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Limiting fossil fuel usage is seen as essential to combat climate change; however, nitrogen fertilizers (or N-fertilizers) heavily rely on fossil fuels. Disruptions in fossil fuel supply are likely to negatively impact N-fertilizer production, worsening food crises and poverty in underdeveloped regions. In this study, we revisit the Coal Resource Consolidation Campaign (CRCC), an industrial reform campaign that aimed at increasing the mechanization and recovery rates to enhance the Chinese coal industry's competitiveness but resulted in a shortage of anthracite lump coal supply, the primary feedstock for Chinese N-fertilizer firms at that time. We examine CRCC's impact on the total factor productivity (TFP) of Chinese coal-based N-fertilizer firms during 2008–2013 using a difference-in-differences model. TFP is decomposed into capacity utilization (CU) and pure TFP. Our findings indicate a significant 33.4–34.2% decline in TFP due to CRCC. Further analysis reveals that a 6.3% decline in CU, not pure TFP, was the primary driver of the TFP loss from 2011 to 2013. We recommend that policymakers should assess the impact of climate change policies comprehensively, and the government should support the adaptation and innovation of feedstock in the N-fertilizer industry to avoid feedstock supply disruptions. [ABSTRACT FROM AUTHOR]

Agriculture is the dominant source of anthropogenic nitrous oxide (N2O) –a greenhouse gas and a stratospheric ozone depleting substance. The US Corn Belt is a large global N2O source, but there remain large uncertainties regarding its source attribution and biogeochemical pathways. Here, we interpret high frequency stable N2O isotope observations from a very tall tower to improve our understanding of regional source attribution. We detected significant seasonal variability in δ15Nbulk (6.47–7.33‰) and the isotope site preference (δ15NSP = δ15Nα–δ15Nβ, 18.22–25.19‰) indicating a predominance of denitrification during the growing period but of nitrification during the snowmelt period. Isotope mixing models and atmospheric inversions both indicate that indirect emissions contribute substantially (>35%) to total N2O emissions. Despite the relatively large uncertainties, the upper bound of bottom‐up indirect emission estimates are at the lower bound of the isotopic constraint, implying significant discrepancies that require further investigation. Plain Language Summary: Increasing use of synthetic nitrogen fertilizers for agricultural production is causing higher atmospheric nitrous oxide (N2O) concentrations. Nitrous oxide is a long‐lived greenhouse gas and degrades the protective stratospheric ozone layer. Using tall tower N2O isotope observations from within the US Corn Belt, we examine how different processes (denitrification vs. nitrification) and sources (corn fields vs. wetlands, rivers, and streams) contribute to variations in atmospheric N2O. The findings indicate that a substantial amount of nitrogen leakage from agricultural crops contributes to N2O emissions via indirect sources such as drainage networks. These findings can help inform mitigation strategies targeting nitrogen use and leakage pathways from agricultural systems. Key Points: Seasonality of N2O isotope fingerprint driven by snowmelt and fertilizer inputSnowmelt and growing season emissions dominated by nitrification versus denitrification pathwaysIsotope fingerprints were used to constrain direct and indirect N2O emissions [ABSTRACT FROM AUTHOR]

Safeguarding the agricultural environment from pollution is one of the most critical challenges facing the world in the context of climate change. The loss of nitrogen fertilizers through agricultural runoff or volatilization in the form of nitrate or ammonia emissions is a significant contributor to pollution. This loss also represents an economic waste that may lead to increased prices of agricultural products. Therefore, finding a solution to this problem has become imperative. An experiment was conducted on wheat plants using various rates of urea coated with slow-release materials. The study aimed to assess the impact of these fertilizers on wheat growth and yield, nutrient uptake, and nitrogen utilization efficiency (NUtE). Results demonstrated that urea fertilizers coated with slow-release materials outperformed conventional fertilizers in terms of wheat growth and yield, uptake of nitrogen, phosphorus, and potassium, as well as NUtE. The most favorable outcomes were achieved using urea-formaldehyde, urea-humic, and urea-biochar fertilizers at 100% of the recommended nitrogen application rate. This resulted in economically viable grain production with high fertilizer efficiency. Based on these findings, we recommend applying either urea-formaldehyde or urea-humic at a rate of 107 kg N ha−1 to produce wheat grain and straw with enhanced NUtE. This approach can help reduce environmental pollution caused by nitrogen losses. [ABSTRACT FROM AUTHOR]

To investigate the effect of nitrogen fertilizer and zinc (Zn) sulfate on growth, physiological, biochemical, and nutrient use efficiency in fodder maize under drought stress, an experiment was conducted during two cropping years 2019 and 2020. The experiment was performed as a split-factorial in the form of a randomized complete block design with four replications. The main factor was irrigation regimes in three levels: full irrigation (without stress or 100% of field capacity), irrigation based on 75% of field capacity, and irrigation based on 50% of field capacity. The first sub-factor included urea fertilizer at three levels of 0, 69, and 138 kg ha−1. The second sub-factor included foliar application of zinc sulfate at three levels of 0, 2, and 4 mg kg−1. The results showed that the highest fresh weight of maize fodder was obtained under conditions of full irrigation and the use of 138 kg ha−1 of N. The use of zinc at all irrigation levels increased the fresh weight of maize fodder. These results confirmed that if higher amounts of N are used, more zinc should be used to achieve a higher yield of maize forage. With the increase in the severity of drought stress, the concentration of nitrogen and phosphorus in the crop tissue, as well as the efficiency of using nitrogen and phosphorus, decreased. The highest value of nitrogen use efficiency was obtained in full irrigation conditions, using 69 kg ha−1 of N and 4 mg kg−1 of zinc. In addition, at all irrigation levels, the efficiency of using this element decreased with increasing zinc consumption. [ABSTRACT FROM AUTHOR]

Current agricultural production systems face challenges of poor economic returns, soil fatigue and negative environmental outcomes from excess use of nitrogenous fertilizers, especially in wheat production under middle gangetic plains. To overcome these challenges, the current study was conducted to optimize nitrogen management in different wheat genotypes with precision nitrogen management tools and approaches. The field experiment was laid out in split-plot design, with three genotypes assigned to the main plot and six nitrogen management practices to the sub-plot. The soil of the experimental field was sandy loam in texture, with low levels of organic carbon and available nitrogen, and medium levels of available phosphorus and potassium. Results revealed that the HD-2967 genotype outperformed others in terms of growth, grain yield (4.7 and 4.81 t ha−1), gross return (1417.41 and 1505.48 US$ ha−1), net return (953.43 and 1019.76 US$ ha−1), and B-C ratio (2.04 and 2.08) in 2015-16 and 2016-17, respectively. Among the nitrogen management practices, application of 150 kg N ha−1 in three equal splits demonstrated improved crop growth, grain yield (4.7 and 4.81 t ha−1), and economic returns (gross return, 1500.40 and 1607.65 US$ ha−1, net return, 1025.40 and 1110.38 US$ ha−1 and B: C ratio, 2.17 and 2.23) in 2015-16 and 2016-17, respectively. However, it resulted in higher nitrogen losses. Green seeker guided N application significantly reduced apparent nitrogen losses compared to all other nitrogen applied treatments. These findings provide valuable insights for optimizing wheat production by selecting appropriate genotypes and implementing precision nitrogen management techniques to enhance yield, profitability, and environmental sustainability. [ABSTRACT FROM AUTHOR]

Cover crops and nitrogen (N) fertilization may affect soil mineral N, N uptake, and N productivity (grain yield per unit plant available N) in wheat (Triticum aestivum L.). We evaluated the effect of summer cover crops and N fertilization rates on soil mineral N and winter wheat grain yield, N uptake, and N productivity in the Loess Plateau of China. We measured cover crop aboveground biomass N, soil mineral N (0-20 cm), and winter wheat yield, N uptake, and N productivity for four seasons from 2017-2018 to 2020-2021. Cover crops were soybean (Glycine max L., SB), sudangrass (Sorghum sudanense [Piper] Stapf, SG], soybean and sudangrass mixture (SS), and no cover crop (CK) and N fertilization rates were 0, 60, and 120 kg N ha−1 applied to wheat. The SB increased cover crop biomass N and soil mineral N by 15 to 65%, but SS increased winter wheat yield, protein concentration, and N uptake by 25 to 55% compared to SG and CK at most N fertilization rates and years. Nitrogen fertilization rate had a variable effect on cover crop and wheat parameters. Wheat N productivity was 55 to 85% greater with CK than cover crops, but decreased with increased N fertilization rates. The N fertilizer equivalence of cover crops for wheat yield and N uptake ranged from 31 kg N ha−1 for SG to 150 kg N ha−1 for SS. Overall, SS with 60 kg N ha−1 can sustain winter wheat N uptake and N productivity compared to SG or CK with or without N fertilization. [ABSTRACT FROM AUTHOR]

The conservation agriculture (CA), presents a promising alternative for restoring soil health and achieving sustainable crop production. In addition, one cannot follow the same nitrogen management of conventional framing in the CA as the crop residue retained leads to N mineralization/immobilization. Hence, the present research was aimed to determine the effect of CA and nitrogen managements on soil nitrogen, phosphorus and sulfur release and the enzymes involved in their mineralization. The results revealed that the CA practice significantly enhanced the mineral N, Olsen P and CaCl2–S release and the soil enzymes involved in this mineralization cycles compared to CT + R plots. Similarly, all the nitrogen fertilizer receiving subplots also recorded significantly higher mineral N, Olsen P and CaCl2–S release and the enzymes involved compared to the control. Furthermore, throughout the incubation period the Urea super granule + Greenseeker treatment significantly outperformed the RDN plot with respect to NO3–N and CaCl2–S release. Whereas, the Urea + Greenseeker treatment registered significantly higher NO3–N and CaCl2–S over RDN plot from 30 and 45 days after incubation, respectively. The NH4–N and Olsen P release had increasing trend up to 45 days after incubation and thereafter it decreased. In nutshell, the research emphasizes the significance of CA alongside optimum nitrogen management approaches in enhancing the soil enzymatic activities and nutrient mineralization. These outcomes hold significance for both farmers and researchers seeking ecologically sound and productive agricultural methods to enhance crop output and maintain soil quality. [ABSTRACT FROM AUTHOR]

