N2o Emission from Miscanthus, Rye and Oilseed Rape

greater than CO2 (Callander et al., 1995). Therefore, the objective of the present work was to quantify the annual emission of N2O from winter rye, M. ‘Giganteus’ and winter oilseed rape. Furthermore the N2O emission will be related to the estimated net CO2-displacement. The annual emissions of N2O were measured using a closed-chamber technique and were based on results obtained by Jørgensen et al. (1997) for winter rye and M. ‘Giganteus’ and the work carried out by Schmädeke et al. (1997) for winter oilseed rape. Total balances of energy and CO2 were estimated, and it was evaluated if N2O emission significantly reduces the net CO2displacement by energy crop production. In order to obtain comparable yield and balances of CO2 and N2O the agricultural management of winter oilseed rape was estimated to fit the site were Jørgensen et al. (1997) did the measurements. MATERIALS AND METHODS The soil was a coarse sandy loam in the northern part of Jutland, Denmark. The annual crop winter rye and the perennial M. ‘Giganteus’ (planted every 20 years) were applied NPK fertiliser at rates of 120, 28, 72 and 75, 22, 66 kg ha yr, respectively. The winter oilseed rape was estimate to need NPK at rates of 190, 28, 93 kg ha yr in order to yield 2.5 t oilseed (dry matter) ha at a coarse sandy loam.