Polysaccharides in soil fabrics.

Treatment of ultrathin sections of natural soil fabrics with heavy metal stains, specific for carbohydrates, showed that polysaccharides are widely distributed in soils. In addition to being associated with living cells and dead remains of plants and microbes, carbohydrates also coat clay platelets and occur in crevices of submicron size within mineral aggregates. The determination of the precise location of polysaccharides in soils explains in part why some carbohydrates are resistant to microbial degradation and why small quantities of microbial polysaccharides are able to stabilize clay aggregates.