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본 연구는 탄질비가 다른 유기자재를 시용하였을 때 유기재배 벼의 수량과 질소이용율이 미치는 기상 조건의 영향을 조사하기 위해서 2010년에 수행되었다. 처리구는 질소함량 9 kg/10a 수준으로 화학비료, 가축분퇴비, 유박1배, 유박2배 (18 kg/10a), 헤어리베치, 베치+호밀을 포함하였다. 유박과 헤어리베치는 가장 낮은 탄질비를 나타내었고 가축분퇴비는 34 : 1의 가장 높은 탄질비를 보였다. 유기자재 처리구의 초기 생육은 양호하였으나 후기 태풍과 같은 기상조건에 따라 전반적으로 생육이 부진하고 수량이 감소하였다. 특히, 유박2배구는 초기생육이 월등하였으나 태풍의 영향으로 도복정도가 가장 심하게 나타났다. 탄질비가 높은 가축분퇴비구는 정상적인 질소공급이 이루어지지 않아 초기생육이 불량하였고 도복하지 않았더라도 낮은 수량을 보였다. 질소흡수량은 유박2배와 베치+호밀구에서 높았고 가축분퇴비에서 가장 낮았으며, 질소이용율도 비슷한 경향을 나타내었다.


BACKGROUND: This study was conducted to investigate growth and yield of organically grown rice under a typhoon during a fall. The treatments included NPK chemical fertilizer, compost, oilcake, oilcake 2X, hairyvetch, and vetch+rye. METHODS AND RESULTS: Nutrient applications were made at rates equivalent to approximately 0.9 kg of actual N per acre. Oilcake and hairyvetch treatments had the lowest C:N ratio, but compost had the highest C:N ratio of 34:1. Rice treated by organic nutrient sources had great growth and development at the beginning of the growing season but had depressed growth and yield at the harvest. Oilcake 2X- treated rice in early growing season, especially, showed better growth and development than rice treated by other nutrient sources but was severely lodged at the harvest season due to the typhoon. Compost treatment with high C:N ratio slowly released inorganic N and produced poor rice growth and yield; however, it recued rice lodging. N uptake was the greatest for the oilcake 2X and vetch+rye treatments but the lowest for the compost, which was the similar pattern to the N use efficiency; the greatest and lowest N use efficiency was observed for the oilcake 2X (55%) and compost (5%), respectively. CONCLUSION(s): Rice lodging should be prevented by reducing the excessive nitrogen supplement, resulting from the lower C:N ratio of the organic materials as well as prevented by the radical midsummer drainage. Vetch+rye treatment with 25:1 of C:N had optimum vegetative growth and reduced rice lodging, which increased N use efficiency and yield.