Precision, accuracy, and efficiency of four tools for measuring soil bulk density or strength.

Abstract

Monitoring soil compaction is time consuming. A desire for speed and lower costs, however, must be balanced with the appropriate precision and accuracy required of the monitoring task. We compared three core samplers and a cone penetrometer for measuring soil compaction after clearcut harvest on a stone-free and a stony soil. Precision (i.e., consistency) of each tool at depths of 0-10, 10-20, and 20-30 cm was determined from two adjacent samples at 21 or more sampling points in each harvested location. Because one bulk density (Db) sampler provided a continuous sample of each decimeter depth, it was designated as the standard; thereby, the relative accuracy and bias of the two shorter core samplers could be calculated. Both shorter samplers overestimated Db as determined by the standard. At least 15 penetrometer samples could be taken and processed in the time required for three Db samples to the same 30-cm depth. Precision of measurements was taken by the core penetrometer, however was clearly less than that with any of the Db samplers. Based on time requirements and precision of each tool, we examined the efficiency of double sampling (using a combination of penetrometer and core sampler) for estimating Db. Results from the stone-free soil indicated an advantage in both precision and efficiency in applying double-sampling theory to estimate Db rather than sampling exclusively by the more time-consuming core samplers.

Citation

Miller, Richard E.; Hazard, John; Howes, Steven. 2001. Precision, accuracy, and efficiency of four tools for measuring soil bulk density or strength. Res. Pap. PNW-RP-532. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 16 p