This field experiment was undertaken to assess the effects of two rates of Ca(OH)₂ (0, 250 Kg/l0a) and five rates of N-P₂O_5-K₂O (0-0-0, 0-10-10, 6-15-15, 12-20-20, 24-25-20 Kg/l0a) on the grassland establishment, forage yield and quality, botanical composition, and persistence of different forage species in a mixed grass/clover sward established by oversowing method on new reclaimed steep mountain. This first part is concerned with the soil properties, vigour of early growth, total yield of mixed forages, and persistence of grassland. The results obtained were summarized as follows; 1. Organic matter in soil was increased by both landuse of grassland and liming. Liming raised pH, increased P and Ca, and reduced Mg in soil, whereas that had inconsistent effect on concentrations cf K and Na. Organic matter, pH, P, Ca, Mg, and K in soil after a 7-year experiment were lower at the optimum rate of NPK than at the low rate. 2. The vigour at early growth of forages was enhanced by liming. Averaging over all NPK treatments and 7 experimental years, the yearly mean yield of mixed forages was increased 21% by liming over no lime. The only one-time liming at establishment of oversown grassland had consistent effect on the yield during 7 experiment years without depression of lime effiency. By increasing the NPK rate, emergence and early growth of seeded forages were enhanced, and yields of mixed forages were greatly increased. 3. The oversown grassland in mountainous area was well established and had high yielding during 7 experiment years with both liming at establishment and 24-25-20 (N-P₂O_5-K₂O) Kg/l0a/year. Lowest application rates of N-P₂O_5-K₂O to perform the economical yielding of oversown grassland ($gt;650 Kg/l0a in DM, and$gt;50% in rate of seeded forages) were 12-20-20Kg/l0a rate at no lime and 6-15-15 at lining.