Effects of a 20-year old Miscanthus × giganteus stand and its removal on soil characteristics and greenhouse gas emissions

Miscanthus is a perennial rhizomatous C4 grass with high yield potentials and low nutrient needs, thus a promising candidate for the production of cellulosic biomass. While optimal management options and yields attainable on a commercial scale are still debated, no study has yet addressed its removal and potential effects on following crops. Here, we present results from a trial involving a 20-year old Miscanthus stand on i) soil C, N, P and K stocks, compared with an adjacent field cultivated with a rotation of annual arable food crops, ii) the greenhouse gases (GHG) emissions following the removal of Miscanthus and iii) the immediate short-term effects on the following land use (re-cultivation to wheat or set-aside). ed to the adjacent field under annual crops, the Miscanthus plot had a larger soil organic C stock (by 13 t C ha−1) but a similar N stock, and lower P and K stocks (with differences of 100 kg P ha−1 and 1170 kg K ha−1, respectively). These losses imply that some degree of fertilization may be necessary as compensation. The effects of Miscanthus removal for the following wheat were significant on crop N content but negligible on grain yield. CO2 ha−1 of CO2 were released after the Miscanthus removal and the N2O emissions increased from 150 g N2O-N ha−1 to 493 g N2O-N ha−1 during the following year. These results highlight the importance of investigation of the end-of-life stage of perennial crops for an accurate assessment of their environmental impacts.