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Halving nitrogen pollution is crucial for achieving Sustainable Development Goals (SDGs). However, how to reduce nitrogen pollution from multiple sources remains challenging. Here we show that reactive nitrogen (Nr) pollution could be roughly halved by managed urban development in China by 2050, with NH3, NOx and N2O atmospheric emissions declining by 44%, 30% and 33%, respectively, and Nr to water bodies by 53%. While rural-urban migration increases point-source nitrogen emissions in metropolitan areas, it promotes large-scale farming, reducing rural sewage and agricultural non-point-source pollution, potentially improving national air and water quality. An investment of approximately US$ 61 billion in waste treatment, land consolidation, and livestock relocation yields an overall benefit of US$ 245 billion. This underscores the feasibility and cost-effectiveness of halving Nr pollution through urbanization, contributing significantly to SDG1 (No poverty), SDG2 (Zero hunger), SDG6 (Clean water), SDG12 (Responsible consumption and production), SDG14 (Climate Action), and so on.

Phosphorus (P) is an essential nutrient for crops and is applied to agricultural soil to bring or keep the soil at a certain target soil P status in view of an optimal crop yield. Environmental objectives, however, are rarely considered in current P fertilizer recommendations. In this review paper, we argue that current P fertilizer recommendations must be revised in order to balance crop yield, water quality and the use of finite P resources. This revision requires insights into the total pool of reversibly bound P and the capacity of the soil to bind P. Current soil P tests (SPTs) used in routine agronomic soil testing do not provide these insights. We identify the oxalate extraction method as a high-potential agri-environmental SPT as it measures the total pool of reversibly bound P acting as a reserve for plant-available P while it also quantifies the maximum soil P sorption capacity from the simultaneous measurement of amorphous iron- and aluminium-(hydr)oxides. From these results, the Phosphorus Saturation Degree (PSD) can be calculated. We show that those insights are pivotal for the combined assessment of crop response, the risk of P losses to the water system and the judicious use of finite P reserves. In practice, agronomic target P levels should be lowered in soils with a low P sorption capacity to decrease the risk of P leaching. Agronomic target levels should also be lowered in soils with a high P sorption capacity to ensure a judicious use of finite P reserves.

Fertilizer recommendations (FR) to improve yields and increase profitability are based on relationships between crop yields and soil nutrient levels measured via soil extraction methods. Within these FR, critical soil nutrient (CSN) levels are used to distinguish nutrient deficient from non-deficient soils. The variation in CSN levels is large, implying a risk of over- or under-fertilization. Here, we review and assess the factors influencing the derivation of CSN levels in order to increase both their reliability and applicability within FR systems. The evaluated factors included site conditions, i.e., crop type and location as a surrogate for climate and soil properties, and methodological factors, i.e., the experimental approach (field or pot experiments), and statistical methods and cut-off point. Results showed that the range of values used to define the medium soil fertility classes coincided with the range of CSN levels derived from experimental data. We show that harmonizing methodological aspects can substantially reduce the uncertainty in the CSN levels (> 50%), implying a substantial enhancement of the reliability of FR systems. Inclusion of site conditions might further improve the reliability. To enable reduction in CSN levels requires well-documented field experiments and standardization of data collection and analysis. We foresee the potential for generic FR systems that make use of reliable data, more process-based interpretation of nutrient pools and accounting for the interactions among nutrients.

Halving nitrogen pollution is crucial for achieving Sustainable Development Goals (SDGs). However, how to reduce nitrogen pollution from multiple sources remains challenging. Here we show that reactive nitrogen (Nr) pollution could be roughly halved by managed urban development in China by 2050, with NH3, NOx and N2O atmospheric emissions declining by 44%, 30% and 33%, respectively, and Nr to water bodies by 53%. While rural-urban migration increases point-source nitrogen emissions in metropolitan areas, it promotes large-scale farming, reducing rural sewage and agricultural non-point-source pollution, potentially improving national air and water quality. An investment of approximately US$ 61 billion in waste treatment, land consolidation, and livestock relocation yields an overall benefit of US$ 245 billion. This underscores the feasibility and cost-effectiveness of halving Nr pollution through urbanization, contributing significantly to SDG1 (No poverty), SDG2 (Zero hunger), SDG6 (Clean water), SDG12 (Responsible consumption and production), SDG14 (Climate Action), and so on.

This dataset contains digital soil maps (.tiff) of predicted soil contents of oxalate-extractable iron and aluminium at a 25 m spatial resolution across six depth layers (0-5 cm, 5-10 cm, 10-25 cm, 25-60 cm, 60-100 cm and 100-200 cm) for agricultural fields in the Netherlands. For each of these depth layers, there is a map of mean predictions, the 5th, 50th (median) and 95th quantile predictions, as well as the 90% prediction interval (PI90 = 95th - 5th quantile) and prediction interval ratio (PIR = PI90 / median). PI90 and PIR represent absolute and relative uncertainty predictions, respectively. The maps were created using Quantile Regression Forest models, which were calibrated using geo-referenced wet-chemical measurements (n = 12,110) and near-infrared (NIR) estimates (n = 102,393) of oxalate-extractable iron and aluminium and over 150 spatial covariates (spatially explicit environmental variables of soil forming factors). See publication for details, including the assessment of map quality using design-based statistical inference.

Amorphous iron- and aluminium-(hydr)oxides are key soil properties in controlling the dynamics of phosphorus availability and carbon storage. These oxides affect the potential of soils to retain phosphorus and carbon, thus affecting ecosystem services such as crop production, water quality and carbon sequestration. In this study, we spatially predicted oxalate-extractable Fe and Al (FeOX, AlOX) contents in the Netherlands at 25 m resolution across six soil depth layers between 0 and 200 cm and quantified the associated prediction uncertainty using quantile regression forest. For model training and validation, geo-referenced data of FeOX and AlOX contents were used including 12,110 wet-chemical observations and 102,393 NIR spectroscopy observations. Over 150 spatial covariates were selected that provide information about soil typology, climate, soil organisms, land use, relief, parent material and space (sampling depth and oblique coordinates). Map quality was assessed by comparing predictions with observations using an independent data set of 4841 soil samples from agricultural fields. Soil sample locations were selected by stratified random sampling, allowing us to assess map quality using design-based statistical inference. Map quality was evaluated using the metrics Model Efficiency Coefficient (MEC), Root Mean Square Error (RMSE) and Mean Error (ME). Map quality differed, depending on the target variable and soil depth, with MEC ranging from 0.19 to 0.80, RMSE from 13.5 to 56.9 mmol kg−1 and ME from −6.8 to 6.8 mmol kg−1. Overall, map quality was better for topsoil than for subsoil and better for AlOX contents than for FeOX contents. Prediction uncertainty quality was evaluated by calculating the Prediction Interval Coverage Probability of the 90 per cent Prediction Interval, which were close to 0.90 in all cases and slightly below 0.90 for AlOX. Thus, prediction uncertainties were generally reliable, though for AlOX contents uncertainty was slightly underpredic

Decomposition of soil organic matter (SOM) plays an important role in nutrient (re)cycling in all ecosystems of the world. Decomposition of SOM in soils is mainly a soil microbial process. Soil pH affect many soil characteristics which in turn affect the microbial indicators, such as microbial composition, biomass and growth and thereby the microbial activity. This activity governs the mineralisation processes of soil organic matter and is strongly pH dependent. This report gives first an overview of the mechanisms behind impacts of pH on these microbial indicators as well of the impacts of pH on microbial indicators themselves of which pH influences on the major decomposition process do get much attention. Next, it presents empirical quantitative relationships between pH and the mineralisation processes respiration, ammonification and nitrification. Finally, the report gives recommendations on how to include pH dependent relationships in SOM decomposition models.

