double-digging n.— «The two have employed a practice called “double-digging,” which involves digging up the top foot of soil, tilling the bottom part of the soil underneath and then replacing and tilling the top foot.» —“Yard Farmers: DeKalb...
volcano mulching n.— «I have seen some landscapers use very deep layers of mulch—a foot or more in tight rings around trees and shrubs. Is this a healthy practice?…This is sometimes called volcano mulching because of the steep sides and hollow...