The current soil test phosphorous ratings of low, medium and high fertility classes and critical limits were revised by studying the response of maize in 24 soils of varied initial P fertility, treated with graded levels of P. The revised SPTR were <15.50, 15.51-28.00, 28.10-48.50 and >48.50 kg P2O5 ha-1, VL: L: M: H, respectively. CL for soil was 17.0 kg P2O5 ha-1 and 0.12 per cent for plant. Maize yield can be maximized by recommending phosphorous @ 150, 125, 100 and 75 percent of the recommended dose in the respective soils of VL: L: M: H fertility ratings.

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