Nitrogen and phosphorus recovery efficiency and agronomic experimentation with phosphorus

Apparent phosphate recovery efficiency is generally determined by difference method (APRE_d) and it requires that both P uptake value and P applied in kg P/ha. It is therefore suggested that the phosphate doses in agronomic experiments be planned, conducted and reported in kg P/ha in place of kg P₂O₅/ha as is being currently done. The suggested doses are 10, 20, 30, 40 kg P/ha or may be higher, depending upon the nature of experimentation. Also to eliminate the response to sulphur, which is present in single superphosphate, it is better to use DAP (diammonium phosphate) or TSP (triple superphosphate).