Development of an optical technique for characterizing presence of soil surface crusts

Abstract

The expansion of the agricultural frontier and recurrent disturbances caused by intensive tillage practices are factors of exposure and degradation of the physical, chemical and biological properties of soil. When the soil is uncovered, the rain causes changes in its surface structure enabling the development of crusts. Surface crusting is a major detrimental issue to agriculture, as it damages the soil structure, reducing the water infiltration, thus modifying soil roughness and porosity, which increases run-off and erosion. Therefore, the monitoring and control of the occurrence of crusts must be continuous; however, the traditional techniques used to do that demand contact and destruction of the observed soil surface as well as time. This opens room for optical techniques that are potential tools in soil surface analysis in a fast, contactless and non-destructive way. Driven by this motivation, the present study developed a non-destructive, robust, low-cost, portable optical method for characterizing soil surface crusting. Images of samples with and without crusts in the laboratory as well as in the field were illuminated and recorded, with identification of parameters that could be related to presence or absence of surface crusts. The results confirmed the feasibility of using an optical technique as a contactless and non-destructive method for differentiating surface crusts in the field that can be also embedded in portable and low-cost apparatus.