XV. Bacteria of two cultivated soils

Abstract

The bacterial flora of two New Zealand soils under native tussock, introduced pasture, and cultivation for crops is described. Where the change to pasture and cultivation is very recent, there is little change in bacterial numbers but there may be more frequent occurrence of leaf strains in the topsoil until the new vegetation is established. Where the change to pasture and cultivation is well established, there is an increase in numbers associated with an increased amount of organic matter in the soil and a recurrence in the pasture soil of fermenting bacteria present in well established grassland soils. The bacterial flora of the leaves and roots of the tussock and pasture plants was studied and also the air-borne flora. The root flora is similar to the soil flora but with an increased proportion of fermenters. The leaf flora is distinct from the soil and root flora and consists predominantly of chromogenic strains. The air-borne flora, apart from sporogenous types, is similar to the leaf flora.