Organic matter determination of components of high organic matter-sand-soil mixes

The purposes of this study were (1) to determine the optimum temperature and time period for use with the loss-on- ignition method of organic matter determination, and (2) to compare the effectiveness of the loss-on-ignition method with the Walkley-Black and hydrogen peroxide methods on components of high organic matter-sand-soil mixes.

Three sands and eight organic materials were heated for different time periods at different temperatures. In most cases the organic fraction of these materials were destroyed effectivelyat400'Cfor6hours. Ignition at higher temperatures or for longer time periods appeared to introduce error resulting from weight loss from unidentified fractions.

Comparison of the three techniques showed that both loss-on-ignition and the Walkley-Black method have consistent results and both were deemed suitable for the high organic matter-sand rootzone mixes used in the turfgrass industry. Loss-on-ignition is the preferred method, however, due to the need of a correction factor to allow for the consistently low values measured by the Walkley-Black method. Hydrogen peroxide values were quite inconsistent and the method was deemed unacceptable for the materials studied.