Effects of Nitrogen Application Levels and Ryegrasses as a Member of Mixture on Improvement of Oversown Pasture I. Establishment, botanical composition and productivity

질소시비수준 및 Ryegrass류혼파가 겉뿌림 초지개량에 미치는 효과 I. 정착률, 식생구성률 및 건물수량에 관한 효과

This experiment was carried out to determine the effect of improvement of oversown pastures, treated with four nitrogen(N) application levels(0, 100, 200, 300 kg/ha) and three species mixtures (A: orchardgrass+ladino clover; B: orchardgrass+ladino clover+perennial ryegrass; C: orchardgrass+ladino clover+perennial ryegrass+Italian ryegrass). The establishment of perennial ryegrass, Italian ryegrass, and ladino clover were increased with increased N applications, but the ryegrass mixed with orchardgrass and ladino clover decreased the establishment of ladino clover. With the increase of N application levels, orchardgrass, perennial ryegrass and Italian ryegrass in comparison on botanical composition were getting better, while the native plants established already were decreased. The botanical composition of newly sown pasture plants was increased as cutting times progressed. The dry matter(DM) yield of pasture species increased significantly with N application up to 300 kg/ha. There was no significance among mixture treatments, although the DM yield of basic treatment(orchardgrass+ladino clover) was higher than other treatments. However, when compared DM yields on each cutting times, newly oversown pastures in A treatment was shown to be significantly higher only on 2nd cutting time than other treatments(P<0.05). The DM yield of native plants survived in basic species mixture was significantly less than those of other mixtures(P<0.05). Results of this study indicate that for improving oversown pastures, at least 300 kg/ha N application should be applied, and basic mixture (orchardgrass+ladino clover) has more advantage than treatments mixed with ryegrass.

겉뿌림초지 개량효과를 높이기 위해 질소시비수준과 보조초종 라이그라스 조합의 필요성 여부를 구명키 위해 4처리 질소시비수준(0, 100, 200, 300kg/ha)과 3처리 혼파조합(A; orchardgrass+ladino clover, B; orchardgrass+ladino clover+perennial ryegrass, C; orchardgrass+ladino clover+perennial grass+Italian ryegrass)으로 본 시험이 수행되었다. Perennial ryegrass, Italian ryegrass 및 dine clover의 정착률은 질소증시로 증가되었고 ladino clover 의 정착률은 ryegrass조합으로 감소되는 경향이었다. 화본과 목초의 식생구성율을 질소증시에 따라 증가하지만 두과목초와 기존야초류는 감소하였으며 예취회수가 진행됨에 따라 목초율이 증가되고 있다. 목초의 건물수량은 질소시비량에 비례하여 유의적으로 증가하였으며(P<0.05), orchardgrass十ladino clover조합구가 다른 조합구에 비해 수량이 높았으나 유의차는 없었다(P<0.05). 그러나 예취시기별로 볼때 orchardgrass+ladino clover 혼파구의 목초수량이 2회 예취시에만 타 혼파조합구 보다 유의적 증수가 이뤄졌고(P<0.05), orchardgrass十ladino clover조합구에서 기존야초류의 건물수량이 1회와 2회 예취시에만 타 조합구에 비해 유의적 감소를 보였다(P<0. 05). 본 시험의 결론으로는 겉뿌림으로 초지를 개량하기위해서 질소를 적어도 300kg/ha 시용해야 하며 orchardgrass와 ladino clover조합이 이 기본조합에 ryegrass류를 혼파하는 것보다 유리하다고 사료된다.