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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. [ABSTRACT FROM AUTHOR]

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. Here the authors demonstrate how managed urbanization in China could halve reactive nitrogen pollution to both the atmosphere and water resources. Investing 61 billion USD could provide 245 billion USD in benefits, while contributing to multiple SDG goals. [ABSTRACT FROM AUTHOR]

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. Enhancing nitrogen use efficiency can improve global food production while minimizing environmental damage. Here, the authors combine 29 meta-analyses revealing that tailored practices based on local conditions can boost NUEr by 30% with variation between high- and middle-income regions. [ABSTRACT FROM AUTHOR]

Cropland is a main source of global nitrogen pollution1,2. 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 farmers3. 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.A meta-analysis of 1,521 field observations from the past two decades led to the identification of 11 key measures to cost-effectively mitigate nitrogen pollution from global croplands. [ABSTRACT FROM AUTHOR]

Purpose: Rapid urbanization has altered regional nutrient cycles and consequently affected soil nutrient availability for plant growth. This study aims to explore the way in which urbanization shapes the spatial patterns of soil phosphorus (P) concentrations as well as the imprint on tree leaf P concentrations across gradients of urban-rural forests. Methods: We collected soil samples of the surface (0-10 cm) and subsurface (10-20 cm) layers and leaf samples of three common tree species (Chinese pine, Pinus tabuliformis; Chinese scholar tree, Sophora japonica; golden rain tree, Koelreuteria paniculata) from forest patches in twenty parks across urban-rural transects in the Beijing metropolitan region, China. By measuring soil total P, soil available P, and leaf P concentrations, we tested the urban soil P hotspot hypothesis and assessed the consequent imprint on tree leaf P concentrations. Results: Soil total P and available P concentrations in the surface and subsurface layers both increased significantly with closer distance to the urban core. Spatially, leaf P concentrations showed an increase with soil available P concentrations only for the legume Chinese scholar tree, while leaf P concentrations of Chinese pine and broadleaf golden rain tree both increased significantly with the diameter at breast height. Conclusion: Our results confirmed the occurrence of an urban soil P hotspot and identified its significant imprint on leaf P nutrition of legume trees across transects of urban-rural forests. The findings improve the understanding of the way that urbanization alters regional P cycles and consequent P availability for plant growth. [ABSTRACT FROM AUTHOR]

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 ( 20 15 25 %) ( mean minimum maximum ) than ammonium ( 12 8 16 %) while soils retain more ammonium ( 57 49 65 %) than nitrate ( 46 32 59 %). We estimate that the N deposition-induced C sink in forests in the 2010s is 0.72 0.49 0.96 Pg C yr−1, higher than previous estimates because of a larger role for oxidized N and greater rates of global N deposition. A study using paired 15N tracers shows atmospheric N deposited in oxidized form is more likely retained by trees, while the reduced form is retained in soil. The authors argue that this is a greater contribution of deposited N to the global forest C sink than previously reported. [ABSTRACT FROM AUTHOR]

Maize production in Zambia is characterized by significant yield gaps attributed to nutrient management and climate change threatens to widen these gaps unless agronomic management is optimized. Insights in the impacts of climate change on maize yields and the potential to mitigate negative impacts by crop management are currently lacking for Zambia. Using five Global Circulation models and the WOFOST crop model, we assessed climate change impacts on maize yields at a 0.5° × 0.5° spatial resolution for RCP 4.5 and RCP 8.5 scenarios. Impacts were assessed for the near future (2035-2066) and far future (2065-2096) in comparison with a reference period (1971-2001). The surface temperature and warm days (above 30 °C) are projected to increase strongly in the southern and western regions. Precipitation is expected to decline, except in the northern regions, whereas the number of wet days declines everywhere, shortening the growing season. The risk of crop failure in western and southern regions increases due to dry spells and heat stress, while crops in the northern regions will be threatened by flooding or waterlogging due to heavy precipitation. The simulated decline in the water-limited and water- and nutrient-limited maize yields varied from 15 to 20% in the near future and from 20 to 40% in the far future, mainly due to the expected temperature increases. Optimizing management by adjusting planting dates and maize variety selection can counteract these impacts by 6-29%. The existing gaps between water-limited and nutrient-limited maize yields are substantially larger than the expected yield decline due to climate change. Improved nutrient management is therefore crucial to boost maize production in Zambia. [ABSTRACT FROM AUTHOR]