•This paper presents a review of the trends and geographic variation of impacts of reactive nitrogen (N) inputs on in Europe through impacts on air, soil and water quality. It illustrates those impacts, by assessing temporal and spatial variation in air, soil and water quality indicators and their exceedances of critical thresholds in view of impacts on human health, terrestrial and aquatic ecosystems, during 1990-2019. Trends are derived from regular inventory and monitoring data and from simulated trends in air quality using the EMEP model. •Well quantified adverse impacts of increased N use are: (i) the effects on human health due to increased tropospheric concentrations of NOx and ozone, and N-induced increases in fine particulate matter, (ii) the contribution of N2O to climate change and stratospheric ozone depletion, (iii) the loss of plant and faunal diversity both in terrestrial and aquatic ecosystems via direct and soil mediated impacts, (iv) the acidification of forest soils, with impacts on tree forest nutrition, tree growth and tree vitality, and (v) the eutrophication of marine ecosystems, and associated biodiversity loss and occurrence of harmful algae blooms. •Over the period 1990-2019, N inputs to agriculture stayed relatively constant, but the emissions of ammonia (NH3) decreased by 27%, while emissions of nitrogen oxides (NOx) decreased by 57%. In response to those reductions, concentrations of NOx, and of N in particulate matter also declined, although less than 50%. In contrast, the reduction in NOx-induced ozone concentrations and ozone related indicators (AOT40, SOMO35 and POD) was much less (ca 15-20%). Exceedances of critical ozone concentrations for human health and of critical AOT40 and POD vales for vegetation reduced in a similar order of magnitude. Despite decreasing NH3 emissions, NH3 concentrations showed a slight and steady increase from 1995 onwards, due to the large reduction in SOx emissions. Nitrogen deposition and exceedances of

Cropland is a main source of global nitrogen pollution. Mitigating nitrogen pollution from global croplands is a grand challenge because of the nature of non-point-source pollution from millions of farms and the constraints to implementing pollution-reduction measures, such as lack of financial resources and limited nitrogen-management knowledge of farmers. Here we synthesize 1,521 field observations worldwide and identify 11 key measures that can reduce nitrogen losses from croplands to air and water by 30–70%, while increasing crop yield and nitrogen use efficiency (NUE) by 10–30% and 10–80%, respectively. Overall, adoption of this package of measures on global croplands would allow the production of 17 ± 3 Tg (1012 g) more crop nitrogen (20% increase) with 22 ± 4 Tg less nitrogen fertilizer used (21% reduction) and 26 ± 5 Tg less nitrogen pollution (32% reduction) to the environment for the considered base year of 2015. These changes could gain a global societal benefit of 476 ± 123 billion US dollars (USD) for food supply, human health, ecosystems and climate, with net mitigation costs of only 19 ± 5 billion USD, of which 15 ± 4 billion USD fertilizer saving offsets 44% of the gross mitigation cost. To mitigate nitrogen pollution from croplands in the future, innovative policies such as a nitrogen credit system (NCS) could be implemented to select, incentivize and, where necessary, subsidize the adoption of these measures.

An increase in nitrogen (N) recovery efficiency, also denoted as N use efficiency (NUEr), is crucial to reconcile food production and environmental health. This study assessed the effects of nutrient, crop and soil management on NUEr accounting for its dependency on site conditions, including mean annual temperature and precipitation, soil organic carbon, clay and pH, by meta-regression models using 2436 pairs of observations from 407 primary studies. Nutrient management increased NUEr by 3.6-11%, crop management by 4.4–8%, while reduction in tillage had no significant impact. Site conditions strongly affected management induced changes in NUEr, highlighting their relevance for site-specific practices. Data driven models showed that the global mean NUEr can increase by 30%, from the current average of 48% to 78%, using optimal combinations of nutrient (27%), crop (6.6%) and soil (0.6%) management. This increase will in most cases allow to reconcile crop production with acceptable N losses to water. The predicted increase in NUEr was below average in most high-income regions but above average in middle-income regions.

Ammonia is one of the most impactful pollutants emitted from agricultural activities, harming human health and contributing to biodiversity loss. In ammonia emission inventories, the spatial distribution of annual emissions is mostly approximated by constant empirical emission fractions, which do not account for spatial variability, nor for temporal variability within a year or between years caused by weather variations. Besides, factors like manure properties, soil properties, and manure application techniques also lead to differences in the amount of ammonia emitted into the atmosphere. By not or only partly accounting for these factors, significant uncertainties are introduced into ammonia emission estimates at regional and national scales. In this study, we applied the empirical ALFAM2 model to derive spatially explicit slurry application emission fractions from cropland for use in the large-scale INTEGRATOR model, using the information on slurry properties (dry matter content and pH), manure application rate, application technique, incorporation time, air temperature, wind speed, and rainfall rate. In addition, the impact of weather on the ammonia emissions from animal housing and manure storage systems was included through a temperature-dependent scaling. We applied the method to investigate the year-to-year spatio-temporal variabilities of ammonia emissions and modeled concentrations across Germany from 2015 to 2018. Through the comparison with in situ measurements and satellite-derived observations, we studied how surface concentrations and total columns relate to local meteorology. We found that the spatio-temporal variability in emission fractions improves the ability to reproduce the interannual variability observed in ammonia concentration and total column measurements. This study shows that the developed approach to derive spatially explicit emission fractions can significantly improve ammonia emission modeling and is of great importance for studying th

This paper was originally published under a standard Springer Nature license (© The Author(s), under exclusive licence to Springer Nature Limited). It is now available as an Open Access paper under a Creative Commons Attribution 4.0 International license, © The Author(s). Additionally, the maps in Figure 3d,e were mistakenly reversed (e.g., Alaska should now appear in red in the top-left of Fig. 3d), while in Figure 5c, the y-axis label for cropland area read “103 ha” rather than “106 ha” as corrected now. The errors have been corrected in the HTML and PDF versions of the article and the source data for are updated.

Irrigation, one of the 28 agri-environmental indicators defined in the European Common Agricultural Policy, is often neglected in agricultural nitrogen (N) budgets, while it can be a considerable source of N in irrigated agriculture. The annual N input from irrigation water sources (NIrrig) to cropping systems was quantified for Europe for 2000–2010 at a resolution of 10 × 10 km, accounting for crop-specific gross irrigation requirements (GIR) and surface- and groundwater nitrate concentration. GIR were computed for 20 crops, while spatially explicit nitrate concentration in groundwater was derived using a random forest model. We show that although GIR were relatively stable (46–60 km3 yr-1), the Nirrig in Europe increased over the 10-year period (184 to 259 Gg N yr-1), approximately 68 % of which occurred in the Mediterranean region. The main hotspots appeared in areas with both high irrigation requirements and high groundwater nitrate concentration, reaching up to averaged values of 150 kg N ha-1 yr1. These were mainly located in Mediterranean Europe (Greece, Portugal and Spain) and to a lesser extent in Northern Europe (The Netherlands, Sweden and Germany). By not including NIrrig, environmental and agricultural policies are underestimating the real extent of N pollution hotspots in European irrigated systems.

