Large pores decrease as a result of the rearrangement of soil particles and as points of contact between soil particles increase. Pore continuity decreases, which affects water movement through the soil, aeration of the soil and root growth. The amount of soil compaction depends on the initial soil water content, the number of passes and the soil condition. Water acts a a lubricant and facilitates particle movement. Under dry soil conditions less soil compaction occurs since there is less water to act as a lubricant and the suction of the water in small pores between soil particles can increase resistance to soil movement.
Subsequent passes result in less compaction.
To lessen the effect of traffic on subsoil compaction, manufacturers snould consider adding more axles to share the load, thereby reducing the load on individual axles. Using large diameter tyres will also reduce the compaction effect and improve mobility. To restrict soil compaction the adoption of controlled traffic is essential. The development of suitable guidance systems will greatly assist in trafficking the same laneway each time. Meanwhile the most obvious strategy to minimise soil compaction is to traffic soil under dry conditions and to minimise the number of passes over the area.