We studied a suitable maize double-cropping system for silage in northern Kyushu region, Japan. First, we evaluated the yield and suitable relative maturity (RM) of the first crop. Then, we evaluated the effect of seeding date on the yield of the second crop. As a result, two cultivation systems were considered. In the first system, RM 100 to 106 varieties were used to plant the first crop and were harvested in late July, and the second crop was seeded in early August. In the second system, RM 114 to 122 varieties were used to plant the first crop and were harvested in early August, and the second crop was seeded in mid-August. In the first system, annual TDN yield was 2201kg/10a and average dry matter ratio of the two crops was 27.9% and 24.8%. However, in the second system, annual TDN yield was 2096kg/10a and average dry matter ratio of the two crops was 28.7% and 18.2%. Therefore, for a suitable maize double-cropping system for silage in this region, RM for the first crop needs to be below 106, the crop should be harvested in late July, and the second crop should be seeded in early August.

We investigated the effects of nitrogen fertilizer application and harvesting stage on the chemical composition and fermentation quality of Tachisuzuka rice (Oryza sativa L.) whole-crop silage (RS). The straw yield and sugar content of Tachisuzuka are higher than those of other rice cultivars. Dry matter, starch, vitamin E and saccharide (mono- and disaccharide) contents of the rice plants increased after reaching the yellow-ripe stage. At the milk-ripe stage, the volatile basic nitrogen/total nitrogen and butyric acid contents of RS increased and the fermentation quality was low because the dry matter and saccharide contents of the rice plants were insufficient for lactic acid fermentation. However, at the yellow-ripe stage, the dry matter and saccharide contents of the rice plants were more than 30% and 8%, respectively, and fermentation quality of RS was high. At the full-ripe stage, lactic acid fermentation of RS was promoted only by the addition of lactic acid bacteria (Lactobacillus plantarum). Therefore, harvesting after the yellow-ripe stage and addition of lactic acid bacteria produced the highest quality RS. The fermentation quality of RS was not influenced by high nitrogen application because Tachsizuka had sufficient saccharide content for fermentation after the yellow-ripe stage.