3.3.1 Phosphorus Pollution in 2050
Based on FAO’s projection for food demand by 2050 (FAO 2018) and our
calculation, the amount of P in harvested crops would increase from 13.6
Tg P yr-1 in 2010 to 20.5 Tg P yr-1in 2050 (Table 3). Increased P in harvested crops indicates that P
inputs would increase, and more P would be lost unless PUE is improved.
The global P surplus was projected to increase from 8.8 in 2010 to 15.3
Tg P yr-1 in 2050, without PUE improvement (Table 3).
By improving PUE, the global P surplus would decrease to 5.6 (MPA), and
even 2.2 Tg P yr-1 (HPA) in 2050 (Table 3), and the
global P surplus rate would decrease from 7 in 2010 to 4 (MPA) and 2
(HPA) kg P ha-1 yr-1 in 2050. This
reduction in P surplus would be more significant in countries with a
relatively larger P surplus rate in 2010, such as China, India, and
Brazil (Fig. 4). For countries with relatively higher PUE and negative P
surplus rate in 2010 (e.g., the U.S. and African countries), their
negative surplus rate would increase to around zero, as we assumed that
PUE higher than one would decrease to around one in 2050 (Fig. 4).