Nitrogen Bacteria and Legumes / With special reference to red clover, cowpeas, soy beans, alfalfa, and sweet clover, on Illinois soils

The bulletin explains the roles of two groups of bacteria in soil nitrogen cycling: nitrifying organisms that oxidize organic nitrogen to plant-available nitrates and nitrogen-gathering bacteria that form legume root nodules. It outlines soil chemistry requirements for nitrification, emphasizing the need for available alkaline elements such as calcium, oxygen, and the effect of acidity, lime, and phosphorus. Experimental results and practical recommendations address species-specific inoculation of legumes, noting cowpeas often carry suitable bacteria while soybeans and red clover generally require inoculation, and that infected sweet clover soil can effectively inoculate alfalfa. Methods to improve legume establishment and restore soil nitrogen are discussed.