Jasper and Jarvis Dig the Field

Jasper and Jarvis spent the entire day digging up every last inch of soil. When Francesca came out to visit, her nephews wore big frowns. Have we really been digging in the wrong place? she asked. So until this puzzle is solved, we must find a way to keep the field safe. Some no good bandits might stumble across this field and wish to dig for treasure themselves. I say we cover the field with manure.