Adsorption, desorption and mobility of metsulfuron-methyl in soils of the oil palm agroecosystem in Malaysia.

ABSTRACT

Laboratory experiments were conducted to evaluate adsorption, desorption and mobility of metsulfuron-methyl in soils of the oil palm agroecosystem consisting of the Bernam, Selangor, Rengam and Bongor soil series. The lowest adsorption of metsulfuron-methyl occurred in the Bongor soil (0.366 ml g-1), and the highest in the Bernam soil (2.837 ml g-1). The Kfads (Freundlich) values of metsulfuron-methyl were 0.366, 0.560, 1.570 and 2.837 ml g-1 in Bongor, Rengam, Selangor and Bernam soil, respectively. The highest K fdes value of metsulfuron-methyl, observed in the Bernam soil, was 2.563 indicating low desorption 0.280 (relatively strong retention). In contrast, the lowest Kfdes value of 0.564 was observed for the Bongor soil, which had the lowest organic matter (1.43%) and clay content (13.2%). Soil organic matter and clay content were the main factors affecting the adsorption of metsulfuron-methyl. The results of the soil column leaching studies suggested that metsulfuron-methyl has a moderate potential for mobility in the Bernam and Bongor soil series with 19.3% and 39%, respectively for rainfall at 200 mm. However, since metsulfuron-methyl is applied at a very low rate (the maximum field application rate used was 30 g ha-1) and is susceptible to biodegradation, the potential for ground water contamination is low.