Most conventional phosphorous (P) fertilizers are highly soluble, which favors P retention in the solid phase of the soil, and this condition hinders P availability to plants. Alternative P fertilizers, such as organominerals and struvite, have a slow release of nutrients into the soil, which in turn favors P uptake by plants; nevertheless, soil acidification caused by nitrogen (N) fertilizers can reduce P availability in the soil. In his study, we assessed the effect of N fertilizers on P availability for maize (Zea mays) grown in tropical soils with alternative P fertilizers. An experiment was set up in columns under greenhouse conditions with maize in two cultivation cycles in two soils with contrasting textures (medium and clayey textures), two N fertilizers (calcium nitrate - CN - and ammonium sulfate - AS), three P fertilizers (triple superphosphate - TSP -, organomineral - OM - and struvite - ST), and a control treatment (without addition of P and N fertilizers). At 45 days after emergence, we measured the biomass production and the N and P contents in plants to calculate fertilization efficiency as well as the soil P content. AS promoted the highest aboveground N accumulation, whereas the highest efficiency was obtained with CN. The alternative P sources did not differ in terms of P availability when combined with both N sources. Soil textures were sensitive to fertilizer combination. Further studies are needed to assess struvite interaction with other elements in the soil and the P release kinetics to plants. [ABSTRACT FROM AUTHOR]

Increasing biological nitrogen (N) fixation (BNF) in maize production could reduce the environmental impacts of N fertilizer use, but reactive N in the rhizosphere of maize limits the BNF process. Using non-transgenic methods, we developed gene-edited strains of Klebsiella variicola (Kv137-2253) and Kosakonia sacchari (Ks6-5687) bacteria optimized for root-associated BNF and ammonium excretion in N-rich conditions. The aim of this research was to elucidate the mechanism of action of these strains. We present evidence from in vitro, in planta and field experiments that confirms that our genetic remodeling strategy derepresses BNF activity in N-rich systems and increases ammonium excretion by orders of magnitude above the respective wildtype strains. BNF is demonstrated in controlled environments by the transfer of labeled 15N2 gas from the rhizosphere to the chlorophyll of inoculated maize plants. This was corroborated in several 15N isotope tracer field experiments where inoculation with the formulated, commercial-grade product derived from the gene-edited strains (PIVOT BIO PROVEN® 40) provided on average 21 kg N ha-1 to the plant by the VT-R1 growth stages. Data from small-plot and on-farm trials suggest that this technology can improve crop N status pre-flowering and has potential to mitigate the risk of yield loss associated with a reduction in synthetic N fertilizer inputs. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION Agronomic uses of biochar have been intensely explored in the last 15 years. Recently, a new generation of biochar‐based fertilizers has been developed. Raw biochar (BCH), nitrogen‐enriched biochar (N + BCH) or urea were added to a coir fiber‐based substrate for tomato cultivation, to assess seed germination, growth and fruiting of two cultivars (Cuarenteno and Moneymaker).BCH stimulated seed germination and early radicle growth, possibly because of the presence of karrikins detected in both BCH and N‐BCH (0.039 and 0.044 mg kg−1, respectively). However, BCH reduced growth in adult plants in both cultivars, probably because of ammonium retention, causing low‐N‐stress‐related symptoms such as accumulation of flavonoids in the leaf. Urea was toxic for seed germination because of the fast release of ammonium, but caused a positive effect on adult plant growth and yield, increasing chlorophyll in both cultivars, quantum yield and ascorbic acid in cv. Cuarenteno, and decreasing flavonoids and peroxide in leaves of both cultivars. Unlike urea, N + BCH showed a positive impact on plant growth and yield, but without releasing high amounts of ammonium or negatively affecting seed germination. Nitrogen‐rich amendments reduced phosphorus and increased iron leaf content in both cultivars.BCH can be effectively used as a growth medium constituent in nurseries for seedling production, whereas N + BCH offers a promising alternative to urea or other nitrogen mineral fertilizers for crop cultivation. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION Oat (Avena sativa L.) is a valuable crop due to its strong adaptability to marginal environments, making it an important component of agricultural systems in regions where other cereals may not thrive. The application of chemical fertilizer can influence oat hay and grain yield significantly. However, large‐scale meta‐analytical studies of the size and variability of oat hay and grain yields in response to fertilizer addition are still lacking. Based on 83 studies worldwide, this meta‐analysis quantifies the impact of the addition of fertilizer on oat hay and grain yields under varying environmental conditions (e.g., soil nutrient levels, texture, and climate).The results confirmed that the fertilizer application increased oat hay yield by 48.9% and grain yield by 36.2%. This study demonstrated that balanced fertilization with nitrogen, phosphorus, and potassium generally enhances oat hay and grain yield despite large temporal and spatial variations. Boosted regression tree (BRT) models suggest that changes in hay and grain yield were primarily dominated by soil pH and nitrogen fertilizer. The response ratio (the natural logarithm of the mean values of hay yield or grain yield with and without fertilization, respectively) of hay yield declined linearly with soil pH. Elevation was the second most important factor affecting the change in response ratio of hay yield and the third most important factor affecting the change in response ratio of grain yield but climatic conditions were not the dominant factors affecting changes in oat hay or grain yield.Overall, these results will benefit producers considering site‐specific fertilization management of oat. They could increase yields and save investment in fertilizer, and help to facilitate the genetic breeding of oat varieties with high nutrient use efficiency. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Sustainable intensification of livestock systems implies greater efficiency in resource utilization resulting in greater output of products and other ecosystem services per unit of resource input. Integrating forage legumes into livestock systems is a viable way to reduce the input of industrial N fertilizer, reducing the use of fossil fuels and helping to mitigate global warming, a major problem during the Anthropocene. Some forage legumes have greater concentrations of secondary compounds, such as condensed tannins, that might reduce the emission of greenhouse gases (GHG) from ruminant eructation and excreta. Furthermore, forage legumes might enhance cattle performance because of greater nutritive value, resulting in greater production per unit of GHG released. Shortening the production cycle and improving cattle reproductive efficiency could have a major impact on reducing the overall carbon footprint of the system. Grazing systems with more diversified plant species are typically more resistant and resilient, adapting to current climate changes during the Anthropocene. Novel technologies might accelerate the development of future grazing systems using forage legumes as a key component. Breeding efforts for the next‐generation legumes must focus on adaptation and potential use for mitigation of negative environmental impacts. There are examples of successful integration of forage legumes into livestock systems in different regions of the world, with a major reduction in off‐farm inputs and maintaining the system productive. These successful examples could be used to increase adoption and improve the efficiency of current livestock systems. [ABSTRACT FROM AUTHOR]

With the increasing demand for crops, the excessive application of fertilizers has gradually become a significant factor affecting water quality. Therefore, studying the relationship between agricultural fertilizer runoff and water quality is crucial for the sustainable development of agricultural production. The present study sets up a new dynamic model of nitrogen fertilizer loss, introducing variables such as precipitation, fertilization application during dry and rainy seasons, and their lagged and interaction terms. The paper analyzed the issue of fertilizer runoff under the complex interactions of various factors, including spatial and temporal scales and climatic conditions, and explored the relationship between agricultural activities and water quality changes in the context of sustainable development. Due to Hainan Island's independent river system, which is free from transboundary pollution, and its low level of industrial pollution, it provides an excellent sample for assessing the impact of agricultural non-point source pollution on water quality. Based on watershed monitoring data from Hainan Island, this study draws the following conclusions: 1. Precipitation exhibits a pronounced seasonal influence on total nitrogen concentration. 2. Nitrogen fertilizer enters into water bodies through precipitation, resulting in a lag effect on total nitrogen concentration. 3. The influence of grain and tropical crops on nitrogen loss is less significant, while cash crops will trigger the nitrogen overloading of rivers in scenarios where they account for a high proportion of the planting structure of the sown area. [ABSTRACT FROM AUTHOR]

The combination of biochar and nitrogen (N) fertilization in agricultural salt-affected soils is an effective strategy for amending the soil and promoting production. To investigate the effect of nitrogen reduction combined with biochar application on a soda saline soil and soybean growth in black soil areas, a pot experiment was set up with two biochar application levels, 0 (B0) and 4.5 t/hm2 (B1); two biochar application depths, 0-20 cm (H1) and 0-40 cm (H2); and two nitrogen application levels, conventional nitrogen application (N0) and nitrogen reduction of 15% (N1). The results showed that the application of biochar improved the saline soil status and significantly increased soybean yield under lower nitrogen application. Moreover, increasing the depth of biochar application enhanced the effectiveness of biochar in reducing saline soil barriers to crop growth, which promoted soybean growth. Increasing the depth of biochar application increased the K+ and Ca2+ contents, soil nitrogen content, N fertilizer agronomic efficiency, leaf total nitrogen, N use efficiency, AN, Tr, gs, SPAD, leaf water potential, water content and soybean yield and its components. However, the Na+ content, SAR, ESP, Na+/K+, Ci and water use efficiency decreased with increasing biochar depth. Among the treatments with low nitrogen input and biochar, B1H1N1 resulted in the greatest soil improvement in the 0-20 cm soil layer compared with B0N0; for example, K+ content increased by 61.87%, Na+ content decreased by 44.80%, SAR decreased by 46.68%, and nitrate nitrogen increased by 26.61%. However, in the 20-40 cm soil layer, B1H2N1 had the greatest effect on improving the soil physicochemical properties, K+ content increased by 62.54%, Na+ content decreased by 29.76%, SAR decreased by 32.85%, and nitrate nitrogen content increased by 30.77%. In addition, compared with B0N0, total leaf nitrogen increased in B1H2N1 by 25.07%, N use efficiency increased by 6.7%, N fertilizer agronomic efficiency increased by 32.79%, partial factor productivity of nitrogen increased by 28.37%, gs increased by 22.10%, leaf water potential increased by 27.33% and water content increased by 6.44%. In conclusion, B1H2N1 had the greatest effect on improving the condition of saline soil; it not only effectively regulated the distribution of salt in soda saline soil and provided a low-salt environment for crop growth but also activated deep soil resources. Therefore, among all treatments investigated in this study, B1H2N1 was considered most suitable for improving the condition of soda saline soil in black soil areas and enhancing the growth of soybean plants. [ABSTRACT FROM AUTHOR]

