Phosphorus Availability and Redistribution in Relation to Profile Development in an Illinois Landscape Segment

Abstract

AbstractMollic Albaqualfs in northwestern and west central Illinois occur sporadically in small isolated areas surrounded by Argiudolls and Haplaquolls. A transect was studied to determine (i) if Mollic Albaqualfs are phosphorus deficient relative to the associated weakly developed soils, (ii) dominant forms of phosphorus present in soils at varying stages of development, and (iii) the quantities of vertical and horizontal phosphorus movement within a landscape segment.Phosphorus availability increases as the degree of profile development increases, which implies that these Albaqualfs have a higher phosphorus‐supplying power than the associated, more productive Argiudolls and Haplaquolls. Fractionation of inorganic phosphorus reveals increasing aluminum, iron, and reductant‐soluble plus decreasing calcium phosphate on progressing toward the Albaqualf end of the transect. Total phosphorus content as well as progressive enhancement of eluvial and illuvial total phosphorus horizons also increases as pedogenetic development increases. Reconstruction of total phosphorus profiles reveals that the most strongly developed Albaqualf has accumulated 493.49 g/m2 of phosphorus whereas the most weakly developed Aquoll has lost 151.34 g/m2. The 1.1‐ha landscape segment studied has incurred a net loss of 188.7 kg of phosphorus. Phosphorus translocations, within the landscape segment studied, greatly aid in explaining the variation in available phosphorus encountered in this transect.