Phosphorus mismanagement threatens food security, water quality, climate and biodiversity. This Comment outlines how countries may establish national working groups and action plans to tackle these challenges, considering context-specificities, local resilience and global commitments.

Human-induced nitrogen (N) deposition poses a serious threat to biodiversity in ecologically sensitive protected areas. India, a major hotspot of reactive nitrogen (Nr) emissions, has so far lacked high-resolution assessments of nitrogen deposition impacts over its national parks (NPs). This study presents the first high-resolution modelling of total nitrogen deposition over India using an updated ammonia (NH3) emission inventory, which remains subject to substantial uncertainty. Ecological risks were evaluated under a baseline scenario (BS-2015) and a future emission scenario (FES-2030) by comparing simulated deposition with critical load (CL) thresholds prescribed for ecosystems in the United States (USA), China, and Europe. Under BS-2015, 6, 12 and 18 NPs already exceeded China, Europe and USA CL values, respectively, whereas under FES-2030, the number of NPs CL exceedances doubled, with 25 NPs exceeding USA CLs and 12 exceeding European CLs. The exceedances of Chinese CLs were less frequent, but a relative increase in the total N deposition ranging from 5 to 124% were projected across the various ecosystems. The findings indicate increasing N stress through 2030 and highlight the need for long-term field studies to establish region-specific critical load thresholds for India.

Excess ammonia (NH3) emissions from human activities pose severe threats to global ecosystems and human health. Although urgent control of NH3 emissions is needed, a comprehensive quantification of mitigation strategies and their cost-effectiveness is lacking on a global scale. Here we employ a multi-model framework to evaluate 32 mitigation measures across 7 sectors in 185 countries. Our analysis reveals that strategic implementation of technological and non-technological (policy and behavioural) measures could reduce global NH3 emissions by up to 60

Emissions of ammonia (NH3) from agricultural activities are a major threat to ecosystems and human health. Its quantification via emissions inventories is vital to the understanding of mitigation strategies and policy formation. South Asia, specifically the South Asian Association for Regional Cooperation (SAARC), is a global hotspot of NH3 emissions from agriculture but also an area of great uncertainty due to a lack of data that are representative of local practices. This study presents a single implementation of a framework into which indigenous data can be ingested to adjust such estimates, to provide spatially distributed (0.1 degrees & times; 0.1 degrees) emissions in five agricultural sectors for improved input data for atmospheric chemistry transport models, by moving away from Tier 1 methods for emission inventories (Tomlinson et al., 2025; 10.5285/e0114a4f-32c2-41d9-9c2a-c46f365d4c30). Results incorporate data such as lower emission factors of NH3 following the application of Urea (13 % of total nitrogen lost as NH3-N) to provide a total estimated emission of NH(3 )in the SAARC of similar to 6 Tg (+/- 1.2 Tg), with high values (>5 g NH3 m(-2) a(-1)) in the Indian states Haryana, Punjab and Uttar Pradesh in the Indo-Gangetic Plain (IGP).

Abstract Excessive nitrogen (N) fertilization improves crop yields but leads to significant environmental concerns, such as ammonia (NH 3 ) volatilization and nitrate (NO 3 − ) accumulation. These losses reduce nitrogen use efficiency (NUE) and contribute to air and water pollution, threatening the sustainability of intensive cropping systems. Therefore, this study was designed to evaluate how N rates and sources influence NH 3 volatilization, wheat ( Triticum aestivum L.) yield, NUE, and post‐harvest soil NO 3 − over two growing seasons. Treatments included were no N fertilizer, 75% recommended N as urea, recommended N as urea, 125% recommended N as urea, recommended N as calcium ammonium nitrate (CAN), and an equivalent to recommended N as animal manure. This study revealed that urea‐N and CAN‐N application significantly enhanced biomass and grain yield in 2022–2023, whereas in 2023−2024, urea‐N75 produced the highest grain yield, closely followed by CAN‐N treatment. Higher level of urea increased biomass but not grain yield, indicating inefficient partitioning and ultimately reduced agronomic efficiency (AE). Reduced level of urea consistently achieved higher AE, whereas Org‐N was limited by slow mineralization. Residual soil analysis showed greater NO 3 − accumulation under higher urea levels, but not in CAN‐N and Org‐N. NH 3 emissions peaked after each fertilization, with increases in urea levels, while CAN‐N and Org‐N mitigated NH 3 emissions. Incorporating these strategies into nutrient management systems can support climate‐smart agriculture and guide policies toward sustainable agriculture.

