There is increasing interest in cultivation of Miscanthus as a source of renewable energy in Europe, but there is little information on its nutrient requirements. Our aim was to determine the nutrient requirement of an established Miscanthus crop through a detailed study of nutrient uptake and nutrient remobilization between plant parts during growth and senescence. Therefore dry matter of rhizomes and shoots as well as N, P, K and Mg concentration under three N fertilizer rates (0, 90, and 180 kg N ha(-1)) were measured in field trials in 1992/93 and at one rate of 100 kg N h(-1) in 1994/95. Maximum aboveground biomass in an established Miscanthus crop ranged between 25-30 t dry matter ha(-1) in the September of both trial years. Due to senescence and leaf fall there was a 30% loss in dry matter between September and harvest in March. N fertilization had no effect on crop yield at harvest. Concentrations of N, P, K and Mg in shoots were at a maximum at the beginning of the growing period in May and decreased thereafter while concentrations in rhizomes stayed fairly constant throughout the year and were not affected by N fertilization, Nutrient mobilization from rhizomes to shoots - defined as the maximum change in nutrient content in rhizomes from the beginning of the growth period measured in 1992/93 was 55 kg N ha(-1), 8 kg P ha(-1), 39 kg K ha(-1) and 11 kg Mg ha(-1). This is equivalent to 21% N, 36% P, 14% K and 27% Mg of the maximum nutrient content of the shoots. Nutrient remobilization from shoots to rhizomes - defined as the increase in nutrient content of rhizomes between September and March - measured in 1994/95 was 101 kg N ha(-1), 9 kg P ha(-1), 81 kg K ha(-1) and 8 kg Mg ha(-1) equivalent to 46% N, 50% P, 30% K and 27% Mg of nutrient content of shoots in September. Results showed that nutrient remobilization within the plant needs to be considered when calculating nutrient balances and fertilizer recommendations.
