Calibration of a Manual Cone Penetrometer Using a Digital Penetrologger

Abstract

Cone penetrometers standardized by American Standards for Agricultural Engineering (ASAE) have been major instruments for investigating and quantifying soil compaction. However, the continuous use of penetrometers often introduces errors to the Cone Index (CI) readings obtained from the instruments over time. An ASAE calibrated digital cone penetrometer and a manual penetrometer were tested on a sandy clay loamy soil at the National Centre for Agricultural Mechanization (NCAM), Ilorin, Nigeria; using the ASAE small cone. The CI readings obtained for the two penetrometers were subjected to a statistical t-test. The results showed that the sensitivity of the manual cone penetrometer is comparable to that of the digital penetrologger at depths greater than 12cm as the mean difference showed no significant difference at this depth. However, at depths 0-11cm, there was significant difference in their mean difference; this shows the relative insensitivity of the manual cone penetrometer. The calibration results also showed that the continuous use of the manual cone penetrometer will require a multiplying facto r of 1.165 to get a CI reading close to ideal. Improvement on the manual cone penetrometer will also assist in obtaining CI readings after tillage operations.