Dairy farming is a notable source of nitrogen (N) emissions, impacting both atmospheric and aquatic ecosystems, thus necessitating a detailed analysis of nutrient dynamics to curtail nutrient wastage. However, N flow variability and its environmental ramifications differ markedly among dairy farms, and a holistic understanding of these differences is lacking in Inner Mongolia, the biggest dairy production province in China. Utilizing data from 187 dairy farms and employing the NUFER-farm model, this study assessed N flows, N use efficiency (NUE), and N losses across four predominant dairy farming systems in Inner Mongolia. These systems include traditional pastoral dairy farms (PF), smallholder dairy farms with croplands (SF), industrial landless farms (IDF), and coupled dairy cattle and cropland-intensive farms (CDF). Our findings indicate considerable differences in N flows, NUE, and losses among the systems. On average, N deposition and N fertilizer were the primary N sources for PF and SF, respectively, whereas IDF and CDF derived over 90% of their N inputs from purchased feeds. PF and SF recycled all available manure N on-farm, whereas IDF and CDF recycled only approximately 36% of the total available manure N. N losses constituted 39–72% of total N outputs, with ammonia emissions accounting for 68–73% of total N losses across all farm types. In particular, PF had a higher N loss per kilogram of dairy product than other systems. Farm-level NUE ranged from 17 to 35%, with manure management practices showing significant variability, underscoring the potential for enhanced strategies to reduce N losses through improved manure treatment. [ABSTRACT FROM AUTHOR]

Soil microorganisms are key indicators of soil health, and it is crucial to investigate the structure and interactions of soil microbial communities among three different provenances of Pennisetum alopecuroides under varying nitrogen fertilizer and temperature levels in Northwest China. This study aims to provide theoretical support for the sustainable use of artificial grassland in this region. Employing a two-factor pot-control experiment with three nitrogen fertilizer treatments and three temperature treatments, a total of all treatments was utilized to examine the composition and abundance of soil microbial communities associated with Pennisetum alopecuroides using high-throughput sequencing, PCR technology, and molecular ecological network analysis. The results revealed that Proteobacteria was the dominant bacterial phylum while Ascomycota was the dominant fungal phylum in the soil samples from three provenances of Pennisetum. Specifically, Proteobacteria exhibited higher abundance in the N3T2 treatment compared to other treatments under N3T2 (25–30°C, 3 g/pot) treatment conditions in Shaanxi and Gansu provinces; similarly, Proteobacteria was more abundant in the N1T2 (25–30°C, 1 g/pot) treatment in Inner Mongolia under N1T2. Moreover, Ascomycota displayed higher abundance than other treatments in both Inner Mongolia and Gansu provinces. Additionally, Pennisetum Ascomycota demonstrated greater prevalence under (25–30°C, 3 g/pot) treatment compared to other treatments; furthermore, Shaanxi's Pennisetum Ascomycota exhibited increased prevalence under N3T1 (18–23°C, 3 g/pot) treatment compared to other treatments. The richness and diversity of soil microbial communities were significantly influenced by nitrogen fertilizer and temperature changes, leading to notable alterations in their structure. Molecular ecological network analyses revealed strong collaborative relationships among microbial species in Shaanxi Pennisetum and Inner Mongolia Pennisetum under high nitrogen and high temperature treatments, while competitive relationships were observed among microbial species in Gansu Pennisetum under similar conditions. Redundancy analysis indicated that soil pH, total potassium, and total phosphorus were the primary environmental factors influencing microorganisms. In summary, this study offers a theoretical foundation for assessing the sustainable utilization of Pennisetum artificial grasslands in Northwest China by investigating the shifts in soil microbial communities and the driving factors under varying nitrogen fertilizer and temperature levels. [ABSTRACT FROM AUTHOR]

Replacing chemical nitrogen (N) fertilizer with monosodium glutamate waste liquid residue (MSGWLR) is beneficial for achieving clean production in both the monosodium glutamate (MSG) industry and agriculture. However, the impact of this method on rice production and environment has not yet been clear. This study adopted field experiments to clarify the rice yield, quality and carbon emissions applying conventional application of chemical N fertilizer (CF), reduction of N fertilizer by 20% (N80%), based on reduction of chemical N fertilizer by 20% and replacing 50% chemical N fertilizer with MSGWLR (MSGWLR50%), and replacing 100% chemical N fertilizer (MSGWLR100%). The results showed that compared with CF treatment, MSGWLR100% showed no significant changes in rice yield, milling quality, fatty acid value, and taste quality. The chalkiness rate of rice significantly decreased, and the protein content significantly increased. On the other hand, the carbon emissions from rice production treated with MSGWLR100% were the lowest, with a 58.5% decrease in global warming potential (GWP) compared to CF treatment. This was mainly because MSGWLR100% treatment could provide rich and balanced nutrients for rice growth, and it did not promote greenhouse gas (GHG) emissions from paddy field. At the same time, it effectively reduced the indirect carbon emissions in chemical fertilizer production by reducing chemical N fertilizer. Therefore, the MSGWLR100% fertilization treatment is beneficial for cleaner production in the MSG industry and rice cultivation. Highlights: • MSGWLR could effectively replace chemical N fertilizer while maintaining rice yield. • Both MSGWLR50% and MSGWLR100% treatments successfully maintained rice quality. • Replacing chemical N fertilizer with MSGWLR significantly reduced carbon emissions from rice production. [ABSTRACT FROM AUTHOR]

Introduction: Global food security is challenged by the increasing levels of air pollutants like ozone (O3) through their impacts on crop productivity. The present study was conducted to quantify the interactive effect of elevated ozone (O3) and carbon dioxide (CO2), on different rice varieties in northern India. Methods: An experiment was conducted in Genetic H field, Environment science, IARI for two consecutive years (2020 and 2021) during the kharif season, to quantify the impact of elevated O3 and CO2 interaction on productivity, and plant N in three rice varieties (Pusa basmati 1121, Nagina 22, IR64 Drt1) under different nitrogen (N) management practices. Rice crop was grown in Free Air Ozone-Carbon dioxide Enrichment rings (FAOCE) rings with two levels of O3 (elevated 60 ±10ppb and ambient) and two levels of CO2 (elevated, 550±25 ppm and ambient) concentration and their interaction with two N fertilizer treatments i.e., 100% RDN (recommended dose of N) and 125% RDN. Results and discussion: Elevated O3 significantly decreased physiological parameters like photosynthesis rate, stomatal conductance and transpiration rate of the crop. Grain yield reduced by 7.2-7.5%, in Pusa Basmati 1121 and from 6.9-9% in IR64 Drt1 varieties in elevated O3 treatment as compared to ambient treatment. Yield reduction in Nagina 22 variety was not significant in elevated O3 treatment. Elevated CO2 concentration of 550 ppm was able to fully compensate the yield loss in Nagina 22 variety and partially compensate (3.9-8.0%) in Pusa Basmati 1121 and IR64 Drt1 varieties. Grain N concentration in rice varieties decreased by 10.8-14.7% during first year and by 7.8-20.6% during second year in elevated O3 plus CO2 interaction treatment than ambient. Grain N uptake also decreased (13.2-17.1% in first year and 4.5-22.8% in second year) in elevated O3 plus CO2 interaction treatment as compared to ambient. Application of additional 25% of recommended dose of N improved grain N concentration, grain N uptake as well as available N of soil as compared to 100% RDN treatment in elevated O3 plus CO2 interaction treatment. Additional 25% N dose could help in sustaining rice productivity and quality under elevated O3 and CO2 condition. [ABSTRACT FROM AUTHOR]

Nitrogen (N) losses from conventional N fertilizers contribute to environmental degradation and low N use efficiency. Highlighting the need for slow-release fertilizers (SRFs) to mitigate these problems, this study aims to develop slow-release N fertilizers using starch-grafted-poly[(acrylic acid)-co-acrylamide] based nanoclay polymer composites (NCPCs) and investigate their efficacy for slow N delivery in soil. Three types of NCPCs, NCPC(A) (poly [(acrylic acid)-co-acrylamide]), NCPC(W) (wheat starch-grafted-poly[(acrylic acid)-co-acrylamide), and NCPC(M) (maize starch-grafted-poly[(acrylic acid)-co-acrylamide) were prepared and characterized using FTIR spectroscopy and X-ray diffraction techniques. N-release behaviour of the products was assessed under two distinct soils, i.e., Assam (Typic Hapludults, pH 4.2) and Delhi (Typic Haplustepts, pH 7.9) soils. Additionally, the effects of varying soil moisture and temperature levels on N release were studied in the Assam soil. The N-release kinetics of the synthesized fertilizers were assessed using zero-order, first-order, Higuchi, and Korsmeyer−Peppas models. Degradability of the NCPCs was evaluated by measuring evolved CO2–C under various soil conditions as an indicator of microbial degradation. The results indicated that NCPC fertilizers significantly slowed down the release of N compared to urea. According to the R2 values obtained, it was evident that the first-order kinetic model most accurately describes the N release from both urea and NCPC-based N fertilizers in the studied soils. Among the formulations, NCPC(A) exhibited the lowest N release (42.94–53.76%), followed by NCPC(M) (51.05–61.70%), NCPC(W) (54.86–67.75%), and urea (74.33–84.27%) after 21 days of incubation. The rate of N release was lower in the Assam soil compared to the Delhi soil, with higher soil moisture and temperature levels accelerating the release. Starch addition improved the biodegradability of the NCPCs, with NCPC(W) showing the highest cumulative CO2-C evolution (18.18–22.62 mg g−1), followed by NCPC(M) (15.54–20.97 mg g−1) and NCPC(A) (10.89–19.53 mg g−1). In conclusion, NCPC-based slow-release fertilizers demonstrated a more gradual N release compared to conventional urea and the inclusion of starch enhanced their degradability in the soil, which confirms their potential for sustainable agricultural applications. However, soil properties and environmental factors influenced the N release and degradation rates of NCPCs. [ABSTRACT FROM AUTHOR]

Increased environmental nitrogen (N) losses have prompted the use of enhanced efficiency nitrogen fertilizers, including nitrification inhibitors. However, the comparative effects of nitrification inhibitors with conventional nitrogen fertilizers and herbicides on soil nitrification and nitrogen losses remain poorly understood. This study evaluated the impact of a nitrification inhibitor (Instinct NXTGEN), two nitrogen sources (broadcast urea vs. injected aqueous ammonia), and a preemergence herbicide (Acuron) on (1) soil nitrification through a 25‐day soil incubation experiment and (2) NH3 volatilization, NO3‐N leaching, and N2O‐N emissions through a 31‐day soil column study in loamy sand soil. In both experiments, treatments included combinations of nitrification inhibitor versus no inhibitor, two nitrogen sources, and preemergence herbicide versus no herbicide. Results revealed that nitrogen source significantly influenced nitrification, with injected aqueous ammonia reducing nitrification by 33% compared to surface broadcast urea. Nitrification inhibitors and herbicide had no effect on soil nitrification. Injected aqueous ammonia reduced NH3 volatilization by 87% compared to surface broadcast urea, but the effect of the nitrification inhibitor on NH3 volatilization was inconsistent across both nitrogen sources. Injected aqueous ammonia led to 39% higher cumulative nitrogen (NO3‐N + NH4‐N) leaching than urea, while the nitrification inhibitor had an inconsistent effect on NO3‐N leaching across both nitrogen sources. No significant differences in N2O‐N emissions were observed among treatments, and the herbicide had no effect on any measured parameters. These findings suggest that nitrogen source plays a more critical role in regulating soil nitrogen losses than nitrification inhibitors or herbicides. Core Ideas: Nitrogen sources had a greater impact on soil nitrification and fertilizer nitrogen recovery than nitrification inhibitors and herbicides.Injected aqueous ammonia reduced NH3 volatilization by 87% compared to surface broadcast urea.Injected aqueous ammonia resulted in 39% higher cumulative nitrogen (NO3‐N + NH4‐N) leaching than surface broadcast urea.The response of the nitrification inhibitor to N losses was inconsistent across urea and aqueous ammonia.Herbicides had no significant effect on soil nitrification or nitrogen losses. [ABSTRACT FROM AUTHOR]

