Abstract
Rainfall and suspended sediment concentration were observed at the sloping arable land of Tokachi district in Hokkaido. Erodibility factor of the USLE obtained by 10 minutes interval data of rainfall were relatively large in autumn. But suspended sediment concentration of runoff water from the arable land was closely correlated to the tillage rather than the rainfall conditions. Suspended sediment concentration rises extremely high after tillage even the rainfall erodibility is relatively low. Tillage must be concerned as one of the most significant issue of the soil conservation at the sloping arable land.
