INFLUENCE OF GRINDING OF SOIL ON APPARENT CHEMICAL-COMPOSITION

The influence of degree of grinding on the apparent chemical composition was studied in 11 different soils (fraction <2 mm) from The Netherlands. Representative subportions were crushed or ground till they just passed a plastic sieve of 1.0, 0.5, 0.25, and 0. 15 mm, respectively. All samples were analyzed in triplicate for soil parameters and for total and bioavailability concentrations of several inorganic constituents. The total concentrations, mainly from aqua regia extractions, were hardly influenced by the grinding procedure. The availability of some nutrients like Na, K, and Mg, estimated by weak extractants, was significantly influenced by the degree of grinding in some soils. Potassium and Mg concentrations were higher in the finer fractions. For P, sometimes an increase, but also in some soils a decrease was found. The variance of the analytical results was in most soils and for most estimated parameters not influenced by the degree of grinding.