Ammonia (NH3) emissions from intensive anthropogenic activities is an important component in the global nitrogen cycle that has triggered large negative impacts on air quality and ecosystems worldwide. An accurate spatially explicit high resolution NH3 emission inventory is essential for modeling atmospheric aerosol pollution and nitrogen deposition. However, existing NH3 emission inventories in China are still subject to several uncertainties. In this review we firstly summarize the widely used methods for the estimate of NH3 emissions and discuss their advantages and major limitations. Secondly, we present aggregated data from ten NH3 emission inventories to assess the trends in total anthropogenic NH3 emissions in China over the period 1980–2019. Almost emission estimates reported that NH3 emissions in China have doubled in the last four decades. We find a substantial differences in annual total NH3 emissions, spatial distributions and seasonal variations among selected datasets. In 2012, the median emission (Tg yr−1) and associated minimum-maximum ranges are 12.4 (8.5_17.2) for total emission, 9.9 (8.1_13.8) for agriculture, 0.3 (0.2_1.0) for industry, 0.4 (0.2_1.1) for residential and 0.1 (0.1_0.3) for transport and other emission of 1.5 (0.3_2.6). In general, peak emissions occur in summer but in different months, the higher NH3 emission intensities are concentrated in the NCP area, and in eastern and south-central China but distinct regional discrepancy among selected datasets. Finally, we made an analysis of the reasons and levels of difference in NH3 emission estimates with recommendations for improvement of China’s NH3 emission inventory.

The stability and resilience of the Earth system and human well-being are inseparably linked1–3, yet their interdependencies are generally under-recognized; consequently, they are often treated independently4,5. Here, we use modelling and literature assessment to quantify safe and just Earth system boundaries (ESBs) for climate, the biosphere, water and nutrient cycles, and aerosols at global and subglobal scales. We propose ESBs for maintaining the resilience and stability of the Earth system (safe ESBs) and minimizing exposure to significant harm to humans from Earth system change (a necessary but not sufficient condition for justice)4. The stricter of the safe or just boundaries sets the integrated safe and just ESB. Our findings show that justice considerations constrain the integrated ESBs more than safety considerations for climate and atmospheric aerosol loading. Seven of eight globally quantified safe and just ESBs and at least two regional safe and just ESBs in over half of global land area are already exceeded. We propose that our assessment provides a quantitative foundation for safeguarding the global commons for all people now and into the future.

Organic amendments (OAs) can improve the hydro-physical properties of a soil and thereby potentially enhance the resilience of agricultural systems to droughts and floods. An OA's contribution to this resilience, however, depends on the timeliness of its impacts, as soil improvements should be achieved when droughts are most frequent or flood risks are greatest. Yet little is known regarding the temporal variability of OA impacts or the influence of OA quantity and quality thereupon. In this research, therefore, we investigated at two agricultural sites the temporal variability of improvements in soil bulk density, aggregate stability, infiltration capacity and water retention after the application of compost, farmyard manure, bokashi, a selection of organic residues from landscape maintenance, and a combination of these residues with manure. Results showed that, depending on management practices and soil type, OAs decrease bulk density by up to 9.8%, increase infiltration capacity by up to 108.1%, aggregate stability by up to 60.0%, and water retention by up to 77.8% relative to unamended controls within 3 years of repeated application. However, the magnitude of these improvements varies up to 96% between seasons, depending on the soil property and OA treatment. On average, for all treatments, impacts relative to the control varied between different seasons by 5% for bulk density, 47.1% for infiltration capacity, 22.6% for aggregate stability, and 26.3% for water retention. When offsetting OA nutrient differences with mineral fertilizers, this variability showed a stronger correlation to differences in OA application quantity than quality (i.e., chemical composition). Results suggest that disregarding temporal variability in OA impacts can result in an inaccurate valuation of OAs as either effective or ineffective in improving soil resilience, given that impacts may, instead of their frequently presumed persistency, actually be highly transient or lagged. Our findi

The stability and resilience of the Earth system and human well-being are inseparably linked1,2,3, yet their interdependencies are generally under-recognized; consequently, they are often treated independently4,5. Here, we use modelling and literature assessment to quantify safe and just Earth system boundaries (ESBs) for climate, the biosphere, water and nutrient cycles, and aerosols at global and subglobal scales. We propose ESBs for maintaining the resilience and stability of the Earth system (safe ESBs) and minimizing exposure to significant harm to humans from Earth system change (a necessary but not sufficient condition for justice)4. The stricter of the safe or just boundaries sets the integrated safe and just ESB. Our findings show that justice considerations constrain the integrated ESBs more than safety considerations for climate and atmospheric aerosol loading. Seven of eight globally quantified safe and just ESBs and at least two regional safe and just ESBs in over half of global land area are already exceeded. We propose that our assessment provides a quantitative foundation for safeguarding the global commons for all people now and into the future.

High demands on forest for carbon storage and provision of timber and biofuel require precise and reliable estimates of the biomass, carbon and nutrient stocks in different tree compartments. Whether the fraction of biomass distributed in aboveground tree compartments and the carbon and nutrient concentrations varies systematically across trees in different canopy positions remains unclear despite its importance for understanding forest ecology. Here, we compared the distribution of biomass, carbon and nutrients from underlying carbon and nutrient concentrations between different aboveground tree compartments for 15 mature trees of European beech (Fagus sylvatica), Douglas fir (Pseudotsuga menziesii) and Scots pine (Pinus sylvestris) with dominant, intermediate and suppressed canopy position. We show that carbon concentrations were relatively constant across tree compartments while nutrient concentrations increased from stem, bark, branches towards needles. Canopy position had only minor effects on carbon and nutrient concentrations and on the distribution of biomass, carbon and nutrients between aboveground tree components. Nutrient concentrations and stochiometric results confirm that the forests were affected by high N deposition and low availability of P and base cations. Our results imply that predictions from allometric scaling theory better apply to aboveground tree components than from functional equilibrium theory. Models aiming for estimating tree and forest biomass and carbon and nutrient stocks can apply equal biomass, carbon and nutrient stocks for trees independent of canopy position as a valid assumption but testing this assumption for a broader range of species and site conditions remains recommended.

The sustainability of tree harvest is questioned since harvest results in increased nutrient losses which may reduce nutrient stocks in forest soils, particularly in forests on acidified and poor soils with low base saturation. We used a new forest experiment to quantify nutrient stocks and nutrient uptake rates in mature forest stands, and to assess the forest nutrient balance in relation to different forest management scenarios: clearcutting, shelterwood and thinning; and whole-tree harvest (WTH), stem-only harvest (SOH) and wood only harvest (WOH, with on-site bark stripping). Forests were dominated by trees of Fagus sylvatica, Pseudotsuga Menziesii or Pinus sylvestris, all situated on poor, acidified soils. We measured forest biomass and nutrient stocks based on destructive sampling of fifteen mature trees per species and by using new, calibrated allometric relationships. Aboveground stocks of N, P, S, K, Ca, Mg, Mn, Cu, Fe and Zn were calculated for foliage, branches, stem bark and stem wood. Annual forest growth and nutrient uptake were determined using tree ring measures and allometric relationships. Organic layer nutrient stocks and available nutrients in the mineral soil were determined following intensive soil sampling. Stands of beech, Douglas fir and Scots pine differed in aboveground biomass and nutrient stocks, with highest biomass stocks in Douglas fir. However, beech stands had the highest aboveground nutrient stocks, nutrient uptake rates and nutrient losses following harvest, followed by Scots pine. Organic layer nutrient stocks generally exceeded aboveground nutrient stocks, except for the base cations and Mn. Compared to SOH, WTH increased nutrient export between 66% (Douglas fir) up to 100% (Scots pine), while WOH decreased the nutrient export between 23% (beech) up to 41% (Douglas fir). High aboveground base cation and Mn stocks indicate potential long-term threats to forest nutrition if trees are harvested. However, in Douglas fir stands, nutr

