle
Fertilizer Use Efficiency and Profitability of Maize Varieties with Different Maturity Classes in Semi-Arid Ghana
by
Dilys Sefakor MacCarthy, Bright Salah Freduah, Yvonne Ohui Kugblenu Darrah, Samuel Godfried Adiku, Daniel Etsey Dodor, Joseph Kugbe and Alpha Yaya Kamara
Nitrogen 2025, 6(3), 48; https://doi.org/10.3390/nitrogen6030048 - 24 Jun 2025
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Optimizing the efficiency of fertilizer use is critical for sustainable maize production and food security, particularly in smallholder systems. Sub-optimal application rates pose a significant risk of soil nutrient depletion and low productivity. Split plot experiments were conducted across four locations in Ghana’s
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Optimizing the efficiency of fertilizer use is critical for sustainable maize production and food security, particularly in smallholder systems. Sub-optimal application rates pose a significant risk of soil nutrient depletion and low productivity. Split plot experiments were conducted across four locations in Ghana’s Guinea Savannah using seven maize varieties from three different maturity classes. The study assessed the response to nitrogen fertilizer applications (0, 60, 90, and 120 kg N ha−1) regarding yield, Agronomic Efficiency (AEN), Water Use Efficiency (WUE), and economic feasibility. Grain yields across locations and varieties demonstrated a strong linear response to nitrogen fertilization. The 90 kg N ha−1 application generally produced the highest AEN for all sites and varieties. Gross Revenue (GR) and WUE increased with higher N rates, with Value-to-Cost Ratios (VCR) consistently exceeding 2. Applying 90 kg N ha−1 resulted in statistically similar Gross Revenues (GRs) to the 120 kg N ha−1 fertilization. Different maturity classes significantly impacted fertilizer efficiency in semi-arid Ghana, with intermediate varieties outperforming extra-early ones. Though a 90 kg N ha−1 rate was generally identified as the economically optimal rate of N fertilization for the locations, targeted fertilizer recommendations based on maize maturity groups and location are strongly advised.
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Open AccessArticle
Productive Performance of Brachiaria brizantha cv. Paiaguás in Response to Different Inoculation Techniques of Azospirillum brasilense Associated with Nitrogen Fertilization in the Brazilian Amazon
by
Gianna Maria Oscar Bezerra, Cleyton de Souza Batista, Daryel Henrique Abreu de Queluz, Gabriela de Jesus Coelho, Daiane de Cinque Mariano, Pedro Henrique Oliveira Simões, Perlon Maia dos Santos, Ismael de Jesus Matos Viégas, Ricardo Shigueru Okumura and Raylon Pereira Maciel
Nitrogen 2025, 6(2), 47; https://doi.org/10.3390/nitrogen6020047 - 17 Jun 2025
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With the increase in prices of correctives and fertilizers, the investigation of the interactions between plants and plant growth-promoting bacteria shows an economically viable and sustainable alternative, and the use of Azospirillum brasilense has shown an increase in efficiency of nitrogen use and
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With the increase in prices of correctives and fertilizers, the investigation of the interactions between plants and plant growth-promoting bacteria shows an economically viable and sustainable alternative, and the use of Azospirillum brasilense has shown an increase in efficiency of nitrogen use and increased pasture yield. This study, conducted in the Brazilian Amazon, aimed to evaluate the effect of different inoculation techniques of Azospirillum brasilense associated with the dose of nitrogen topdressing on the productive performance of Brachiaria brizantha cv. Paiaguás is a grass species commonly cultivated in this region. The experiment was conducted in the Experimental Forage Sector of the Federal Rural University of the Amazon, Parauapebas city, Brazil. The experimental design was a randomized block design in a 3 × 3 factorial arrangement, with three inoculation methods (control, seed, and foliar) and three nitrogen fertilization doses (0, 75, and 150 kg ha−1 of N), with four replicates. An effect was observed in interaction between inoculation and nitrogen fertilization (p ≤ 0.05) for the variables total forage green mass, total forage dry mass, dry mass of leaf blade, dry stem mass, and number of tillers m−2. The dose of 150 kg ha−1 of N promoted a positive effect of N on the total forage dry mass and LAI (leaf area index). Inoculation with Azospirillum brasilense, especially foliar application, efficiently increased Brachiaria brizantha cv. Paiaguás yield, potentially reducing the use of nitrogen fertilizers, promotes greater sustainability in pasture management.
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