Jean Alberto Sampietro

Avaliação da umidade na compactação do solo submetido ao tráfego de máquinas de colheita florestal

This study evaluated the moisture effect in soil compaction submitted to wood harvesting machine traffic in Pinus taeda L. stands. The study was conducted in the operational areas of a forestry company located in Santa Catarina. The data were obtained in a Humic Cambisol soil in different periods in order to contemplate variations in soil moisture. It was compared the situation without traffic (WT) and after machine traffic (AT) by determining the bulk density (Ds) and soil total porosity (Pt) at the depths of 0 to 15, 15 to 30 and 30 to 50 cm, and soil penetration resistance (PR) in the depths between 0 to 80 cm. The results showed that the major changes caused by traffic of machines in the physical properties occurred with increasing of moisture content. It was also detected changes in the entire soil profile. This demonstrated that the wood harvesting when performed in soils with high moisture contents will cause greater compaction. Among the models compared to estimate the soil penetration resistance, Stepwise Arithmetic Model with Mixed variables (MSAM), which estimated the RP by inverse Ds and Ug in pure form was the one with the best adjustement, explaining 71% of the variation of this property, and evidencing the possible influence of other factors in the estimation of soil compaction.

Compactação causada pelo tráfego de Feller buncher e skidder em um neossolo regolítico sob distintas umidades

This research evaluated the influence of water content on soil compaction of an Entisol under traffic of forest harvesting machines and developed models to estimate soil compaction. The study was conducted in areas of a forest company, located in the state of Santa Catarina, Brazil. The sampling was performed under various conditions of soil moisture, contemplating three classes: Ug1 (Ug < 0,30 kg kg-1); Ug2 (0,30 ≤ Ug < 0,40 kg kg-1); Ug3 (Ug ≥ 0,40 kg kg-1). The soil bulk density was determined (Ds), total (Pt) and air-filled porosity (PA) and penetration resistance (RP), under the conditions without traffic (WT) and after traffic (AT) of a Feller-buncher (CAT 522) and a Skidder (CAT 545) employed in wood harvesting of Pinus taeda stands. Multiple regression equations were adjusted to estimate the soil penetration resistance, through arithmetic and logarithmic models with pure and mixed variables. The results indicate that in moisture condition above than 0,40 kg kg-1 (Ug3), the traffic promoted increase in Bd and PR of 10 and 24%, respectively, and decrease in αt and αair, in order of 12 and 43%. In low moisture content (Ug < 0,30 kg kg-1), the increase of Bd and PR was 3 and 13%, respectively, and the decrease of αair of 8% and without effect in αt. The stepwise logarithmic model with mixed variables (SLMM) showed the best results for the estimation of soil penetration resistance, but caution must be raised in their employment due to the possible influence of other factors in the estimation and determination of PR.