Prevention strategies for field traffic-induced subsoil compaction: a review: Part 1. Machine/soil interactions

Subsoil compaction is a severe problem mainly because its effects have been found to be long-lasting and difficult to correct. It is better to avoid subsoil compaction than to rely on alleviating the compacted structure afterwards. Before recommendations to avoid subsoil compaction can be given, the key variables and processes involved in the machinery–subsoil system must be known and understood. Field traffic-induced subsoil compaction is discussed to determine the variables important to the prevention of the compaction capability of running gear. Likewise, technical choices to minimise the risk of subsoil compaction are reviewed. According to analytical solutions and experimental results the stress in the soil under a loaded wheel decreases with depth. The risk of subsoil compaction is high when the exerted stresses are higher than the bearing capacity of the subsoil. Soil wetness decreases the bearing capacity of soil. The most serious sources of subsoil compaction are ploughing in the furrow and heavy wheel loads applied at high pressure in soft conditions. To prevent (sub)soil compaction, the machines and equipment used on the field in critical conditions should be adjusted to actual strength of the subsoil by controlling wheel/track loads and using low tyre inflation pressures. Recommendations based on quantitative guidelines for machine/soil interactions should be available for different wheel load/ground pressure combinations and soil conditions.