Show Organic Matter Rids Cropland o of Bacteria Viruses Prevent Plant Diseases From Spreading By R R. C. C Thomas Ohio State College Few disease causing bacteria will survive in soil soU whose organic matter mat ter supply has been built up by the use of green manure crops and the return of crop residues and manure Those that do live are so changed that they are arc no longer a menace to crops Extracts from soil rich in organic matter contain viruses that depend for their existence upon living bac teria These viruses are especially numerous in organic matter added y t s 1 Fighting bacteria with application application I tion of organic matter to the soil through residues from grasses legumes and grain crops When these viruses come In contact contact contact con con- tact with plant disease forming bacteria bacteria bac bac- teria they have a profound influence on them changing the form of these bacteria and making them harmless harmless harmless harm harm- less so far as plants are concerned I The intensity of competition for food materials and life itself among organisms inhabiting soil particles are indicated by the fact that a single ounce of soil has an estimated living population of 50 million bacterial cells besides many forms of fungi Added to these are five million protozoa as aswell aswell aswell well as other forms of organisms Beneficial bacteria thrive best in soil well-stocked well with organic matter matter matter mat mat- ter and tend to crowd out the disi dis dis- dis- dis ease-causing ease kinds i |