TILLAGE EFFECTS ON RAIN-GENERATED WETTING FRONT MIGRATION THROUGH A GRISWOLD SILT LOAM SOIL

Information on the effects of different conservation tillage treatments on rain-generated wetting front migration (WFM) through layered soils is limited. In this study, conducted on a Griswold silt loam soil (Typic Argiudoll) formed in loess overlaying glacial till, the effects of three conservation tillage (CT) treatments: chisel (CH); no-tillage (NT); and till-plant (TP); were compared with conventional moldboard plowing (CN) on rain-generated WFM. Different rainstorm patterns (amount and duration) had different effects on WFM through soil profiles of the different tillage treatments. Irrespective of storm duration, wetting fronts were observed to migrate faster in CH and NT treatments during larger storm events (> 20 mm) but only in NT treatment during storm events > 5 and < 15 mm. Smaller rainstorms (< 5 mm) did not generate WFM in any of the four tillage treatments. Wetting front migration during storm events > 5 and < 15 mm did not advance beyond 15 cm depth in CH, CN, and TP, but were noted to the 64-cm depth in NT. Wetting front migration for larger storms were observed to pass the 75-cm depth in all treatments. However, NT (with conductive micropores) saturated much quicker than the other treatments, suggesting that it might generate as much runoff as CN and TP, but more than CH (which had enhanced infiltration owing to its conductive macropores) during large storms.