Effect of partially acidulated phosphate rocks on phosphorus availability in rice soil

摘要

Relative efficiency of the partially acidulated phosphate rocks (PAPRs) made with acid mixtures, viz. HNO_3 + H_2SO_4, HNO_3 + HCI and HNO_3 + H_3PO_4 at 10 and 20% acidulation in increasing the ;available phosphorus status of submerged alkaline soilat three temperatures (10,25 and 40°C) was studied. All PAPRs increased the available phosphorus of soil over the unacidulated phosphate rock. The PAPRs did not increase the available phosphorus in soil over superphosphate. Most of the PAPRs recorded highest Available phosphorus after 45 and 60 days of application. The efficiencies of the degrees of acidulation, temperatures and acids which were mixed with HNO_3 were graded, respectively as: 30% > 10%, 25°C > 40°C > 10°C and H_3PO_4 > H_2SO_4 > HCI.