Growth, yield and mineral content of Miscanthus x giganteus grown as a biofuel for 14 successive harvests

Miscanthus x giganteus, a perennial rhizomatous grass commercially used as a biofuel crop was grown in a field experiment on a silty clay loam soil for 14 years. There were 3 rates of fertilizer nitrogen (N), none (control), 60 kg N ha(-1) yr(-1) and 120 kgN ha(-1) yr(-1) as cumulative applications. The crop was harvested in winter and dry matter yield measured. N did not influence yield. Yield, which increased for the first 6 years, decreased in years 7 and 8, but then increased again and was highest in the 10th year averaging 17.7 tha(-1) across all treatments. Differences in total production over the 14 years were only 5% between the highest and lowest yielding treatments and averaged 178.9 tha(-1) equivalent to 12.8 tha(-1) yr(-1). In the first 10 harvests, 92% of dry matter was stem. Although the study showed N fertilizer was not required, it is considered that an application of 7 kg P ha(-1) yr(-1) and 100 kg K ha(-1) yr(-1) would avoid soil reserve depletion. Pesticides were not required every year and the crop can be considered as low input with a high level of sustainability for at least 14 years. (C) 2008 Elsevier B.V. All rights reserved.