This inquiry is aimed at discerning the impact of various agricultural practices, such as crop rotation, the incorporation of plant residues, and the application of mineral fertilizers, on soil health and crop productivity, notably focusing on maize production. Cultivation included maize (Zea mays), velvet beans (Mucuna pruriens), soybeans (Glycine max), and vetch (Vicia sativa). After harvest, maize seeds were sown across all 48 plots to evaluate the influence of preceding crop rotation on soil properties and maize yield. Hypotheses posited in the study suggested that crop rotation, nitrogen fertilizer application, and the incorporation of crop residues positively impact soil fertility. The study further argues that the utilization of cover crops in crop rotation aids in nitrogen retention within the soil and enhances yield. The results were processed utilizing a two‐way analysis of variance (ANOVA) with interaction and post hoc comparisons. The findings confirm that crop rotation, nitrogen fertilizer application, and incorporation of crop residues influence soil fertility. The study found that crop rotation and nitrogen fertilizers have a significant impact on soil properties. Crop rotations such as "velvet beans‐maize" and "soybeans‐maize" increased soil fertility by 10%–15% compared to crop rotations of "vetch‐maize" and maize monocultures. Nitrogen fertilizers increased the total nitrogen content in the soil by 5%–10% in both years. Crop residues also positively affected soil properties, increasing pH and total nitrogen by 1%–5%. The study demonstrates that crop rotation, nitrogen fertilizers, and crop residues can be effective management methods for improving soil fertility and reducing the risk of nitrate leaching. Core Ideas: A 3‐year experiment was performed in the Astrakhan region of Russia.The aim of this study is to quantify changes in the physical and chemical properties of soils.The study focused on the effects of organic and mineral farming methods on soil properties. [ABSTRACT FROM AUTHOR]

AbstractConservation agriculture (CA) covers nearly 3.5 mha in Indian. And there is lack of studies on the CA effects soil nutrient dynamics. So, this study examines the effects of nine years of conservation agriculture on soil nitrogen (N), phosphorus (P), and sulfur (S) fractions in an Inceptisol under maize–wheat–mungbean cropping system. Different tillage and nitrogen management practices were evaluated to understand how nutrient management in CA, contrasts with conventional methods. The CA practices and N fertilizer addition significantly enhanced the soil mineral N, alkali-permanganate N, potentially mineralizable N and microbial biomass N. The CA and N fertilization enhanced soluble and loosely bound P by dissolving the iron-bound, aluminum-bound, reductant soluble and calcium-bound P. All the soil S fractions i.e. available S, total water-soluble S, heat soluble S, sodium bicarbonate extractable S, inorganic sulfur, organic sulfur and total sulfur was positively affected by CA and N fertilization practices over conventional tillage and control plots, respectively. It is important to note that the green seeker-based N management options especially with urea super granules showed tendency in enhancing the available nutrient pools of N, P and S compared to recommended dose of N (RDN) applied and control plots indicating that in due course of time it may reduce the amount of RDN without hindering any soil nutrient dynamics. These findings contribute crucial knowledge for sustainable development by offering valuable perspectives on N, P and S management strategies. [ABSTRACT FROM AUTHOR]

Soil salinity is a significant abiotic stress and poses risks to environmental sustainability. Thus, the improvement of the time for recovering the salt-affect soil is crucial for the phytoextraction process using halophytes plants, especially regarding on nutritional management. We evaluated the responses of Atriplex nummularia Lindl. to nitrogen (N) and phosphorus (P) under different salinity levels. The treatments comprised doses of N (N1 = 80 kg ha−1) and P (P1 = 60 kg ha−1): (1) without N and P (N0P0) (control); (2) with N and without P (N1P0); (3) without N and with P (N0P1); and (4) with N and P (N1P1) and five levels of electrical conductivity from irrigation water: 0.08, 1.7, 4.8, 8.6, and 12.5 dS m−1. The. We evaluated dry biomass of leaves, stems, and roots 93 days after transplantation. We also assessed the leaf and osmotic water potential, the osmotic adjustment, and the nutrient contents (N, P, Na, and K). N application increased 22.3, 17.8, and 32.8% the leaf biomass, stem biomass, and osmotic adjustment, respectively; and consequently, boosts Na extraction in 27.8%. Thus, the time of the phytoextraction process can be improved with N fertilizer at a rate of 80 kg ha−1. NOVELTY STATEMENT: Very few studies have investigated the nutrient dynamics responses in Atriplex species in salt-affected soils; thus, this study represents a novelty. We tested the management of nitrogen (N) and phosphate (P) fertilizers to increase crop yield and optimize the phytoextraction process in salt-affected soils. We believe our results contribute to the improvement of the knowledge of this relevant topic, mainly in terms of the recovery of areas degraded by salinity. There is a paucity of studies associating salinity and nutritional management of soils worldwide. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) is one of the most important climate-forcing gases, and a large portion of global anthropogenic N2O emissions come from agricultural soils. Yet, how contrasting global change factors and agricultural management can interact to drive N2O emissions remains poorly understood. Here, conducted within a rice–wheat cropping system, we combined a two-year field experiment with two pot experiments to investigate the influences of elevated atmospheric carbon dioxide (eCO2) and crop straw addition to soil in altering N2O emissions under wheat cropping. Our analyses identified consistent and significant interactions between eCO2 and straw addition, whereby eCO2 increased N2O emissions (+ 19.9%) only when straw was added, and independent of different N fertilizer gradients and wheat varieties. Compared with the control (i.e., ambient CO2 without straw addition), eCO2 + straw addition increased N2O emission by 44.7% and dissolved organic carbon to total dissolved nitrogen (DOC/TDN) ratio by 115.3%. Similarly, eCO2 and straw addition significantly impacted soil N2O-related microbial activity. For instance, the ratio of the abundance of N2O production genes (i.e., nirK and nirS) to the abundance of the N2O reduction gene (i.e., nosZ) with straw addition was 26.0% higher than that without straw under eCO2. This indicates an increased denitrification potential and suggests a change in the stoichiometry of denitrification products, affecting the balance between N2O production and reduction, leading to an increase in N2O emissions. Taken together, our results emphasize the critical role of the interaction between the specific agronomic practice of straw addition and eCO2 in shaping greenhouse gas emissions in the wheat production system studied, and underline the need to test the efficacy of greenhouse gas mitigation measures under various management practices and global change scenarios. [ABSTRACT FROM AUTHOR]

Organic carbon based amendments can improve soil structure and fertility, as well as increase composition and diversity of soil microbial community. One of the major functions of improving soil fertility is to achieve effective nitrogen (N) management and mineralization. In this study, 746 paired observations were pooled from 20 long-term field experiments to verify the hypothesis that compared to synthetic only fertilization, long-term application of organic fertilization alone or in combination with synthetic fertilization could strengthen multiple internal pathways for soil N supply under various climatic conditions. We found that long-term application of synthetic N fertilizers alone or in combination with phosphorus (P) and potassium (K) led to an increase only in the recalcitrant organic N mineralization rate (MNrec) by 210% and 263%, respectively. However, long-term application of organic fertilizers alone or in combination with synthetic N fertilizers increased MNrec, labile organic N mineralization rate (MNlab) and release of adsorbed ammonium from cation exchange sites (RNH4a) by 160% and 200%, 153% and 353%, and 1025% and 541%, respectively. This indicates that organic fertilization can strengthen multiple internal pathways for mineral N production. The long-term co-application of organic and synthetic fertilizers stimulated MNlab (197%), MNrec (151%) and RNH4a (563%) in subtropical regions, but it had no effect on heterotrophic nitrification (ONrec). In contrast, it stimulated MNrec (505%), RNH4a (633%) and ONrec (184%) in temperate regions, with no observed effect on MNlab. These data confirm that if one N supply source is shut-off under specific climatic conditions the other pathways continue to provide N. The meta-analysis advances our understanding of agroecosystems and as such help to improve frameworks for enhancing soil health. [ABSTRACT FROM AUTHOR]

BACKGROUND: Nitrogen is a key factor affecting the quality of rice. Studying the impact of nitrogen fertilizer on the taste, physicochemical properties, and starch structure of Indica rice with different amylose contents is of great significance for scientifically fertilizing and cultivating high‐quality rice varieties for consumption. RESULTS: The results indicate that increasing nitrogen fertilizer application reduces the amylose content and increases the protein content, resulting in a decrease in taste quality. Simultaneously, it reduces the intergranular porosity of starch particles, improving the appearance and milling quality of rice. Compared to the N1 treatment (nitrogen fertilizer application rate of 90 kg ha−1), the taste of low‐amylose rice (Yixiangyou 2115) and high‐amylose rice (Byou 268) decreased by 14.24% and 19.79%, respectively, under N4 treatment (nitrogen fertilizer application rate of 270 kg ha−1). The effect of nitrogen fertilizer on low‐amylose rice is mainly reflected in increased rice hardness, enthalpy value, and setback viscosity, resulting in a decline in taste. The effect of nitrogen fertilizer on high‐amylose rice is mainly reflected in a decrease in peak viscosity, an increase in gelatinization temperature, and crystallinity under high nitrogen levels. CONCLUSION: Increasing nitrogen fertilizer application can improve the appearance and milling quality of rice, but it also leads to an increase in protein content, hardness, gelatinization enthalpy, decrease in breakdown value, and a decline in palatability. In practical production, different production measures should be taken according to different production goals. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study investigated the impact of biochar on Zea mays L. yield and greenhouse gas (GHG) emissions in rainfed maize fields in Northwest China. Four treatments were compared: unmodified control (CK), conventional nitrogen (BC0), nitrogen + 20 t ha−1 biochar (BC20), and nitrogen + 50 t ha−1 biochar (BC50). Results showed significant increases in grain yields with BC20 (11.1%) and BC50 (8.6%) compared to BC0. Emissions of nitrous oxide (N2O) were reduced by 14.0%–19.5% in biochar treatments compared to CK. Methane (CH4) uptake by the fields, acting as CH4 sinks, was not significantly impacted by biochar treatments, clarifying that the biochar did not alter the farmland's inherent ability to uptake CH4. Over 2 years, the addition of nitrogen fertilizer and biochar did not markedly alter cumulative CH4 uptake. Both net greenhouse gas (NGHG) emissions and yield‐scaled GHG intensity (NGHGI) were lowered by 16.7%–23.5% and 24.2%–30.3%, respectively, with biochar application. The integration of biochar effectively mitigated the GHG emission enhancement due to nitrogen fertilizer, mainly by decreasing nitrogen oxide emissions and boosting maize yields. Thus, proper biochar application would be an economical and effective strategy for mitigating gas emissions from rainfed maize cropping system in semiarid regions. Core Ideas: Biochar significantly increased maize yield in a rainfed cropping system.N2O emission was significantly decreased by 10.9%–19.5% by biochar application.Biochar significantly decreased net global warming potentials (NGWP) and greenhouse gas intensity (GHGI).Higher amount of biochar had no further decrease effect on NGWP and GHGI. [ABSTRACT FROM AUTHOR]

