Sandhya Karki


Sandhya Karki


Title: Energy crop production on rewetted peatland at optimal level of water table for mitigation of greenhouse gas emissions


Drained peatland used for agricultural purpose are the major source of carbon dioxide (CO2) and nitrous oxide (N2O) emission. Rewetting of drained peatlands has been recommended to mitigate the greenhouse gas emissions and to restore the carbon sink function of peatlands. Cultivation of bioenergy crops in rewetted peatland (paludiculture) is a new and emerging land use practice which can additionally reduce the CO2 emissions by substituting fossil fuel. However, information on the overall greenhouse gas balance from paludiculture is lacking. Rewetting of peatlands can create favourable anoxic conditions for methane (CH4) emissions. Growing of wetland plants can further accelerate the greenhouse emissions by acting as conduit for CH4 and N2O transport. The objective of this study is to investigate the overall greenhouse gas balance from peatlands grown with reed canary grass (RCG) and rewetted to various extents (i.e., with different water table levels) at field and semifield conditions. For the semifield experiment40 soil mesocosms will be collected from a drained peatland used for agricultural purposes. 25 of these mesocosms will be sown with RCG and manipulated to five different levels of water table, i.e., 0, 10, 20, 30 and 40 cm below the soil surface. 15 of the mesocosms, will be kept bare and manipulated to three different levels of water table, i.e., 0, 10 and 20 below the soil surface. Gas fluxes of CO2, CH4 and N2O will be measured with static chamber techniques from these mesocosms. Net ecosystem exchange of carbon will also be quantified using the transparent chamber method.

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