Soil structure assessment and 3-dimensional visualisation of a Vertosol under controlled traffic

Abstract

There is evidence that controlled traffic can be detrimental to crop growth due to soil structural degradation in the wheel tracks. An experiment was conducted in which the effects of 2 different types of wheel tracks (raised and recessed) on soil structure were assessed. Large monoliths were taken and impregnated with epoxy resin. A special jig was employed to create and expose smooth level surfaces in which the crack pattern was highlighted with UV light. Images from the patterns were used to describe soil structure with 4 different attributes. Special image analysis software was used to combine multiple images to reconstruct the structure of the soil blocks. From the images and the 4 attributes, it was concluded that after 2 years the raised wheel track had a more massive soil structure than the recessed wheel track. The reconstructed soil structure revealed an intricate network of cracks and a large variability over a short distance, as well as dominant features of continuous cracks parallel to the plant row. From this work it is proposed that, in these soils, the well-documented benefit of controlled traffic in the Australian cotton industry is primarily related to minimising structural decline caused by cultivation rather than by traffic.