Abstract
An experiment was carried out in order to find out the efficient techniques for improving the Miscanthus type natural grassland, one of the most common type in Japan. The aerial parts of the vegetation, mostly herbaceous plants, were chopped by rotary cutter, and afterward, two treatments were made as the methods of seedbed preparation i.e. conventional (ploughing and harrowing) and surface tillage. Seeds of orchardgrass and ladino clover were broadcasted in these treated fields. Yields of dry matter and crude protein, vegetation of particular native species and soil characteristics were compared in these two pastures from 1968 to 1972. The following results were obtained. 1. The pasture established by surface tillage was inferior to that of established by ploughing-harrowing in seedling establishment, owing to competition with native species which escaped from elimination. The native species persisted for relatively long duration after disturbunce were Miscanthus sinensis, Pteridium aquilinum, Cirsium Japonicum, Lactuca dentata, Hydrocotyle ramiflora etc. However, their species number decreased gradually year by year, and their weight and coverage decreased considerably after the first harvest of the first year, in particular in third and the fourth year. 2. Dry matter yield of the pasture established by surface tillage was inferior to that of established by ploughing-harrowing, buttheir difference was only a small amount. No significant difference was recognized between the two pastures in total dry matter yield including weeds and in crude protein yield excluding weeds. 3. Soil layer of 0〜5cm of the pasture established by surface tillage had higher nitrogen content and more developed crumbled structure than that of the pasture established by ploughing-harrowing. 4. It is suggested that the pasture establishment by surface tillage is advantageous in steep lands, because it keeps the fertile humus soil in surface layer and maintains native plants which protect soil erosion and young seedlings of sown species in adverse condition. Techniques of the surface tillage method comparing with the convensional method for improving the natural grasslands in hilly country were discussed from these results as well as from the other informations.