Forest biomass harvesting guidelines help ensure the ecological sustainability of forest residue harvesting for bioenergy and bioproducts, and hence contribute to social license for a growing bioeconomy. Guidelines, typically voluntary, provide a means to achieve outcomes often required by legislation, and must address needs related to local or regional context, jurisdictional compatibility with regulations, issues of temporal and spatial scale, and incorporation of appropriate scientific information. Given this complexity, comprehensive reviews of existing guidelines can aid in development of new guidelines or revision of existing ones. We reviewed 32 guidelines covering 43 jurisdictions in the USA, Canada, Europe and East Asia to expand upon information evaluated and recommendations provided in previous guideline reviews, and compiled a searchable spreadsheet of direct quotations from documents as a foundation for our review. Guidelines were considered in the context of sustainable forest management (SFM), focusing on guideline scope and objectives, environmental sustainability concerns (soils, site productivity, biodiversity, water and carbon) and social concerns (visual aesthetics, recreation, and preservation of cultural, historical and archaeological sites). We discuss the role of guidelines within the context of other governance mechanisms such as SFM policies, trade regulations and non-state market-driven (NSMD) standards, including certification systems. The review provides a comprehensive resource for those developing guidelines, or defining sustainability standards for market access or compliance with public regulations, and/or concerned about the sustainability of forest biomass harvesting. We recommend that those developing or updating guidelines consider (i) the importance of well-defined and understood terminology, consistent where possible with guidelines in other jurisdictions or regions; (ii) guidance based on locally relevant research, and periodically updated to incorporate current knowledge and operational experience; (iii) use of indicators of sensitive soils, sites, and stands which are relevant to ecological processes and can be applied operationally; and (iv) incorporation of climate impacts, long-term soil carbon storage, and general carbon balance considerations when defining sustainable forest biomass availability. Successful implementation of guidelines depends both on the relevance of the information and on the process used to develop and communicate it; hence, appropriate stakeholders should be involved early in guideline development. [ABSTRACT FROM AUTHOR]

Background: Over fertilization with nitrogen (N) is considered the main driver of agricultural soil acidification in China. However, the contribution of this driver compared to other causes of soil acidification on intensive croplands has seldom been quantified under field conditions.Methods: We measured the fate of major nutrients, and calculated the related H+ production, based on the difference between inputs and leaching losses of those nutrients for a wheat-maize rotation system on a moderate acid silty clay loam soil in a two-year field experiment.Results: Topsoil pH decreased 0.3 units in the plots with conventional (current farmer practice) high N fertilization after two years, with a proton production of 13.1 keq H+ ha−1 yr.−1. No apparent changes in topsoil pH were observed in the plots without N application, in spite of a proton production of 4.7 keq H+ ha−1 yr.−1. Crop uptake was the primary driver of H+ production, followed by N transformation processes and HCO3− leaching in both plots.Conclusions: Nitrogen fertilization had a relative small direct impact on soil acidification due to a very limited nitrate leaching, induced by large N losses to air by denitrification in this specific moderately acid soil, whereas elevated base cation uptake by crops induced by N fertilization indirectly had a relative large impact. [ABSTRACT FROM AUTHOR]

The food system is a major driver of climate change, changes in land use, depletion of freshwater resources, and pollution of aquatic and terrestrial ecosystems through excessive nitrogen and phosphorus inputs. Here we show that between 2010 and 2050, as a result of expected changes in population and income levels, the environmental effects of the food system could increase by 50-90% in the absence of technological changes and dedicated mitigation measures, reaching levels that are beyond the planetary boundaries that define a safe operating space for humanity. We analyse several options for reducing the environmental effects of the food system, including dietary changes towards healthier, more plant-based diets, improvements in technologies and management, and reductions in food loss and waste. We find that no single measure is enough to keep these effects within all planetary boundaries simultaneously, and that a synergistic combination of measures will be needed to sufficiently mitigate the projected increase in environmental pressures. A global model finds that the environmental impacts of the food system could increase by 60-90% by 2050, and that dietary changes, improvements in technologies and management, and reductions in food loss and waste will all be needed to mitigate these impacts. [ABSTRACT FROM AUTHOR]

