English

M Cunha Jos Eacute,C Gaio Denilton,M P Silva Douglas,S Nogueira Jos Eacute,C C Campos Milton,D R Soares Marcelo,A De Oliveira Ivanildo

doi:10.5897/ajar2015.10649

Abstract

Understanding the variability of soil properties is crucial to identify areas susceptible to physical degradation. The soil degradation is often determined by the current state of the soil structure, that is, the aggregate size distribution. Therefore, this article suggested evaluating aggregate sizes’ distribution by using the fractal theory. The goals were: (i) to calculate the fractal mass dimension of soil aggregates in areas under agroforestry, forestry, sugarcane, cassava and pasture in Southern Amazonas state, Brazil, showing correlations with soil properties; (ii) to compare the means of fractal dimension mass of the distribution of particle sizes on different soil under the different uses; and (iii) to investigate spatial variability of such fragmentation for each management system. Fragmentation was determined from fractal mass dimension. Aggregates were sampled within a depth range of 0.00 to 0.10 m, over a regular sample grid of 70 × 70 m, with georeferenced sample points, and regular spacing each 10 m, totaling 64 points per mesh. Higher mean values of fractal mass dimension were found in agroforestry use system and the lowest under native forest and pasture, with no statistical difference fractal mass dimension, when assessed in relation to the type and land use. The degree of fragmentation of soil aggregates was found to be influenced by the type of soil and strongly correlated with fine particles, higher in Red-Yellow Oxisols with better physical quality when compared with other areas. It showed a strong spatial dependence and the exponential model that got the best adjustment of the semivariogram. Key words: Soil physics, geostatistics, fractional dimension.

Highlights

Changes in vegetation composition of natural ecosystems associated with management practices, which are attributed to factors such as farm, livestock, bring consequences in relation to biodiversity, and when analyzing the damage caused to the soil and its ability reuse and / or storage (Chaves et al, 2012)
The degree of fragmentation of soil aggregates was found to be influenced by the type of soil and strongly correlated with fine particles, higher in Red-Yellow Oxisols with better physical quality when compared with other areas
The quality of the soil structure is a good indicator of sustainability management systems, which in turn is influenced by pedogenetic conditions

Summary

Introduction

Changes in vegetation composition of natural ecosystems associated with management practices, which are attributed to factors such as farm, livestock, bring consequences in relation to biodiversity, and when analyzing the damage caused to the soil and its ability reuse and / or storage (Chaves et al, 2012). The soil is considered a complex system resulting from the interaction of geological, topographical and climatic factors, among others, which together form indicators (variables) that characterize (Freitas et al, 2014). Compositions difference of the soil particles sizes exhibit fractal features with irregular shapes and structures of self-similarity (Tyler and Wheatcraft, 1992). This aroused the academic community to use the fractal as an effective descriptive tool to characterize the size of the soil particles’ (Prosperini and Perugini, 2008; Xia et al, 2015), structure, aggregation and soil erodibility (Ahmadi et al, 2011; Xu et al, 2013; Tang et al, 2013; Xiao et al, 2014)

Objectives

Methods

Results

Conclusion