SIMULTANEOUS SOIL MOISTURE AND CONE INDEX MEASUREMENT

Soil compaction can restrict root growth and water infiltration, resulting in yield reduction. Maps of yield monitor data aid in visualization of variations in yield, without identifying underlying factors for these variations. Soil penetration resistance can help identify areas where soil physical characteristics are negatively impacting yield. However, penetration resistance is a function of soil moisture content and soil type as well as compaction. A standard penetrometer cone was modified to collect near-infrared reflectance and estimate moisture content. The instrument was tested in the laboratory on a selection of soil types with varying moisture tension levels using stepwise and continuous probe insertions. Soil moisture, dry bulk density, and clay content were significant variables in predicting soil cone index at the lower moisture tension level.