The effect of cattle grazing in a wasted mulberry (Morus sp.) plantation on productivity of mulberry leaves and nutritional condition of cattle was investigated. Four grazing paddocks and one enclosure area were set in a wasted mulberry plantation in Minamisanriku town, Miyagi prefecture. Japanese Black pregnant cows grazed one to three times per paddock depending on the amount of mulberry leaves, from late spring to mid-autumn for three years. Transfer of animals from each paddock was done when almost all available mulberry leaves (0-2m from the ground) were consumed. Mulberry leaf mass greatly decreased over the three years. Total digestible nutrients, crude protein and mineral concentrations of mulberry leaves were high across seasons, but tended to be higher in June than in August. Body weight of the cows temporarily decreased after beginning of grazing season, thereafter recovered to or increased over initial weight. However, great increase of blood urea nitrogen concentration was observed on the first several days after beginning of grazing in each paddock, probably due to increase of intake of mulberry leaves. Blood non-esterified fatty acids concentration also greatly increased at the end of each grazing period when available mulberry leaf mass was depleted, suggesting energy shortage of the cows.

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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.

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