Modeling and correction of soil penetration resistance for variations in soil moisture and soil bulk density

This study aimed to describe the behavior of models for adjusting data of soil penetration resistance for variations in soil moisture and soil bulk density. The study was carried out in Lucas do Rio Verde, MT, Brazil in a typic dystrophic red-yellow Latosol (Oxisol) containing 0.366 kg kg−1 of clay. Soil penetration resistance measurements were conducted in the soil moistures of 0.33 kg kg−1, 0.28 kg kg−1, 0.25 kg kg−1 and 0.22 kg kg−1. Soil penetration resistance behavior due to variations in soil moisture and soil bulk density was assessed by estimating the soil resistance values by non-linear models. There was an increase of the soil penetration resistance values as soil was losing moisture. For the same edaphic condition studied, small differences in the data of soil bulk density affect differently the response of soil resistance as a function of moisture. Both soil bulk density and soil moisture are essential attributes to explain the variations in soil penetration resistance in the field. The good representation of the critical soil bulk density curve as a limiting compression indicator requires the proper choice of the restrictive soil resistance value for each crop.