Numerical analysis applied to the study of soil stress and compaction due to mechanised sugarcane harvest

Crop harvesting has been pointed as the main source of soil compaction in sugarcane fields because of the high stresses induced by the machinery; however, little is known about the magnitude of the stress transmitted to the soil by these machines in the compaction process. The aim of this study was to use numerical simulations to analyse the impact of vehicles used in mechanised sugarcane harvesting on soil stress and soil compaction response. For that, numerical simulations were performed for a set of machines and tyre configurations used to harvest sugarcane: tractor, truck and trailer. The model was formulated as a 2D plane strain problem, meshed for a soil domain 9.0 m in width and 4.0 m in depth, while using the Modified Cam Clay model as the constitutive relationship. Up to 1 m depth, the domain was layered every 0.20 m using measured soil mechanical properties. Effective vertical stress, precompression stress and soil total porosity were analysed in response to the applied stress by the harvest machines. The truck and the trailer applied stresses to the soil surface that reached 800 kPa, while the stresses applied by the tractor did not exceed 300 kPa. Numerical simulations showed that the truck and the trailer can transmit stresses higher than precompression stress that exceeds 1.00 m depth, causing a reduction in the soil total porosity and hence subsoil compaction. These stresses can extend to the planting row by stress bulbs overlapping at around 0.60 m, and could cause soil damage in case of greater stress than precompresion stress. Finally, the simulations revealed variability in soil compaction as dependent on the magnitude of the transmitted stress, as well as due to heterogeneity of mechanical properties along the soil profile. The simulations indicate the relevance of detailing the compressive properties of arable soils rather than considering the soil profile as homogeneous.

Automated summary

The study examines the impact of vehicles used in mechanised sugarcane harvesting on soil stress and compaction response, finding that trucks and trailers apply higher levels of stress leading to soil compaction. The stress can extend to the planting row, potentially causing soil damage.