2.7.1 The herbaceous biomass means

Herbaceous biomass includes grasses and legumes growing on grasslands. It includes under utilized wild species as well as cultivated forages with higher forage quality. Broadly speaking, food crops, such as rice, wheat, maize, and sugarcane represent sources of herbaceous biomass. By-products or residues, such as rice straw, are also considered herbaceous biomass; however, their use as herbaceous biomass is dependent on quality issues. Bamboos (Phyllastachys spp.) and sasas (Sasa spp.) are considered gramineous woody-type biomass species. Tropical grasses grow faster than trees and produce higher biomass in a shorter period. Grasses are classified into annual species, which include many cereals, and perennial species, which include many forage grasses. Legumes consist of shruby, viny, and wood-types, of which the two former types are considered herbaceous biomass. An important component of legumes is their ability to fix nitrogen in symbiosis with Rhizobium bacteria located in root nodules. It is economically necessary that a reduction in the use of chemical nitrogen fertilizers will be a component of biomass production. By rotating or sowing a mix-culture of forage and leguminous species in biofuel production pastures, the application of nitrogen fertilizer can be minimized. Published biomass production of leguminous species is 8-17 t/ha/year for alfalfa (Medicago sativa) in temperate Aichi Prefecture and 5-19 t/ha/year for tropical legumes in the subtropical Ishigaki Island. This production level is much lower than that for tropical grasses.