Establishment of stable production technology of region specialty and labor saving production technology with machine utilization. Fertility management technology for feed sorghum under region rotation. Estimation method of available nitrogen quantity by ultraviolet secondary differentiation spectrum of autoclave extract. (Iwate Prefect. Agricultural Res. Center S, Yamagata Prefect. Agricultural Exp. Stn. S, Fukushima Prefect. Agricultural Exp. Stn. S, Nagano Agricultural Res. Center S, Animal Husbandry Exp. Stn. of Nagano Prefect. S, and Nagano Chushin Agricultural Exp. Stn. S).