INFILTRATION CHARACTERISTICS OF RESIDENTIAL LAWNS

Sixty-minute, constant-intensity simulated rains were applied to seven infiltration treatments designed to evaluate the influence of strippi ng and compaction on home lawns. Three treatments simulated home lawn construction practices. The control treatment was undisturbed, the ''s tripped'' treatment had the topsoil removed and replaced, and the ''co mpacted'' treatment had the topsoil removed, the exposed surface compa cted and the topsoil replaced. All plots were rototilled and raked bef ore sodding to establish the grass. In addition, stripped and compacte d treatments were identified and tested on a 6- and a 12-year-old lawn . All treatments were replicated six times. The K and lambda = n psi na parameters in the Green and Ampt infiltration model were fitted to the cumulative infiltration data far each replication of each of the seven treatments. The time, t(r), when runoff began was recorded for e ach replication. The treatments generally divided into three groups. T he most rapid infiltration occurred on the newly constructed control a nd stripped treatments (K = 85 mm/h), though the shape of the infiltra tion response and the time to the start of runoff were quite different The slowest infiltration occurred on the newly constructed and the 12 -year-old compacted treatments (K = 33 mm/h). The reduction in infiltr ation into the compacted layer could still be seen 12 years after the compacted layer was developed even though there was a trend toward fas ter infiltration with age. An intermediate infiltration response occur red on both the 6-year-old stripped and compacted lawn and the strippe d portion of the 12-year-old lawn (K = 54 mm/h). The reduced infiltrat ion into the compacted layer in the 6-year-old lawn was attenuated by repeated aerations.