[reposted from Earth Science since more relevant here]
I am at a farm where previous tenants left a non-biodegradable plastic film roughly 10-15 years ago. It is inconsistently spread over a few acres and was not discovered until we attempted plowing the fields. The fields are overgrown with weeds (grasses, thistles, small shrubs, etc.) about 1m tall and this growth has fragmented the plastic considerably (see image, left). The plastic must be removed in order for food to be safely grown there, and to meet the organic standards of the farm. The fragments are in a wide range of sizes and easily breaks when handled.
What method and equipment (such as an excavator) would best remove the plastic and top layers of soil, with minimal damage to the remaining soil (i.e. minimal degradation)? What types of remediation could help deal with microscopic remnants of plastic?