Differences in Exchangeable Aluminum and Soil Acidity in Loess Soils of Iowa

Abstract

AbstractThe relationship of soil natural drainage, native vegetation, and textural development to exchangeable aluminum, exchange acidity, pH (CaCl2), total carbon and clay was studied in selected loess soils in Iowa. Greatest differences in measured properties in the laboratory were observed along biosequences. Prairie soils had only trace amounts of exchangeable aluminum, but usually had the most A‐horizon exchange acidity. Forest soils had both maximum exchangeable aluminum and exchange acidity in the B‐horizon, corresponding to maximum clay accumulation. “Transition” soils, presumably an encroachment of forest on a former prairie, were similar to forest soils. Only minor differences in measured properties were observed in natural drainage sequences. Acidity correlates with organic matter in prairie soils and with clay content in forest soils. The organic matter appears to act as a buffer in prairie soils and in the A‐horizon of transition and forest soils. Aluminum acts to buffer the forest and transition soil B‐horizons.