The aim of this work was to provide practical information on the efficient utilization of urea-nitrogen by wheat, cotton and sorghum using15N isotopic tracer method. The utilization efficiency of applied nitrogen was found to be dependent on the crop ability to remove nitrogen from the soil solution over a relatively short period. Mixing 42 kg P per ha with 84 kg N increased wheat grain yield by about 30%, and N recovery by about 50% over the same N treatment without P. Placement of urea 10–20 cm deep increased %Ndff by cotton over surface-application by about 45% and the % N recovery by about 55%. N recovery by sorghum was low, and was improved slightly by application of urea four weeks after sowing compared to application at sowing. Loss of N as NH3 from surface applied urea was presumably the major avenue of loss which reduced N recovery by the different crops, especially sorghum and cotton. Urea-N recoveries calculated by the difference method and the15N isotopic method show the more reliability of the latter method.