Sheet mulching is like conducting a large-scale science experiment in your yard. Or, like making a giant batch of lasagna—except with ingredients you’d find at the hardware store or in the trash. Plus, it’s probably less complicated to put together than a layered casserole or a sixth grade science fair project.
About two years ago, Shelley Brant and her husband decided to make a change.
“We took out our lawn and covered it in sheet mulching in order to turn it into a vegetable garden,” Brant recalls. When they first moved into their Sparks home, they landscaped it with grass, trees and gravel, but after a few years realized the gravel created too much heat. They removed all of the hard landscaping from the yard. The soil underneath those areas was essentially dead, so they turned to sheet mulching to help repair the soil.
Brant, who is a member of Permaculture Northern Nevada, is interested in bringing permaculture to this region. Permaculture is a self-sustaining form of agriculture that mimics natural ecological systems.
“If you are going to water it, it should serve some purpose,” says Brant. Especially in the desert.
Sheet mulching is the first step in establishing a permaculture. The primary reason for doing it is to create a thick layer of high quality soil that essentially anything will grow in. If you are interested in replacing your lawn, the big advantage of sheet mulching is that you can do it right on top of the grass. If you start the process of sheet mulching over lawn, then the lawn will be the first layer in the organic sandwich. You can even do this in the winter when the grass isn’t green. It also works on garden areas and is a good way to build up the soil.
What follows is the ideal scenario for sheet mulching. However, it will work even if you don’t follow these directions to the letter—it just might take a little longer to produce results.
To start, lay down some sort of nitrogen base layer. Manure from any kind of herbivore (horses, cows) or from chickens works well. You can also use alfalfa pellets. The manure should be dry when you lay it down. Then, put a layer of cardboard on top of that. Any cardboard from packaging and boxes will do. The next layer is another coating of manure—this time, it should be about two to four inches thick, the more the better. To top off the strata, place 10-12 inches of wood chips over the second layer of manure. The wood chips you use should be bark and heartwood (the entire tree). Then add water.
The Brants started their sheet mulching in March of last year. They got all of the materials for free: A friend donated llama manure to the cause, they found cardboard around town, and they received wood chips from a local arborist. They watered the mulching twice a week, much like their lawn, from March through July. Brant admits, “We were actually watering a bit more the first year than we did the lawn. This year we anticipate it will be significantly less.”
Then, the worms come. They are attracted to the nitrogen and eat through the first layer closest to the earth. Then, they eat through the cardboard to get to the other layer of nitrogen above that. “The worms just show up with sheet mulch,” says Brant. “This year, if you dig down underneath the layer of wood chips, you see black, chunky soil.”