This experiment was carried out in order to compare the productivity among seasons and the effect of nitrogen on the dry matter production, Cutting frequency was f our times in a year, 1st (June 1 , early spring) , 2nd (July 10, spring), 3rd (Aug. 18, summer) and 4th(Oct. 2, autumn), respectively, Nitrogen fertilizer was applied at 4 levels, 0 ㎏(N_o), 16㎏(N₁), 32㎏ (N₂) and 48 ㎏/l0a (N₃), split into 4 applications by cutting frequency. The results are summarized as follows; 1. Dry matter yield was highest in the early spring, followed in spring, autumn and summer. (Table 1 ) 2. Annual dry matter yield increased by 9.25㎏ DM/㎏ N, but this value was lower than that of other grasses. Dry matter yield increase per N applied was the highest in early spring and the lowest in the autumn. (Fig. 1 ) 3. Dry matter yield indicated highly significant correlation with plant height, leaf area index(LAI) and the efficiency of dry matter production(DW /LAI). (Table 2) 4. LAI indicated highly positive correlation with plant height and negative correlation with the light extinction coefficient (K). (Table 2 ) 5. In some yield component s, the seasonal difference was recognized in LAI, DW/LAI and specific leaf weight (SLW), but not in K, Therefore, it may concluded that the dry matter yield was the highest in the early spring because the leaf area was largest and the efficiency of dry matter production was the highest. (Table 1, Fig. 2, 3 ) 6. LAI increased almost linearly up to N, level, and K was smaller at high N level than at low N level, But DW/LAI wasn`t influenced by N fertilization, And it was assumed that the dry matter production increased at high N level by these reasons. (Table 1, Fig. 2, 3)