Minimizing the Impacts From Dynamic Vehicle Systems On Soil Conditions.

Minimising the impact from dynamic vehicle systems on soil conditions.

 

R. J. Godwin

 

This paper reports on methods and systems for reducing surface damage and soil compaction with the aim of sustaining agricultural production and the environment. Initially the paper considers the potential for novel ground drive systems, controlled traffic systems and alternative remediation options and then explores in more detail the results of a number of individual but interconnected projects that provide evidence on the relative benefits when applied to dynamic vehicle systems.

The results of the following of studies, conducted in both controlled laboratory conditions and the field, are related to the classical theory for soil vehicle systems. These consider the estimation of the true mean and maximum contact pressure using piezoelectric pressure matting and the distribution of the pressure below the soil surface both horizontally and vertically for a range of agricultural tyres. The vertical soil strain, rut depth and bulk density changes for a range of heavily loaded (up to 24 tonne/axle) vehicle systems indicate that the level of compaction in the upper layers of soil are similar between tyres and rubber belted tracks, but the depth to which compaction occurs is substantially less and hence easier and less costly to repair. Studies with the wheel systems of travelling irrigators working in pure sands indicate shallower rut depths and lower rolling resistance when the soil is at field capacity rather than in air-dry or saturated conditions. The impact of the effect of an annual cycle of vehicle traffic on the resulting subsoil pressure for a range of tillage systems show that as tillage depth is reduced the severity of the pressure transmitted to the subsoil is substantially reduced.

The adoption of controlled traffic systems to meet different agricultural practices is discussed together with the results of agronomic studies that show an improvement in crop yield. Which together with the benefits of targeted remediation (soil loosening) can be cost effective management practices.

The paper concludes by recommending that where possible:

1.       vehicle weights should be minimised by the use of new materials and design procedures,

2.       contact pressures reduced by the use of improved tyre/track systems,

3.       the wheel systems of should be designed in an attempt to more evenly distribute the load,

4.       field traffic should be controlled to given lanes, and

5.       repair to soil structural damage should be targeted.