Abstract Agricultural ammonia (NH3) emissions adversely affect air quality, threatening ecosystems and human health. The extent to which global NH3 emissions respond to a warmer climate and the effects of changing agricultural management practices remain poorly quantified. Here, we show that global warming drives NH3 emission increases of 5-22% across plausible ranges of climate projections in 2091-2100, with > 10% regional increase in NH3 emissions per °C warming. A package of six linked measures could reduce present global agricultural NH3 emissions by 31% but only by 16-28% globally for contrasting climate scenarios (2091-2100), with up to 97% decrease in the effectiveness of measures at a continental scale. Our study underscores the need to consider temperature dependence when evaluating the efficacy of NH3 emissions reduction policies under a changing climate, and highlights that achieving ambitious NH3 emission abatement targets will require enhanced efforts to mitigate climate change.

Cost-benefit analysis (CBA) is increasingly used to inform environmental policy decisions by identifying interventions with the highest net societal benefits. Here we focus on CBAs for nitrogen (NCBA), explaining its history, presenting results of a recent first global NCBA and discussing opportunities and limitations. NCBAs have been conducted since the late 1990s for various geographic regions in Europe, the US, and China, primarily to support air quality and eutrophication policies. A first valuation of damages and benefits of the full nitrogen (N) cycle was conducted for the European Nitrogen Assessment in 2011, followed by NCBAs for the USA, the Netherlands and Germany. Here we present a first comprehensive global NCBA. Total global damage cost of N pollution in 2010 was estimated at US$1.1 trillion, primarily from increases in premature mortality by N derived PM 2.5 (35%), terrestrial biodiversity loss by N deposition (33%), and marine eutrophication by N river loads (21%). Global benefits of N in 2010 were estimated at US$ 2.2 trillion with >95% from increased crop yields. By 2050, global N-related costs will rise faster than N benefits because underlying models project that economic growth (GDP) increases willingness-to-pay to prevent N pollution more than crop prices. The geographical distribution of N-related costs will also shift, with China and India surpassing Europe and North America as regions contributing most to global N-related costs. The estimated N cost range for 2010 was US$ 0.6–2.2 trillion with uncertainty largely in dose-impact and damage cost relations. Given the large uncertainties, when using valuation and NCBA to select a N mitigation option, the net benefits should be substantially higher than the costs and markedly better than for a rejected alternative option. Use of NCBA is discouraged to compare international policy options that involve regions with very different levels of GDP, cultures and political systems.

Over the past century, the inefficient use of reactive nitrogen (Nr) has raised concerns regarding global food production and planetary sustainability. This study investigates nitrogen (N) losses in tomato production near Kabul, Afghanistan, aiming to improve nitrogen use efficiency (NUE) for enhanced food security and environmental protection. Three fertilizer treatments were tested: (A) animal manure + ¼ dose of chemical fertilizer, (B) night soil + ¼ dose of chemical fertilizer, and (C) full dose of chemical fertilizer, with sub-treatments varying in N application (25% less, 25% excess, and farmers’ practice). A no-fertilizer control treatment was included. Nitrogen losses through ammonia emissions and nitrate–N leaching were monitored, while nitrogen balances and NUE were calculated. The findings revealed that ammonia emissions decreased by 33% in treatment A2 and by 30% in treatment B3 compared to surface application. However, nitrate–N leaching peaked at 145 kg N ha−1 in A2 and 128 kg N ha−1 in B3, with positive N balances observed across treatments, the highest being 300 kg N ha−1 in treatment A. NUE ranged from 30% (A and B) to 55% (control), highlighting the widespread overapplication of N in Afghan agriculture. This study demonstrates that efficient N management practices can reduce environmental losses while maintaining tomato yield, offering a novel pathway toward sustainable farming in the region.

