Soil compaction caused by harvest and logging operations in eucalyptus forests in coarse-textured soils from northeastern Brazil

Abstract

Planted forests occupy more than 6.5 million ha in Brazil, where harvest and logging operations are performed with increasingly heavier machinery, increasing the risk of soil compaction. Soil compaction can be avoided if soil load bearing capacity is not exceeded, what makes it important to assess both the soil strength and the impact of different operations. The aim of this study was to evaluate the load bearing capacity of some coarse textured soils (two Hapludult and one Haplorthod) in two soil horizons (BA and B), from northeastern Brazil; and to assess the impact of harvest and logging operations performed with harvester and forwarder. Although the Haplorthod presented higher load bearing capacity in both the BA horizon (for the whole moisture range) and the B horizon (for higher water contents), it suffered the greatest soil compaction. Traffic with the harvester resulted in soil compaction in both the BA and the B horizons, but the increase in bulk density was higher on the later, reaching 18.7% in the Haplorthod. The forwarder traffic intensity and the presence of plant residue cover significantly affected the occurrence of soil compaction. In the BA horizon, the increase in soil bulk density for different forwarder traffic intensities was 3 passes ~ 6 passes < 12 passes ~ 16 passes. The increase in bulk density was higher in the Haplorthod, reaching 32% after 16 forwarder passes over bare soil. Significant linear regressions were obtained from the number of forwarder passes and the increase in bulk density. Index terms:Harvester; forwarder; precompression stress; soil load bearing capacity. RESUMOAs florestas plantadas ocupam mais de 6,5 milhões de ha no Brasil, nas quais as operações de colheita e baldeio são realizadas com maquinário cada vez mais robusto, o que aumenta o risco de compactação do solo. A compactação do solo pode ser evitada se a sua capacidade de suporte de carga não for excedida, o que torna importante a avaliação tanto da resistência mecânica do solo quanto o impacto de diferentes operações. O objetivo deste estudo foi avaliar a capacidade de suporte de carga de solos de textura grosseira (dois Hapludult e um Haplorthod) em dois horizontes (BA e B) do Nordeste do Brasil; além de avaliar o impacto das operações de colheita e baldeio de madeira realizadas com harvester e forwarder. Apesar de o Haplorthod ter apresentado a maior capacidade de suporte de carga no horizonte BA (para toda a faixa de umidade) e no horizonte B (para maiores umidades) ele foi a classe de solo que apresentou maior compactação. O tráfego com o harvester resultou em compactação tanto no horizonte BA quanto no B, mas o aumento da densidade do solo foi maior no último, chegando a 18,7% no Haplorthod. A intensidade de tráfego do forwarder e a presença de resíduos de plantas na superfície do solo afetaram significativamente a ocorrência de compactação do solo. No horizonte BA, o aumento da densidade do solo em decorrência da intensidade de tráfego do forwarder foi de 3 passadas ~ 6 passadas < 12 passadas ~ 1...

Soil compaction caused by harvesting, skidding and wood processing in eucalyptus forests on coarse‐textured tropical soils

“…Bulk density is probably the most common soil physical attribute for measuring soil compaction in forest soils research (e. g. Andrade et al., ; Cambi et al., ; Solgi & Najafi, ). It is used to detect soil structural degradation following harvest and logging operations, usually having higher values at shallower depths (Bottinelli, Hallaire, Goutal, Bonnaud, & Ranger, ; Cambi et al., ) and during the first few machinery passes (Naghdi, Solgi, & Ilstedt, ; Toivio et al., ).…”

“…Soil strength prior to the harvest operations was assessed in a previous study by Andrade et al. (). The authors collected undisturbed soil samples from the upper BA and B horizons (respectively 10–13 and 45–48 cm depth), which were observed during field inspection as the layers with higher mechanical resistance.…”

“…The authors collected undisturbed soil samples from the upper BA and B horizons (respectively 10–13 and 45–48 cm depth), which were observed during field inspection as the layers with higher mechanical resistance. These samples were used to generate the soil load‐bearing capacity models (for a detailed description of the methods and of the resultant load‐bearing capacity models refer to Andrade et al., ) that represent the initial state of soil strength (prior to the mechanized operations), from which we evaluated whether there was or not any significant additional compaction after the mechanized operations.…”

“…The impact of machinery traffic was assessed using the samples collected after the mechanized operations and then submitted to the compression tests at field moisture. Their precompression stress and water content values were plotted on soil load‐bearing capacity models (LBCM) for these soil classes (from Andrade et al., ). These models were obtained prior to traffic and represent the initial strength level of the soil.…”

“…In tropical soils planted with Eucalyptus forests, soil load‐bearing capacity models have been used in the past few years to evaluate the amount of soil compaction during harvest operations in relation to differences in soil type, soil depth, climatic season, the kind of machinery used, traffic intensity and the effect of slash over the soil surface (Andrade et al., ; Martins, Dias Junior, Carvalho, Silva, & Fonseca, ; Silva, Dias Junior, & Leite, , ). Management strategies aiming to prevent soil compaction should take into account the soil load‐bearing capacity model, as it quantifies the soil precompression stress for a given water content, indicating the maximum load that the soil could withstand without suffering additional compaction in a given situation (Araujo Junior, Dias Junior, Guimarães, & Alcântara, ; Martins et al., ; Pacheco & Cantalice, ; Pais et al., ; Pires, Dias Junior, Rocha, Araujo Junior, & Carvalho, ).…”