SSS26

Organic soils: impact of land-use change on peatlands degradation
Convener: Professor Szajdak  | Co-Convener: T. Miano 
Oral Programme
 / Tue, 21 Apr, 08:30–12:00  / Room 2
Poster Programme
 / Attendance Tue, 21 Apr, 17:30–19:00  / Hall A
Peat represents a highly organic material, which in nature contains typically 80-90% water. A principal feature of humic materials of peat is their ability to absorb and retain large quantities of water. Peat comprises relatively unstable substances, whose reactivity contributes to its usefulness. The evolution of hydrogenic peat soils is closely related to the genesis of peat and to the changes in water relations. Thus the hydrology of peatlands and the flow of water through peat profiles have been the subject of practical scientific study. Peat is characterized by colloidal behavior and by irreversible loss of wettability, produced by drying. Long-term cultivation and agricultural use of peatlands and their exploitation has revealed a number of effects including lowering of the water table, increased aeration, changes in plant communities, and the release of carbon gases. These processes show the disturbance of the thermodynamic balance in peat. The decline in peat soil moisture content resulting from drainage leads to shrinkage of the peat. Volume change due to shrinkage is the result of several forces acting at micro-scale, and its mechanism and magnitude differ from those in mineral (clay) soils. Drainage in particular results in a sharp change of biotic and abiotic conversions and consequent degradation of peat organic matter. As results of drainage and due to a number of factors including oscillation of ground water level, changes of aerobic conditions, different plant communities, root exudates and products of degradation of plant remains, peat-muck soils may undergo a process of secondary transformation.
The aeration of the upper peat layers due to drainage and forestry or agricultural land-use starts the aerobic decomposition process, which causes carbon dioxide (CO2) emissions from the soil. The nitrogen cycling is also intensified in drained peats, the processes of nitrification, denitrification and dezamination promote the rate of the production of nitrous oxide (N2O) and N2 (dinitrogen). These three gases (CO2, N2O, N2) are strong greenhouse gases, which contribute to a large extent to the impact on the global climate changes in the world. Drainage and cultivation of peatlands significantly increase the emission of the greenhouse gases (CO2 and N2O) to the atmosphere. Moreover, peat soils play an important role in the global budget of these gases.