Can infrared thermography be used to estimate soil surface microrelief and rill morphology?

•Infrared thermography can be used to visualize preferential flow paths.•Thermography can be used to identify surface structures in the presence of mulching.•Infrared thermography can be used to estimate soil surface microrelief.

This study presents a new technique to estimate soil surface microrelief and rill morphology using infrared thermography. This technique can be specifically useful to characterise soil surface microrelief to identify preferential flow paths in mulching conditions and to estimate soil surface elevation where other microrelief measurement techniques cannot be successfully applied. Laboratory tests were carried out using two soil flumes where different conditions were tested: with artificial rills created at the soil surface and with a surface eroded by flowing water. The technique was tested both in bare soil conditions and in the presence of different mulching surface cover densities. Heated water was used to create a temperature gradient on the soil surface and high resolution soil surface thermal imaging was obtained using a portable infrared video camera.The proposed technique allows us to identify different microrelief structures at the soil surface and to visualize preferential flow paths in mulching densities up to 4 ton/ha. Where other microrelief measurement techniques cannot be used, the thermography allows to obtain 3D models of the soil surface elevation, with satisfactory accuracy. Higher mulch cover densities (above 4 ton/ha) strongly affected the performance of the technique.