Abstract
ABSTRACT 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.
Highlights
Soil compaction identification and your location in soil profile can be performed by measuring various attributes, such as density, water infiltration rate, porosity and penetration resistance, being the latter the most used (FRANCHINI et al, 2011; MORAES et al, 2013)
Modeling and correction of soil penetration resistance for variations in soil moisture and soil bulk density such as those of BIANCHINI et al (2002) have demonstrated the use of penetrometer as a practical and reliable way to characterize the soil compaction and estimate the resistance it offers to the growth of plant roots
For values between 3.0 and 4.5 matric potential (MPa), these fits of BDc for the same variation of θ can be combined with the ranges of 3.0–3.5, 3.5–4.0 and 4.0–4.5 MPa. This indicates that from 3.0 MPa, there is a less influence of soil penetration resistance (SPRr) in the responses of BDc. These results suggest that the choice of the SPRr value presents a great importance in determinations of BDc, for evaluations of limiting effect of soil compaction on plant growth, since a slight variation in the value of the adopted SPRr may lead to significantly different responses of BDc for the same soil and moisture condition
Summary
Soil compaction identification and your location in soil profile can be performed by measuring various attributes, such as density, water infiltration rate, porosity and penetration resistance, being the latter the most used (FRANCHINI et al, 2011; MORAES et al, 2013). As postulated by SILVA et al (2008), there is a great variability of soil penetration resistance (SPR) for a given degree of compaction or coincidence of values for different degrees of compaction This variability of SPR in field is linked to several controlling variables, which, as described by the review study of MORAES et al (2014a), include soil bulk density (OTTO et al, 2011), soil water content (ASSIS et al, 2009; MORAES et al, 2012), water pressure in the pores (KIM et al, 2008), particle size distribution (VAZ et al, 2011), clay content (MOLIN et al, 2006), and soil- metal friction (DEXTER et al, 2007). This procedure is important to reduce misinterpretation of results obtained in different field conditions and soil management systems (BUSSCHER et al, 1997)
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