GREENHOUSE-GAS EMISSIONS FROM FARMED ORGANIC SOILS - A REVIEW

The large boreal peatland ecosystems sequester carbon and nitrogen fro m the atmosphere due to a low oxygen pressure in waterlogged peat. Con sequently they are sinks for CO2 and strong emitters of CH4. Drainage and cultivation of peatlands allows oxygen to enter the soil, which in itiates decomposition of the stored organic material, and in turn CO2 and N2O emissions increase while CH4 emissions decrease. Compared to u ndrained pear, draining of organic soils for agricultural purposes inc reases the emissions of greenhouse gases (CO2, CH4 and N2O) by roughly it CO2 equivalents/ha per year. Although farmed organic soils in most European countries represent a minor part of the total agricultural a rea, these soils contribute significantly to national greenhouse gas b udgets. Consequently, farmed organic soils are potential targets for p olicy makers in search of socially acceptable and economically cost-ef ficient measures to mitigate climate gas emissions from agriculture. D espite a scarcity of knowledge about greenhouse gas emissions from the se soils, this paper addresses the emissions and possible control of t he three greenhouse gases by different managements of organic soils. M ore precise information is needed regarding the present trace gas flux es from these soils, as well as predictions of future emissions under alternative management regimes, before any definite policies can be de vised.