Enhanced nitrogen (N) and phosphorus (P) fertilizer applications have strongly elevated agricultural productivity, but also caused significant soil acidification (by N) and increased N and P losses to water bodies leading to eutrophication. There is an urgent need to integrate soil acidification amendment and nutrient management strategies to stimulate sustainable soil use and minimize environmental risks. This study aimed to derive the optimal combination of fertilizer, manure and lime to mitigate soil acidification and minimize nutrient losses by assessing the impacts of different nutrient management strategies on soil pH and nutrient budgets at a field level. The dynamic soil acidification model VSD+ was calibrated on measured pH changes in a long-term fertilization experiment (1990–2018), in which variable amounts of inorganic N, P and potassium (K), lime (L) and organic manure (M) were applied annually to a maize-wheat rotation on red soil. Adding NPK inorganic fertilizers only sharply decreased the soil pH by 1.5 units within 10 years. The pH remained relatively constant, however, in the experiment in which 70% of the N given by fertilizer was replaced by manure (NPKM) while lime addition after 20 years of NPK addition (NPKL) increased the pH by approximately 1.5 units. Historic soil pH changes were well reconstructed by VSD+. The model quantified that nitrogen transformations contributed up to 89% of the total acidity production in the NPK treatment, which could be fully neutralized by replacing 70% of the total N fertilizer input with manure. Scenarios were assessed to explore the future impacts of adapted nutrient management on soil acidification and nutrient surplus. Balancing the N and P input with crop demand (BNP) significantly reduces the N and P surplus but hardly affects the acidification rate compared to Business as Usual (BAU, equal to the NPK treatment). Balancing the N input and substituting N fertilizer with manure (BM) counteract acidification

Ammonia emissions to the atmosphere have a range of negative impacts on environmental quality, human health, and biodiversity. Despite the considerable efforts in quantifying spatially explicit ammonia emissions, there are significant uncertainties in ammonia emission estimates at regional scales. We aimed to improve the modeling of atmospheric ammonia emission variability in space and time across the Netherlands by updating an agricultural ammonia emission model with a newly derived high-resolution crop map and a livestock housing location database of the Netherlands. To generate a crop map of 12 agricultural land cover classes, we applied random forest classification to the multi-temporal multispectral observations of surface reflectance and vegetation indices derived from Sentinel-2. The crop statistics were used to calculate ammonia emission distribution based on nitrogen demand (manure and mineral fertilizer needed) of different crop types using the INTEGRATOR model. Next, the crop map was utilized to spatially allocate the ammonia emissions to a high-resolution grid across the Netherlands. In addition, ammonia emissions from livestock housing systems were introduced as point sources using location data from the Geographic Information Agricultural Business system. The temporal emission variability was updated using a recently developed TIMELINES module. After the spatial and temporal distribution of ammonia emission was obtained with the crop map and housing information, it was imported into the chemistry transport model LOTOS-EUROS to model ammonia surface concentration for validation with in situ measurements. The performed crop classification has an average accuracy score of 0.73. The derived crop map was compared with Dutch national statistics, and the results showed that the absolute median of the relative difference between Sentinel-2 derived crop areas and national statistical information is around 5%. The newly modeled ammonia monthly surface concentrat

The application of nitrogen (N) fertilizer is key to realize high crop yields and ensure food security. Excessive N application and relatively low N use efficiency (NUE), however, have led to substantial N losses to air and water with related impacts on biodiversity and health. We used historical data from 13 long-term experiments to unravel how the NUE depends on fertilizer strategy and site conditions such as crop rotation, soil properties and climate. During nearly 40 years of fertilization, NUE decreased when crops were fertilized with N and potassium fertilizers only, while the NUE increased when multi-nutrient or organic fertilizers were used. The highest NUE was found when 25–30% of the total N input was supplied in organic form. Among the site conditions analysed, soil pH was the most important factor controlling NUE with an optimum pH around 6. In addition to soil acidity, phosphorus availability increased NUE. Crop rotation, soil properties and fertilizer management together explained 46–85% of the variation in NUE, allowing site specific fertilizer strategies to be developed boosting NUE. Current NUE equalled on average 30% in paddy soils, 39% in upland soils and 42% in paddy upland soils. Optimizing all fertilizer inputs and soil nutrient levels might increase the NUE up to 40–47% in paddy soils, up to 40–77% in upland soils and even up to 40–87% in a paddy upland soils.

To gain insight in the environmental impacts of crop, soil and nutrient management, an integrated model framework INITIATOR was developed predicting: (i) emissions of ammonia (NH3) and greenhouse gases (GHG) from agriculture, including animal husbandry and crop production and (ii) accumulation, leaching and runoff of carbon, nutrients (nitrogen, N, phosphorus, P, and base cations) and metals in or from soils to groundwater and surface water in the Netherlands. Key processes in soil are included by linear or non-linear process formulations to maintain transparency and to enable data availability for spatially explicit application from field up to national level. Calculated national trends in nutrient losses over 2000–2020 compared well with independent estimates and showed a reduction in N and P input of 26 to 33 %, whereas the surplus declined by 33 % for N and 86 % for P due to increased crop yields and reduced inputs. This was accompanied by a reduction of 30–35 % in atmospheric emissions of ammonia and nitrous oxide as well a decline in N and P runoff of 35 and 10 %, respectively, whereas the emission of methane increased with 4 %. Model results compared well with (i) large scale observations of ammonia concentrations in air and nitrate concentrations in upper groundwater and ditch water, (ii) with nitrous oxide emissions and phosphorus adsorption in experiments at field scale and (iii) with metal adsorption in large scale soil datasets. Various mitigation measures were evaluated in view of policy ambitions for climate, soil and environmental quality for 2030, i.e. a reduction of 50 % for NH3, 11–17 % for GHG, 20 % for N runoff and 40 % for P runoff and an ambition of 50 % GHG emission reduction for 2050. The measures focused on a combination of animal feeding, low emission housing and application technologies, improved crop, soil and nutrient management, all being applied with an effectiveness of 100 % and 50 %, respectively. In addition, we evaluated impacts of

There is a global need to improve the environmental performances and circularity of livestock production systems. This relates also to poultry production systems in China, however, the benefits of optimized, more circular systems have not been quantified. Here, we applied a substance flow analysis to estimate the reactive nitrogen (Nr) losses and greenhouse gas (GHG) emissions from housing, manure processing and manure application to cropland in a conventional decoupled and an optimized coupled crop-poultry system. We hypothesized that an optimized coupled system has lower Nr losses and GHGs emissions, and a higher economic return for farmers. We used data from experimental measurements, a farm survey, literature and local market prices to estimate the farm performance for both systems. In the conventional system the manure was only partly (58%) utilized and the remaining 42% was wasted and discharged into the environment. In the optimized system a series of emission mitigation measures was adopted, including low-protein feeding, manure composting with additives and a partial replacement of synthetic fertilizers by manure. The optimized system produced 24% more products per 100 units of N input, leading to a whole-system nitrogen use efficiency (NUE) increase from 33% to 50%. The Nr losses per unit of product-N decreased by 55%, whereas the GHG emissions (N2O and CH4) decreased by 35%. Moreover, the net economic benefit increased by 21%. Evidently, the optimized and more circular system had significant economic and environmental benefits compared to the conventional one. These benefits will be drivers for the transformation to more sustainable production systems, but governmental policy incentives will be needed to remove current cultural and institutional barriers.