Pasture systems that include cool‐ and warm‐season species have the potential to enhance tall fescue (TF) [Schedonorus arundinaceus (Schreb.) Dumort.] forage systems beyond their typical season. The objectives of this study were to incorporate crabgrass (Digitaria ciliaris Retz.) into TF swards and compare the production of monoculture TF to a binary mixture of crabgrass and TF as well as its effect with different sources of nitrogen (such as red clover [Trifolium pratense L.] or sunn hemp [Crotalaria juncea L.]). The experiment was conducted in Crossville, TN, in 2020 and 2021. The treatments were as follows: (1) TF + 0 N (T), (2) TF + ammonium nitrate (TA), (3) TF + red clover (TR), (4) TF + sunn hemp (TS), (5) TF + crabgrass + 0 N (TFC), (6) TF + crabgrass + ammonium nitrate (TCA), (7) TF + crabgrass + red clover (TCR), and (8) TF + crabgrass + sunn hemp (TCS). The plots containing red clover indicated a greater herbage mass (HM) and crude protein (CP) along with lesser neutral detergent fiber compared to the other treatments. Sunn hemp performed best during the mid‐summer, contributing to the increase of HM. Tall fescue swards that were mixed with crabgrass and a source of N (legumes or N fertilizer) had greater HM during the warm season, having the potential to decrease the stationarity of production. Thus, including crabgrass, red clover, and sunn hemp (grass and legumes, respectively) in TF pasture can be a great strategy to increase HM and improve nutritive value. Core Ideas: Inclusion of cool‐ and warm‐season grasses increases the seasonality of production.Crabgrass is a warm‐season grass that improves nutritive value in mixed pasture.Nitrogen fertilizer increases forage mass and nutritive value.Increasing the use of legumes in pastures may decrease the use of synthetic N fertilizer. [ABSTRACT FROM AUTHOR]

The rising prices of N fertilizer led to exploring cost‐saving efforts, such as intercropping cool‐ or warm‐season legumes serving as alternative sources of N for managing fall‐stockpiled tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.; TF]. We aimed to evaluate red clover (Trifolium pratense L.; RC) and sunn hemp (Crotalaria juncea L.; SH) mixed with TF as alternative sources of N for stockpiling TF to increase productivity and animal performance. The experiment was conducted in Crossville, TN, in 2020 and 2021 and consisted of TF pastures mixed with RC (TRC) or SH (TSH), and TF fertilized with urea (TU). The experiment was divided into two periods: the pre‐grazing period (stockpiling) (April–October) and the grazing period (October–December). After the stockpiling period, Black Angus beef (Bos taurus) steers were used for the grazing period. The study evaluated the botanical composition, herbage mass (HM), nutritive value, steer average daily gain (ADG), and net returns (NR). The TRC pastures had a greater proportion of legumes compared to TSH plots in May, October, November, and December of both years. There were no differences among treatments for the total HM and nutritive value in 2020; however, in 2021, TU had greater HM at the beginning of the grazing period and greater average crude protein values compared to the other treatments. In both years, there were no differences among treatments for ADG or NR. Therefore, producers can make the same profit considering the beef steer price and the cost of conventional and alternative N sources. Core Ideas: Legumes have the potential to suppress weeds when mixed with grasses.Nitrogen is the most important nutrient that contributes to forage production.Stockpiling forages contributes to the extension of grazing season.Grass and legume mixtures can increase the nutritive value and, consequently, improve animal performance. [ABSTRACT FROM AUTHOR]

Nitrogen (N) fertilizer management in rice (Oryza sativa L.) varies with production practices. In drill‐seeded, delayed‐flood production systems, the most common production practice in Louisiana N fertilizer is applied at two application timings. The first application timing is just before the permanent flood is established. The second application is at midseason. Nitrogen fertilization before flooding is critical for maximum N uptake, nitrogen recovery efficiency (NRE), and yield. Field experiments were conducted from 2017 to 2020 to evaluate N timing effects on N uptake, NRE, and rice yield. The rice cultivar CL153 was drill‐seeded into a stale seedbed at a seed rate of 85 kg ha−1. Fertilizer‐N was applied utilizing multiple application timings and rates adding up to a seasonal rate of 155 kg ha−1 across treatments. A single N application 1‐day before flooding significantly increased grain yield in all trials, ranging from 8523 kg ha−1 in 2019 to 11,322 kg ha−1 in 2018. Compared to post‐flood applications, preflood N increased plant height, N uptake, and NRE. Split N application rates and timings after flooding did not impact rice yield or its agronomics, such as height, aboveground biomass, and time of heading. NRE and yield were significantly correlated (r = 0.805; p < 0.001). Our results indicated that a single N application before flooding has the potential to be an alternative option for N management in the drill‐seeded, delayed‐flood rice system. Core Ideas: Preflood N application outperforms post‐flood N application regardless of application methods.Single preflood N application increased yield up to 12,579 kg ha−1 compared to 5524 kg ha−1 for post‐flood.Single preflood N extended growth duration and plant height while increasing N content and uptake.Post‐flood N applications proved inefficient with just 7% average NRE compared to 65% with preflood. [ABSTRACT FROM AUTHOR]

Climate‐smart agricultural practices, such as no‐tillage (NT) and cover cropping, have been widely adopted and are anticipated to yield multiple benefits, including soil carbon sequestration, enhancing soil health, and crop yield stability. However, their influence on nitrous oxide (N2O) emissions varies, with the potential of both increasing and decreasing N2O emissions. Increasing N2O emissions under these practices may potentially offset the climate mitigation benefits from increased soil carbon sequestration. We investigated N2O emissions in response to 42 years of long‐term adoption of NT and legume cover crop, under nitrogen (N) rates of 0 and 67 kg N ha−1, in a continuous cotton system in the Southeastern United States. Intensive manual chamber‐based measurements were conducted over two growing seasons (2021–2022 and 2022–2023). Long‐term NT did not significantly affect cumulative N2O emissions during the study period (p > 0.05). Hairy vetch cover crop‐grown plots emitted two to three times more N2O than those without cover crops in 2021–2022, with no significant effect observed in 2022–2023. Cumulative emissions in cover crop plots were greater compared to those in no cover crop plots when fertilized with 67 kg N ha−1 in 2021–2022; however, this trend did not persist in 2022–2023. While interannual variability exists, our results generally suggest that long‐term NT may not increase N2O emissions, hence its adoption could enhance its broader soil health and climate benefits via soil carbon sequestration, whereas managing legume cover crop residues in N‐fertilized systems is critical to mitigate N2O emissions. Core Ideas: Nitrous oxide emissions from continuous cotton were measured in response to long‐term NT and cover cropping.No‐tillage did not increase N2O emissions compared to conventional tillage.Inclusion of a legume cover crop (hairy vetch) in cotton cropping systems increased N2O emissions.The impact of hairy vetch was more pronounced in presence of mineral N fertilizer. [ABSTRACT FROM AUTHOR]

Surfactants are commonly employed in sand‐based turfgrass systems to address soil water repellency, which often results in the formation of preferential flow channels leading to non‐uniform wetting patterns. While the influence of soil moisture on nutrient dynamics is well documented, the potential of surfactants to improve N uptake remains poorly understood. A 2‐year study was conducted on 'Celebration' bermudagrass [Cynodon dactylon (L.)] fairway to better understand the interaction between fertility programs (296 or 586 kg N ha−1 year−1 from ammonium sulfate and 564 kg N ha−1 year−1 primarily from a controlled‐release N fertilizer) and surfactant rate and frequency (3.2 L ha−1 every 14 or 28 days, or at 6.4 L ha−1 every 28 days) on turfgrass performance, leaf N content, and soil moisture. Overall, no significant interaction was observed between surfactant treatment and fertility program. During the dry season (November to May), fertility programs influenced turfgrass performance parameters with higher N rates consistently leading to improvements in visual quality, normalized difference vegetation index, percent green cover, and dark green color index; however, no differences were observed during the rainy season (June to October). Surfactants showed no effect on turfgrass performance but led to minimal increase in leaf N content from 3.72% to 3.85%. All surfactant treatments reduced water drop penetration time at 0 cm. Moreover, surfactant treatments applied every 28 days regardless of the rate exhibited a higher volumetric water content compared to those applied every 14 days. Surfactant applications might not be an economically feasible strategy to improve leaf N content in South Florida well‐watered bermudagrass fairways. Core Ideas: Surfactant applied at half rate had the same effect as full rate on soil moisture and water penetration.Surfactant applications might not be necessary to improve leaf N content in South Florida fairways.Higher N rates sustained bermudagrass quality over winter.Leaf N content within optimal ranges did not always translate to sufficient optimal turfgrass quality. [ABSTRACT FROM AUTHOR]

