TRANSFORMATION OF SUGARS WHEN RYE HEMICELLULOSE LABELLED WITH 14 C DECOMPOSES IN SOIL

Summary Incubation of soil with 14 C hemicellulose from rye straw for 448 days resulted in the evolution of about 70 per cent of the substrate as CO 2 . The two major sugar components of the hemicellulose, xylose (50 per cent) and arabinose (5 per cent), were almost completely decomposed. After 56 days only 5 per cent of the xylose remained and after 448 days only 1‐2 per cent. Similar results were obtained for soil derived from either granitic or basic igneous parent material. Almost 4 per cent of the hemicellulose was transformed to glucose and I per cent to mannose during the first 14 days of incubation. Fine grinding of 14C rye straw increased the extent of its decomposition on incubation but after 448 days 20 per cent of both its xylose and arabinose remained. It is suggested that the isolated hemicellulose is decomposed faster because it has been made water soluble.