Abstract
A field experiment was carried out in Nasushiobara City (Japan) for 4 years to clarify the optimal fertilization and planting density for Erianthus arundinaceus, perennial biofuel crop. We established four treatments that combined two planting densities (0.25 and 0.5hills/m2) with two fertilizer application levels (N : P2O5 : K2O＝90 : 90 : 90kg/ha/yr ［standard rate］ and twice the standard rate), and tested their effects on three Erianthus lines. Dry matter yields in Year 1 were poor in all lines and all treatments, but thereafter, all lines had good yield (>15Mg/ha/yr). However, genotypic variation in yield increased over time, with the most productive line yielding 39Mg/ha/yr in Year 4. Planting density did not affect the dry weight per hill in Year 1 in either fertilization treatment, but in subsequent years, larger dry weights were obtained at lower density, resulting in no significant difference in yield per unit area in Years 3 and 4. Although fertilization increased the nitrogen and potassium concentrations in harvested parts in Year 2 and later at both planting densities, fertilization rate had no significant effect on dry matter yield.
