Activity and mobility of metsulfuron-methyl in soils
Ismail B. Sahid and Linna Quirinus, Department of Botany, Faculty of Life Sciences, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Malaysia.
The influence of different levels of organic matter on the biological activity and mobility of metsulfuron-methyl was investigated. The effect of rainfall on the mobility of metsulfuron-methyl was also determined under greenhouse as well as under natural conditions. The presence of the herbicide was assessed by bioassay. Biological activity was inversely related to the organic matter content of the soil. Dry weight of Chinese cabbage (Brassica chinensis L.) in sandy soil decreased by 56% of the control at 1.0 g ha-1 of metsulfuron-methyl. However, a similar concentration in soil containing 100% organic matter did not affect fresh weight. Movement of the herbicide down the soil profile, assessed by bioassay, was inversely related to the organic matter content of the soil. In soil containing 100% organic matter, phytotoxic levels of metsulfuron-methyl were restricted to the surface layers when the soil columns were applied with a total 88 mm of simulated rain over 21 days of experimental duration. After four weeks of daily application of simulated rain, metsulfuron-methyl had leached to a depth of 20-25 cm in Sungai Buluh series. The compound was duly detected at a depth of 15-20 cm when the columns containing Sungai Buluh series were exposed to 110 mm natural rainfall for a period of one month.
Plant Protection Quarterly (1997) 12 (3) 125-127.