The use of visual soil assessment schemes to evaluate surface structure in a soil monitoring program

The use of visual soil assessment schemes has been shown to be effective in identifying the structural condition of soils, especially in identifying the degree of sodicity and self-mulching for a range of soils. The visual soil assessment scheme developed by Shepherd (VSA) and the SOILpak score are both strongly related to soil structural condition for the range of soils tested. The proposed use of the aggregate display from a drop test as used in the VSA test to develop a quantitative estimate of friability has also shown indications of being a potentially useful test to distinguish the self-mulching behaviour and sodicity of surface soils, especially clay surface soils. The results provide evidence that the combination of soil texture and the degree of sodicity and self-mulching provide a useful system of predicting soil behaviour and soil condition in the field for a soil monitoring program. Future work is required to test the behaviour of a wider group of surface soils including weakly sodic loam and clay loam surface soils and some of the friable/oxic surface soils.