Dearbháil Ní Chualain & Munoo Prasad
Proceedings of the 14th International Peat Congress
colour, lignin, stability, von-post
Ní Chualain & Prasad 2012: Colour of Peats as an Indicator of Chemical and Physical Properties
Theme II. Peat for horticulture, energy and other uses
The degree of decomposition of peats is measured by the von Post scale, given by H values, ranging from 1 being totally un-decomposed, to 10, completely decomposed. It is determined by squeezing peat and analysing the escaped water for amongst other things, colour. This is an approximate determination, and it is proposed that the colour of peats be measured by a more accurate method using a colour reader. Minimal sample preparation is needed; peats are dried and ground and colour determined by a proprietary colour reader. The lignin content of the same peat samples was determined, and relationships between colour and lignin content examined. A number of peat samples from H5-H6 as well as H4 sources were analysed, and compared for differences in lignin and colour. The sensitivity of the colour determination was examined through the analysis of peats from one bog, and variation within a bog in relation to colour was also investigated. A strong correlation between peat colour and lignin content was evident. The determination of colour for classification proved to be a more sensitive method than the von Post method and there proved to be significant variation within bogs in relation to colour and therefore lignin. Colour determination may be a fast and cheaper alternative to lignin determination for the evaluation of peat stability.