FORMS AND DISTRIBUTION OF PHOSPHORUS IN THE HORIZONS OF SOME NEBRASKA SOILS IN RELATION TO PROFILE DEVELOPMENT

Abstract

Total P, acid-soluble P (0.1 N HC1), fluoride-soluble P, organic P and P soluble at pH 3 and 9 were detd. on different horizons of a number of Nebraska soils varying rather widely in profile characteristics but developed from similar loessial parent material. There appeared to be some movement of P within the soil profile, since the total P content of soils with lime zones tends to be at a max. near the top of the lime zone. In the more highly developed soils, an accumulation of P in the A horizon was evident, probably due to the action of plants in redistributing the P. In the soils that remain neutral or only slightly acid during soil formation, a shift of acid-soluble forms of P to organic P compounds seems to be the major change. However, in soils that are leached to a greater degree and are somewhat more acid, surface-absorbed and/or Fe and Al phosphates are formed. The formation of the latter forms of phosphates presumably begins in the surface horizons of the soil but may occur to considerable depth in highly leached soils.