Impact of drainage and soil properties on carbon dioxide emissions from intact cores of cultivated peat soils

Drained peatlands contribute to anthropic emissions of carbon dioxide (CO2), so a better understanding of the underlying processes and identification of mitigation options for agricultural peatlands are urgently required. Peatland soil properties vary greatly and, in combination with drainage, can affect emissions of CO2 both directly and indirectly. Drainage reduces soil water content but increases CO2 production, so it is important to find the optimum drainage level that minimises CO2 emissions without affecting agricultural use. Intact soil cores from nine different sites (topsoil, plus subsoil at four sites) were collected and brought into a controlled laboratory environment. Repeated measurements of CO2 fluxes were performed at increasing soil water suctions corresponding to different drainage levels. Physical and chemical properties of the soils were determined and compared with the CO2 emissions. The soil cores displayed different CO2 emission patterns with increasing soil water suction head. In some cores, emissions increased rapidly to a high level, while in others they remained at lower levels. At a soil water suction head of only 0.5 m of water, the average soil CO2 emissions had already reached a maximum. The soil cores represented peat soils with a wide range of soil properties, e.g. bulk density from 0.17 to 0.47 g cm(-3) and total carbon from 26.3 to 43.5 %, but none of the properties measured was clearly correlated with CO2 emissions