First popularized back in the 1970s, “lasagna gardening” involves piling up thick layers of cardboard and uncomposted kitchen scraps on top of (sometimes) double-dug soil. The practice is touted as a way of removing lawns and improving soil with little work.
Linda Chalker-Scott, Extension Urban Horticulturist at Washington State University, proposes a vastly simpler version of lasagna gardening. Chalker-Scott suggests skipping the double digging, cardboard and kitchen scraps. The double digging disrupts soil texture, the cardboard interferes with water penetration (I know this from experience) and the kitchen scraps create a plant nutrient overload. Instead Chalker-Scott suggests simply a very thick layer of mulch–12 inches.
Mulch is often free, as many cities give it away, and it does wonders for the soil. Mulch, in fact, breaks down into soil, retains moisture and creates habitat for earthworms.
Read more in Chalker-Scott’s post, “Is lasagna gardening really worth the effort.“