Survey of moisture distribution between tile drainage laterals and its relationship to compaction and rooting depth in flat clay soils
Three tile drained farms on flat, poorly drained Brookston clay soil in northern Essex County were studied with respect to soil moisture distribution between drainage laterals and its relationship to compaction, root growth, crop development, and yields. The survey type study was carried out under uncontrolled conditions in order not to interfere with the cropping program and schedule of the three farmer cooperators. No significant increase in soil density (and hence compaction) was observed on one farm which had tomatoes in its rotation the year before the study. Mean dry densities were lower on this farm than on the other farms studied.Information from this study suggests that a soil moisture content of 20% represents optimum conditions for soil compaction on Brookston clay, and that agricultural equipment and implement traffic should be avoided at or near this moisture content, if possible. It was noted that soil moisture contents at harvest time are generally below 20%. Therefore, harvesting equipment and loaders for intensive cropping (tomatoes) should not pose a soil compaction problem on Brookston clay soil, unless there is a wetter than normal harvesting season. Marked soil cracking was observed on all farms during the summer months. Principally because of these cracks, summer rains percolate very quickly below tile drain invert level. This tendency for relatively quick drainage during summer months is felt to be limiting adequate wetting of the root zone, and may also be contributing to undesirable removal of soil nutrients. Due to the small number of farms and the overview scope of this study, firm conclusions could not be drawn for all parameters studied. Some observed trends require confirmation through further specific dedicated research, under controlled conditions, as outlined in the recommendations given in this report.