TILLAGE AND WHEEL TRAFFIC EFFECTS ON RUNOFF AND SEDIMENT LOSSES FROM CROP INTERROWS

The influence of wheel traffic on soil surface runoff and sediment losses under cropping conditions in the northeastern USA has not been previously addressed. A study was initiated to evaluate potential interrill runoff and sediment losses from wheel-tracked and non-wheel-tracked interrows of Glenelg (fine-loamy, mixed, mesic Typic Hapludult and Mattapex (fine-loamy, mixed, mesic Aquic Hapludult) silt loam soils under conventionally (CT) and no-tilled (NT) continuous corn (Zea mays L.) at Piedmont and Coastal Plain locations in Maryland. Rainfall was randomly applied at 76, 94, and 120 mm h-1 intensities for 30-min duration storms representative of storm return frequencies of once every 2, 5, and 20 yr, respectively. Runoff from 0.76-m2 interrow areas was collected over time and evaluated for sediment load. Runoff from the CT soils was consistently greater than runoff from the NT soils. Sediment losses from the CT soils were as much as six to seven times greater than the losses from the NT soils. Wheel traffic applied with an axle mass of <4.5 Mg had minimal effects on runoff and sediment losses from the CT and NT soils. Wheel-tracked interrows displayed a pattern of greater sediment losses for the Piedmont CT soils, but this pattern was reversed for the Coastal Plain CT soils. The differences in sediment losses between the two sites were relatively large. The larger sediment losses at the Coastal Plain site could be partially attributed to the Piedmont site having twice the clay content of the Coastal Plain site in the surface layer.