Load-bearing capacity and critical water content of the coffee plantation soil with management in full sun and shaded

ABSTRACT New management practices applied to coffee crops may influence the soil’s capacity to tolerate vertical stresses. This paper aimed to evaluate the influence of two coffee crop management systems on the soil load-bearing capacity and critical soil water content to agricultural machinery traffic. This study was performed in the experimental area of the Federal Institute of the Southeast of Minas Gerais - Rio Pomba college, in Rio Pomba city, Minas Gerais, Brazil. Dystrophic Red-Yellow Oxisol (Latossolo Vermelho-Amarelo distrófico) (LVA7) with clayed texture predominating in the experimental unit. Undisturbed soil samples were collected from layers of 0.00-0.03, 0.12-0.15 and 0.27-0.30 m, randomly, in the center of the interrows of coffee plants (Coffea arabica L.) in monoculture plots under traditional management (in full sun) and in the plots of coffee plants intercropped with gliricidia (Gliricidia sepium) (shaded) to estimate pre-consolidation pressures, through uniaxial compression tests and adjustment of soil load-bearing capacity models. The average and maximum normal stresses applied to the soil and the vertical stress distribution of three agricultural tractors used in mechanized farming operations were estimated, and the critical soil water content to the traffic of these tractors was determined for both treatments, aiding in the decision-making process regarding additional compaction risks in the area. Cultivation of gliricidia in consortium with coffee did not influence the soil load-bearing capacity. The soil layer of 0.12-0.15 m was the most vulnerable to vertical stresses in both treatments. Agricultural tractors Agrale 4100, MF 265 and MF 275 presented values of vertical stresses of 335.76, 200.24 and 245.55 kPa, respectively, and the soil water content for the traffic of agricultural machines without plastic deformation was higher in the coffee plants in full sun for all studied depths.