Increased machine size and the need for timely field operations have led agricultural producers to express concern about the effects of excessive soil compaction induced by wheel traffic. Wheel induced compaction may affect soil in all horizons, but this is especially true for topsoil where there is direct interaction between a driving wheel and soil surface. The detrimental effects of soil compaction on crop growth include reduced seed emergence and root extension, limited water and nutrient uptake, and decreased infiltration and drainage. Annual yield losses were estimated to be over a billion dollars. Therefore, a better understanding of the mechanics of wheel induced soil compaction is needed to identify the cause and the effects of the compaction in order to improve management decisions for production agriculture.; A two-dimensional numerical model using both finite difference and finite element was developed to study the impact of driving wheel induced soil compaction. Finite element analysis was used to compute the stress states in a soil mass while finite difference was used to simulate interactions between soil and a driving wheel. The result of the finite difference analysis served as an input boundary condition of the finite element study. Coupling finite difference to finite element provided a link between wheel traction and soil compaction.; The model was able to predict soil stresses and to simulate the effect of tire size, soil condition and wheel slip. Soil deformation and stress propagation were computed under normal and tangential loads with non-uniform distributions at interface. Increasing both soil moisture and wheel slip increased wheel sinkage. A 2.6% increase of soil deformation was obtained for every percent increment in soil moisture content.; Simulation showed that increasing tire width was more effective at reducing soil compaction than increasing tire diameter. Soil deformation and soil stress at 2 cm depth were reduced on average by 13.0% and 5.2% respectively, when tire width was increased 7.7% from 10.8 cm to 11.6 cm. Only 6.6% and 3.8% reductions were obtained when tire diameter was increased 7.7% to 35.6 cm from 33 cm. The results suggested farmers to use wide tires rather than tall ones in order to effectively reduce soil compaction.
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