A study of highly phos-phatic soils in a karst region of the humid tropics.

Abstract

Soils developed on biothermal limestone in the Karst region of the Ajamaroe plateau contained much PO₄ (up to 30% P₂O₅). The limestone involved was not a phosphorite, but contained 0.02-0.70% P₂O₅. Analysis of a silty-clay sample containing 18.6% P₂O₅ showed that the PO₁ was present as crandallite (found in coral limestones & supposedly CaAl₃(PO₄)₂(OH)₆). Pedological investigations in the field & analytical studies of soil & limestone samples confirmed the hypothesis that the highly phosphatic soils represent the accumulation product of insoluble & secondarily precipitated compounds originally contained in the limestone strata. Six principles seem to control the outcome of the accumulative process & the final PO₄ content of the soil; on account of these principic-& the relationship between specific weights of rock & soil it is conceivable that not more than 75m of limestone must dissolve to form 1m of residual soil. The occurrence of this soil type in other parts of West New Guinea & the significance of this phos-phatic material for industrial, commercial & agricultural use are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)