Comparison of Density and Water Content Determinations Using Soil Cores and a Dual Probe Density Gauge

Wet bulk density and water content were determined with the standard soil-core method and by using a density and moisture gauge (gamma radiation and fast neutrons). Four soils collected at different forest sites were tested in the laboratory under different degrees of compression and at various water contents. Using the count ratios of the gauge for density and water as independent variables and wet bulk density and water content determined by soil cores as dependent variables, calibration equations were developed. For the soils used, the gauge values concerning wet bulk density were in close agreement with values determined with soil cores. However, the water content readings of the gauge had to be recalculated using the equations developed. The equations were tested on soil cores collected in the field after measurements with the gauge. The dry bulk density calculated as the wet bulk density given by the gauge minus the water content recalculated using the presented equations differed by an average of -1.6 percent from the soil-core values