Precision, accuracy, and efficiency of four tools for measuring soil bulk density strength - Introduction

Monitoring soil compaction is time consuming. A desire for speed and lower costs, however, must be balanced with the appropriate precision and accurac y required of the monitoring task. We compared three core samplers and a co ne penetrometer for measuring soil compaction after clearcut harvest an a s tone-free and a stony soil. Precision (i.e., consistency) of each tool at d epths 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 (D-b) sampler provided a continuous sample of each decimeter depth , it was designated as the standard; thereby, the relative accuracy and bia s of the two shorter core samplers could be calculated. Both shorter sample rs overestimated D-b as determined by the standard. At least 15 penetromete r samples could be taken and processed in the time required for three D-b s amples to the same 30-cm depth. Precision of measurements taken by the cone penetrometer, however, was clearly less than that with any of the D-b samp lers. Based on time requirements and precision of each tool, we examined th e efficiency of double sampling (using a combination of penetrometer and co re sampler) for estimating D-b. Results from the stone-free soil indicated an advantage in both precision and efficiency in applying double-sampling t heory to estimate D-b rather than sampling exclusively by the more time-con suming core samplers.