Effect of Peat Properties On the Emissions of N2O and CO2.

Drainage of pristine peatlands is followed by increased emissions of nitrous oxide (N₂O) and carbon dioxide (CO₂) because of enhanced mineralization of the surface peat. The emissions are further enhanced due to liming, fertilisation and ploughing especially if the peat soil is used for arable agriculture. Cultivated organic soils are the largest single source of greenhouse gases in the agricultural sector in Finland. Only about 10% of the agricultural fields in Finland are peat soils but they cause 60% of the N₂O and CO₂ emissions caused by agriculture. Increasing the accuracy of the emission estimates requires information on the effect of different background factors on the emissions. We selected six peatland sites and studied the potential denitrification activity in six samples with a declining trend in the organic carbon content along a transect within each site. The field fluxes of N₂O and CO₂ were also monitored by chamber measurements for one year on the same transect on three of the sites. The rates of potential denitrification in the soil samples correlated strongly with the total C and N, DOC and pH of the soil. However, the fluxes of N₂O and CO₂ measured on the field for a year in the same sampling points correlated poorly with the measured background variables. The results indicate that these peat properties can determine the potential for N₂O production but additional background variables are needed to estimate the rates of actual field fluxes.