Negative global phosphorus budgets challenge sustainable intensification of grasslands

Abstract

Grasslands provide grass and fodder to sustain the growing need for ruminant meat and milk. Soil nutrients in grasslands are removed through withdrawal in these livestock products and through animal manure that originates from grasslands and is spread in croplands. This leads to loss of soil fertility, because globally most grasslands receive no mineral fertilizer. Here we show that phosphorus (P) inputs (mineral and organic) in global grasslands will have to increase more than fourfold in 2050 relative to 2005 to achieve an anticipated 80% increase in grass production (for milk and meat), while maintaining the soil P status. Combined with requirements for cropland, we estimate that mineral P fertilizer use must double by 2050 to sustain future crop and grassland production. Our findings point to the need to better understand the role of grasslands and their soil P status and their importance for global food security.

The fluvial flux of total reactive and total phosphorus from the UK in the context of a national phosphorus budget: comparing UK river fluxes with phosphorus trade imports and exports

“…In contrast, other aquifer systems can exhibit much shorter timescales of P storage and remobilisation, for example in karst groundwaters, where P storage and remobilisation can occur within the order of a decade . Sattari et al (2016) have proposed that at the global scale, grasslands have a negative P budget because the return of manure and sewage sludge is not sufficient compared to the offtake of food from grassland implying that grassland would not be the site of accumulation. However, the analysis of Sattari et al (2016) did not allow for the increase diversion of human sewage (as is noted in this study); the fact a proportion of the P in sewage sludge that is returned to land most come from industrial products and not from human sewage; and the return P via rendered animal carcasses (even after incineration as is required in the UK).…”

Nutrients release from powder phonolite mediated by bioweathering actions

“…Among the factor related to the pastures degradation, stands out the soil use with high susceptibility to erosion, the excessive grazing, and the inadequate management of soil fertility (Peron and Evangelista 2004;Li et al 2013;Sattari et al 2016). In pastures areas, the fertility management is usually done with low nutrient intake, as well as in systems with one forage specie, or not used in consortium with larger plants, to optimize the nutrient cycling (Alves Filho et al 2003;Calil et al 2016).…”

Distant Views and Local Realities: The Limits of Global Assessments to Restore the Fragmented Phosphorus Cycle

“…Such outcomes are valuable to understand, and they follow on disparities identified in other global assessments of P budgets (e.g., MacDonald et al, 2011). In this example, however, the meta-analysis centered on testing long-term forage production strategies that overcome limits to plant available P in soil, concluding that a fourfold increase in P inputs to the world's grasslands is required (Sattari et al, 2016).…”

“…A recent assessment by Sattari et al (2016), for instance, drew on global P budgeting combined with continental modeling of soil P cycling to highlight the long-term outcome of using the world's grasslands to meet growing demands for livestock production: declining fertility. Such outcomes are valuable to understand, and they follow on disparities identified in other global assessments of P budgets (e.g., MacDonald et al, 2011).…”