Gypsum effects on the spatial distribution of coffee roots and the pores system in oxidic Brazilian Latosol

Abstract

The aim of this study was to jointly evaluate the root system and soil pore distribution in depth and their relation to the development of the coffee crop. Three trenches were dug at random, longitudinal to the plant row, in a very clayey oxidic Latosol (Oxisol), subject to the following dose of gypsum: G0: absence of additional gypsum; G7: 7 Mg ha−1; and G28: 28 Mg ha−1 of additional gypsum, both applied on the surface in the plant row. For the root system evaluation we used the crop profile method associated with 2D image analyzes, and subsequent elaboration of root variables maps. Soil pores system was quantified in 3D images, originated by X-ray CT scan, in undisturbed soil cores (0.06 m diameter and 0.14 m high) sampled at 0.20–0.34; 0.80–0.94; and 1.50–1.64 m depth. Roots and pores were classified by diameter. The statistical inferences were performed in R language. The increasing doses of gypsum favored the development of fine roots efficient in water absorption, and the highest gypsum dose promoted the better spatial distribution of the root system and was more homogeneous in the vertical direction of the soil profile, with highlighting to G28. The highest pore number and volume occurs in the 0.20–0.34 m structural layer, particularly pores with a diameter less than 2 mm. This management system that employs high gypsum doses contributed beneficially to a new structural organization in all depth studied, and most meaningful at 0.20–0.34 m depth, especially with the increase of pores and expertise of roots (smallest diameter: 1 mm) contributing to better exploitation of the soil conditions by the coffee plant. Image analyses are an tool with high predictive power to evaluated soil pores and roots system without destruction of the soil structure.