Livestock remains the world's largest user of land and is strongly related to grassland and feed-crop production. Assessments of environmental impacts of livestock farming require detailed knowledge of the presence of livestock, farming practices, and environmental conditions. The present Europewide livestock distribution information is generally restricted to a spatial resolution of NUTS 2 (province level). This paper presents a modelling approach to determine the spatial distribution of livestock at the landscape level. Location factors for livestock occurrence were explored and applied to consistent and harmonized EU-wide regional statistics to produce a detailed spatial distribution of livestock numbers. Both an expert-based and an empirical approach were applied in order to disaggregate the data to grid level. The resulting livestock maps were validated. Results differ between the two downscaling approaches but also between livestock types and countries. While both the expert-based and empirical approach are equally suited to modelling herbivores, in general, the spatial distribution of monogastrics can be better modelled by applying the empirical approach. [ABSTRACT FROM AUTHOR]

We present results from a Keck optical and near IR spectroscopic study of the giant emission line halos of the z>3 High Redshift Radio Galaxies (HiZRGs) 4C 41.17, 4C 60.07 and B2 0902+34. The outer regions of these halos show quiet kinematics with typical velocity dispersions of a few hundred km s−1 and velocity shears consistent with rotation. The inner regions contain shocked, clumpy cocoons of gas closely associated with the radio lobes with disturbed kinematics and expansion velocities and/or velocity dispersions >1000 km s−1. We also find evidence for the ejection of chemically enriched material in 4C 41.17 up to a distance of ∼60 kpc along the radio-axis. We infer that these HiZRGs are undergoing a final jet-induced phase of star formation with the ejection of most of their interstellar medium before evolving to become “red and dead” Elliptical galaxies. [ABSTRACT FROM AUTHOR]

As part of the UN-ECE Intensive Monitoring Program, data on precipitation, throughfall and soil solution concentrations are measured on a regular basis in approximately 300 forest stands. These data were used to construct element budgets for European forests. To construct such budgets drainage fluxes have to be modeled. In this paper, the research chain from model selection to data derivation and application of the selected model to 245 of the 300 sites is described. To select a suitable hydrological model the Cl- balance method, two capacity models (a multi and a single layer version) and a Darcy model have been applied to two forest sites. The results indicate that drainage fluxes calculated with the Darcy model are more accurate than fluxes derived with the capacity model, in particular in situations where water availability is limited. The Darcy model was applied to the sites using a mixture of generic data and site data. Despite the use of generic data, the calculated drainage fluxes appear feasible. Median transpiration fluxes were 350 mm and the lowest values are found in northern Europe and highest values are found in central Europe. Median drainage fluxes were 150 mm yr-1 with the highest values in areas with high rainfall. Uncertainty analyses indicate that the use of local instead of interpolated meteorological data leads to lower drainage fluxes at 70% of the sites. The median deviation in calculated drainage fluxes is 20 mm yr-1. The use of local soil data had little impact on the calculated fluxes. [ABSTRACT FROM AUTHOR]

This paper describes the application of an optimisation model for calculating cost-effective abatement strategies for the reduction of acidification in Europe while taking into account the dynamic character of soil acidification in a number of countries. Environmental constraints are defined in terms of soil quality indicators, e.g., pH, base saturation or the aluminium ion concentration in the soil solution within an optimisation model for transboundary air pollution. We present a case study for Ireland and the United Kingdom. Our results indicate that reduction of sulphur dioxide emission is more cost-effective than that of nitrogen oxides or ammonia. The reduction percentages for sulphur dioxide are highest, for two reasons: (i) marginal sulphur dioxide reduction costs are relatively low compared to marginal reduction costs of nitrogen oxides and ammonia and (ii) sulphur dioxide reduction is more effective in reducing acidification in physical terms than nitrogen oxides or ammonia abatement. Our dynamic analysis shows that a (fast) improvement of soil quality requires high emission reduction levels. These reduction levels are often higher than reduction levels that are typically deduced from the static critical loads approach. Once soil quality targets are reached, in our model, less stringent emission reductions are required to maintain the soil quality at a constant and “good” target level. Static critical load approaches that ignore dynamic aspects therefore may underestimate the emission reductions needed to achieve predefined soil quality targets. [ABSTRACT FROM AUTHOR]

