Structural changes in latosols of the cerrado region: II - soil compressive behavior and modeling of additional compaction

Eduardo Da Costa Severiano,Vinícius De Melo Benites,Moacir De Souza Dias Júnior,Silvio Marcos Ferreira Filho,Katia Aparecida De Pinho Costa,Geraldo César De Oliveira

doi:10.1590/s0100-06832011000300014

Abstract

Currently in Brazil, as in other parts of the world, the concern is great with the increase of degraded agricultural soil, which is mostly related to the occurrence of soil compaction. Although soil texture is recognized as a very important component in the soil compressive behaviors, there are few studies that quantify its influence on the structural changes of Latosols in the Brazilian Cerrado region. This study aimed to evaluate structural changes and the compressive behavior of Latosols in Rio Verde, Goiás, through the modeling of additional soil compaction. The study was carried out using five Latosols with very different textures, under different soil compaction levels. Water retention and soil compression curves, and bearing capacity models were determined from undisturbed samples collected on the B horizons. Results indicated that clayey and very clayey Latosols were more susceptible to compression than medium-textured soils. Soil compression curves at density values associate with edaphic functions were used to determine the beneficial pressure (σ b) , i.e., pressure with optimal water retention, and critical pressure (σcrMAC), i.e., pressure with macroporosity below critical levels. These pressure values were higher than the preconsolidation pressure (σp), and therefore characterized as additional compaction. Based on the compressive behavior of these Latosols, it can be concluded that the combined preconsolidation pressure, beneficial pressure and critical pressure allow a better understanding of compression processes of Latosols.

Highlights

The degradation of agricultural areas has become a worldwide concern and is related to the dissemination of soil compaction caused by the movement of machinery and equipment in most cases (Canillas & Salokhe, 2002).In the region of the Brazilian Cerrado, the development of agriculture has become increasingly based on production technologies depending on the use of agricultural machinery in every stage of the agricultural process
The objective of this study was to evaluate the structural changes of Latosols by evaluating the compressive behavior and modeling additional soil compaction
Studies showed an increase in the bulk density (Bd) values at preconsolidation pressure (Bdσp) of approximately 10 % (Kondo & Dias Junior, 1999)

Summary

Introduction

The degradation of agricultural areas has become a worldwide concern and is related to the dissemination of soil compaction caused by the movement of machinery and equipment in most cases (Canillas & Salokhe, 2002).In the region of the Brazilian Cerrado, the development of agriculture has become increasingly based on production technologies depending on the use of agricultural machinery in every stage of the agricultural process. The Latosols of this region have a wide variety of textures with clay contents varying from 150 g kg-1 (Embrapa, 2006) to > 750 g kg-1 (Gontijo et al, 2008) These soils, which are already highly susceptible to compaction under natural conditions (Ajayi et al, 2009), become even more vulnerable due to the intensity of machinery traffic during the rainy season. Increased soil water contents (Kondo & Dias Junior, 1999; Silva et al, 2003; Cardoso, 2007; Cavalieri et al, 2009; Severiano et al, 2010) permit additional compaction by the machinery traffic that is part of the production process

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