Abstract
1. Degradation of Asulam in soil.
Asulam [methyl N- (4-aminophenylsulfonyl) carbamate] was rapidly decomposed by microorganisms in the soils in a relatively short period. The rapid disappearance of asulam occured in the volcanic ash soil with about 30% of initial concentrations during 14 days after the treatment.
2. Adsorption and desorption of Asulam.
Asulam was not adsorbed to any marked extent by the soils, but was adsorbed in large amount by the thatch and the turf leaves, and asulam was more easily released from the leaves than the thatch.
Asulam was adsorbed strongly by humic acid and lignin, which were major components of humus, and the desorption from these components was a little.
3. Downward movement of Asulam in soil.
Asulam easily moved downward in many different soils after artificial rainfall. But it hardly moved in organic soils, clayish soils and thatch accumulated soils, because it was strongly adsorbed in these soil surface.
Asulam moved downward deeply in wet soils, but moved to a lesser extent in dry soils.
