Abstract
This study was carried out to elucidate the proper split application method of nitrogen fertilizer for early dry seeding culture of rice in Honam plain area from 1997 to 1998 in Korea. Dongjinbyeo was selected as rice variety for this experiment. The rate of $160kg\;ha^{-1}$ of nitrogen was split as 40-30-30% of total nitrogen at three different application time combination ; T1) basal-5th leaf-panicle formation(PF) stage, T2) 3rd leaf-5th leaf-PF, and T3) 3rd leaf-7th leaf-PF. The content of $NH_4-N$ in soil at 5th leaf stage was higher in top dressing plots(T2, T3) compared with basal application(T1), at 7th leaf stage it was most in top dressed at 3rd leaf and 5th leaf stage, but there was no difference at heading stage. Amount of nitrogen uptake and nitrogen use efficiency was higher in the order of T3, T2 and T1(basal application). Spikelet number per unit area was more in the order of T3, T2 and T1, but rate of ripened grain and 1,000 grain weight were not significantly different among three nitrogen split application methods. Milled rice yields were higher in top dressed plots compared with basal nitrogen application plots. From the results of this experiment, reasonable nitrogen split application method for early dry seeding culture of rice could be 40-30-30% of total nitrogen at 3rd leaf, 7th leaf and panicle formation stage.
호남평야지에서 건답직파 조기파종재배에 알맞은 질소 분시방법을 구명하고자 '97~'98년에 호남농업시험장 수도포장인 전북통(미사질양토)에서 동진벼를 공시하여 시험한 결과를 요약하면 다음과 같다. 질소분시방법간 토양 중 암모니아태 질소 함량을 보면 5엽기에는 관행(T1, 기비시용)보다 추비중점시비(T2, T3)에서 많았고 그 이후는 점차 줄어들어 출수기에는 질소 분시방법간에 차이가 적었다. 엽면적 및 지상부 건물중은 생육초기에는 차이가 없었으나 최고분얼기 이후에는 3엽기:7엽기:수비=40:30:30%로 분시 한 처리에서 가장 많았다. 질소 흡수량과 질소 이용율은 관행 분시방법보다 추비중점시비에서 높았는데, 2차 추비시기 간에는 5엽기보다 7엽기에 시비한 처리에서 높았다. 수량구성요소 중 등숙비율과 현미천립중은 질소 분시방법간에 별 차이가 없었으나 $m^2$당 수수는 T3 > T2 > T1 순으로 많아, 쌀 수량은 관행에 비하여 3엽기:5엽기:수비=40:30:30%로 분시한 처리에서 3%, 3엽기:7엽기:수비=40:30:30%로 분시한 처리에서 6% 증수되었다. 따라서 벼 건답직파 조기파종재배에 알맞은 질소분시방법은 3엽기:7엽기:수비로 각각 40:30:30%로 분시하는 것이 적당한 것으로 판단되었다.
