초록
사질답에서 벼 재배시 강우, 관개수, 규산질비료 시용에 의한 규소의 유입량과 침투수에 의한 규소 유출량 및 벼의 규소 흡수량을 평가하기 위하여 포장조건에서 시험을 수행한 결과 Si 농도는 강우 $0.02{\sim}0.19mg\;L^{-1}$, 관개수 $8.4{\sim}8.6mg\;L^{-1}$, 침투수 $5.9{\sim}17.9mg\;L^{-1}$이었고, 강우 및 관개수로 공급된 Si의 량은 약 $28{\sim}29kg\;ha^{-1}$, 침투수로 유출된 양은 $63kg\;ha^{-1}$였다. 벼에 의한 규산의 흡수는 무처리구 $335.6kg\;ha^{-1}$, 삼요소구 $406.6kg\;ha^{-1}$, 삼요소+규산처리구는 $471.1kg\;ha^{-1}$였다. 규소의 유입량과 유출량의 차이는 무처리 $357.4kg\;ha^{-1}$, 삼요소구 $412.1kg\;ha^{-1}$, 삼요소+규산처리구 $238.2kg\;ha^{-1}$였다. 시험후 토양의 유효규산 함량은 시험전 $71mg\;kg^{-1}$에 비해 무처리구와 삼요소구는 $49{\sim}58mg\;kg^{-1}$으로 감소하였고, 삼요소+규산 처리구는 $97mg\;kg^{-1}$으로 증가하였다. 논토양으로부터 흡수하는 규소의 흡수량은 벼의 생육에 따라 다라질 수 있으나, 약 $300{\sim}350kg\;ha^{-1}$ 정도로 추정되므로, 토양에 의한 규소의 공급은 벼의 생육 및 규소의 흡수에 매우 큰 영향을 주는 것으로 판단된다.
The silica uptake of rice plant(Oryza sativa L.) and a potential capacity of paddy soil as a source of silica supply for rice plant was studied under field experimental condition. Amount of Si from irrigation water, rainfall, which was a source of silica supply, and percolating rate of water through paddy soil profile as a source of silica loss from paddy soil, was investigated. Rice plants were grown in three different conditions, which included Control as non-fertilized, RDA's recommandation(NPK, Urea-Fused phophate-Potassium chloride=$110-45-57kg\;ha^{-1}$) and RDA's recommandation with supplement of silicate fertilizer(NPK+Si, Urea-Fused phosphate-Potassium chloride+Si=$110\;N-45\;P_2O_5-57\;K_2O+267.2\;Si\;kg\;ha^{-1}$). An amount of silica supply from rainfall was $0.5kg\;ha^{-1}$ and average amount of silica supplied from irrigation water $42.5kg\;ha^{-1}$, ranging from $28.1kg\;ha^{-1}$ to $58.8kg\;ha^{-1}$. Silica amount percolated through the soil profile have uniform trend comparatively showing $62.9kg\;ha^{-1}$ in Control, $64.8kg\;ha^{-1}$ in NPK treatment and $62.9kg\;ha^{-1}$ in NPK+Si treatment. Silica uptaked by Rice plant was $335.6kg\;ha^{-1}$ in Control, $406.6kg\;ha^{-1}$ in NPK+Si treatment and $471.1kg\;ha^{-1}$ in NPK+Si treatment. The difference between an amount of Si input(from rainfall, irrigation water and silicate fertilizer) and an amount of Si output(percolated Si in soil, uptaked Si by rice plant) was $357.4kg\;ha^{-1}$ in control, $412.1kg\;ha^{-1}$ in NPK treatment and $238.2kg\;ha^{-1}$ in NPK+Si treatment. Results of our study imply that paddy soil is a potential pool as a source of Si supply during growing periods of rice plant.
