The link between peat hydrology and decomposition: Beyond von Post

SummaryHydrology is central to the formation, growth and utilisation of peat soils. However, peat presents a difficult medium in which to measure hydrologic properties, due to its soft structure and high water content. The von Post scale is a widely used measure of the extent of decomposition of peat, which can be applied in the field or the laboratory without specialised equipment. von Post decomposition has been shown to correlate with hydraulic conductivity. However, it is a categorical and subjective measure of decomposition. Technological advances now enable peat chemistry to be described quantitatively and objectively. 13C nuclear magnetic resonance (NMR) is now routinely used to describe peat chemistry, and the capability of this technique has been extended by the development of the molecular mixing model (MMM). The MMM predicts the molecular composition of organic material from the spectral information provided by 13C NMR. We found significant relationships between the hydrologic properties hydraulic conductivity and water yield and peat chemistry as described by 13C NMR and the MMM. These relationships have potential application in all fields where the hydrologic properties of peat soils are of interest (i.e. peat mining, peatland restoration, catchment management) and also in modelling of peatland development and responses to climate change.

► New easy to measure proxies for peat hydrology.
► 13C NMR predicted hydraulic conductivity and water yield with 89% and 94% accuracy.
► The molecular mixing model further improved the fit to measured data.