To assess the impact of acid deposition on forested loess and clay soils in the Netherlands, changes in base saturation and soil solution concentrations were simulated with the dynamic soil acidification model ReSAM for 38 loess soils and 16 clay soils. The selected locations represent the range in geographical position and diversity in parent material occurring in forested loess and clay soils in the Netherlands. Two deposition scenarios were used for the period 1992–2050: a business as usual scenario (BAU) and a scenario in which deposition was reduced according to present Dutch policy plans (MV-3). A comparison of simulated and measured soil solution concentrations and base saturation in 1992/1993 showed that the model simulated concentrations and base saturation in the loess soils quite good. However, the model tended to overestimate acidification in the top (0–10 cm) of the clay soils. Despite the reasonable agreement between measured and simulated data some uncertainty in the validity of the model predictions remains because time trends to validate the model were not available. The model predicted a small but ongoing acidification during the BAU scenario in the loess soils as indicated by a decline in median base saturation and pH in the topsoil in 2050. Present policy plans (MV-3) lead to a slight recovery of the base saturation in 2050 and a decline in Al concentrations. In the clay soils a strong decline in base saturation is simulated in the topsoil, whereas an increase in base saturation is predicted for the subsoil. [ABSTRACT FROM AUTHOR]

This paper is the first in a series of four, describing the hypothesis and approach of a correlative study between observed data on crown condition in Europe, monitored since 1986 at a systematic 16 × 16 km grid, and site-specific estimations of various natural and anthropogenic stress factors. The study was based on the hypothesis that forests respond to various natural and anthropogenic stress factors, whose contribution depend on the geographic region considered. In view of this hypothesis, major stand and site characteristics, chemical soil composition, meteorological stress factors (temperature and drought stress indices) and air pollution stress (concentrations and/or depositions of SOx, NOy, NHx and O3) were included as predictor variables. The response variables considered were actual defoliation and changes/trends in defoliation for five major tree species. The spatial distribution of the average defoliation during the period 1986–1995 shows high defoliation in Central Europe and in parts of Scandinavia and of Southern Europe. There are, however, sharp changes at country borders, which are due to methodological differences between countries. The spatial distribution of the calculated trends show a distinct cluster of large deterioration in parts of Central and Eastern Europe and in Spain and a rather scattered pattern of positive and negative trends for most of Europe, indicating that other factors than air pollution only have a strong impact on defoliation. The limitations of the study are discussed in view of the quality of the considered response and predictor variables. [ABSTRACT FROM AUTHOR]

In order to assess the relationship between environmental stress and crown condition of forest trees monitored since 1986 in Europe, estimates of stress factors, including temperature stress, drought stress and air pollution stress, were derived with the best data, methods and models currently available. This paper presents information on the methods used to derive such stress factors, and on the overall ranges, the temporal trends, the spatial distribution and the reliability of the calculated stress factors. The temperature stress indices did not show much temporal variation between 1985 to 1995. As expected spatial patterns were north-south orientated, going from colder northern regions to warmer southern regions. The calculated relative transpiration showed a more complex pattern, coinciding to a large extend with patterns of rainfall and temperature. Potential acid deposition decreased between 1986 and 1992, but remained fairly constant after 1992. The strong decrease was mainly the result of the decrease in SOx deposition, and to a small decrease in NOy deposition. Highest levels of the S and N deposition were calculated in Central and Western Europe. Base cation deposition was largest in coastal areas and in southern Europe. This is mainly due to soil dust, Sahara dust and sea salt. Base cation deposition can compensate almost entirely for the potential inputs in the south of Europe, whereas in central Europe it equalled about 25% of the potential acid input. A comparison between site specific modelled deposition and deposition derived from throughfall data showed that the total acid deposition is usually overestimated by the model, whereas the total nitrogen deposition is underestimated, especially at plots with high nitrogen loads. There is, however, a significant correlation between measured and modelled data for all S and N deposition, thus allowing their use in a statistical analyses. [ABSTRACT FROM AUTHOR]

Site-specific estimates for various environmental stress factors were related with measured crown condition data at a systematic 16 ×: 16 km2 grid over Europe, according to previously stated hypotheses, using a multiple regression approach, including interactions, and lagged effects of stress factors. Methodological differences among countries accounted for >30% of the variation in defoliation. Nevertheless, crown condition was found to vary naturally with tree age, altitude, drought stress and, most likely, also pathogenic fungi and insects. Significant impacts of air pollution (specifically ozone but also NOx, SOx and acid deposition) were found at regional levels in parts of central Europe, particularly for deciduous species. Impacts seemed less significant for conifers, especially for spruce, but this might be affected by confounding effects or strong correlations between (a harsh) climate and (low) atmospheric deposition in the area where spruce predominates. National studies indicate that ozone and acid deposition can have a significant effect on the defoliation of spruce as well. We conclude that while forest condition varies naturally, continued emissions will contribute further to forest decline in the long term. [ABSTRACT FROM AUTHOR]

