THE QUANTITY AND QUALITY OF NUTRIENT CATIONS IN SOME MICHIGAN SPODOSOLS

Abstract

Using total and exchangeable cation composition and mineralogy, we evaluated the quantity and character of nutrient cations in some Michigan forest Spodosols. Quantities of bound calcium and magnesium in the A horizons of these soils were found to be about 7 to 20 times the exchangeable amounts, while bound potassium was present at levels about 300 times the exchangeable quantities. The total elemental analyses were consistent with mineralogical evaluations of the 0.1 to 1-mm fractions of the A horizons of these coarse-textured soils, which showed orthoclase feldspar as the most abundant nutrient-bearing mineral. Quantities of coarse fragments (>2 mm) were variable but generally small, and these fragments were largely composed of minerals that appeared resistant to weathering and nutrient release. These data and other available information indicate that although significant bound reserves are evident, the exchangeable nutrient pools probably provide most of the cations necessary for tree growth on these and similar soils.