Excess ammonia (NH3) emissions from human activities pose critical risks to global ecosystems and human health. Despite the urgent need for NH3 emission controls, a comprehensive evaluation of the cost-effectiveness of mitigation strategies remains underdeveloped. In this study, we adopt a multi-model framework to assess the cost and impact of 32 mitigation measures across seven key sectors in 185 countries. Our results indicate that targeted implementation of these measures, particularly in the agricultural sector, could reduce global NH3 emissions by 49% (36–57%). The estimated implementation cost of $279±69 billion outweighs the projected environmental, health, and resource benefits of $568±182 billion. China and India emerge as critical regions for prioritizing NH3 mitigation, offering the highest societal returns, while Sub-Saharan Africa shows limited economic viability. Future scenario analysis reveals that sustainable policy pathways could reduce NH3 emissions by 55% by 2050. Conversely, weak climate action and inadequate nitrogen regulations may result in a 19% increase in emissions, exacerbating environmental degradation and hindering progress toward sustainable development goals. Our findings underscore the urgent need for coordinated global efforts and region-specific policies to establish and achieve effective NH3 mitigation targets.

This review paper discusses the potential and limitations of polymer composites for smart nitrogen (N) supply to meet the needs of agricultural crops. Unlike most conventional fertilizers, nano-clay polymer composites (NCPCs) offer a slow-release mechanism that enhances nitrogen use efficiency and reduces its loss to the environment. NCPCs are normally synthesized using solution blending, melt blending and in situ polymerization. Solution blending offers a better clay dispersion in the polymer matrix than melt blending owing to its low viscosity and strong stirring force. NCPCs have been characterized by several techniques, including equilibrium water absorbency, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and nutrient release kinetics. The potential benefits of using these composites are highlighted, including improved nitrogen use efficiency and reduced environmental impacts, as are their prospects for widespread use in agriculture and mitigation of the adverse environmental effects from conventional fertilizers. In addition, the limitations of NCPC technology, such as cost, scalability and potential negative environmental effects, are also investigated. The paper provides a wide perspective on the NCPC technology, including the regulatory environment and policy, industry trends and commercialization potential. NCPCs offer many benefits to increase nitrogen use efficiency and reduce pollution affecting water quality, air quality and climate. The main current barrier to overcome is to reduce production costs, so that farmers may also benefit financially from the higher nitrogen use efficiency and associated reduced amounts of nitrogen wasted to the environment.

Countries in South Asia are suffering severe PM 2.5 pollution with rapid economic development, impacting human health and the environment. Whilst much attention has been given to understanding the contribution of primary emissions, the contribution of agriculture to PM 2.5 concentrations, especially from agricultural ammonia (NH3) emissions, remains less explored. Using an advanced regional atmospheric chemistry and transport modelling system (WRF-EMEP) with a new estimate of anthropogenic NH3 emissions inputs, we estimate the influence of agricultural NH3 emissions on surface PM 2.5 in South Asia and evaluate the health impacts and the economic losses attributable to PM 2.5 in 2018. Results show that WRF-EMEP can reproduce magnitudes and variations of PM 2.5 well, with a high annual mean PM 2.5 concentration that exceeds 120 mu g/m 2 and mainly appeared in the Indo-Gangetic Plain. We estimate 2,228,000 (95 % Confidence Interval: 2,052,000-2,400,000) premature deaths and US$ 596,000 (95 % CI: 549,000-642,000) million in economic losses are attributable to total ambient PM 2.5 under the current emissions. We calculate that NH3 emissions are associated with 11 % of the annual average PM 2.5 concentrations across South Asia. Changes in PM 2.5 concentrations follow a non-linear response to NH3 emissions reductions, highlighting increased efficiency with 70 %-100 % reductions in NH3 emissions reductions. We estimate that 247,000 (227,000-265,000) premature deaths and US$ 66,000 (61,000-71,000) million economic losses through this pathway can be attributed to NH3 emissions. These findings confirm that in the current NH3-rich chemical environment of South Asia, the efficiency of PM 2.5 reduction is only moderately sensitive to the reduction in intensity of NH3 emissions until emissions are cut very severely. Thus, SO2, NOx and NH3 emissions controls need to be considered jointly for greater mitigation of ambient secondary PM 2.5 in South Asia.

