Abstract
Unpasteurized horse manure composts were given radiation doses of 0.1 and 1.0 Mrad in an attempt to increase mushroom yields by eliminating competing microorganisms. Yields were enhanced by 0.1 Mrad but were lower than those obtained with heat-pasteurized composts. Composts subjected to 1.0 Mrad gave the lowest yields, probably because of the generation of ammonia and other toxic compounds. Only temporary changes in the predominant microflora could be detected as a result of ionizing radiations.