Observations of the reduction in surface artifact frequency as a result of multimodal plowing

Abstract The frequency and distribution of plowzone artifacts are compared with the timing and duration of two plow modes at two study locales on the Delmarva Peninsula, United States. Our results indicate that historic moldboard plowing created a maximum plowzone of ca . 0.30 m, in which artifacts were retained over time. Later, soil‐conservative chisel plowing mixed the top ca . 0.15 m of soil, creating a shallow, minimum plowzone. With time and repeated plowing, our data suggest that the number of artifacts at the surface diminished via a combination of vertical mixing and/or degradation, physical and chemical weathering, and avocational collecting. When moldboard plowing is reapplied to fields after decades of chisel plowing, the historic maximum plowzone is inverted and the surface is re‐saturated with artifacts. This inverted maximum plowzone retains an inherent pattern of artifact transport from moldboard plowing, which supports other studies that have measured such displacements over time. Our results suggest that the frequency of artifacts observed at the surface of agricultural fields, or lack thereof, is a likely outcome of natural and mechanical processes, and removal within the minimum plowzone. This inevitable depletion of artifacts may have negative repercussions for many research designs that systematically sample the plowzone.