Introduction: Leaching losses of applied N are an indirect source of nitrous oxide (N2O) emission, a major greenhouse gas emitted from fertilized soils. Mineral nitrogen (N) leaching research has largely concentrated on nitrate (NO3-), while ammonium (NH4+) leaching remains understudied. The cultivation conditions for rice and wheat are distinctly different, impacting the leaching losses of both NH4+ and NO3-. Methods: This study investigated the influence of different N treatments, i.e., no-N control, neem coated urea (NCU-N 100%; 120 kgN ha(-1)), 60 kgN ha(-1) Neem coated urea +30 kgN ha(-1) compost (75% N); 90 kgN ha(-1) Neem coated urea +30 kgN ha(-1) compost (100% N) and 120 kgN ha(-1) Neem coated urea +30 kgN ha(-1) compost (125% N) in comparison with prilled urea (PU, 120 kgN ha(-1)). Compost was applied @ 2.6 tonnes ha(-1) to all integrated treatments to provide 30 kgN ha(-1). Results and discussion: The peak concentration of soil NH4+ and NO3- was delayed by two-three days in NCU and integrated NCU + compost compared to PU in both rice and wheat, due to the slow-release effect of neem oil coating in NCU. In rice, the percolation rate of water was almost half than in wheat soil. The mineral N leaching loss in rice ranged from 0.4 to 4.6 kg NH4+-N ha(-1) and 0.46-5.12 kg NO3-N ha(-1) during the 2 years. In an annual rice-wheat cycle, the total N leaching loss was 6.2%-7.0% of the applied N fertilizer. The total mineral N loss was higher in PU than NCU by 7.8% and 10% in rice and wheat, respectively. Substitution of 25% of mineral N with compost decreased the total N leaching by 14.8% and 10.3% in rice and wheat, respectively, compared to NCU (100%). The crop N uptake increased significantly (p < 0.05) with NCU and integrated NCU + compost (100%) over PU. Application of 125%-N significantly increased the total mineral N leaching. The total mineral-N leaching loss was 15.9% higher in rice than wheat across the different treatments. The integrated N application, combining 75% NCU and 25% compost, can reduce mineral-N leaching, improve nitrogen uptake and maintain economic yields in rice-wheat cropping system.

Rapid advances in species distribution modelling have been facilitated by open availability of ‘big data’ and powerful statistical methods. A key consideration remains the time window over which field recorded occurrence data are sampled to develop a baseline species distribution. Too narrow, and distributions are incomplete and affected by sampling bias, too broad and distributions may fail to meet an assumption of equilibrium, having been affected by dynamic change across a range of different predictors. Lichens are a case in point; being diverse, functionally important and the subject of bioclimatic modelling for conservation assessment, they are nevertheless a specialist taxonomic group that is comparatively less well recorded compared to birds, mammals or vascular plants, for example. In this study, we examined the distribution of the ‘hair-lichen’ Bryoria fuscescens , based on UK record data. We partitioned records into sub-decadal periods (1970s, 1990s, 2010s), and accounting for recording effort, we compared these distributions to three predictors: an historical reconstruction of two different pollutants (sulphur dioxide and nitrogen deposition), and the climate (minimum mean temperature). We asked whether the strength of evidence for the effect of environmental predictors on Bryoria fuscescens distribution varied among the different decades, while also considering a potential for lag-effects. We show that a Bryoria fuscescens distribution that appears static, is dynamic when referenced against patterns of field recording effort. Climate was consistently important in explaining Bryoria fuscescens distribution, which was also affected by the changing pattern of pollution over time. This included a lag-effect of peak sulphur dioxide in the 1970s, and accrued effects of nitrogen deposition that strengthen over time. Overall, we conclude that Bryoria fuscescens has undergone a long-term decline in extent over the last six decades, caused by complex multivariate effects of air pollution, probably combined with climate warming. The ability to resolve these trends for assessment against future conservation targets depends critically on maintaining field identification skills and a sufficiently robust recording effort.

A data-driven conceptual framework that benchmarks sustainable nitrogen management for wheat production in China and shows strong potential for fostering locally adapted strategies that balance agricultural productivity with environmental sustainability.

