The soil erodibility factor (K factor) of the Universal Soil Loss Equation (USLE) refers to the natural soil susceptibility to erosion and represents the quantity of lost soil per rain erosivity unit (R factor), a factor, which is of great importance in conservation management. Using data of soil loss, measured under natural rainfall conditions in collector ponds of superficial runoff, and of natural rainfall erosivity (EI30) in the period from 1989 to 1998 in Lages (SC), the soil erodibility factor for a Inceptisol was calculated with an average incline/gradient of 0.102 m m-1 by the quotient and simple linear regression between these variables. With this objective, erosivity values (EI30) of 437 rainfalls and soil loss were used, measured in 3.5 x 22.1 m plots, without vegetation or superficial covering. Soil preparation, carried out twice a year parallel to the incline/gradient, consisted in ploughing/tillage and two discings. Annual average erodibility values, estimated by the quotient and by simple linear regression between soil loss and erosivity, were 0.0115 and 0.0151 Mg ha h ha-1 MJ-1 mm-1, respectively. The estimated average seasonal erodibility values were 0.0105 and 0.0121 Mg ha h ha-1 MJ-1 mm-1 for spring/summer and 0.0132 and 0.0220 Mg ha h ha-1 MJ-1 mm-1 for fall/winter, according to the respective ways of measurement.
Factor K; water; soil loss; USLE