Soil organic matter as an indicator of mineralizable nitrogen

One important reason to pay attention to the soil organic matter content is its relationship to mineralizable soil nitrogen. Soil organic matter is about 5% nitrogen, by mass. This is a lot of nitrogen. Almost none of it is immediately plant available, but from 1 to 4% of the nitrogen in the soil organic matter is expected to become plant available through mineralization each year. Soils with organic matter content at levels high enough to release mineralized N at rates…