Agricultural ammonia (NH3) emissions are a major pathway of nitrogen loss, which can have significant environmental consequences, such as air and water pollution, ecosystem damage, and biodiversity loss. Ammonia emissions related to livestock farming are major sources in the agricultural sector, resulting from animal housing, manure management and land application. This paper is the second part of the description of the AMmonia-CLIMate (AMCLIM) model, presenting the development and application of all three main modules to estimate NH3 emissions from livestock, including pigs, poultry (chickens), cattle, sheep and goats. The AMCLIM model simulates the flows of N species at different stages of livestock agriculture. It incorporates the effects of environmental factors and also provides an adequate level of detail for the representation of human management practices. According to simulations by AMCLIM, it is estimated that NH3 emissions from global livestock farming are about 29.9 Tg N yr-1, accounting for around 30 % of total excreted nitrogen. Cattle and buffalo systems are estimated to be the largest sources of NH3 emissions, contributing over 60 % of total livestock emissions. Both pig and poultry systems result in more than 15 % of estimated total emissions, while sheep and goats are responsible for the remaining 7 %. High volatilization rates frequently occur in hot regions, indicating the climate-dependence of NH3 volatilization. It is also shown how AMCLIM can simulate the influence of management practices on NH3 volatilization, e.g. illustrating how fully enclosed animal houses with heating and forced ventilation can result in higher emissions than naturally ventilated barns, while poorly managed manure leads to substantially increased NH3 emissions.

Ammonia (NH3) pollution has emerged as a major cause of concern as atmospheric concentrations continue to increase globally. Environmentally damaging NH3 levels are expected to severely affect sensitive and economically important organisms, but evidence is lacking in many parts of the world. We describe the design and operation of a wind-controlled NH3 enhancement system to assess effects on forests in two contrasting climates. We established structurally identical NH3 enhancement systems in a temperate birch woodland in the UK and a tropical sub-montane forest in central Sri Lanka, both simulating real-world NH3 pollution conditions. Vertical and horizontal NH3 concentrations were monitored at two different time scales to understand NH3 transport within the forest canopies. We applied a bi-directional resistance model with four canopy layers to calculate net deposition fluxes. At both sites, NH3 concentrations and deposition were found to decrease exponentially with distance away from the source, consistent with expectations. Conversely, we found differences in vertical mixing of NH3 between the two experiments, with more vertically uniform NH3 concentrations in the dense and multilayered sub-montane forest canopy in Sri Lanka. Monthly NH3 concentrations downwind of the source ranged from 3 to 29 mu g m- 3 at the UK site and 2-47 mu g m- 3 at the Sri Lankan site, compared with background values of 0.63 and 0.35 mu g m- 3, respectively. The total calculated NH3 dry deposition flux to all the canopy layers along the NH3 transects ranged from 12 to 162 kg N ha- 1 yr- 1 in the UK and 16-426 kg N ha- 1 yr- 1 in Sri Lanka, representative of conditions in the vicinity of a range of common NH3 sources. This multi-layer model is applicable for identifying the fate of NH3 in forest ecosystems where the gas enters the canopy laterally through the trunk space and exposes the understorey to high NH3 levels. In both study sites, we found that cuticular deposition was the dominant flux in the vegetation layers, with a smaller contribution from stomatal uptake. The new facilities are now allowing the first ever field comparison of NH3 impacts on forest ecosystems, with special focus on lichen bio-indicators, which will provide vital evidence to inform NH3 critical levels and associated nitrogen policy development in South Asia.

