Effect of tillage on soil mechanical parameters, fine root growth, and productivity of young <i>Pinus taeda</i> plantations

The use of heavy machinery during forest establishment and/or harvest can contribute to limiting the productivity of Pinus taeda plantations, due to possible structural damage or soil compaction. However, the impact of tillage-induced changes in the soil mechanical properties on fine roots growth and shoots in P. taeda plantations remains unclear. Thus, we aimed to evaluate the effects of tillage on development and spatial distribution of P. taeda root systems in southern Brazil. Thus, we compared three tillage methods in a P. taeda plantation: no tillage, manual tillage, and mechanized tillage. Soil penetration resistance, area and diameter of fine roots, fine root length density across various soil layers (0–5, 5–10, 10–15, 15–20, and 20–40 cm), and height, diameter, and stem volume were assessed. Mechanized tillage improved the soil’s mechanical conditions, reducing compaction and favoring root growth (≈150%), increasing the absorption of water and nutrients and the productivity of P. taeda. In contrast, the no-tillage showed severe compaction, limiting root development. Manual tillage had less of an effect, especially in deep layers. Thus, mechanical tillage is essential to optimize growth and productivity, especially in compacted soils or areas undergoing forest reform.