Human alteration of the global nitrogen and phosphorus soil balances for the period 1970-2050

The Millennium Ecosystem Assessment scenarios for 2000 to 2050 describe contrasting future developments in agricultural land use under changing climate. Differences are related to the total crop and livestock production and the efficiency of nutrient use in agriculture. The scenarios with a reactive approach to environmental problems show increases in agricultural N and P soil balances in all developing countries. In the scenarios with a proactive attitude, N balances decrease and P balances show no change or a slight increase. In Europe and North America, the N balance will decline in all scenarios, most strongly in the environment-oriented scenarios; the P balance declines (proactive) or increases slowly (reactive approach). Even with rapidly increasing agricultural efficiency, the global N balance, ammonia, leaching and denitrification loss will not decrease from their current levels even in the most optimistic scenario. Soil P depletion seems to be a major problem in large parts of the global grassland are

Anthropogenic nitrogen autotrophy and heterotrophy of the world's watersheds: Past, present, and future trends

Anthropogenic nitrogen autotrophy of a territory is defined as the nitrogen flux associated with local production of harvested crops and grass consumed by livestock grazing (in kg N/km(2)/yr). Nitrogen heterotrophy is the nitrogen flux associated with local food and feed consumption by humans and domestic animals. These two summarizing characteristics (anthropogenic nitrogen autotrophy and heterotrophy (ANAH)) indicate the degree of anthropogenic perturbation of the nitrogen cycle by agriculture and human consumption: their balance value provides information on either the potential for commercial export or the need to import agricultural goods; in a watershed, their vector sum is related to the nitrogen flux delivered to the sea. These indicators were calculated for all the watersheds in the Global Nutrient Export from Watersheds (NEWS) database for 1970 and 2000, as well as for 2030 and 2050, according to Millennium Ecosystem Assessment scenarios. During this 30 year period, many watersheds shifted from relatively balanced situations toward either more autotrophic or more heterotrophic conditions. This trend is predicted to become more pronounced over the next 50 year

N:P:Si nutrient export ratios and ecological consequences in coastal seas evaluated by the ICEP approach

The Indicator for Coastal Eutrophication Potential (ICEP) for river nutrient export of nitrogen, phosphorus, and silica at the global scale was first calculated from available measurement data. Positive values of ICEP indicate an excess of nitrogen and phosphorus over silica and generally coincide with eutrophication. The sign of ICEP based on measured nutrient fluxes was in good agreement with the corresponding one calculated from the Global-NEWS models for more than 5000 watersheds in the world. Calculated ICEP for the year 2050 based on Global NEWS data for the four Millennium Ecosystem Assessment scenarios show increasing values particularly in developing countries. For further evaluation of the ICEP at the outlet of the rivers of the world based on measurements, there is a need for additional determination silica fluxes and concentrations, which are scarcely documented

Global Opportunities to Increase Agricultural Independence Through Phosphorus Recycling

Food production hinges largely upon access to phosphorus (P) fertilizer. Most fertilizer P used in the global agricultural system comes from mining of nonrenewable phosphate rock deposits located within few countries. However, P contained in livestock manure or urban wastes represents a recyclable source of P. To inform development of P recycling technologies and policies, we examined subnational, national, and global spatial patterns for two intersections of land use affording high P recycling potential: (a) manure‐rich cultivated areas and (b) populous cultivated areas. In turn, we examined overlap between P recycling potential and nation‐level P fertilizer import dependency. Populous cultivated areas were less abundant globally than manure‐rich cultivated areas, reflecting greater segregation between crops and people compared to crops and livestock, especially in the Americas. Based on a global hexagonal grid (290‐km2 grid cell area), disproportionately large shares of subnational “hot spots” for P recycling potential occurred in India, China, Southeast Asia, Europe, and parts of Africa. Outside of China, most of the remaining manure‐rich or populous cultivated areas occurred within nations that had relatively high imports of P fertilizer (net P import:consumption ratios ≥0.4) or substantial increases in fertilizer demand between the 2000s (2002–2006) and 2010s (2010–2014). Manure‐rich cultivated grid cells (those above the 75th percentiles for both manure and cropland extent) represented 12% of the global grid after excluding cropless cells. Annually, the global sum of animal manure P was at least 5 times that contained in human excreta, and among cultivated cells the ratio was frequently higher (median = 8.9). The abundance of potential P recycling hot spots within nations that have depended on fertilizer imports or experienced rising fertilizer demand could prove useful for developing local P sources and maintaining agricultural independence

De status van het rekeninstrumentarium STONE 2.0

Het STONE-ontwikkelingstraject is gestart in 1993 door Wageningen UR, RIVM en RIZA. STONE is ook een netwerk van deskundigen om als discussieplatform te dienen voor wetenschappers en gebruikers. Voorjaar 2001 is een nieuwe ruimtelijke schematisering van Nederland opgeleverd en zijn nieuwe modulen voor berekening van de gewasopname, denitrificatie en mineralisatie van organisch stof geomplementeerd. Dit resulteerde in STONE 2.0. STONE 2.0 genereert uitvoer voor 6405 unieke combinaties (voornamelijk van landgebruik, bodemtype en hydrologie) voor tiendaagse periodes tussen 1986 en 2000. Prognoses kunnen worden berekend tot het jaar 2100. Interpretatie van de resultaten is alleen geoorloofd voor grotere ruimtelijke eenheden (indicatief 250 kmr) en voor meerjarige gemiddelden van nutriëntconcentraties en -fluxen. De meest robuuste resultaten van STONE 2.0 zijn de nitraatgehalten in het bovenste grondwater en de mate van fosfaatverzadiging van de bodem, en met name de resultaten op nationale schaal. Toepassingsmogelijkheden van STONE 2.0 op het gebied van milieubeleid zijn groot. STONE wordt sinds najaar 2001 toegepast voor berekeningen ten behoeve van de evaluatie van het mestbeleid, voor de Milieubalans en Milieuverkenningen, voor rapportages aan de Europese Commissie, en voor rapportages aan diverse nationale en internationale commissies. Sinds juli 2001 is een intensief traject ingezet van aanvullende toetsing/onzekerheidsanalyse en documentatie/review van STONE 2.0

Future projections of river nutrient export to the global coastal ocean show persisting nitrogen and phosphorus distortion

Nitrogen (N) and phosphorus (P) from anthropogenic sources are needed to produce food for the growing world population. As a result, these nutrients can be found in nearly every water body across the globe. Not only nutrient loading is important but also the molar ratio and its deviation from the “natural” Redfield ratio. Here we show that rivers, which have more than 50% anthropogenic sources and at the same time elevated N:P ratios (> 25) contributed 36% to the total global N export to coastal waters in 2015. The five Shared Socioeconomic Pathways (SSP) were used in combination with the Representative Concentration Pathways climate scenarios to project river nutrient loadings for 2050. Future nutrient export is projected to decline in high-income countries (with N:P ratios exceeding Redfield). In Brazil, India and China, however, a decline of N:P is only the case in a scenario oriented toward sustainable development (SSP1). The human-dominated river N and P export with elevated N:P ratios will increase in all SSPs, except in SSP1 where it stabilizes. Integrated strategies for both N and P considering all relevant trade-offs and societal sectors are urgently needed to reduce the nutrient pressure on surface waters