Arising from: F. Magnani et al. 447, 849–850 (2007); Magnani et al. replyMagnani et al. present a very strong correlation between mean lifetime net ecosystem production (NEP, defined as the net rate of carbon (C) accumulation in ecosystems) and wet nitrogen (N) deposition. For their data in the range 4.9–9.8 kg N ha-1 yr-1, on which the correlation largely depends, the response is approximately 725 kg C per kg N in wet deposition. According to the authors, the maximum N wet deposition level of 9.8 kg N ha-1 yr-1 is equivalent to a total deposition of 15 kg N ha-1 yr-1, implying a net sequestration near 470 kg C per kg N of total deposition. We question the ecological plausibility of the relationship and show, from a multi-factor analysis of European forest measurements, how interactions with site productivity and environment imply a much smaller NEP response to N deposition. [ABSTRACT FROM AUTHOR]

Reports optical and near-infrared observations of the galaxy STIS123627+621755, which was previously suggested to be at a redshift of 6.68. Expectation that a galaxy at this redshift should be invisible at wavelengths less than 9,300 Angstroms and relatively bright at near-infrared wavelengths; Findings which were contrary to the expectations; Conclusion that the redshift must be less than 6.

Reducing nutrient discharge from wastewater is essential to mitigating aquatic eutrophication; however, energy- and chemicals-intensive nutrient removal processes, accompanied with the emissions of airborne contaminants, can create other, unexpected, environmental consequences. Implementing mitigation strategies requires a complete understanding of the effects of nutrient control practices, given spatial and temporal variations. Here we simulate the environmental impacts of reducing nutrient discharge from domestic wastewater in 173 countries during 1990–2050. We find that improvements in wastewater infrastructure achieve a large-scale decline in nutrient input to surface waters, but this is causing detrimental effects on the atmosphere and the broader environment. Population size and dietary protein intake have the most significant effects over all the impacts arising from reduction of wastewater nutrients. Wastewater-related impact hotspots are also shifting from Asia to Africa, suggesting a need for interventions in such countries, mostly with growing populations, rising dietary intake, rapid urbanisation, and inadequate sanitation. The environmental impacts of increasing wastewater management are poorly understood. Here, the authors simulate impacts for 173 countries between 1990 and 2050; despite the development of wastewater infrastructure, they identify hotspots of unexpected detrimental effects which are shifting from Asia to Africa. [ABSTRACT FROM AUTHOR]

The article discusses the importance of plant nutrients including nitrogen, phosphorus and potassium for carbon sequestration in forests. It highlights the use of global scale data set and advanced statistical modeling approach to show the relationship between nutrient availability and forest carbon sequestration. It also cites the utilization of model projections to design strategies to preserve carbon sinks by the policymakers.

An erratum is presented concerning the article "Ecologically implausible carbon response?" which was published in the volume 451 (2008) issue, pages E1 - E3.

