Small particles slip between the larger particles, filling the pore spaces. Loose soils will compact more than tight soils, and soils that have a broad range of particle sizes can be more severely compacted than more uniform soils. Few soils can withstand traffic without becoming severely compacted. Compaction depends not only on the amount of pressure exerted, but also on the duration and frequency of exertion. Pressure spreads with depth, so the compacting effects of pedestrians and vehicles usually occur to the top four inches of the soil.
Compaction is easier to prevent than to remedy.
Avoid cultivating wet soils. Keep foot and vehicle traffic over the roots to a minimum. Where traffic is necessary, confine it to a few paths that stay well away from the driplines of trees. Light-weight vehicles with large, smooth, low pressure tires compact the soil less than heavy vehicles with smaller, heavily treaded, high pressure tires. A thick, coarse mulch spread on the soil surface where travel must occur helps to disperse the load.