Current status, uncertainty and future needs in soil organic carbon monitoring

Increasing human demands on soil-derived ecosystem services necessitate reliable data on global soil resources for sustainable development. However, information on the soil organic carbon (C) pool and its temporal and spatial dynamics is unbalanced. Even in well-studied regions with a pronounced interest in environmental issues information on soil C is rather inconsistent. Different approaches for soil sampling and chemical analyses make even regional comparisons highly uncertain. The procedures used so far have not yet allowed the estimation of a total soil C pool, mainly because the soil sampling depth is often rather shallow. Prime issues that need to be tackled are the agreement on protocols of soil surveying, and lab procedures. Long-term ecological research sites are an important opportunity for soil monitoring programs.