Tive Effects of Soil Nitrogen and Soil Organisms on Survival of Ophiobolus Graminis

Abstract

All previous work on the effect of nitrate enrichment of soil upon the survival of Ophiobolus graminis on wheat straw has been with unsterilized soil (Garrett 1938, 1940,1944; Butler 1953, 1959; Lucas 1955; Macer 1961; van der Watt 1965). While this has approximated field conditions, it has precluded any determination of the direct effect of the amendment as distinct from its effect through the growth of other soil organisms. Use of an initially sterile soil may provide a method of separating these effects. As ionizing radiation will completely sterilize soil with a minimum of side effects (van Groenewoud 1959; Bowen and Rovira 1961; Bowen and Cawse 1962), such a treatment was selected for studying the effects of soil nitrogen and soil micro-organisms on survival of O. graminis.