Penetrometers to Determine the Resistance to Penetration in Oxisol in Pasture Land in the Cerrado

Abstract

Soil penetration resistance (PR) is the most common and practical way to estimate the level of soil densification/compaction. The use of PR is evident in most studies, but a large unexplained the differenttypes of penetrometers capable of quantifying it. Their principle is to measure the soil resistance when isinserting a cone-tipped rod to a specific depth. This study aimed to compare the use of two penetrometers/penetrographs to determine the PR of a clayey soil: one static penetrometer (impact) and another dynamic(digital). For this purpose, three treatments in distinct forage plants were evaluated: i) Cynodon nlemfuensis,ii) Cynodon dactylon and iii) Cynodon plectostachyus. Soil penetration resistance and soil moisture wereassessed at two depths, i.e., 0–20 cm and 20–40 cm. PR values ranged from 3.0 to 3.9 MPa between the areas,and soil moisture ranged from 13 to 14%. We found a high correlation between the results of penetrometerswith R2=0,93 and R2=0,95 at 0-20 and 20-40 cm, respect from impact and digital penetrometer. The ANOVAdid not show significant differences (0.05 scored in Tukey test) for the three selected treatments, indicatingsimilar efficiency of the penetrometers for determining PR values in clayey soil in Cerrado. The methods forevaluating soil penetration resistance can present equal values through the adjustment equation.