ISSN: 0041-3216

ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 70 Number 2
Research Papers
Interaction of phosphate rocks with selected sugar-cane soils of Guyana
Harold B. Davis
Laboratory experimentation on the interactions of a phosphate rock from Florida and a phosphate limestone from Curacao with three acid sugar-cane soils is discussed. Over a 48-week period, Bra! I phosphate increased after addition of the phosphate rocks. However, the magnitude of Bray-I increase did not parallel soil phosphate adsorption properties and it was concluded that while Bray I P provided a useful index of available P from admixture with phosphate rock, it could not consistently predict reactivities of individual soils to phosphate rocks. Lime decreased apparent rates of phosphate rock dissolution. It was found that despite high free CaCO3 content (>50%), low phosphate content (approximately 6%), and coarse particle size, the phosphatic limestone from Curacao Island had significantly increased (P?5 0.05) Bray-I P in each soil at the end of the 48-week experimental period. It was concluded that it had good potential as a source of phosphate and calcium in acid soils.
Keywords: Acid soils; Phosphate rocks; Adsorption; Availability