The influence of the addition of goethite to soil on the dissolution of North Carolina phosphate rock

Abstract

This laboratory experiment investigated changes in the dissolution of North Carolina phosphate rock and NaHCO3-soluble P arising from the addition of goethite (á-FeOOH) to soil. Increasing goethite in the soil increased the amount of phosphate rock (PR) dissolution as measured by the increase in exchangeable Ca (ÄCa) values. Increased dissolution was, however, associated with decreased NaHCO3- soluble P due to P retention by goethite. The proportion of P dissolved from PR that was soluble in 0.5 M NaHCO3 solution decreased with contact period and with increased goethite. The increase in exchangeable Ca (ÄCa) was a better indicator of the extent of PR dissolution in goethite-containing soils than NaHCO3-soluble P.