EFFECTS OF AGGREGATION ON SOIL ERODIBILITY - AUSTRALIAN EXPERIENCE

A method for estimating the erodibility (K) factor for the Revised Uni versal Soil Loss Equation with particular application to aggregated cl ay soils is reviewed. Based on the proportion of particles (aggregates and disaggregated material) <0.125 mm at the soil surface under rain together with the wet density of sediment, the approach gives better e stimation of K factors for aggregated clay soils than does the nomogra ph of Wischmeier et al. (1971). One problem with a nomograph approach is that there is no indication from the nomograph of a particular soil 's likely sensitivity to slope length, which is needed for selection o f appropriate LS (slope length and steepness factor) tables when using the Revised Universal Soil Loss Equation. Also, the new approach may not apply for soils showing particularly strong disaggregation on wett ing. Examples are given for dispersive soils, an which detachment by o verland flow, is (at least under some conditions) reduced by very stab le surface seals.