초지의 관개효과에 관한 연구 6 . 관개와 질소시비수준이 계절별 , 생육시기별 목초의 건물생산과 질산태질소 함량 및 관개효율에 미치는 영향 = Studies on the Pasture Irrigation 6 . Effect of irrigation and nitrogen fertilization on grass production , nitrate nitrogen concentration , and irrigation efficiency by growing season and growth stage

다국어 초록 (Multilingual Abstract)

For basic understanding on pasture irrigation, an experiment was conducted to determine the effects of irrigation and nitrogen(N) fertilization (200 and 400kg ha^-1 y^-1) on the seasonal grass dry matter (DM) production, nitrate nitrogen(N0₃-N) concentration, and irrigation efficiency in pasture mixtures dominated by orchardgrass, 1988. It was investigated on 7, 14, 21, and 28 days after harvesting in spring(May), summer(July) and autumn (Sept.), respectively. During experimental period, rainfall was controlled artificially, and irrigation point was ca. 1.0 bar. Higher DM production was observed in spring (1967 kg ha^-1), irrigated plot, and higher N fertilization plot, respectively. Also the DM production was increased with advancing maturity of plants. Irrigation efficiency in spring (20kg ha^-1 mm^-1) was significantly higher than summer(9kg), especially in high N fertilization plot. On the other hand, the efficiency in summer season was high in low N plot. NO₃-N concentration in spring was very low (less than 0.1%), however, the N0₃-N was high (more than 0.2%) in summer and autumn. Also the NO₃-N was increased remarkably with increasing of N level, and decreased slightly with advancing of plant growth. Based on the results, it is suggested that higher N in spring, and lower N fertilization in summer and autumn are more effective for grass production and irrigation efficiency. Also enough regrowth period is desirable to decline N0₃-N in summer and autumn.