Subsidence and Erosion of a Histosol

Abstract

The usual model of Histosol subsidence emphasizes the influence of the water table level on peat shrinkage and biochemical oxidation. It predicts a decrease in subsidence rate with time. However, erosion may increase the rate of subsidence significantly. The long‐term subsidence rate of the Histosol under study, where vegetable crops were grown yearly, was estimated at 2.06 ± 0.35 cm/year between 1936 and 1974. In 1974, part of the fields was sown in oats, as a conservation measure, whereas a windbreak was removed in 1976 and unusual meteorological events were recorded in 1974 and 1975. Erosion patterns were detected on the portion of the experimental site where there was no conservation measure. Between 1974 and 1978, the subsidence rate was reduced to 0.99 ± 1.59 cm/year in fields protected against erosion but increased to 4.53 ± 2.29 cm/year in unprotected fields. The decrease in subsidence rate predicted by the model was observed only in fields protected by conservation measures. Consequently, subsidence and erosion should be estimated separately for modelling adequately the subsidence process as a whole.