Peat oxidation in a changing world

Mariet Hefting, Karlijn Brouns, Joost Keuskamp, Jos Verhoeven

Chair(s): Esther Stouthamer

Tuesday 30 june 2015

14:25 - 14:45h at Asia (level 0)

Themes: (T) Special session, (ST) Deltas from multiple pressures to integrated solutions

Parallel session: 6C. Special session: Deltas - from multiple pressures to integrated solutions

Peat lands consist of partially decomposed organic material that accumulates due to an imbalance between primary production and decomposition rates, usually because of restrictions on oxygen availability, temperature and nutrients. In the western and Northern Peat district in the Netherlands substantial areas of peat lands are reclaimed for agricultural use. However, as soon as agricultural peat lands are drained and fertilized, decomposition of organic matter is stimulated resulting in irreversible subsidence rates of 1 to 2 cm per year. The present study assessed the risk of microbial-driven subsidence in drained peat soils of contrasting origin (fen and bog peat) and land uses (dairy meadow and nature reserve). In these peat types, we studied the microbial activity and respiration dynamics under drought events and salinization and assessed the total and active microbial biomass and potential enzyme activities. Decomposition rates were significantly higher under aerobic conditions and the decomposition rates remained high in anaerobic conditions after a brief period of oxygenation. Increased decomposition rates were however highly dependent on peat type. Retarded aerobic decomposition was observed with salinization, whereas the anaerobic decomposition rates remained unchanged. The enzyme analyses revealed higher phenol oxidase and phenol peroxidase activities in eutrophic peat samples indicating adaptations of the microbial community to fertilization events. Mechanistic knowledge on the susceptibility of different peat types for microbial peat oxidation can be used to design specific strategies to combat future peat subsidence.