ORGANIC MATTER DISTRIBUTION WITH PARTICLE-SIZE IN SURFACE HORIZONS OF SOME SOMBRIC SOILS IN VANCOUVER ISLAND

Abstract

The surface horizons of some Sombric Brunisols and Podzols were fractionated to determine the distribution of the organo-mineral complexes. The soils were dispersed in water using ultrasonics and fractionated by wet sieving and the continuous flow supercentrifuge. The amounts of organic matter and the surface area of each fraction were determined. The weight of organic matter per unit of surface area increased with increasing size of soil separates. A considerable amount of organic matter is associated with the coarser fractions, with 5, 12 and 49% of the total organic matter being associated with the sand, coarse silt and fine silt fractions, respectively.