Chapter 20 - Benefits of Limited Axle Load

Abstract

Many farm vehicles have high weights and axle loads. Unless the ground contact pressure is extremely low, this leads to high stresses and detrimental compaction in deep subsoil layers. Repeated passes cause cumulative effects. Subsoil compaction is very persistent, maybe permanent, and loosening can only partly alleviate the effects. In field experiments, vehicles with high axle loads have reduced crop yield for decades and caused detrimental environmental effects. Therefore, subsoil compaction is an urgent soil conservation problem, and the axle load of off-road vehicles must be limited. This means that heavy machines must have many axles and wheels. In the former U.S.S.R., a State Standard was adopted for agricultural vehicles concerning maximum ground contact pressures and stresses exerted in the subsoil. In some other countries, recommendations concerning upper limits on the axle or wheel load have been developed. Subsoil compaction can also be reduced by the use of suitable tyres and light-weight vehicles, the combination of field operations, a good organization of the field traffic, many entrances to the fields, a suitable field geometry and special transport lanes. Most of these measures would also considerably reduce topsoil compaction.