Carbohydrates in some Australian soils

Abstract

Carbohydrate contents of soils and soil fractions were determined by acid hydrolysis, clarification of the hydrolysate with charcoal, and the use of anthrone for the colorimetric determination of monosaccharides. Between 4 and 14% of the soil organic carbon was present as carbohydrate. During the growth of a pasture there is an accumulation of carbohydrate materials in partly decomposed plant remains in the soil. When such materials are removed, the proportion of the remainder of the soil organic matter in the form of carbohydrate is not changed by different cropping practices, in spite of large changes in the absolute amounts of carbohydrates present. Neither total organic matter nor total carbohydrate content is very closely correlated with aggregate stability. The differences in aggregate stability brought about by changes in seasons and cropping practices, and indicated by the periodate technique to be associated with polysaccharides, are most likely a result of qualitative changes within the soil carbohydrate fraction.