Soil column중 제초제 bentazon의 용탈 행적

Leaching behavior of the herbicide bentazon in soil column

토양의 물리화학적 특성에 따른 제초제 bentazon의 용탈행적을 구명하기 위하여 3종의 토양을 soil column(내경 5 cm ${\times}$ 길이 34 cm)에 30cm 높이까지 충전하고 [$^{14}C$]bentazon을 처리한 후 벼(Oryza sativa L.)를 9주간 관행법에 따라 재배하였다. 용탈된 $^{14}C$ 방사능의 양은 벼를 재배하지 않은 경우는 토양의 물리화학적 특성에 관계없이 총처리 방사능의 약 $91{\sim}92%$이었으나 벼를 재배한 경우는 $21{\sim}50%$로서 $^{14}C$ 용탈량이 현저히 감소하였으며, pH가 높고 유기물 함량이 낮은 토양에서 더 많았다. $^{14}CO_{2}$의 발생량은 총처리방사능의 0.2% 미만으로 매우 적었고 유기물 함량이 높은 토양일수록 뿌리를 통한 지상부로의 이행율이 적었다. Soil column으로부터 모은 용탈수의 $^{14}C$ 방사능이 수상에 분포하는 양은 용탈기간과 벼의 생육에 따라 증가하였으나 토양의 이화학적 특성에 따른 영향은 나타나지 않았다. 토양결합잔류물의 양은 벼를 재배하고 유기물 함량이 높은 토양에서 증가하였다.

In order to elucidate the leaching behaviour of the herbicide bentazon in soil, soil columns(5cm ID ${\times}$ 34 cm L) were packed with three different soils up to 30 cm height, followed by the treatment of [$^{14}C$]bentazon, and rice plants(Oryza sativa L.) were grown for 9 weeks on these columns, with the columns without growing rice plants as the control for comparison. The amounts of $^{14}C$ activities percolated were about 92% of the originally applied $^{14}C$ irrespective of the physicochemical properties of the soils in the absence of rice plants, whereas $21{\sim}50%$ of the originally applied $^{14}C$ was percolated in the presence of rice plants, suggesting that the amounts of $^{14}C$ leached decreased remarkably in rice-cultivating soils. Bentazon leached faster in soil with higher pH and with lower organic matter content in the presence of growing rice plants. The amounts of $^{14}CO_{2}$ evolved from the soil columns were less than 0.2% of the originally applied $^{14}C$. Smaller amounts of $^{14}C$ were translocated into shoots via roots in soils with higher organic matter content. $^{14}C$ activities distributed into the aqueous phase of the leachate collected from the soil columns increased with leaching period and by rice cultivation, whereas the physico-chemical properties of soils did not exhibit any effect. The amounts of soil-bound residues increased remarkably by cultivating rice plants.