Infiltration of Soils as Affected by the Pressure and Water Content at the Time of Compaction

Abstract Infiltration rates, volume reduction, and bulk densities of soils were determined on soils as a function of compacting pressures and water content at the time of compaction. Maximum compaction generally occurred when the soils were packed at water contents near field capacity. When compacting loads were < 1 kg/cm 2 the minimum bulk densities occurred when soils had water contents of about one half field capacity, indicating that surface tension of water films in the soils plays a major role in cohesiveness and stabilization against compaction under these conditions. Compacting loads of 3.46 kg/cm 2 , at field capacity on sandy loams and finer textured soils, reduced infiltration rates to < 0.1% of values obtained after these soils had been compacted when they were air dry. In a loamy sand soil this reduction was to about 1%. The low infiltration rates following compaction were increased by wetting and drying, although several cycles of wetting and drying did not raise the infiltration rate to the level observed before packing. Freezing and thawing cycles also increased the infiltration rates of previously compacted soils. Most of the change took place in the first freezing and thawing cycle. The large changes in infiltration rates using achievable levels of compaction at the “optimum” water contents indicate that compaction can play a major role in the management of water in ditches, reservoirs, furrows, and watersheds.