EFFECT OF TEMPERATURE AND SOIL DRYING ON THE TRANSFORMATION OF (14C) GLUCOSE IN SOIL

Two different soils, either fresh, or dried and remoistened, were incubated with 1% labelled glucose for 28 days at about 20° or 5 °C and the transformation of the glucose to other sugars measured. Xylose formed a much greater proportion of the sugars synthesized at low temperature in pre-dried soil than in fresh soil, or at 20 °C in pre-dried or fresh soil. Numbers of bacteria, fungi (including actinomycetes) and yeasts were determined for each type of incubation. Because the combination of conditions leading to xylose synthesis by yeasts in predried soil are unlikely in the natural state it is concluded that most soil xylose originates in the residues of plants.