Soil Potassium‐Moisture Relations: I. Potassium Release Observed on Drying Iowa Soils With Added Salts or HCl

Abstract

Abstract Increments of salts or HCl were added to field‐moist samples of selected Iowa soils. The soils were then dried and extracted with neutral 1 N NH 4 Ac to determine the K released under these conditions. When no salt or HCl was added, there was a continuous increase in K release when the moist soils were first dried at room temperature and then at progressively higher temperatures. The release of K at elevated temperatures appears to be part of the same extractable K‐moisture relationship that has been observed when soils are airdried. Soils that normally released K on drying showed a continuous net fixation of K on drying when enough KCl was added to the moist soil. When lesser amounts of KCl were added both fixation and release were observed in the same drying sequence. The release of K was reduced when NH 4 Cl, NaCl, or HCl was added to the soil prior to drying. The NH 4 Cl additions were particularly effective. CaCl 2 additions had little or no effect on the K released by drying.