Orchardgrass (Dactylis glomerata C.), tall fescue (Festuca arundinacea L.), perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (poa pratensis L.), and ladino clover ( Trifolium repens L.) were sown on a native grassl and dominated by Imperata cylindrica by the oversown method. When the different levels of nitrogen, phosphorus and potassium were applied, the following results were obtained : 1. The dry matter yields of whole pasture were increased by increment of nitrogen fertilizer. Of the newly sown pasture plants, the botanical composition of grasses was increased, but that of clover was decreased. 2. The botanical composition, however, was not influenced by the phosphorus and potassium level. The rate of the newly sown pasture plants in the second year was 20-63% and the ratio of the grasses and legume was 60 : 40. 3. There was statistically marked significance for the dry matter yield by the increment of nitrogen levels; 122.4㎏ (0 ㎏ N), 182. 6㎏ (O ㎏ N) and 230. 9㎏ (20㎏) per 10 a were shown in the first year while 111. 3㎏ (0 ㎏ N), 135. 2㎏ (10 ㎏ N) and 182. 8㎏ (20 ㎏ N) per l0a in the second year. 4. There was no difference among dry matter yields obtained from various phosphorus and potassium levels in the first year, whereas some increased yield was observed in the second year.