Quality Herbage Production of Dwarf Napiergrass with Italian Ryegrass Cropping under Digested Effluent Application in Southern Kyushu, Japan

Digested effluent produced by a biogas-plant contains essential plant nutrients to solve the treated and disposal problems of livestock manure. Dwarf variety of late-heading type (dwarf) napiergrass as a perennial summer crop and intercropping of over-sown Italian ryegrass as an annual winter crop were applied to 3 levels of digested effluent in southern Kyushu from 2007 to 2009. Digested effluent revealed so effective fertilizer as chemical one to increase dry matter yield, wintering ability and forage quality in crude protein concentration and in vitro dry matter digestibility (digestibility) with increasing application rate. Digestibility in leaf blade of napiergrass and that in whole Italian ryegrass were positively correlated with acid detergent lignin and neutral detergent fiber concentrations, respectively, which might be mediated with reducing tiller size with defoliation proceeded. The present cropping systems have a potential under sufficient application of the effluent to achieve sustainable quality herbage production in southern Kyushu, Japan.