A DYNAMIC PENETROMETER FOR MEASURING MECHANICAL RESISTANCE IN FOREST SOILS

A dynamic cone penetrometer (DCP) was designed for measuring soil penetration resistance in forest soils. The designed DCP is lightweight as it weighs only 4.1 kg, accurate because it was validated in field and laboratory testing, portable because disassembled it fits into a cruising vest, and practical because it is very easy to use. It is suitable for forest and soil inventory work. Test results showed that use of the designed prototype is practical in different ecosystems, as it was used to detect the mechanical resistance profile of surface soil in pine and oak forests and shrubland. Soil samples with different bulk density and moisture content were prepared in the laboratory to test the sensitivity of the penetrometer. The designed DCP is sensitive to changes in soil penetration resistance at low bulk densities (0.6-1.0 Mg.m(-3)), which are common in forest soils, and changes in soil moisture (5-25 %). With the validation protocol for its use, it was found that ten successive blows are enough to generate reliable data on the mechanical resistance of the surface soil.