Phosphorus management in rice (Oryza sativa) - wheat (Triticum aestivum) cropping system

The field trials on rice (Oryza sativa L.)-wheat (Triticum aestivum L emend. Fiori & Paol.) cropping system were conducted during 1996–97 to 2001–2002 at Bihar Agricultural College, Sabour (Bhagalpur), for optimizing dose and frequency of phosphorus application. Rice and wheat responded significantly only up to 60 kg P₂O₅/ha. Average of 6 years data revealed that for getting optimum yield of wheat, P application was essential to the crop whereas in rice if the preceding wheat crop was raised with phosphorus, it was not essential to supply phosphorus to the rice crop. Application of P to both the crops every year resulted in the maximum P uptake, which was also higher with increase in P level. The same treatment (P to both the crops) fetched the maximum net return (Rs 28, 738/ha) and had the highest benefit: cost ratio (1.36). Application of P only to wheat every year, however, proved to be equally good in realizing higher net return (Rs 26, 466/ha). Higher P rates and its repeated application every year resulted in higher P build up in soil.