Soil ecological stoichiometry (SES) provides an important approach in exploring chemical element balance relationships and ecosystem structure and function, but the characterization, significance, and drivers of SES in saline–alkali areas have not been well studied. Soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) were measured and their SES ratios were calculated from 155 soil samples collected at a depth of 20 cm in the saline–alkali soil zone of western Jilin Province, China. The results showed that SOC, TN, and TP contents and SES ratios (52:4:3) were lower in this region than in terrestrial ecosystems both in China as a whole and globally. The distribution of SOC, TN, and TP in saline–alkali soil varied significantly across land use types, with high concentrations mainly in woodland, grassland, and cropland. SOC, TN, and TP were tightly coupled, with significant positive correlations (p < 0.01), and C:N was significantly negatively correlated (p < 0.01) with the other SES ratios, indicating that saline–alkali soils are susceptible to carbon and nitrogen limitation. The distribution patterns of SOC, TN, TP, and their eco‐chemometrics on the environmental gradient were variable, mainly in the form of significant decreases with increasing mean annual precipitation, mean annual temperature, and elevation. Cropland was most affected by environmental factors, and all SES except TP were affected by environmental factors. Soil nutrient (44.9%) and soil texture (9.8%) contributed the most to explaining SES in the saline–alkali soil zone, while climate (1.6%) and vegetation (0.4%) contributed the least to the explanation. All land use types were most explained by AN, except for woodland SES, which was most explained by AP. Elevation (17.4%) possessed a high degree of explanation for SES on underutilized land, except for the soil itself. Grassland is the land category most affected by climatic factors (12.7%). By applying biochar, nitrogen fertilizer, and planting saline‐tolerant crops such as Leymus chinensis, the soil structure can be effectively improved and the content of carbon and nitrogen in the soil can be increased, which has a positive effect on the improvement of saline–alkali soil. The results of the study provide information that can be used to help saline–alkali areas cope with environmental and climate change and restore degraded ecosystems. [ABSTRACT FROM AUTHOR]

Enhancing irrigation and nitrogen fertilizer application has become a vital strategy for ensuring food security in the face of population growth and resource scarcity. A 2-year experiment was conducted to determine to investigate the effects of different irrigation lower limits and nitrogen fertilizer application amounts on millet growth, yield, water use efficiency (WUE), N utilization, and inorganic nitrogen accumulation in the soil in 2021 and 2022. The experiment was designed with four irrigation lower limits, corresponding to 50%, 60%, 70%, and 80% of the field capacity (FC), referred to as I50, I60, I70, and I80. Four nitrogen fertilizer application were also included: 0, 50, 100, and 150 kg·hm−2 (designated as F00, F50, F100, and F150), resulting in a total of 16 treatments. Binary quadratic regression equations were established to optimize the irrigation and nitrogen application. The results demonstrated that the plant height, stem diameter, leaf area index, aboveground biomass, yield, spike diameter, spike length, spike weight, WUE, and nitrogen agronomic efficiency for millet initially increased before subsequently decreasing as the irrigation lower limit and nitrogen fertilizer application increased. Their maximum values were observed in the I70F100. However, the nitrogen partial factor productivity (PFPN) exhibited a gradual decline with increasing nitrogen application, reaching its peak at F50. Additionally, PFPN displayed a pattern of initial increase followed by a decrease with rising irrigation lower limits. The accumulation of NO3−-N and NH4+-N in the 0~60 cm soil layer increased with the increase of nitrogen fertilizer application in both years, while they tended to decrease as the irrigation lower limit increased. An optimal irrigation lower limit of 64% FC to 74% FC and nitrogen fertilizer application of 80 to 100 kg ha−1 was recommended for millet based on the regression equation. The findings of this study offer a theoretical foundation and technical guidance for developing a drip irrigation and fertilizer application for millet cultivation in Northeast China. [ABSTRACT FROM AUTHOR]

The present study endeavored to tackle the challenges posed by limited diversity in oat varieties and suboptimal nitrogen fertilizer utilization in the arid landscapes of the Loess Plateau. We selected three oat varieties, including early-maturing oats (E), medium-maturing oats (M), and late-maturing oats (L). In 2022, four nitrogen applications were set up as CK (0 kg N ha−1), N1 (60 kg N ha−1), N2 (90 kg N ha−1), and N3 (120 kg N ha−1). We introduced two additional nitrogen applications, N4 (180 kg N ha−1) and N5 (240 kg N ha−1), in 2023. The two-year study results demonstrated a significant increase in oat yield due to nitrogen application (p < 0.05). The highest grain yield was observed for E oats at 2216.63 kg·ha−1 under the N3 treatment, while M and L oats had the highest grain yields at 2505.43 kg·ha−1 and 2946.30 kg·ha−1 under N4, respectively. The protein content of L oats reached a peak of 14.15% under N4, and the order of protein contents in oat protein components was globulin > gliadin> glutenin > albumin. The β-glucan content of L oats reached a peak of 4.92% under N3. The nitrogen fertilizer utilization efficiency (NFUE) of the three oats was highest under N2. L oats exhibited enhanced NFUE owing to an elevated pre-flowering nitrogen translocation amount (PrNTA), with a 42.94% and 29.51% increase relative to E and M oats, respectively. The pre-flowering nitrogen translocation contribution (PrNTC) in oats surpassed the post-flowering nitrogen accumulation contribution (PoNAC). Therefore, nitrogen application positively impacted oat growth, yet excessive application had an inhibitory effect. There is a significant positive correlation among oat yield, quality, nitrogen accumulation, and utilization efficiency. In summary, oat crops exhibited optimal performance in terms of yield, quality, and nitrogen use efficiency when nitrogen application rates ranged between 90 and 180 kg·ha−1. Late-maturing oats coincide with the rainy and hot season in the northern dryland regions, making them more suitable for planting in the dryland areas of the Loess Plateau. [ABSTRACT FROM AUTHOR]

Intensified atmospheric nitrogen (N) deposition, coupled with increased application of N fertilizers in forest plantations, has resulted in N and phosphorus (P) imbalance in the forest soil system. However, it is seldom investigated whether an addition of N counteracts the effects of low P stress on N and P nutrient absorption and utilization efficiencies. Thus, we conducted a greenhouse experiment on three clones of Chinese fir (clones 061, 020 and 2 C) with four levels of N addition (2, 5, 10, and 15 mmol·L− 1 sodium nitrate) under normal P supply (1.0 mmol·L− 1 KH2PO4), moderately P deficiency (0.5 mmol·L− 1 KH2PO4) and severely P deficiency (0.1 mmol·L− 1 KH2PO4) conditions. The results showed that addition of moderate concentration of N (10 mmol·L− 1 N) significantly promoted root elongation, root dry mass accumulation, root surface area and root APase activity of Chinese fir seedlings under P-deficient conditions, with distinct clonal variation. Seedlings of clone 061 showed the most root APase activity in response to addition of moderate concentration of N under P deficient condition while clones 061 and 020 had the longest roots and the largest root dry mass accumulation. Under severe P deficiency, the N and P absorption efficiencies (NAE and PAE) of Chinese fir seedlings increased with increasing N concentration, while the N and P utilization efficiencies (NUE and PUE) decreased. The findings demonstrate that addition of moderate level of N modulates the adaptive responses of Chinese fir to P deficiency and enhances the absorption efficiency of P. The variation among clones suggests that the responses are genetically controlled and there exists great potential for breeding highly phosphorus efficient genotypes under coupled conditions of P deficiency and increased atmospheric nitrogen deposition. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the impact of various chemical nitrogen fertilizers on the profile of antibiotic resistance genes (ARGs) in soil. A microcosm experiment was conducted with four treatments, including CK (control with no nitrogen), AN (ammonium nitrogen), NN (nitrate nitrogen), and ON (urea nitrogen), and the abundance of ARGs was assessed over a 30-day period using a metagenomic sequencing approach. The levels of core ARGs varied between 0.16 and 0.22 copies per cell across different treatments over time. The abundance of core ARGs in the ON treatment closely resembled that of the CK treatment, suggesting that environmentally friendly nitrogen fertilizers, particularly those in controlled release formulations, may be preferable. The core ARG abundance in the AN and NN treatments exhibited noticeable fluctuations over time. Overall, chemical nitrogen fertilizers had minimal effects on the core ARG profile as determined by principal component analysis and clustering analyses. Conversely, distinct and significant changes in bacterial communities were observed with the use of different nitrogen fertilizers. However, the influence of nitrogen fertilizers on the core ARGs is limited due to the unaffected potential bacterial hosts. Nitrogencycling-related genes (NCRGs), such as those involved in nitrogen-fixing (nifK, nifD, nifH) and denitrification (narG, napA, nirK, norB, nosZ) processes, exhibit a positive correlation with ARGs (rosA, mexF, bacA, vanS), indicating a potential risk of ARG proliferation during intense denitrification activities. This study indicates that the application of chemical nitrogen has a minimal effect on the abundance of ARGs in soil, thereby alleviating concerns regarding the potential accumulation of ARGs due to the use of chemical nitrogen fertilizers. [ABSTRACT FROM AUTHOR]

The article presents the results of a three-year field study that was conducted in Poland to evaluate the yield and quality of seeds and oil from traditional (SAM) and canola-quality white mustard (SAC) in response to different N fertilizer rates (0, 40, 80, 120, and 160 kg ha–1). Seed yields were 25% higher in SAM than SAC. The seeds of SAC contained more crude fat (by 3%) and crude fiber (by 6%) than the seeds of SAM. In turn, the seeds of SAM were a richer source of total protein (by 7%). The content of glucosinolates (GSLs) was 8–10 times lower in the seeds of SAC than SAM. The seeds of both mustard cultivars were most abundant in γ-tocopherol (γ-T) (90–94%). The seeds of SAC were characterized by a higher content of γ-T and a lower α-T/γ-T ratio than SAM seeds. White mustard oil contained mostly MUFAs (69–75%). However, C22:1 accounted for more than 50% of MUFAs in the oil SAM. In the oil SAC, the proportion of C22:1 did not exceed 6%, whereas C18:1 accounted for nearly 85% of total MUFAs. Nitrogen fertilization induced a significant increase in seed yields (by 33%), a decrease in crude fat content (by 3–4%), and an increase in total protein content (by 4%), and crude fiber content (by 7%). Nitrogen decreased GSL levels by 31% in SAM seeds. In SAC, N fertilization induced differences in the qualitative composition of GSLs, but did not affect the total GSL content of seeds. Higher N rates increased the content of α-T and γ-T, the α-T/γ-T ratio, and total T content. Nitrogen fertilization decreased the content of C18:3 in the seeds of the SAM. In SAC, the application of N decreased the content of C18, C18:1, and C18:3, and increased the biosynthesis of C18:2, C20:1, and C22:1. [ABSTRACT FROM AUTHOR]

