THE OCCURRENCE OF BLUE-GREEN ALGAE IN SILT LOAMS OF WHITMAN COUNTY, WASHINGTON

Abstract

The occurrence of blue-green algae in cultivated and noncultivated soils in Whitman County, Washington, was studied over a 12-month period. Nostoc and Anabaena were found in the soils, Nostoc being ubiquitous. Microbial enumeration was by the most-probable-number method. Moisture and temperature were recorded on each sampling date, while climatic and agronomic events were noted and chemical properties estimated for four soil series. The infrequent occurrence and low densities of blue-green algae in the soils make improbable any assumption that nitrogen input by blue-green algae is significant in this region. Rapid loss of surface soil moisture, seasonal climatic fluctuations, slightly acid soils, and agricultural practices were probably the major reasons why greater numbers and diversity of blue-green algae were not observed on cultivated soils, while uncultivated soils supported more kinds and numbers.