Abstract
ABSTRACT Soils are highly variable across landscapes, which can be assessed and characterized according to scale, as well as fractal and multifractal concepts of scale. Thus, the objective of this study was to analyze the multifractality of the penetration resistance (PR) of vertical profiles from different slope forms (concave and convex). The experimental plot incorporated 44.75 ha, and the PR was measured at 70 sampling points in the 0-0.6 m layer, distributed in concave (Type A: 38 sampling points) and convex pedoforms (Type B: 32 sampling points). Data analysis was performed using the PR value (every 0.01 m depth) for each of the sampling points (PRmean), and their respective maximum (Prmaximun) and minimum (PRminimum) values. Multifractal analysis was performed to assess the changes in the structure, heterogeneity, and uniformity of the vertical profiles according to the scale, characterizing the partition function, generalized dimension, and singularity spectrum. The multifractal parameters of the generalized dimension and singularity spectrum demonstrated greater homogeneity and uniformity in the vertical PR profiles of pedoform B (convex) compared to those of pedoform A (concave). The minimum PR values in pedoform A (PRminimum) showed the greatest scale heterogeneity, indicating that in terms of soil management, it is more relevant to monitor the minimum values than the maximum values. The fractal analysis allowed us to describe the heterogeneity of the data on scales not evaluated by conventional analysis methods, with high potential for use in precision agriculture and the delimitation of specific management zones.
Highlights
Knowledge of soil resistance to penetration (PR, Mean penetration resistance (MPa)) allows inferences concerning the state of soil compaction throughout the landscape and the determination of management alternatives with the least possible impact on soil attributes, especially with regard to increasing density and decreasing soil porosity (SOUZA et al, 2015; BURR-HERSEY et al, 2017; SEIDEL et al, 2018)
According to Cortez et al (2018), Seidel et al (2018), and Leiva et al (2019), high PR values are related to soil management, and crops in no-tillage systems need management strategies that consider the state of soil compaction (BURR-HERSEY et al, 2017)
The statistical analysis of the PRmean, PRmaximum, and PRminimum for the vertical PR profiles (Table 3) demonstrated that the lowest PRmean value occurred in the Type B slope (PRmean = 2.277 MPa), followed by the 70 sampling points (PRmean = 2.333 MPa) and the Type A slope (PRmean = 2.374 MPa)
Summary
Knowledge of soil resistance to penetration (PR, MPa) allows inferences concerning the state of soil compaction throughout the landscape and the determination of management alternatives with the least possible impact on soil attributes, especially with regard to increasing density and decreasing soil porosity (SOUZA et al, 2015; BURR-HERSEY et al, 2017; SEIDEL et al, 2018). The understanding of PR along the landscape is a key factor for the development of management alternatives with less impact on natural soil characteristics (SIQUEIRA et al, 2013), in addition to favoring the development of crops (SEIDEL et al, 2018). According to Goovaerts (1998), variability is composed of defined or intrinsic variations and random fluctuations or noise, which need to be understood individually to facilitate a better understanding of the processes and dynamics of soil properties throughout the landscape. In this way, knowledge of landscape forms allows us to describe the variability of soil attributes and their relationships with crops at different scales. It is necessary to understand how PR varies across the landscape in the context of the occurrence of different patterns on the horizontal and vertical scales, especially over small distances (KRAVCHENKO; PACHEPSKY, 2004)
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