Preliminary Studies on the Inoculation of Selected Micro-Organisms into Partially-Sterilized Soils

SUMMARY: Samples of Rothamsted and Woburn soil were either partially sterilized, totally sterilized or untreated. Representative samples of each treatment were inoculated with a pure culture of Nocardia cellulans and other samples, uninoculated, were kept as controls. The change in numbers of nocardias/g. soil was followed at intervals for one year. In partially-sterilized soil wide fluctuations occurred during the first month, followed by a steadying in count, and at the end of the year N, cellulans was still present in high numbers. The numbers of bacteria in such a soil were depressed in comparison with the uninoculated control. N. cellulans disappeared from an untreated soil in 6 months. The wide fluctuations in numbers in partially sterilized soil were correlated with a regular cyclical morphological development of N. cellulans. This was demonstrated by morphological observations and a soilshaking method. Peak counts corresponded to the rod form and troughs to the mycelial form and the steadying in count to the rod form.