The five Shared Socioeconomic Pathways (SSP) show similar global crop P uptake and P inputs, despite differences in population and incomes. In the sustainability scenario SSP1, the increase in P uptake comes entirely from increased production per hectare, with varying contributions from cropland expansion in the other SSPs.
Global phosphorus inputs
In addition to global fertilizer P inputs in croplands increasing from 14.5 Tg P yr−1 in 2005 to 22–27 Tg P yr−1 in 2050 with small differences between the SSPs, this study also estimates that 4–12 Tg P yr−1 would be needed in 2050 in global intensively managed grasslands to maintain fertility. Our new model approach can pinpoint the contribution of area expansion and crop yield improvement toward the total production, whereby the latter is shown to contribute 100% in the sustainability scenario SSP1 to 83-69% in the other SSPs.
This article has a twin which uses the same set of scenarios, but focusing on global nitrogen requirements and fertilizer use. In this article the SSPs are described.
Future P usage will play an important role in sustaining food production
for the projected world population growth from 7.3 in 2015 to 8.5 (SSP1) or more than 10 billion (SSP3) inhabitants in 2050. Nevertheless, phosphate rock is a finite resource and the high-quality and high-grade phosphate rock reserves are decreasing, although the estimates are quite variable.
The IMAGE-DPPS model results show major differences in future P requirements and fertilizer use among world regions for the various scenarios. High-income countries with a history of P accumulation during the 1960s and 1970s, will require relatively low P inputs up to 2050. In stark contrast, India and China are currently accumulating soil P by virtue of extensive soil P fertilizer application, a trend that is predicted to continue in order to increase crop production to meet high future P demand under all SSP scenarios. The low production developing regions will also have to scale up their level of P inputs to increase P uptake and keep up with the future agricultural production demand.
The model used is discussed in detail in this article.