Study on the Weeds Emergence at the Rice Field Applied Successively with Green Manure

Study on weed emergence in the 3 paddy fields, successively applied with green manure for 3, 4 and 7 years, respectively was conducted to investigate the changes in weed emergence. According to the results of this study, 3-year-application of green manure induceed changes in weed emergence, 4-year-application of it caused them in weed community and 7-year-application of it made it necessary to change the conventional weed control method. The emergence of barnyard grass, Echinochloa crus-galli, and common false pimpernel, Lindernia procumbens was increased, weed community was changed. The gross emergence of weeds was increased through applying green manure successively. The emergence of biennial water foxtail, Alopecurus aequalis var. amurensis, was decreased while the number of species of summer annual was increased. In the paddy field applied successively with green manure for 7 years, the leaf number of barnyard grass ranged from 3.6 to 4.2 at about 13 days after transplanting and the population of it, surviving soil-applied herbicide treatment, ranged from 4.3 plants $m^{-2}$ to 6.1 plants $m^{-2}$, and these were estimated to be troublesome enough to cause yield loss.

녹비 연용 벼 재배 논에서 잡초발생 조사

녹비연용 논 포장에서 벼 재배 시 잡초발생 변화를 조사하기 위해 3년, 4년 7년간 녹비를 연용한 국립식량과학원 논 포장에서 각각 잡초발생을 조사하였다. 3년간 녹비를 연용하면 잡초발생에 변화가 시작되고 4년간 녹비를 연용하면 잡초군락에 변화가 오고 7년간 연용하면 잡초방제법을 달리하여야 할 정도로 잡초발생에 변화가 온다. 녹비를 연용하면 피, 밭뚝외풀의 발생이 많아지고 잡초군락이 변화하며 총발생수가 많아진다. 잡초종류로는 월년생 뚝새풀 발생이 줄어드는 대신 하잡초의 초종수가 증가한다. 녹비를 7년간 연용한 논포장에서의 피는 이앙 후 13일경 엽수가 3.6~4.2개였으며, 토양처리 제초제를 처리하여도 방제되지 않은 피 개체수가 4.3~6.1개 $m^{-2}$로 벼 수량감소에 영향을 줄 수 있는 정도였다.