Anthropogenic activities have increased atmospheric N, precipitation, and temperature events in terrestrial ecosystems globally, with N deposition increasing by 3- to 5-fold during the previous century. Despite decades of scientific research, no consensus has been achieved on the impact of climate conditions on soil respiration (Rs). Here, we reconstructed 110 published studies across diverse biomes, magnitudes, and driving variables to evaluate how Rs responds to N addition, altered precipitation (both enhanced and reduced precipitation or precipitation changes), and warming. Our findings show that N addition significantly increased Rs by 44 % in forests and decreased it by 19 % and 26 % in croplands and grasslands, respectively (P < 0.05). In forests and croplands, altered precipitation significantly increased Rs by 51 % and 17 % (all, P < 0.05), respectively, whereas impacts on grassland were insignificant. In comparison, warming stimulated Rs by 62 % in forests but inhibited it by 10 % in croplands (all, P < 0.05), whereas impacts on grassland were again insignificant. In addition, across all biomes, the responses of Rs to altered precipitation and warming followed a Gaussian response, increasing up to a threshold of 1800 mm and 25 °C, respectively, above which respiration rates decreased with further increases in precipitation and temperature. Our work suggests that the dual interaction of warming × altered precipitation promotes belowground CO2 emission, thus enhancing global warming. In general, the interactive effect of N addition × altered precipitation decreases Rs. Soil moisture was identified as a primary driver of Rs. Given these findings, we recommend future research on warming vs. changed precipitation to better forecast and understand the interaction between Rs and climate change.

Maintaining an appropriate soil phosphorus level is key to ensure sustainable phosphorus management for crop production and to minimise phosphorus losses to water bodies. However, the effects of long-term fertilization on different soil phosphorus pools, crop yields and phosphorus loss risk remain unclear. This requires insights into the responses of soil phosphorus pools, crop phosphorus uptake with related crop yields and phosphorus loss to long-term phosphorus inputs. Changes in four soil phosphorus pools (PCACL2, POLSEN, POX and PTOTAL, respectively) and crop yield responses to various fertilization rates were examined in a 29-year long-term phosphorus fertilization experiment in China. Results showed that the increase in the four soil phosphorus pools was proportional to the accumulated phosphorus surplus, i.e., the input minus uptake. POLSEN and POX increased linearly with continuous phosphorus application and peaked at a phosphorus accumulation near 3200 kg P ha−1. Beyond this threshold, continuous phosphorus application caused a gradual increase in PTOTAL and a linear increase in PCACL2, which implies an increasing risk for leaching. The POX pool accounted for 87% of the accumulated phosphorus surplus until soil phosphorus saturation occurred. The crop yields of wheat and maize responded clearly to changes in PTOTAL, POX, POLSEN and PCACL2, with POX explaining most of the yield variation. Furthermore, POX was highly correlated with PCACL2, being a risk indicator for phosphorus leaching. Given that POX explains best how much of phosphorus surplus accumulates in soil, the variation in crop yield, and the risk for P leaching, it can be used as a valuable and reliable indicator to manage phosphorus sustainably.

Soil amendments, including lime, biochar, industrial by-products, manure, and straw are used to alleviate soil acidification and improve crop productivity. Quantitative insight in the effect of these amendments on soil pH is limited, hampering their appropriate use. Until now, there is no comprehensive evaluation of the effects of soil amendments on soil acidity and yield, accounting for differences in soil properties. We synthesized 832 observations from 142 papers to explore the impact of these amendments on crop yield, soil pH and soil properties, focusing on acidic soils with a pH value below 6.5. Application of lime, biochar, by-products, manure, straw and combinations of them significantly increased soil pH by 15%, 12%, 15%, 13%, 5% and 17%, and increased crop yield by 29%, 57%, 50%, 55%, 9%, and 52%, respectively. The increase of soil pH was positively correlated with the increase in crop yield, but the relationship varied among crop types. The most substantial increases in soil pH and yield in response to soil amendments were found under long-term applications (>6 year) in strongly acidic (pH < 5.0) sandy soils with a low cation exchange capacity (CEC, <100 mmolc kg−1) and low soil organic matter content (SOM, <12 g kg−1). Most amendments increased soil CEC, SOM and base saturation (BS) and decreased soil bulk density (BD), but lime application increased soil BD (1%) induced by soil compaction. Soil pH and yield were positively correlated with CEC, SOM and BS, while yield declined when soils became compacted. Considering the impact of the amendments on soil pH, soil properties and crop yield as well as their costs, the addition of lime, manure and straw seem most appropriate in acidic soils with an initial pH range from <5.0, 5.0–6.0 and 6.0–6.5, respectively.

Increasing use of manure nutrients in crop production and decreasing the input of chemical fertilizers, is a promising way to achieve a more circular economy and more sustainable food systems. The integrated effects of amended composting manure with additives and a 50% substitution of chemical fertilizer nitrogen (N) input by amended manure N input to cropland were proved to halve ammonia (NH3) emissions from an integrate manure-cropland system. However, the accompanied impacts of these measures on greenhouse gas (GHG) emissions from the integrate manure-cropland system have not been well quantified. Here, we examined the effects of improved manure storage and treatment and its usage at field on GHG emissions from a system perspective, based on a two-year experiment in the North China Plain (NCP). Manure storage and treatment included natural storage (NS) and composting with straw, with or without amendment by zeolite (Z) and superphosphate (SP). Manure products were applied as basal fertilizer for both crops. Results showed that CH4 was the dominant GHG source in the natural storage treatment, whereas N2O dominated in the manure composting treatments. Amending manure with straw, Z and SP stimulated 15–48 times N2O emission and decreased CH4 emissions by 82%–91% during storage and treatment. Replacement of 50% synthetic fertilizer N by manure N decreased total system GHG emissions by 25%–34%. Differences between composted manure treatments in total system GHG emissions were relatively small, although comparatively higher in amended manure treatments; however, they promoted greater soil organic carbon sink activity, resulting in no significant difference in net global warming potential (GWP) and greenhouse gas emission intensity (GHGI). Application of amended manure produced high nitrogen use efficiency (NUE) in the integrated crop–manure system. The NH3 mitigation approach of replacing 50% of synthetic fertilizer N by amended manure N synergistically decreased total

Rapid urbanization has profoundly altered the spatial patterns of multiple element cycles. Whether and how urbanization shapes the spatial patterns of atmospheric trace element deposition remains, however, poorly understood. Using a newly compiled database on bulk deposition of eight trace elements (i.e., Cu, Ni, Zn, As, Cd, Cr, Hg and Pb) in China, we assessed the urban imprints on the spatial patterns of trace element deposition. Bulk deposition of the eight trace elements all showed a significant increase with closer distance to the nearest large cities, while the urban effect was also mediated by point emission sources and precipitation. We further compiled a database of urban topsoil (0–10 cm) concentrations of the eight trace elements and found that urban soil quality standards were exceeded in 80% of the studied cities for Cr, 49% for As, and less than 25% for other trace elements, respectively. The urban topsoil concentrations of six trace elements (except As and Hg) showed no significant correlations with their background values for natural soils, while we found a significant correlation between bulk deposition and urban topsoil concentrations of trace elements corrected by background values. We also demonstrated that current levels of trace element deposition would substantially increase urban soil pollution over the coming decades. Our findings confirm the occurrence of urban hotspots of trace element deposition and their impact on soil pollution and highlight a need of emission control of trace elements for safety urban soil quality.