Background and aims: Phosphorus (P) availability in calcareous soils is limited. Acidifying the soil by adding sulfur (S) or enhancing microbial activity by adding carbon (C) can increase P bioavailability. However, understanding of the impact of the combined application of P, S and C on P availability in calcareous soils is lacking. In this study, we investigated the effects of heterogeneous (co-localized) supply of different combinations of P, S and C on the maize (Zea mays L.) shoot and root growth and soil P availability in calcareous soil with low available P.A rhizo-box experiment with heterogeneous supply of P, S and C was conducted to assess the responses of maize growth, root morphology and physiology, as well as soil P availability.Heterogeneous low P (P1) with S supply significantly increased shoot and root biomass, shoot P content and P-use efficiency (PUE) compared to homogenous or heterogeneous P1 supply alone. Application of S decreased the rhizosphere soil pH and stimulated the proliferation of maize roots. By contrast, heterogeneous P1 and C supply did not change shoot biomass, P uptake or PUE but decreased root biomass. The addition of C, however, enhanced acid phosphatase activity and carboxylates concentration in the rhizosphere, and increased NaHCO3-extractable P, implying enhanced P availability.Adding S combined with P is an effective approach to engineer the rhizosphere by increasing maize growth and PUE in calcareous soil, whereas adding C increased NaHCO3-extractable soil P but did not influence maize shoot growth.Methods: Phosphorus (P) availability in calcareous soils is limited. Acidifying the soil by adding sulfur (S) or enhancing microbial activity by adding carbon (C) can increase P bioavailability. However, understanding of the impact of the combined application of P, S and C on P availability in calcareous soils is lacking. In this study, we investigated the effects of heterogeneous (co-localized) supply of different combinations of P, S and C on the maize (Zea mays L.) shoot and root growth and soil P availability in calcareous soil with low available P.A rhizo-box experiment with heterogeneous supply of P, S and C was conducted to assess the responses of maize growth, root morphology and physiology, as well as soil P availability.Heterogeneous low P (P1) with S supply significantly increased shoot and root biomass, shoot P content and P-use efficiency (PUE) compared to homogenous or heterogeneous P1 supply alone. Application of S decreased the rhizosphere soil pH and stimulated the proliferation of maize roots. By contrast, heterogeneous P1 and C supply did not change shoot biomass, P uptake or PUE but decreased root biomass. The addition of C, however, enhanced acid phosphatase activity and carboxylates concentration in the rhizosphere, and increased NaHCO3-extractable P, implying enhanced P availability.Adding S combined with P is an effective approach to engineer the rhizosphere by increasing maize growth and PUE in calcareous soil, whereas adding C increased NaHCO3-extractable soil P but did not influence maize shoot growth.Results: Phosphorus (P) availability in calcareous soils is limited. Acidifying the soil by adding sulfur (S) or enhancing microbial activity by adding carbon (C) can increase P bioavailability. However, understanding of the impact of the combined application of P, S and C on P availability in calcareous soils is lacking. In this study, we investigated the effects of heterogeneous (co-localized) supply of different combinations of P, S and C on the maize (Zea mays L.) shoot and root growth and soil P availability in calcareous soil with low available P.A rhizo-box experiment with heterogeneous supply of P, S and C was conducted to assess the responses of maize growth, root morphology and physiology, as well as soil P availability.Heterogeneous low P (P1) with S supply significantly increased shoot and root biomass, shoot P content and P-use efficiency (PUE) compared to homogenous or heterogeneous P1 supply alone. Application of S decreased the rhizosphere soil pH and stimulated the proliferation of maize roots. By contrast, heterogeneous P1 and C supply did not change shoot biomass, P uptake or PUE but decreased root biomass. The addition of C, however, enhanced acid phosphatase activity and carboxylates concentration in the rhizosphere, and increased NaHCO3-extractable P, implying enhanced P availability.Adding S combined with P is an effective approach to engineer the rhizosphere by increasing maize growth and PUE in calcareous soil, whereas adding C increased NaHCO3-extractable soil P but did not influence maize shoot growth.Conclusion: Phosphorus (P) availability in calcareous soils is limited. Acidifying the soil by adding sulfur (S) or enhancing microbial activity by adding carbon (C) can increase P bioavailability. However, understanding of the impact of the combined application of P, S and C on P availability in calcareous soils is lacking. In this study, we investigated the effects of heterogeneous (co-localized) supply of different combinations of P, S and C on the maize (Zea mays L.) shoot and root growth and soil P availability in calcareous soil with low available P.A rhizo-box experiment with heterogeneous supply of P, S and C was conducted to assess the responses of maize growth, root morphology and physiology, as well as soil P availability.Heterogeneous low P (P1) with S supply significantly increased shoot and root biomass, shoot P content and P-use efficiency (PUE) compared to homogenous or heterogeneous P1 supply alone. Application of S decreased the rhizosphere soil pH and stimulated the proliferation of maize roots. By contrast, heterogeneous P1 and C supply did not change shoot biomass, P uptake or PUE but decreased root biomass. The addition of C, however, enhanced acid phosphatase activity and carboxylates concentration in the rhizosphere, and increased NaHCO3-extractable P, implying enhanced P availability.Adding S combined with P is an effective approach to engineer the rhizosphere by increasing maize growth and PUE in calcareous soil, whereas adding C increased NaHCO3-extractable soil P but did not influence maize shoot growth. [ABSTRACT FROM AUTHOR]