Effects of Nitrogen Levels on Green Yield and Nitrate Content of Italian Ryegrass (Lolium multiflorum Lam.)

질소시비수준(窒素施肥水準)이 이탈리안라이그라스의 생초생산량 및 질산태질소(窒酸態窒素) 함량(含量)에 미치는 영향

Study was conducted to investigate the optimum amount of nitrogen fertilizer for the green forage production of Italian ryegrass at the paddy field after rice harvesting in southern part of Korea in 1987 and 1988. Effects of three levels of nitrogen fertilizer application (15, 30 and 45 kg N/10a) on the green yield and nitrate content of green forage at three cutting times (April 30, May 20 and June 10) were examined in 1988. The results were as follows. 1. Yield of green forage at all cutting times increased in order of 45 > 30 > 15 kg N/10a, and it increased about 14 percent in the 45 kg N/10a and decreased about 35 percent in the 15 kg N/10a compared with the 30 kg N/10a. 2. Nitrate content in the green forage at all cutting times was high with increasing amount of nitrogen fertilizer and with decreasing ratio of K/(Ca+Mg) in green forage. The nitrate content at the second and the third cutting times in the 45 kg N/10a might be outrunned the tentative limitation for cattle. 3. Maximum amount of nitrogen fertilizer was 48 kg/10a for total green forage production, but it was 38 kg/10a near at cattle's harmful limit of nitrate content in green forage.

남부지방(南部地方)의 답리작(沓裏作) 이탈리안라이그라스 청예사료(靑刈飼料) 생산에 알맞는 질소시비량(窒素施肥量)을 결정하고자 질소(窒素)를 10a 당(當), 15, 30 및 45 kg을 처리(處理)하여 예취시기별(刈取時期別)로 생초(生草) 생산량과 식물체(植物體)의 질산태질소(窒酸態窒素) 함량(含量)에 대하여 다음과 같은 결과(結果)를 얻었다. 1. 생초수량(生草收量) 전예취시기(全刈取時期)에 질소(窒素) 45 > 30 > 15 kg/10a 순(順)으로서 질소(窒素) 30 kg/10a에 비(比)하여 질소(窒素) 45kg/10a에서는 14% 증수(增收)된 반면에 질소(窒素) 15 kg/10a에서는 35% 감수(減收)되었다. 2. 생초(生草)의 $NO_3-N$함량(含量)은 전예취시기(全刈取時期)에서 질소시비수준(窒素施肥水準)이 높아질 수록 많았고, 생육(生育)이 왕성(旺盛)한 2차(次)와 3차(次) 예취기(刈取期)에서 질소(窒素) 45 kg/10a구(區)의 $NO_3-N$함량(含量)은 가축(家畜)에 유해기준치(有害基準値)를 초과(超過)하였으며, 생초(生草)의 K/(Ca+Mg)비(比)와는 부(負)의 상관관계(相關關係)를 보였다. 3. 생초생산에 필요(必要)한 질소(窒素)의 최대시비량(最大施肥量)은 10a 당(當) 48 kg이었으며, 생초(生草)의 질산태질소(窒酸態窒素) 임계함량(臨界含量)에 이르는 질소시비량(窒素施肥量)은 38 kg/10a 이었다.