New in situ soil bulk density sensor using gamma radiation

Soil compaction and soil bulk density are gaining in importance as soil parameters. The standard measurement with rings is labour intensive and therefore expensive. Medusa Explorations developed a sensor for in situ density measurements, the RhoC. This sensor measures in situ a full soil profile of bulk density every 5 cm up to 1 m depth in 15 minutes, without the need to extract a soil core. The measurement uses gamma ray attenuation combined with a soil moisture sensor. A validation study was performed in two locations, on sandy clay loam and sand soil, both with large within field variation in subsoil compaction. The first results show a good correspondence between both methods. Statistical analysis shows a slightly lower precision for the RhoC measurements than for the rings measurements. The results of this validation study will be discussed.