Relation of Extractable Molybdenum to Soil Series and Parent Rock in Kentucky

Abstract

AbstractMolybdenum extracted by the ammonium oxalate procedure proposed by Grigg was determined on 73 Kentucky soils. The Mo extracted by this method was related to the parent rock. Soils formed from Devonian black fissile shale contained approximately 20 times as much Mo as any other soil. Among the other soils the parent rock averages varied from 0.44 ppm Mo for older Ordovician limestone (generally high phosphatic) to 0.08 ppm Mo for Pennsylvanian sandstones and shales. The parent rock group differences were highly significant. Grigg‐extractable Mo and soil pH give some indication of Mo availability in the soil, and it is suggested that knowledge of the general level of Grigg‐extractable Mo in soils of a given parent rock group may allow useful prediction of Mo availability on these soils. The data provide some indication of a degree of uniformity within soil series. If further work supports this indication, a more accurate prediction based on soil series should be possible.