To boost crop production, China uses almost a third of the world's nitrogen (N) fertilizer. However, N losses due to enhanced application of N fertilizers has led to surface water and groundwater pollution. A reduction in N losses without reducing crop yields is possible by increasing nitrogen use efficiency (NUE), which is important for the effective management of local crop production and water quality. This study used two representative agricultural counties in China (Quzhou and Qiyang) to assess if it is possible to achieve N loss thresholds in surface and groundwater by optimizing N management measures while maintaining actual crop production. We used a spatially explicit N balance model to assess the spatial variation in actual N inputs to soil and N losses to water, and in critical N losses and associated agricultural N inputs. We also used this model to calculate the spatial variation in actual NUEs and the required NUE to align actual crop production with N thresholds. We then assessed the feasibility of achieving the necessary NUE changes through optimizing agricultural N management strategies. It was found that actual N input exceeded critical N input in 95 and 83 % of the agricultural area in Quzhou and Qiyang, respectively. To meet actual crop production without exceeding N loss thresholds, the NUE needs to increase with 11 to 15 % whereas the total N input needs to be reduced by 37 %. NUE gaps can be closed by reducing N rates, enhancing organic manure recycling, and using efficiency-enhancing fertilizers, with optimal combinations being dependent on site conditions.

Human activities have drastically increased inputs of reactive nitrogen globally. Increased deposition of N onto forests may alleviate N limitation and thereby stimulated productivity and carbon (C) sequestration in forest aboveground woody biomass (AGWB), a stable C pool with long turn-over times. The associated reduction in atmospheric CO2 concentrations use represents a cooling effect of human N use that may partly offsets the warming effect of human-induced N2O emissions.The accompanying datasets give information on global spatial variation in the contribution of atmospherically deposited nitrogen (N) to carbon (C) sequestration in forest aboveground woody biomass, as well as the net climatic footprint of human N use resulting from the warming effect of N-induced direct and indirect N2O emissions on the one hand, and the cooling effect of N-induced C sequestration in forest aboveground woody biomass on the other., Human activities have drastically increased inputs of reactive nitrogen globally. Increased deposition of N onto forests may alleviate N limitation and thereby stimulated productivity and carbon (C) sequestration in forest aboveground woody biomass (AGWB), a stable C pool with long turn-over times. The associated reduction in atmospheric CO2 concentrations use represents a cooling effect of human N use that may partly offsets the warming effect of human-induced N2O emissions.The accompanying datasets give information on global spatial variation in the contribution of atmospherically deposited nitrogen (N) to carbon (C) sequestration in forest aboveground woody biomass, as well as the net climatic footprint of human N use resulting from the warming effect of N-induced direct and indirect N2O emissions on the one hand, and the cooling effect of N-induced C sequestration in forest aboveground woody biomass on the other.

Steeds opnieuw klinkt in de Kamer en in de media twijfel aan de wetenschappelijke basis van het stikstofplan. Han Olff, Wim de Vries en 34 andere wetenschappers* leggen nog maar eens uit hoe het zit.

Context: Forest harvest removal may cause nutrient depletion of soils, when removal of essential nutrients, including nitrogen (N), phosphorus (P), sulphur (S), calcium (Ca), potassium (K) and magnesium (Mg) exceeds their net input by deposition and weImpacts of acid atmospheric deposition on woodland athering minus leaching. Nutrient removal by harvest depends on tree species and the harvesting method, i.e. whole-tree harvesting (removal of stems and branches) versus stem wood removal only. Aim: The aim of this study was to assess the impacts of these two harvesting methods on nutrient removal in Dutch forests exposed to high-nitrogen deposition. Methods: To assess those impacts, we measured nutrient concentrations in stem wood and branch wood of seven major tree species in the Netherlands, i.e. Japanese larch (Larix kaempferi Lamb.), Norway spruce (Picea abies L. Karst.), Douglas fir (Pseudotsuga menziesii Mirb.), Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth), beech (Fagus sylvatica L.) and common oak (Quercus robur L.). Average nutrient concentrations in stems were based on measured concentrations in heartwood, sapwood and bark and estimated volumes and densities of these compartments. Similarly, average nutrient concentrations in branches were based on measured concentrations in coarse branches, fine branches and the bark of coarse branches and estimated volumes and densities of these compartments. Removal was assessed by using the average growth rates of these tree species on nutrient poor sandy soils in the Netherlands. Results: Compared to other countries, N concentrations in the Netherlands were higher in stems, while phosphorus, Ca, K and Mg concentrations in both stems and branches were nearly always lower. The elevated long-term N deposition levels in the Netherlands most likely contribute to this finding, since N deposition causes soil acidification reducing the availability of Ca, K, Mg and P, that could become limiting to growth.

The global urban area is expanding continuously, resulting in unprecedented emissions and deposition of reactive nitrogen (N) in urban environments. However, large knowledge gaps remain in the ecological effects of N deposition on urban forests that provide key ecosystem services for an increasing majority of city dwellers. The current understanding of the spatial patterns and ecological effects of N deposition in urban forests was synthesized based on a literature review of observational and experimental studies. Nitrogen deposition generally increases closer to cities, resulting in an urban hotspot phenomenon. Chemical components of N deposition also shift across urban-suburban-rural gradients, showing higher ratios of ammonium to nitrate in and around urban areas. The ecological effects of N deposition on urban forest ecosystems are overviewed with a special focus on ecosystem N cycling, soil acidification, nutrient imbalances, soil greenhouse gas emissions, tree growth and forest productivity, and plant and soil microbial diversity. The distinct effects of unprecedented N deposition on urban forests are discussed in comparison with the common effects in natural forests. Despite the existing research efforts, several key research needs are highlighted to fill the knowledge gaps in the ecological effects of N deposition on urban forests

In this study we investigated critical nitrogen (N) inputs and N losses and their exceedances (actual inputs or losses minus critical inputs or losses) for agricultural soils in the EU-27 region in view of adverse effects. Critical N inputs were calculated based on a critical (i) ammonia emission rate related to critical N loads in view of biodiversity protection, (ii) N concentration in runoff to surface water of 2.5 mg N l-1, related to the protection of aquatic ecosystems and (iii) nitrate (NO3-) concentration in leachate to groundwater of 50 mg NO3- l-1, based on the safe limit for drinking water. In addition, we calculated the required N inputs to achieve target crop yields, which were set at 80% of the water-limited yield potential. Calculations were performed with the INTEGRATOR model for ca 40,000 unique soil-slope-climate combinations and then aggregated at NUTS3-, country- or EU-27 level. Results show that critical N inputs at EU-27 level as compared to actual (year 2010) N inputs are 31% lower to protect biodiversity and 43% lower to protect surface water quality. Critical N inputs are most strongly exceeded in regions with high livestock densities, such as Ireland, the Netherlands, Flanders in Belgium, Brittany in France and the Po valley in Italy. Inversely, required N inputs to attain target crop yields at EU-27 level are ca. 40% higher. Especially in Eastern Europe, there is a large potential to increase yields by increasing N fertilization, but this generally requires strongly improved N use efficiency (NUE), since critical N inputs are mostly lower. Using a maximum plausible NUE, the surface water criterion cannot be achieved on 17% and 25% of all agricultural land at actual crop yield and target crop yields, respectively. Similarly, a maximum plausible reduction in NH3 emission fractions also still causes exceedances of critical N loads in view of biodiversity protection. Reducing agricultural production is needed to protect biodiversity and/or wat

