Difference of fertilizer rates between VRF and FPM accurately
accounted for the high N and low K fertility of the soils in the
experimental farm. Basal N application amount of VRF was
similar to that of FPM, but N top-dressing amounts at tillering
and panicle initiation stages were 20 and 12 kg N ha-1 higher in
FPM, respectively. On the other hand, P2O5 fertilizer use in VRF
fields was almost the same as FPM fields. In the FPM fields,
farmers felt that the standard amount of fertilization was not
optimum for their fields and hence adjusted their fertilizer appli-
cation amounts arbitrarily. The mean amount of N, P2O5, and
K2O were lower by 7, 11, and 5 kg ha-1, respectively, than the
standard amount of fertilization. The use of low phosphate com-
pound fertilizer was one of the reasons for lowering the amount
of P2O5 fertilizer used. These results show that total amount of
fertilizer used in VRF fields was significantly lower than the
standard amount of fertilization further proving the benefits of
VRF in reducing fertilizer use.