COMPARISON OF CLOD AND CORE METHODS FOR DETERMINATION OF SOIL BULK-DENSITY

An interagency forest monitoring program has been initiated on a syste matic network of forested plots often accessible only by foot traffic along a compass line. Extensive site classification and physiochemistr y data are being collected for vegetation and soil indicators of fores t health. In order to select a suitable technique for obtaining an est imate of mineral soil bulk density, conventional clod and core methods were compared across a wide range of forest soils within the Coastal Plain of southeastern Virginia. Replicate soil clods and cores were co llected from two to four horizons within each of six pedons representi ng different soil series. Following analysis, the sample data were use d to evaluate main and interaction effects due to differences in the m ethod, series, horizon, and texture effects. Differences between the c lod and core data were highly significant on average (P < 0.001) as we re all of the main effects. Both methods exhibited high precision (ave rage CV < 5%) within the individual horizons sampled. The two data set s were highly correlated (r = 0.98), and the regression equation used to predict clod bulk density with data from the core method is: Clod B D = (1.011 x Core BD) + 0.068; standard errors of +/-0.042 and +/-0.04 8 for the slope and intercept, respectively. From an operational stand point, the core method appears to have many advantages over the clod m ethod for sampling in remote locations.