Different soil organic matter pools are known to have different C:N values, with pools that are more labile having a higher C:N value and containing more of the colour of the original plant material (this is in reference to the commonly-used terms for pools of organic matter in soil, e.g. Decomposable Plant Material (DPM), Resistant Plant Material (RPM) etc., and not to the C:N values for different raw materials, where lower C:N values imply more labile material).