The Effects of Existing Vegetation and Fertilization on the Improvement of Natural Grassland by Oversowing

지표추파법에 의한 목야지 개량시 선점식생과 시비의 영향

A review of factors influencing grass and clover establishment, survival and yield at oversowing was made from the experimental results of home and abroad. The following conclusions are considered: (1) The existing vegetation present at oversowing appeared to be the most critical factor reducing establishment and survival of grass. Therefore, it is essential to check competition from the native vegetation before oversowing. (2) Although lime had comparatively little effect on yield of grassland, the general effect of lime should be more emphasized under our acid soil conditions to promote the availability of all the essential elements and the growth of microorganisms, and to reduce the toxic effects of nutrients. One to two tons of lime per ha at oversowing would be useful. (3) Phosphorus is one of the nutrients most generally deficient in grassland soils of Korea, consequently, this nutrients applied at oversowing is very effective. Application as much as 200kg of phosphorus per ha would be essential. (4) The effect of nitrogen on the establishment and survival of grass depends on the amount and density of the herbage present. The use of nitrogen in dense herbage adversely affected grass establishment and survival, possible because the fertilizer stimulated the growth of the eisting herbage. Around 40kg of nitrogen per ha may be enough at oversowing (5) Potassium is not as universally deficient in soils of native grassland as phosphorus. Therefore, it cannot be over-emphasized at oversowing. Studies determinig the optimum amount of potassium at of oersowing are needed.