Since the 1980s, the widespread use of N fertilizer has not only resulted in a strong increase in agricultural productivity but also caused a number of environmental problems, induced by excess reactive N emissions. A range of approaches to improve N management for increased agricultural production together with reduced environmental impacts has been proposed. The 4R principles (right product, right amount, right time and right place) for N fertilizer application have been essential for improving crop productivity and N use efficiency while reducing N losses. For example, site-specific N management (as part of 4R practice) reduced N fertilizer use by 32% and increased yield by 5% in China. However, it has not been enough to overcome the challenge of producing more food with reduced impact on the environment and health. This paper proposes a new framework of food-chain-nitrogen-management (FCNM). This involves good N management including the recycling of organic manures, optimized crop and animal production and improved human diets, with the aim of maximizing resource use efficiency and minimizing environmental emissions. FCNM could meet future challenges for food demand, resource sustainability and environmental safety, key issues for green agricultural transformation in China and other countries

The pivotal role of nitrogen to achieve environmental sustainable development goals and transform our food system is recognized in an ambitious nitrogen waste reduction target in the Farm to Fork Strategy of the European Commission. But is this a realistic objective and if so, what are the pathways that lead to success? To answer these questions, we first established, as a baseline, an updated food system nitrogen budget for the EU for the year 2015. The EU used 20 Tg of virgin (new) N to deliver 2.5 Tg N in food and 1.2 Tg N in fibres to consumers, yielding a food-system nitrogen use efficiency (NUE) of 18%. We then built a simple model to combine intervention options that (a) increase farm level nitrogen use efficiencies, (b) reduce food waste increase recycling of waste and improve waste treatment, or (c) achieve a dietary shift towards healthier dietary patterns. The largest potential to increase N efficiency of the current agro-food system was found to lie in the livestock sector. From 144 possible combinations of intervention options analysed, we found that 12 combinations of interventions would reduce nitrogen losses by about 50%, 11 involving diet change. We further carried out an assessment of the societal appreciation of combinations of interventions considering private and public costs of the intervention measures, public benefit through effects on health and increased biodiversity of ecosystems, and public costs for overcoming socio-cultural barriers. Results show that a combination of moderate intervention options achieve halving of N losses at lowest societal costs. We conclude that systemic approaches are paramount to achieve deep nitrogen reduction targets and diet change appears to be an essential condition for success.

To represent the sustainability of nitrogen management in the Sustainable Development Goals indicator framework, this paper proposes a sustainable nitrogen management index (SNMI). This index combines the performance in N crop yield and N use efficiency (NUE), thereby accounting for the need for both food production and environmental protection. Applying SNMI to countries around the world, the results showed improvement in the overall sustainability of crop N management over the past four decades, but this improvement has been mainly achieved by crop yield increase, while global NUE has improved only slightly. SNMI values vary largely among countries, and this variation has increased since the 1970s, implying different levels of success, even failure, in improving N management for countries around the world. In the standard SNMI assessment, the reference NUE was defined as 1.0 (considered an ideal NUE) and the reference yield was defined as 90 kg·ha−1·yr−1 N (considering a globally averaged yield target for meeting food demand in 2050). A sensitivity test that replaced the reference NUE of 1.0 with more realistic NUE targets of 0.8 or 0.9 showed overall reduction in SNMI values (i.e., improved performance), but little change in the ranking among countries. In another test that replaced the universal reference yield with region-specific attainable yield, SNMI values declined (i.e., improved performance) for most countries in Africa and West Asia, whereas they increased for many countries in Europe and South America. The index can be improved by further investigation of approaches for setting region-specific yield targets and high-quality data on crop yield potentials. Overall, SNMI offers promise for a simple and transparent approach to assess progress of countries toward sustainable N management with a single indicator

Data files belonging to manuscript: Schulte-Uebbing, LF, AHW Beusen, AF Bouwman & W de Vries (2022): From planetary to regional boundaries for agricultural nitrogen pollution. Nature, Vol 610 (7932), https://doi.org/10.1038/s41586-022-05158-2 * Input datafiles: Contains complete set of input files used in the calculations of global, spatially explicit critical nitrogen surpluses and critical nitrogen inputs. All input files are output from the IMAGE-GNM model. * Output datafiles: Selection of output datafiles, supporting results presented in the paper.

Human activities have drastically increased nitrogen (N) deposition onto forests globally. This may have alleviated N limitation and thus stimulated productivity and carbon (C) sequestration in aboveground woody biomass (AGWB), a stable C pool with long turnover times. This ‘carbon bonus’ of human N use partly offsets the climate impact of human-induced N2O emissions, but its magnitude and spatial variation are uncertain. Here we used a meta-regression approach to identify sources of heterogeneity in tree biomass C-N response (additional C stored per unit of N) based on data from fertilization experiments in global forests. We identified important drivers of spatial variation in forest biomass C-N response related to climate (potential evapotranspiration), soil fertility (N content) and tree characteristics (stand age), and used these relationships to quantify global spatial variation in N-induced forest biomass C sequestration. Results show that N deposition enhances biomass C sequestration in only one-third of global forests, mainly in the boreal region, while N reduces C sequestration in 5% of forests, mainly in the tropics. In the remaining 59% of global forests, N addition has no impact on biomass C sequestration. Average C-N responses were 11 (4–21) kg C per kg N for boreal forests, 4 (0–8) kg C per kg N for temperate forests and 0 (−4 to 5) kg C per kg N for tropical forests. Our global estimate of the N-induced forest biomass C sink of 41 (−53 to 159) Tg C yr−1 is substantially lower than previous estimates, mainly due to the absence of any response in most tropical forests (accounting for 58% of the global forest area). Overall, the N-induced C sink in AGWB only offsets ~5% of the climate impact of N2O emissions (in terms of 100-year global warming potential), and contributes ~1% to the gross forest C sink.

Forests play a key role in a bio-based economy by providing renewable materials, mitigating climate change, and accommodating biodiversity. However, forests experience massive increases in stresses in their ecological and socioeconomic environments, threatening forest ecosystem services supply. Alleviating those stresses is hampered by conflicting and disconnected governance arrangements, competing interests and claims, and rapid changes in technology and social demands. Identifying which stresses threaten forest ecosystem services supply and which factors hamper their alleviation requires stakeholders' perceptions. Stakeholder-oriented stress tests for the supply of forest ecosystem services are therefore necessary but are not yet available. This perspective presents a roadmap to develop a stress test tailored to multiple stakeholders' needs and demands across spatial scales. We provide the Cascade and Resilience Rosetta, with accompanying performance- and resilience indicators, as tools to facilitate development of the stress test. The application of the stress test will facilitate the transition toward a bio-based economy in which healthy and diverse forests provide sustainable and resilient ecosystem services.

