Department of Agricultural Chemistry and Soil Science, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, 741 252.
* Present address: Office of the Agricultural Development Officer, P.O. Alangayam, North Arcot Ambedkar District, Tamil Nadu, 635701.
The effect of partially acidulated rock phosphates prepared with acid mixtures, viz. HNO3 + H2SO4, HNO3+ HCl and HNO3 + H3PO4 at 10 and 20 per cent acidulation on Bray and Kurtz No.1 extractable phosphoP1S status of an acid Typic Ustifluvent incubated at 50 per cent water holding capacity at three temperatures, viz. 10, 25 and 40°C was studied. All the partially acidulated rock phosphates increased the Bray and Kurtz No. 1 extractable phosphorus status of soil over unacidulated rock phosphate but not over single superphosphate. Most of the partially acidulated rock phosphates recorded maximum Bray and Kurtz No. 1 extractable phosphorus after 30 days of application. Higher degree of acidulation (20%) recorded higher Bray and Kurtz NO.1 extractable phosphorus over lower degree of acidulation (10%). Among the acid mixtures used as acidulants, the mixture of HNO3 and H3PO4 was the best. The medium temperature (25°C) recorded maximum Bray and Kurtz No. 1 extractable phosphorus, while the low temperature (l0°C) recorded the minimum.
Partially acidulated rock phosphate, Bray and Kurtz No. 1 extractable phosphorus, degree of acidulation, incubation period, temperature, acidulant, acid soil
