Long-term no tillage management impact on soil hydro-physical properties in coffee cultivation

Abstract

Tillage management in agricultural fields has consequences on the dynamics of the soil structure and soil’s pore functions with far reaching effects on the sustainability of cropping system. The purpose of this study is to investigate changes in both capacity and intensity properties of a very clayey Rhodic Hapludox after 37-year of continuous conventional tillage (CT) and no till (NT) management for weed control under coffee plantations. Undisturbed soil samples were collected at four depths and used for hydro-physical characterization. The tillage treatments modified the capacity and intensity parameters differently depending on the sampled depth. Bulk density was similar at the 0–20 cm layer in both CT and NT treatments, but at the 20–40 cm layer, NT significantly increased the bulk density by (6–8%). Also, NT increased the stability of 8–2 mm macroaggregate fraction in water and significantly increased the geometric mean diameter and the mean weight diameter of the water-stable aggregates in most of the layers relative to CT. Moreover, CT increased hydraulic conductivity by 53% in the surface layer. Generally, the magnitude of the differences in soil properties as a consequence of the 2 tillage treatments was greater for hydraulic conductivity (soil intensity parameters) than the bulk density (soil capacity parameters). In the NT plots, more water was retained within the available water range, while CT presented steeper water retention curves and poorly graded pore-size distributions. The pore-size distribution and hydraulic capacity function curves showed that the impact of CT management was more pronounced at the 10–20 cm layer, while that of NT management was most significant at the 0–10 cm layer (soil surface). This study showed that in addition to soil strength indicators, soil intensity parameters (hydraulic conductivity, hydraulic capacity and soil structure) more succinctly explained differential impact of tillage systems on soils, as compared to the capacity parameters (bulk density, pore size distribution, air capacity and available water capacity).