A study by Lawton and Pierre (1946) of different soil types in Iowa and their potassium availability showed that the Marshall series were consistently higher in exchangeable potassium than the Clarion series. The Marshall series is developed in Wisconsin loess and is classified as a Medial Brunizem. The Clarion series is developed in Cary and Mankato till and is classified as a Minimal Brunizem. The Marshall series is dominantly a silty clay loam, whereas the Clarion series is dominantly a loam. Pratt and Morse (1954) found, when they grouped several Ohio soils by areas, the potassium release was lowest from the sandy soils of the lake bed and highest from the associated fine textured soils. Volk (1942) found the percentage of Alabama soils responding to the second increment of applied potassium fertilizer increased as the texture became coarser. Lawton and Pierre (1946) reported that potassium release from Iowa soils was (1) highest in fine textured alluvial soils and (2) that loess derived soils showed higher release than soil derived from glacial till.
Proceedings of the Iowa Academy of Science
©1956 Iowa Academy of Science, Inc.
Daniels, Raymond B.
"Relationship Between Particle Size and Potassium Release in the Clarion and Marshall Soils,"
Proceedings of the Iowa Academy of Science, 63(1), 453-459.
Available at: https://scholarworks.uni.edu/pias/vol63/iss1/48