Near infrared spectroscopy for characterisation of plant litter quality

Petra Vávøová, Bo Stenberg, Marjut Karsisto, Veikko Kitunen, Tarja Tapanila and Raija Laiho

After Wise Use – The Future of Peatlands, Proceedings of the 13th International Peat Congress: Chemical, Physical and Biological Characteristics of Peat

decomposition, litter-quality, nirs, peatlands

Vávøová et al. 2008: Near infrared spectroscopy for characterisation of plant litter quality


We investigated the ability of Near Infrared Reflectance Spectroscopy (NIRS) for the rapid determination of several chemical properties of plant litters. The chemical properties included fractions that potentially affect de- composition dynamics in peatlands: total carbon, total nitrogen, extractable (soluble) substances, holocellulose (sum of cellulose and hemicelluloses), sulphuric acid insoluble lignin (Klason lignin), CuO oxidation products of lignin: vanillin (V1), vanillic acid (V2), acetovanillone (V3), 4-hydroxybenzaldehyde (P1), 4hydroxyace- tophenone (P2), 4-hydroxybenzoic acid (P3) and ferulic acid (C2), as well as C:N and N:lignin ratio. Samples included litters of 9 plant species, representing 5 groups of plant litter: graminoid, deciduous foliage, conifer foliage, wood and moss. Relationships were found between the chemical properties and NIR spectra using partial least squares (PLS) regression. The predictive power of NIR spectroscopy varied for the different litter properties as well as the datasets. Using both the combined and the branch data sets, very good NIR calibra- tions were obtained for total carbon and nitrogen, ash content, nonpolar (dichlormethane) extractives, ethanol extractives and total extractives (sum of all soluble substances), holocellulose, C:N, and N:lignin ratio, with r2 that from 0.80 to 0.99. Using only the combined dataset very good calibrations were also obtained for acetone extractives, water extractives, lignin, P2, P3, C2, V1, V2 and V3, with r2 from 0.81 to 0.97. NIRS proved to be an accurate and fast method for the determination of plant litter quality in peatlands.