Abstract
Knowing the variation of particle-size fractions, considering the relief forms, contributes for understanding the variation of other soil attributes. This work aimed to study the spatial distribution of the probability of particle-size fractions occurrence (clay, silt, very fine sand, fine sand, coarse sand, and total sand) in a clayey Oxisol with predominance of concave and convex curvatures. A sampling grid with 94 sampling points in 33x33m spacing at a depth of 0–0.20 m was built using a GPS. The spatial analysis was performed through indicator kriging. The spherical model was fit for all soil fractions, with ranges varying from 130 m to 280 m. In the region of convex curvature, the clay fraction presented the highest probability of occurrence (0.75 to 1.00), whereas in the concave region the coarse sand and total sand fractions presented the highest probability of occurrence. The very fine sand fraction and the silt did not present pattern of distribution in relation to the dominant curvatures of the relief.
Highlights
The landforms that are part of the landscape influence the dynamics of rainfall
The forms of relief may be indicators of variations in soil attributes, because this variability is caused by small changes in slope that affect pedogenic processes and transport and storage of water in the soil profile (SANCHEZ et al, 2009)
Artur et al (2014) researched the spatial variability of soil chemical properties and identified relations with microrelief, concluding that the highest mean values of the attributes occurred in concave landforms
Summary
The landforms that are part of the landscape influence the dynamics of rainfall. The features of concave, linear, and convex landforms have direct effects on the convergence and dispersion of water in the runoff process, contributing in the modeling and spatial variability of the soil. The forms of relief may be indicators of variations in soil attributes, because this variability is caused by small changes in slope that affect pedogenic processes and transport and storage of water in the soil profile (SANCHEZ et al, 2009). Guo et al (2007) state that the forms of relief influence the display of source material, intensity, and direction of water flow in the soil profile. According to these authors, the adopted practices of soil management can intensify the variability of physical, chemical, and biological attributes, which, combined with the form of the landscape, result in imbalance of the natural and productive system. Artur et al (2014) researched the spatial variability of soil chemical properties and identified relations with microrelief, concluding that the highest mean values of the attributes occurred in concave landforms. Nizeyimana & Bicki (1992) observed higher mean values of cation exchange capacity (CEC) in concave terrain, attributing them to the drainage conditions of the area and to the convergent characteristics of relief’s slope
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