Beyond the copious amount of nutrients in manure is one of the most underrated and misunderstood ingredient--the final link between the dead and the living world. Without this ingredient, life on the plant would not exist. This miracle is called bacteria. These micro-organisms break down all living matter and even rock to its basic elements which can then be consumed by plants. Rhizobium has an extremely rare ability to take nitrogen from the air and convert it to the only form usable by the plant. Rhizobium survives through a symbiotic relationship with plants such as legumes. The legumes supply them with sugars and organic acids and they in turn repay the favour with nitrogenous compounds. Manure introduces these bacterium and helps to maintain the culture. So when you smell your garden dirt that is the actinomyces.