Soil Erodibility Factor (K)

 The soil erodibility factor (K) in the USLE relates to the rate at which different soils erode. Under the conditions of equal slope, rainfall, vegetative cover, and soil management practices, some soils may erode more easily than others due to inherent soil characteristics. The direct measurement of K on unit runoff plots reflects the combined effects of all variables that significantly influence the ease with which soil is eroded or the particular slope other than 9% slope. Some of the soil properties which affect the soil loss to a large extent are the soil permeability, infiltration rate, soil texture, size and stability of soil structure, organic content, and soil depth. These are usually determined at special experimental runoff plots or by the use of empirical erodibility equations which relate several soil properties to the factor K. The soil erodibility factor (K) is expressed as tons of soil loss per hectare per unit rainfall erosivity index, from a field of 9% slope and 22 m (in some cases 22.13m x 1.83m) field length. The soil loss obtained from the above unit plot is divided by yearly EI30 to obtain the soil erodibility factor (K). It ranges from less than 0.1 for the least erodible soils to close to 1.0 in the worst possible case.

The formula used for estimating K is as follows:


Based on runoff plot studies, the values of erodibility factor K have been determined for use in USLE for different soils of India as reported by Singh et al. (1981). Values of K for several stations are given in Table.

Table. Values of K for Several Stations



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