More efficient phosphorus use can avoid cropland expansion.

Global projections indicate that approximately 500 Mha of new arable land will be required to meet crop demand by 2050. Applying a dynamic phosphorus (P) pool simulator under different socioeconomic scenarios, we find that cropland expansion can be avoided with less than 7% additional cumulative P fertilizer over 2006-2050 when comparing with cropland expansion scenarios, mostly targeted at nutrient-depleted soils of sub-Saharan Africa. Additional P fertilizer would replenish P withdrawn from crop production, thereby allowing higher productivity levels. We also show that further agronomic improvements such as those that allow for better (legacy) P use in soils could reduce both P outflows to freshwater and coastal ecosystems and the overall demand for P fertilizer.