Feasibility study on the potential of electrical conductivity sensor Veris® 3100 for field mapping of topsoil strength

Abstract

With advances in technology for precision agriculture, numerous attempts have been made towards development of on-the-go sensors for measuring soil compaction. Most of the on-the-go sensors developed so far have been mechanical sensors providing a soil strength parameter that can be related to degree of soil compactness. In this study, a commercial electrical conductivity sensor (Veris ® 3100) in combination with a previously developed combined horizontal penetrometer (equipped with a dielectric sensor for water content) were tested in a field in order to examine whether the apparent electrical conductivity (EC a ) within the 0–0.3 m depth (EC a -shallow) could be helpful in detecting the topsoil strength (here the horizontal penetrometer resistance). Interpolated field maps of horizontal penetrometer resistance (PR), volumetric water content ( θ v ) and EC a showed comparable patterns within some areas (but not over the field). No significant correlation (but a negative trend) was found between EC a and dry bulk density. A significant correlation between EC a and PR/ θ v (a previously proposed water content-independent PR) was found ( R 2 = 0.37, P a was strongly affected by soil water content and texture. It was concluded that PR may be indirectly related to EC a through θ v , which greatly affects both EC a and PR. The results suggested that the EC sensor could potentially be helpful for detecting zones of high soil strength (i.e. high PR/ θ v ). Further studies are suggested to address whether EC a is better related to the state of soil compaction at dry state of soil due to more significant effect of soil–soil electrical conductivity.