Soil Colour as a Simple Indicator of Load Bearing Capacity in Brazilian Latosols

Land degradation due to soil compaction has been recognized as a major problem in mechanized agriculture and modern forestry operations. Soil compaction has been attributed to some factors including the use of heavy machines during field operations and unregulated moisture regime during these operations. The problem is growing unabated owing to the cumbersome procedure of assessing the inherent strength attribute of the soil and its ability to support load. In this study, we investigated the possibility of assessing the load support capacity of Latosols (Oxisols - U.S. Soil Taxonomy, Sols ferralitiques - French classification, and Ferralsols - World Reference Base for Soil Resources) samples using the soil colour and its derivative. Our result showed that soil colour derivatives including redness factor (RF) and redness rating (RR) are good indicators of soil mineralogy and thus, some intrinsic attributes could affect its response to loading. We observed that red soils had higher load support capacity (LSC) than the yellow soils. The load support capacity of soils within the same colour group reduces, as the degree of redness of yellowness in the soil sample reduces. Thus, soil colour could be used to understand the load support capacity of soils for agricultural operations and to detect changes in the strength attributes of the soil. We also observed that moisture retention potential of soils which have an overbearing influence of the load bearing capacity of soil could be assessed from the soil colour.