Abstract: Effect and recommended NPK fertilization for mustard green were studied with field experimentations.Thirty tests were conducted and the results showed that the average rate of soil fertility contributed to the mustard yield was merely 26.3%.The effect of yield increase by individual fertilizers was 55.5%, 14.1% and 15.3% for the applied N, P and K, respectively.The fertilization benefits as shown by the output/input ratios were 36.9 and 21.3 and 12.2 for N, P and K, respectively.The result indicated that there was a remarkable effect on yield with the applied fertilizers.Maximum yield was achieved by using Olsen-P and available K at the rate of 42 mgkg-1 and 88 mgkg-1, respectively.Optimal application rate and NPK proportion varied for soils of different fertilities.On average, the application rates for the soil of high fertility grade were N 315 kghm-2,P2O5 85 kghm-2 and K2O 146 kghm-2; those for the soil ofmedium fertility grade were N 348 kghm-2, P2O5 127 kghm-2 and K2O 196 kghm-2; and, those for the soil low fertility grade were N 319 kghm-2, P2O5 146 kghm-2 and K2O 241 kghm-2.The regression equations between the available NPK in soil and fertilizer application rate were established to facilitate proper fertilization according to soil testing results.