Introduction: This study investigated the combined effects of molybdenum (Mo) and nitrogen (N) fertilization on N metabolism and amino acid content in the leaves of flue-cured tobacco (Nicotiana tabacum L.) during its mature stage through a pot experiment. Methods: Different application levels of Mo (0, 0.15, 0.30 mg/kg soil) and N (0.06, 0.24, 0.42 g/kg soil) were set to observe and analyze changes in leaf quality, N, and amino acid content in the tobacco plants. Results: The results revealed that the N fertilizer application level exhibited a primary effect on regulating the total nitrogen, nitrate nitrogen, soluble protein, and amino acid nitrogen concentrations within tobacco leaves, while the effectiveness of Mo fertilization was influenced by the level of N applied. Specifically, under the conditions of 0.24 g/kg soil N and 0.30 mg/kg soil Mo application, the N content, N accumulation, and dry matter mass of the tobacco plants increased significantly by 110%, 204%, and 48%, respectively. Concurrently, nitrate reductase activity increased by 107-fold, and the nitrate nitrogen content was relatively low, contributing to enhanced tobacco yield and safety. Moreover, this treatment led to a notable (170%) increase in free amino acid nitrogen content, with minimal impact on total amino acids and soluble proteins. Notably, it effectively increased the content of free amino acids beneficial to the sensory quality of tobacco (such as histidine, arginine, aspartic acid, isoleucine, and glutamic acid) without reducing the total amino acid content, while simultaneously reducing other amino acids that might affect quality. Therefore, the combined application of 0.30 mg/kg soil Mo and 0.24 g/kg soil N specifically optimized the amino acid composition in tobacco leaves, positively impacting overall quality and market competitiveness. Discussion: This study provides a theoretical basis for the rational application of Mo fertilizer in Mo-deficient areas to improve the yield and quality of fluecured tobacco. [ABSTRACT FROM AUTHOR]

Introduction: The chickpea (Cicer arietinum L.) is well-known for having climate resilience and atmospheric nitrogen fixation ability. Global demand for nitrogenous fertilizer is predicted to increase by 1.4% annually, and the loss of billions of dollars in farm profit has drawn attention to the need for alternative sources of nitrogen. The ability of chickpea to obtain sufficient nitrogen via its symbiotic relationship with Mesorhizobium ciceri is of critical importance in determining the growth and production of chickpea. Methods: To support findings on nodule formation in chickpea and to map the genomic regions for nodulation, an association panel consisting of 271 genotypes, selected from the global chickpea germplasm including four checks at four locations, was evaluated, and data were recorded for nodulation and 12 yield-related traits. A genome-wide association study (GWAS) was conducted using phenotypic data and genotypic data was extracted from whole-genome resequencing data of chickpea by creating a hap map file consisting of 602,344 single-nucleotide polymorphisms (SNPs) in the working set with best-fit models of association mapping. Results and Discussion: The GWAS panel was found to be structured with sufficient diversity among the genotypes. Linkage disequilibrium (LD) analysis showed an LD decay value of 37.3 MB, indicating that SNPs within this distance behave as inheritance blocks. A total of 450 and 632 stringent marker-trait associations (MTAs) were identified from the BLINK and FarmCPU models, respectively, for all the traits under study. The 75 novel MTAs identified for nodulation traits were found to be stable. SNP annotations of associated markers were found to be related to various genes including a few auxins encoding as well as nod factor transporter genes. The identified significant MTAs, candidate genes, and associated markers have the potential for use in marker-assisted selection for developing high-nodulation cultivars after validation in the breeding populations. [ABSTRACT FROM AUTHOR]

Background: The pervasively imprudent practices of irrigation and nitrogen (N) application within Oasis Cool Irrigation zones have led to significant soil nitrogen loss and a marked decrease in water and nitrogen use efficiency. Methods: To address this concern, a comprehensive field experiment was conducted from April to September in 2023 to investigate the impact of varying degrees of water and fertilization regulation strategies on pivotal parameters including potato yield, quality, nitrogen balance, and water-nitrogen use efficiency. The experimental design incorporated two water deficit degrees at potato seedling (W1, 55%-65% of Field Capacity (FC); W2, 45%-55% of FC), and four distinct nitrogen application gradients (N0, 0 kg ha-1 of N; N1, 130 kg ha-1 of N; N2, 185 kg ha-1 of N; N3, 240 kg ha-1 of N). A control was also included, comprising N0 nitrogen application and full irrigation (W0, 65%-75% of FC), totally eight treatments and one check. Results: The results indicated that the tuber yield, plant dry matter accumulation, plant height, plant stem, and leaf area index increased with higher nitrogen fertilizer application and irrigation volume. However, tuber starch content, vitamin C, and protein content initially increased and then decreased, while reducing sugar content consistently decreased. Except for W1N2 treatment, the irrigation water use efficiency increased as the N application rate rose, while the nitrogen partial factor productivity, crop nitrogen use efficiency and soil nitrogen use efficiency decreased with an increase in N fertilizer application. The W1N2 treatment resulted in a higher yield (43.16 t ha-1), highest crop nitrogen use efficiency (0.95) and systematic nitrogen use efficiency (0.72),while maintaining moderate levels of soil nitrate and ammonium nitrogen. Conclusion: Therefore, through the construction of an integrated evaluation index (IEI), the W1N2 treatment of mild water deficit (55%-65% of FC) at potato seedling combined with the medium nitrogen application (185 kg ha-1 of N) has the highest IEI (0.978), it was recommended as the optimal water-nitrogen regulation and management strategies to facilitate high-yield, high-efficiency, and environmentally sustainable potato production in the cold and arid oasis areas of northwest China. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is an essential element for plant growth, development, and metabolism. In apple production, the excessive use of N fertilizer may cause high N stress. Whether high N stress can be alleviated by regulating melatonin supply is unclear. The effects of melatonin on root morphology, antioxidant enzyme activity and 13C and 15N accumulation in apple rootstock M9T337 treated with high N were studied by soil culture. The results showed that correctly raising the melatonin supply level is helpful to root development of M9T337 rootstock under severe N stress. Compared with HN treatment, HN+MT treatment increased root and leaf growth by 11.38%, and 28.01%, respectively. Under high N conditions, appropriately increasing melatonin level can activate antioxidant enzyme activity, reduce lipid peroxidation in roots, protect root structural integrity, promote the transport of sorbitol and sucrose to roots, and promote further degradation and utilization of sorbitol and sucrose in roots, which is conducive to the accumulation of photosynthetic products, thereby reducing the inhibitory effect of high N treatment on root growth. Based on the above research results, we found that under high N stress, melatonin significantly promotes nitrate absorption, enhances N metabolism enzyme activity, and upregulates related gene expression, and regulate N uptake and utilization in the M9T337 rootstock. These results presented a fresh notion for improving N application and preserving carbon-nitrogen balance. [ABSTRACT FROM AUTHOR]

Wheat grain yields, quality, and nitrous oxide (N2O) emissions were controlled through the type and application rate of nitrogen (N) fertilizer. Here, we investigated the optimal management of N fertilization by examining the combined effects of organic and N fertilizers on wheat yields, quality, and N2O emissions. Field trials under six treatments were located on campus farms at Anhui Science and Technology University, including farmer's common practice (270 kg N ha-1, N270), 2/3 reduction in N270 (90 kg N ha-1, N90), organic fertilizer with equal N270 (OF270), 2/3 reduction in OF270 (OF90), 4/5 reduction OF270 + 1/5 reduction N270 (20% OF270 + 80% N270), and 4/ 5 reduction OF90 + 1/5 reduction N90 (20% OF90 + 80% N90) were applied to winter wheat. The plots were arranged in a randomized complete block experimental design. The N2O emissions were quantified under different fertilization measures in the peak wheat growing season during sowing, jointing, and grain filling stages, respectively. Compared with N270 and N90 treatments, N2O emissions were significantly decreased by 18.6% and 27.2%, respectively, under 20% OF270 + 80% N270% and 20% OF90 + 80% N90 (p < 0.05). Further, N2O emissions in N270 were increased by 50.8% relative to N90. Wheat yields increased significantly under 20% OF90 + 80% N90 by 27.6% (N270) and 16.4% (N90), and were considerably enhanced under 20% OF270 + 80% N270 by 40.6% (N270) and 12.7% (N90) in contrast to OF270 and N270 (p < 0.05). Compared with N90, the content of wet gluten, protein and starch under 20% OF90 + 80% N90 treatment significantly increased by 7.7%, 13.8% and 7.9%, and enhanced by 7.6%, 4.8%, 8.0% relative to OF90, respectively (p < 0.05). The starch content increased significantly by 2.0%, whereas the settlement value decreased considerably by 2.9% under 20% OF270 + 80% N270 (p < 0.05), and there was no notable difference in the wet gluten and protein contents (p > 0.05). Our findings indicated that organic fertilizer mixed with N fertilizer can effectively reduce N2O emissions, increase both the grain yields and quality in wheat field compared with N fertilizer alone. [ABSTRACT FROM AUTHOR]

Onions are among the most important cash crops in developing countries, including Ethiopia. However, its production and productivity are very low, which is associated with inappropriate fertilization and the use of low-yielding varieties. Therefore, the present study was conducted to evaluate the effects of the nitrogen fertilizer rate on the growth, yield, and quality of hybrid onion varieties in northwest Ethiopia. The experiment was conducted at three locations (Koga, Woreta, and Woramit) during the 2021/2022 cropping season under irrigated conditions. The treatments consisted of three hybrid onion varieties (Russet, Jambar, Red Coach) and one open-pollinated onion variety (Bombay Red) and four nitrogen rates (0, 41, 82, and 123 kg ha-1), which were laid out in a randomized complete block design with a factorial arrangement of 4*4 in three replications. The results of the present study revealed that onion growth, yield and quality were influenced by the nitrogen fertilizer rate and onion variety across all locations. Compared with the open pollinated Bombay Red variety, the hybrid varieties (Russet and Jambar) performed well in terms of bulb diameter, bulb weight, total yield, marketable bulb yield, and pungency. Nitrogen fertilizer applied at a rate of 82 kg ha-1 resulted in the highest growth and yield parameters of onion. The Russet and Jambar varieties recorded the highest marketable bulb yields of 26.50 t ha-1 and 24.57 t ha-1, respectively. Onion varieties treated with the highest nitrogen fertilizer dosage of 123 kg ha-1, particularly the Bombay Red variety, exhibited the longest duration to reach maturity. Onion plants supplied with 82 kg ha-1 nitrogen presented the highest marketable bulb yields, with a value of 26.77 t ha-1. Too much nitrogen above 82 kg ha-1 leads to decreased yield; hence, excess nitrogen is lost to the environment. Furthermore, the Jambar and Russet hybrid varieties and the application of 82 kg ha-1 nitrogen fertilizers provided the highest net benefit. The hybrid varieties Jambar and Russet and the application of 82 kg ha-1 nitrogen fertilizer can be recommended for onion production in the study area and areas with similar agroecosystems. Since this study is the first of its kind, considering other hybrid onion varieties and optimizing agronomic practices such as spacing and phosphorus fertilizer are also recommended in future research. [ABSTRACT FROM AUTHOR]

