Efficiency of Nitrophosphates of Varying Water Solubility in Regard to Uptake and Utilization of Phosphorus by Wheat

A pot culture experiment was conducted on four different nitrophosphates with 78, 58, 43 and 18 per cent of their phosphorus in water soluble form (WSP) using wheat (variety Sharbati Sonora) as the test crop. These nitrophosphates were prepared and tagged with ³²P in the laboratory and compared at three rates of P application (44.8, 89.6 and 134.4 kg P₂O₅/ha) on four typical soils namely, black (Nagpur), submountainous acid (Palampur), calcareous alluvial (Pusa, Bihar) and alluvial (Delhi).

The yield of dry matter, P uptake and per cent utilization of fertilizer P showed that nitrophosphate containing 58% of its phosphorus in water soluble form was 81–98% as effective as 78% water soluble nitrophosphate and the nitrophosphate with 43% water solubility was 67–90% as effective; the lowest efficiency was observed on the black soil of Nagpur in both the cases. Efficiency of nitrophosphate of 18% water solubility was generally very poor.