Traction Effects on Soil Compaction

Abstract

The problem of soil compaction has paralleled the growth in farm machinery size and mass. Compaction problems have been reported from virtually every form of mechanised agriculture in the world. This study examined the effect that the passage of a driven wheel had on soil compaction and the subsequent effect on crop growth. The parameters studied were vehicle mass, inflation pressure, the number of passes and wheelslip. Soil density readings were taken prior to compaction, immediately after compaction and prior to crop harvest. The individual plots were harvested with a combine harvester. Increasing the load, the inflation pressure of the tire, and the number of passes increased the soil density to a depth of 200 mm. After reaching a threshold tire load, an increase in soil density depended more on an increase in inflation pressure than on an increase in mass. The greatest amount of soil compaction occurred as a result of the first pass. Wheelslip appeared to be a surface phenomenon and any effect on soil density was removed by cultivation. Crop yield was dependent on soil density. The relationship was quadratic in nature with maximum yields attained when the soil densities reached a level equivalent to 10% air filled porosity at field capacity. The growth of the crop reduced soil compaction by approximately 50% of the original compaction.