Fertilizers are an essential input in agriculture as they can enhance crop yields. However, their use also poses significant environmental risks. To thoroughly explore the intensity of fertilizer use and its potential threats to the ecological environment, this study analyzed the environmental risks of fertilizer use from a temporal and spatial perspective based on fertilizer application data in China from 1978 to 2022. Additionally, the contribution of fertilizer application in Chinese farmland to greenhouse gas N2O emissions was quantified using IPCC emission factor methodology. The results indicated that fertilizer application intensity and N2O emissions in China initially increased and then decreased from 1978 to 2022. Despite the implementation of various fertilizer control measures at the policy level, such as the Zero Growth of Fertilizer Action in 2015 and the Efficiency-Increasing Action for Reducing Fertilizer Use in 2022, the intensity of fertilizer application in China still exceeded international safety standards by 1.33-fold in 2022, reaching 298.79 kg/hm2. Furthermore, N2O emissions amounted to 50.17 × 104t, accounting for 16% of China's total agricultural greenhouse gas emissions that year. Correlation and regression analyses demonstrated that with increasing fertilizer application, crop production exhibits an inverted U-shaped growth trend, indicating limited effectiveness of high-intensity fertilizer use in increasing crop yields. These findings highlight the profound greenhouse effect resulting from the use of agricultural nitrogen fertilizer. Therefore, this study proposed technical and policy-level mitigation measures to address the issues caused by excessive fertilizer application, aiming to provide insights for controlling agricultural non-point source pollution and preserving the agroecological environment. [ABSTRACT FROM AUTHOR]

Urban rivers worldwide have been increasingly threatened by nitrate (NO3−) pollution. The Xianyang-Xi'an segment of the Weihe River, located in the loess plateau with serious soil erosion, has been highly urbanized and with intensive agricultural activities. Tracing the sources and transformations of NO3− is particularly challenging for this watershed which has multiple N sources and variable environmental factors. In this study, integrating antecedent studies with multiple stable isotopes and MixSIAR models, these river basins can be categorized into three classes: (1) urban areas, sewage, and manure were the predominant sources of NO3− in the Weihe River's mainstream, accounting for 73.4 ± 12.8%; (2) suburban areas, sewage and manure (Fenghe River, 58.0 ± 14.0%; Bahe River, 53.9 ± 15.0%) were recognized as the main sources of NO3−; (3) and the rural areas, ammonium nitrogen fertilizers were identified as the primary source of NO3− in the Heihe and Laohe Rivers. In addition, nitrification dominated the mainstream of the Weihe, Fenghe, and Bahe Rivers, while neither denitrification nor nitrification was evident in the Heihe and Laohe Rivers. In conclusion, this study is important for the improvement of surface water quality of rivers with different land use types and the development of targeted water environment management. [ABSTRACT FROM AUTHOR]

Symbiotic nitrogen fixation (SNF) in legume-rhizobia serves as a sustainable source of nitrogen (N) in agriculture. However, the addition of inorganic N fertilizers significantly inhibits SNF, and the underlying mechanisms remain not-well understood. Here, we report that inorganic N disrupts iron (Fe) homeostasis in soybean nodules, leading to a decrease in SNF efficiency. This disruption is attributed to the inhibition of the Fe transporter genes Natural Resistance-Associated Macrophage Protein 2a and 2b (GmNRAMP2a&2b) by inorganic N. GmNRAMP2a&2b are predominantly localized at the tonoplast of uninfected nodule tissues, affecting Fe transfer to infected cells and consequently, modulating SNF efficiency. In addition, we identified a pair of N-signal regulators, nitrogen-regulated GARP-type transcription factors 1a and 1b (GmNIGT1a&1b), that negatively regulate the expression of GmNRAMP2a&2b, which establishes a link between N signaling and Fe homeostasis in nodules. Our findings reveal a plausible mechanism by which soybean adjusts SNF efficiency through Fe allocation in response to fluctuating inorganic N conditions, offering valuable insights for optimizing N and Fe management in legume-based agricultural systems. Symbiotic nitrogen fixation is a tightly regulated process serving as a sustainable source of nitrogen (N) in agriculture. Here it is shown that external N sources precisely regulate N fixation efficiency by modulating iron transport in nodules of legumes. [ABSTRACT FROM AUTHOR]

Guar is a typical legume cash crop native to India. Guar beans are ever-rising in the market share at present. Among them, the guar gum of its seed endosperm has been mainly used in the oil exploration industry. Water-based fracturing fluid can be formulated to increase the permeability of oil-bearing strata during oil production. In addition, guar gum is also widely used in paper making, textiles, food, spices, drugs, as well as mining and metallurgical industries. The nutrient-rich green seeds of guar beans are edible for food vegetables, due to a large amount of protein and a small amount of fat. The plant can be used as fodder and green manure. However, the low supply of guar gum on the market cannot fully meet the broad market space. Only a small number of planting areas of guar beans are suitable for the cultivation of guar beans in the food industry. Among them, Xinjiang located in the northwestern inland arid zone is very similar to the unique geographic conditions for the production and cultivation of guar beans. The temperature and heat conditions are suitable for the origin of guar, rich in the light and heat resources under the soil and water environment, with the high temperature difference between day and night, due to the scarce rainfall and high evaporation. But the relatively small region of guar bean planting still remains so far. Therefore a broad prospect can be expected to optimize the water and nitrogen management for the high crop yield and efficient use of water and nitrogen. This study aims to explore the water and nitrogen mode suitable for drip irrigation of guar beans under film in the Xinjiang area of China. Four irrigation levels were set: W1:1170 m³/hm², W2:1 530 m³/hm², W3:1 890 m³/hm², W4: 2 250 m³/hm²; Two levels of nitrogen application were: N1:30 kg/hm², N2:50 kg/hm². A systematic investigation was made to clarify the effects of water and nitrogen interaction on the growth index, yield, water, and nitrogen use efficiency, as well as the quality of guar bean during drip irrigation under film. The results showed that the coupling effect of water and nitrogen shared a significant effect on the yield, irrigation water use efficiency, and partial factor productivity of nitrogen fertilizer (W3>W4>W2>W1). There was an increase in the plant height, stem diameter, dry matter accumulation, yield, water use efficiency, galactomannan, soluble sugar, and polysaccharide content of Guar bean under the N2 level, compared with the N1 level. Only the partial productivity of nitrogen fertilizer decreased slightly. Principal component and membership function analysis showed that the optimal treatment was achieved in the irrigation amount of 1 890 m³/hm² and the nitrogen application rate of 50 kg/hm²(W3N2). The finding can also provide a theoretical basis to promote the yield, water, and nitrogen use efficiency of Guar bean under mulched drip irrigation. [ABSTRACT FROM AUTHOR]

Superabsorbent hydrogels (HGs) are three-dimensional, polymeric networks that have been shown to increase soil water holding capacity, but little is known about their effect on nitrogen (N) transformations in soil. The objective of this study was to determine the effect of two types of HGs (polyacrylate (TS) or cellulose-based (H30)) applied as soil amendment on pH, urea hydrolysis, nitrification, NH3 volatilization, and soil respiration in two soils receiving urea or ammonium sulfate. Separate studies with each HG in each of two soils (four studies) were conducted with an acidic sandy loam collected in Georgia (USA) and a basic sandy loam collected in the Veneto region of Italy. The results showed that the addition of TS increased the pH of the acidic soil, whereas H30 did not have a major effect on soil pH in either soil. In the acidic soil receiving urea, H30 increased nitrification, whereas TS decreased initial nitrification. Neither HG affected urea hydrolysis, N immobilization and NH3 volatilization in either soil, but both HGs increased soil respiration in the basic soil, possibly due to HG degradation by microorganisms. These results show that the use of HGs together with N fertilizers may affect soil pH, nitrification, and respiration. [ABSTRACT FROM AUTHOR]

A peat substrate is made from peat from drained peatlands, which is a limited resource. A realistic estimate is that 50% of the world's wetlands have been lost. Peat is used in horticulture, especially for the cultivation of vegetables in greenhouses. The consequences of peatland exploitation are an increase in the greenhouse effect and a decrease in carbon stocks. Wood fiber can be used as an alternative to peat. The chemical properties of growing media interact and change continuously due to the small volume of growing media, which is limited by the growing container. This study aims to gain new knowledge on the impact of nutrient changes in the microbial degradation of carbon compounds in wood fiber and mixtures with a peat substrate on the content and uptake of nutrients required by plants. The cucumber (Cucumis sativus L.) variety 'Dirigent H' developed in the Netherlands was cultivated in growing media of a peat substrate and wood fiber: (1) peat substrate (PS); (2) wood fiber (WF); (3) wood fiber and peat substrate 50/50 v/v (WF/PS 50/50); (4) wood fiber and peat substrate 25/75 v/v (WF/PS 25/75). The rates of fertilization were the following: (1) conventional fertilization (CF); (2) 13 g N per plant (N13); (3) 23 g N per plant (N23); (4) 30 g N per plant (N30). The experiment was carried out with three replications. As the amount of wood fiber increased, the humidity and pH of the growing media increased. The fertilization of the cucumbers with different quantities of nitrogen influenced the nutrient uptake. The plants grown in the 50/50 and 25/75 growing media had the best Cu uptake when fertilized with N23. When the plants grown in the wood fiber media and the 50/50 media were fertilized with N13, N23, and N30, the Mn content in the growing media at the end of the growing season was significantly lower than the Mn content in the media with conventional fertilization. Thus, nitrogen improved the uptake of Mn by the plants grown not only in the wood fiber, but also in the combinations with a peat substrate. Growing plants in wood fiber and fertilizing them with N13 can result in the optimum uptake of micronutrients. The number and biomass of cucumber fruits per plant were influenced by the amount of wood fiber in the growing media and the application of nitrogen fertilizer. The highest number of fruits and biomass of fruits per plant obtained were significantly higher when the cucumbers were grown in WF/PS 50/50 growing media with additional N13 fertilization. [ABSTRACT FROM AUTHOR]