The food demand is rapidly increasing. This influences the demand for fertilizers, and phosphorus (P) in particular. Rock phosphate is a non-renewable resource, which may be depleted within 100 years, with the currently known resources (Cordell et al., 2009, Koning et al., 2008).
The aim of this research is to examine the role of the residual soil of P fertilizer as chemical fertilizer and manure in China and Nepal’s croplands to achieve the target crop P in 2050.
We applied a two-pool soil P model (Wolf et al., 1987) to reproduce historical crop uptake as a function of P applied through fertilizer and manure. We then used the model to estimate P requirements for crop production in 2050. The simulations for 2008 to 2050 are done for two different scenarios; a) the Global Orchestration (GO) scenario of the Millennium Ecosystem Assessment (MEA) (Alcamo, 2006, Bouwman et al., 2009) b) the equal uptake scenario (EU) that means the same P uptake in 2050 and 2007. For 2050 the GO scenario has a target P uptake of 25 kg P ha-1 and 24 kg P ha-1 for China and Nepal, respectively. The EU scenario has a P uptake of 16 kg P ha-1 for China and 12 kg P ha-1 for Nepal equivalent to the P uptakes in 2007 in both countries. The required P applications can decrease in both China and Nepal to have the same or higher yields because of the residual soil P.