SOIL ERODIBILITY - K
ØMeasure of soil erodibility under standard unit plot condition
-72.6 ft long, 9% steep, tilled continuous fallow, up and down hill tillage
ØIndependent of management
ØMajor factors
-Texture, organic matter, structure, permeability
A key point is that soil erodibility is determined under the standard reference condition where management effects have been eliminated by maintaining the unit plots in a continuous tilled, fallow conditions for a number of years.
The K value that is used if for the soil fines, but the influence of rock fragments in the soil profile should be considered in setting K values.
The effects of rock fragments on the soil surface is considered in the cover-management computations.
Do not use a K value that has been adjusted for rock fragments on the soil surface because use of such an adjusted K value can cause a major mathematical error in RUSLE2.
RUSLE2 computes a time varying K value as a function of monthly temperature and rainfall.
In contrast to RUSLE1, the time varying K value can be used throughout the US except in the Northwest Wheat and Range Region (NWRR).