The impacts of enhanced nitrogen (N) deposition on the global forest carbon (C) sink and other ecosystem services may depend on whether N is deposited in reduced (mainly as ammonium) or oxidized forms (mainly as nitrate) and the subsequent fate of each. However, the fates of the two key reactive N forms and their contributions to forest C sinks are unclear. Here, we analyze results from 13 ecosystem-scale paired 15N-labelling experiments in temperate, subtropical, and tropical forests. Results show that total ecosystem N retention is similar for ammonium and nitrate, but plants take up more labelled nitrate (201525%) (meanminimummaximum) than ammonium (12816%) while soils retain more ammonium (574965%) than nitrate (463259%). We estimate that the N deposition-induced C sink in forests in the 2010s is 0.720.490.96 Pg C yr−1, higher than previous estimates because of a larger role for oxidized N and greater rates of global N deposition.

Widespread adoption of improved cropland management measures is advocated to increase soil organic carbon (SOC) levels, thereby improving soil fertility and mitigating climate change. However, spatially explicit insight on management impacts is limited, which is crucial for region-specific and climate-smart practices. To overcome these limitations, we combined global meta-analytical results on improved management practices on SOC sequestration with spatially explicit data on current management practices and potential areas for the adoption of these measures. We included (a) fertilization practices, i.e., use of organic fertilizer compared to inorganic fertilizer or no fertilizer, (b) soil tillage practices, i.e., no-tillage relative to high or intermediate intensity tillage, and (c) crop management practices, i.e., use of cover crops and enhanced crop residue incorporation. We show that the estimated global C sequestration potential varies between 0.44 and 0.68 Gt C yr−1, assuming maximum complementarity among all measures taken. A more realistic estimate, not assuming maximum complementarity, is from 0.28 to 0.43 Gt C yr−1, being on the lower end of the current range of 0.1–2 Gt C yr−1 found in the literature. One reason for the lower estimate is the limited availability of manure that has not yet been recycled. Another reason is the limited area for the adoption of improved measures, considering their current application and application limitations. We found large regional differences in carbon sequestration potential due to differences in yield gaps, SOC levels, and current practices applied. The highest potential is found in regions with low crop production, low initial SOC levels, and in regions where livestock manure and crop residues are only partially recycled. Supporting previous findings, we highlight that to encourage both soil fertility and SOC sequestration, it is best to focus on agricultural soils with large yield gaps and/or where SOC values are belo

As a response to the increased pressure of global climate change on most ecosystems, national and international agreements aim at creating forests that are productive, resilient to climate change, and that store carbon to mitigate global warming. However, these aims are being challenged by increased tree mortality rates and decreased tree growth rates in response to increased incidence of extreme drought events. These phenomena make us aware of a lack of crucial insights into the effects of forest management on the growth and survival of trees, and on carbon storage in both trees and forest soils under increased incidence of drought. Here we compile current knowledge on how forest management and drought impact on tree growth and survival, and above- and belowground carbon storage in forest ecosystems. Based on this, we propose that climate-smart forestry may benefit from controlling stand density at intermediate levels (>60%, e.g.∼80%) by applying low levels of tree harvest intensity on a regular base. Furthermore, we propose that the actual optimal density will depend on the tree species, site conditions and management history. As a next step, studies are needed that take an above- and belowground approach and combine forest experiments with mechanistic models on water, carbon and nutrient flows in trees and soils within forests in order to transform current results, which focus on either soil or trees and are often highly-context dependent, to a more generic forest framework. Such a generic framework would be needed to enhance understanding across forest ecosystems on how forest management may promote forest resilience, productivity and carbon storage with increasing drought.

As a response to the increased pressure of global climate change on most ecosystems, national and international agreements aim at creating forests that are productive, resilient to climate change, and that store carbon to mitigate global warming. However, these aims are being challenged by increased tree mortality rates and decreased tree growth rates in response to increased incidence of extreme drought events. These phenomena make us aware of a lack of crucial insights into the effects of forest management on the growth and survival of trees, and on carbon storage in both trees and forest soils under increased incidence of drought. Here we compile current knowledge on how forest management and drought impact on tree growth and survival, and above- and belowground carbon storage in forest ecosystems. Based on this, we propose that climate-smart forestry may benefit from controlling stand density at intermediate levels (>60%, e.g.∼80%) by applying low levels of tree harvest intensity on a regular base. Furthermore, we propose that the actual optimal density will depend on the tree species, site conditions and management history. As a next step, studies are needed that take an above- and belowground approach and combine forest experiments with mechanistic models on water, carbon and nutrient flows in trees and soils within forests in order to transform current results, which focus on either soil or trees and are often highly-context dependent, to a more generic forest framework. Such a generic framework would be needed to enhance understanding across forest ecosystems on how forest management may promote forest resilience, productivity and carbon storage with increasing drought.

The impacts of enhanced nitrogen (N) deposition on global forest carbon (C) sink and other ecosystem services may depend on whether N is deposited in reduced (mainly as ammonium) or oxidized forms (mainly as nitrate) and the subsequent fate of each. However, the fates of the two key reactive N forms and its contribution to forest C sink is unclear. We conducted ecosystem-scale paired 15N-labelling experiments in nine forests across China to quantify N retention fractions for both deposited ammonium and nitrate, including tropical and sub-tropical forests for the first time. By combining these results with four previous experiments from temperate Europe and North America, here we show that total ecosystem N retention is similar for ammonium and nitrate, but plants consistently take up more of the labelled nitrate than ammonium while soils retain more ammonium than nitrate. Nitrogen retention in plants and soils across sites is predicted by a combination of tree (NPP and woody biomass) and soil (organic layer mass and soil C/N ratios) variables. Greater proportions of deposited N are retained in N-limited ecosystems with low soil N availability and high soil C/N ratios. We estimate that N deposition-induced C sink in forests contributes more than 20% of the total terrestrial C sink. Although less N is deposited in oxidized than reduced state, their total contributions to the global forest C sink are approximately equal due to more efficient use by trees of the oxidized than the reduced form. Our study demonstrates differential fates of reduced and oxidized N deposition that improves current understanding of the C-N interaction in forests and indicates a greater C sink attributable to atmospheric N deposition than previous estimates.

As a response to the increased pressure of global climate change on most ecosystems, national and international agreements aim at creating forests that are productive, resilient to climate change, and that store carbon to mitigate global warming. However, these aims are being challenged by increased tree mortality rates and decreased tree growth rates in response to increased incidence of extreme drought events. These phenomena make us aware of a lack of crucial insights into the effects of forest management on the growth and survival of trees, and on carbon storage in both trees and forest soils under increased incidence of drought. Here we compile current knowledge on how forest management and drought impact on tree growth and survival, and above- and belowground carbon storage in forest ecosystems. Based on this, we propose that climate-smart forestry may benefit from controlling stand density at intermediate levels (>60%, e.g.~80%) by applying low levels of tree harvest intensity on a regular base. Furthermore, we propose that the actual optimal density will depend on the tree species, site conditions and management history. As a next step, studies are needed that take an above- and belowground approach and combine forest experiments with mechanistic models on water, carbon and nutrient flows in trees and soils within forests in order to transform current results, which focus on either soil or trees and are often highly-context dependent, to a more generic forest framework. Such a generic framework would be needed to enhance understanding across forest ecosystems on how forest management may promote forest resilience, productivity and carbon storage with increasing drought.