PENETROMETERS TO DETERMINE THE RESISTANCE TO PENETRATION IN OXISOL IN PASTURE LAND IN THE CERRADO

Resumo

 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 different
types of penetrometers capable of quantifying it. Their principle is to measure the soil resistance when is
inserting 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 were
assessed 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 penetrometers
with R2=0,93 and R2=0,95 at 0-20 and 20-40 cm, respect from impact and digital penetrometer. The ANOVA
did not show significant differences (0.05 scored in Tukey test) for the three selected treatments, indicating
similar efficiency of the penetrometers for determining PR values in clayey soil in Cerrado. The methods for
evaluating soil penetration resistance can present equal values through the adjustment equation.