물개구리밥(Azolla)이 논 잡초 발생, 질소공급 및 쌀 수량에 미치는 영향

Azolla is a genus of small aquatic ferns native to Asia, Africa, and America. Azolla is potentially significant as a nitrogen source in agriculture, particularly in conjunction with rice (Oryza sativa L.) cultivation. In addition, Azolla may either control weeds or act as a weed depending on management; therefore, we aimed to determine the effect of Azolla incorporation on weed (e.g., Monochoria vaginalis, Rotala indica, Aeschynomene indica, and Cyperus amuricus) control and its other benefits during rice cultivation. The effects of Azolla on weed emergence were evaluated based on plot area coverage by the Azolla mat, which appears as a green sheet over water, and the rate of weed emergence in paddy field. Weed occurrence was investigated 40 days after Azolla inoculation. Soil samples from the experimental plots were collected following harvest in 2014-2015, and analyzed. Moreover, rice growth, yield, and grain quality were measured. Azolla suppressed weed growth by 72%. Azolla mat incorporation in rice fields suppressed weed growth by over 60%. In addition, Azolla promoted nitrogen fixation. Compared with nitrogen management using chemical fertilizers, Azolla incorporation showed the potential for various positive effects, including the improvement of soil fertility by increasing total nitrogen, and organic matter content. Rice grown with Azolla maintained its yield without additional herbicide treatment. Moreover, the palatability of cooked rice was better when grown with Azolla. 논에서 개구리밥의 수면피복은 잡초의 초종, 본수, 생체중의 감소로 잡초발생억제 효과가 있었다. 개구리밥 초종 중 물개구리밥(Azolla)을 처리한 경우 잡초 억제 효과와 더불어 제초하지 않음에도 수량성의 감소는 없었으며 이듬해 토양에 유기물 함량을 높임으로서 토양비옥도를 증진시키는 효과를 보인 것으로 판단되었다. 물개구리밥은 증식이 빠르고 벼 재배시 수량 증가, 암모니아 휘산 방지, 잡초억제 등의 효과가 있으며, 오염된 수질에서는 중금속 제거 효과도 뛰어나 녹비용 사료용 가치 등 농업적가치가 뛰어난 자원이다. 한국에서는 월동을 시켜야 하는 등의 일부 단점이 있긴 하지만 그 활용가치가 뛰어나고 관리가 용이 하므로 친환경 농업의 발전을 위하여 추가적인 연구와 현장 적용 시험이 필요한 것으로 판단된다.