Characteristics of phosphate rock materials and their dissolution in some acidic Indonesian soils

Abstract

Dissolution of phosphate rock (PR) materials in soil is a primary concern for phosphorus (P) in the PR to become plant available. The dissolution of three PR materials, China PR (CPR), Ciamis PR (CiamisPR) and Gafsa PR (GPR), in eight acid Indonesian soils was evaluated in a closed incubation system. Dissolution of PR was measured from the increase in either 0.5M NaOH extractable P (DP) or 1M BaCl 2 -triethanolamine (TEA)-extractable Ca (DCa) in soils amended with PR compared with control soil. Dissolution of the CiamisPR was the highest (30 -100%) followed by GPR (17 -69%) and then by CPR (20 -54%). The maximum dissolution of PR in soil followed the order: Bogor Ultisols ! Bogor Oxisols ! Subang Inceptisols 4 Bogor Inceptisols 4 Sukabumi Oxisols 4 Lebak Ultisols 4 Sukabumi Inceptisols ! Lampung Ultisols. A curvilinear relationship was obtained between PR dissolution and P retention capacity and between DP and DCa.