Relative Response of Phosphatic Fertilizers At Varying Levels of Nitrogen and Phosphorus in Tomato¹

Relative response of three phosphatic fertilizers (Single superphosphate, monoammonium phosphate and potassium metaphosphate) at three different phosphate levels (30, 60 and 90 kg P₂O₅/ha) in combination with three nitrogen levels (50, 100 and 150 kg N/ha) was studied in tomato during the period 1963–1965 at the Indian Agricultural Research Institute, New Delhi.

Potassium metaphosphate was found as efficient as superphosphate and monoammonium phosphate on equal nutrient basis in autumn crop. In hot weather crop, which is of shorter duration, the response of potassium metaphosphate was equivalent to superphosphate plus potassium sulphate, but monoammonium phosphate was more efficient than superphosphate and metaphosphate. The optimum level of phosphorus fertilization was found to be 68.37 and 74.94 kg P₂O₅/ha in autumn and hot weather crops respectively. The optimum rate of nitrogen fertilization was 127.65 and 134.55 kg N/ha in autumn and hot weather crops respectively.