The future of reactive nitrogen (N) for subtropical lowland rice to be characterised under diverse N -management to develop adequate sustainable practices. It is a challenge to increase the efficiency of N use in lowland rice, as N can be lost in various ways, e.g., through nitrous oxide (N2O) or dinitrogen (N2) emissions, ammonia (NH3) volatilization and nitrate (NO3-) leaching. A field study was carried out in the subsequent wet (2021) and dry (2022) seasons to assess the impacts of different N management strategies on yield, N use efficiency and different N losses in a double -cropped rice system. Seven different N -management practices including application of chemical fertilisers, liquid organic fertiliser, nitrification inhibitors, organic nutrient management and integrated nutrient management (INM) were studied. The application of soil test -based neem-coated urea (NCU) during the wet season resulted in the highest economic yield, while integrated nutrient management showed the highest economic yield during the dry season. Total N losses by volatilization of NH3, N2O loss and leaching were 0.06-4.73, 0.32-2.14 and 0.25-1.93 kg ha - 1, corresponding to 0.06-5.84%, 0.11-2.20% and 0.09-1.81% of total applied N, respectively. The total N -uptake in grain and straw was highest in INM (87-89% over control) followed by the soil test -based NCU (77-82% over control). In comparison, recovery efficiency of N was maximum from application of NCU + dicyandiamide during both the seasons. The N footprint of paddy rice ranged 0.46-2.01 kg N-eq. t-1 during both seasons under various N management. Ammonia volatilization was the process responsible for the largest N loss, followed by N2O emissions, and NO3- leaching in these subtropical lowland rice fields. After ranking the different N management practices on a scale of 1-7, soil test -based NCU was considered the best N management approach in the wet year 2021, while INM scored the best in the dry year 2022.

The dependence of countries on phosphorus fertilisers derived from phosphate rock to maintain crop yields and ensure food security is well established. Yet, exposure of national food systems to constrained reserves of phosphate rock and supply chain complexities still pose risks to farmers’ access to this critical nutrient in many countries. Whilst phosphorus scarcity can threaten food security, suboptimal fertiliser use and poor wastewater treatment can lead to pollution of freshwaters and coasts, causing eutrophication. This impacts biodiversity, drinking water and aquatic food production. In some countries, national plans targeting the recycling of phosphorus losses back into food production are being considered, offering environmental and socio-economic benefits. Here, we review the literature on assessing risks to food security and water quality associated with national reliance on phosphate rock as the primary source of phosphorus for fertilisers. The scientific community has developed data and tools to enable countries to assess exposure in food systems from phosphorus supply and management and in the environment from pollution. However, current assessment approaches often overlook economic vulnerability, a key gap that hinders our understanding of the urgency and severity of impacts from inaction. Exposure assessments could be used to develop National Sustainable Phosphorus Plans embedding priority actions and financial instruments across existing policy frameworks. Actions include identifying local to national sources and sites for phosphorus recycling, identifying catchments and ecosystems where the benefits of reducing phosphorus pollution are greatest, and establishing an infrastructure development plan to enable greater recycling and reduced pollution. We discuss four integrated actions that will enable countries to take the first steps towards a circular phosphorus economy in the context of a challenging global situation.

Introduction Climate change significantly impacts food production by influencing crop growth and soil processes. Rising atmospheric CO2 levels and temperatures may affect reactive nitrogen losses from cultivated soils. This study aimed to quantify the effects of nitrification and urease inhibitors on reactive nitrogen losses from wheat soils in the context of elevated CO2 and temperature interactions.Methods An experiment was conducted in open top chambers for two consecutive years to quantify the effect of nitrification and urease inhibitors on ammonia (NH3), and nitrous oxide (N2O) emissions in wheat under elevated carbon dioxide (EC), elevated temperature (ET) and their interaction (ECT). The carbon dioxide (CO2) concentration ranged from 552 to 568 ppm in the EC treatment, while the average temperature was 2.1-2.5 degrees C higher in ET treatment than ambient (AMB).Results and discussion The N2O-N emission increased under ECT than ambient. Use of neem oil coated urea (NOCU) reduced the N2O-N emission by 10.3%, whereas, Limus coated urea reduced N2O-N emission by 14% as compared to prilled urea treatment under ECT. NH3-N emission from wheat soil also increased under ECT treatment as compared to AMB. Application of N through Limus, reduced NH3-N emission from wheat by 35.7-36.8% when compared with NH3-N emission from prilled urea ECT condition. Elevated temperature reduced grain weight by 7.6%. The grain N content reduced by 10.9% with prilled urea under ECT. The application of NOCU and Limus increased grain N by 6 and 9%, respectively, as compared to urea under ECT interaction. The application of nitrification and urease inhibitors may reduce reactive nitrogen losses and enhance nitrogen use efficiency under future climatic conditions.