Sheet mulching your lawn is a great way to save water and create an area that can be planted with edible plants.  A quick lesson in sheet mulching your lawn:

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There are many ways to mulch, but the following is a very thorough way to approach creating great soil while providing a weed barrier and ensuring less evaporation from the soil. If you are getting rid of your lawn (by sheet mulching to build soil), you can simply cover it with cardboard (with no gaps – be sure the edges overlap!), hose down the cardboard, and then proceed with the following steps…

  1. First Compost Layer: Instigate microbial activity by adding enriched compost, chicken manure or worm castings at the rate of about 1 lb/2 square feet. This high nitrogen matter stimulates soil life. A soil analysis will indicate the need for adjustment of pH or mineral amendments to your soil. Ask your local nursery about appropriate amendments for whatever soil pH you have. Soak the compost layer before adding the next layer.
  2. The Weed Barrier: Put down an organic weed barrier to prevent the germination of weeds through your mulch. Underneath this weed barrier grasses and weeds die and quickly become food for earthworms. The worms will turn and aerate the soil, as they do naturally. The weed barrier has no natural counterpart on the forest floor because there is a lack of space and light. By planting an area properly, there will eventually be no room for weeds. The weed barrier is needed only for establishment of the mulch, and disappears with time. If your area is planted appropriately, weeds will not emerge after the decomposition of the weed barrier.
    Use wither 4-6 sheets of newspaper, cardboard, burlap bags, old rugs of natural fiber, worn-out jeans, gypsum board, or whatever you can find around. Banana, ape and ti leaves also work if laid down in several layers. Overlap the pieces of the material so as to completely cover the ground without any gaps, except where there are plants you want to save. Around these leave a generous opening for air circulation around the root crown.
  3. Second Compost Layer: This layer is on top of the weed barrier – it must be weed seed free. Well-conditioned compost, grass clippings, and leaves are ideal materials to spread over the weed barrier. This should form a dense layer about 3 inches thick.
  4. The Top Layer: Good materials for the top layer include wood chips, sawdust, bark, leaves, twigs and small branches, straw, etc.. This layer should be about 3-5 inches deep. The top layer will slowly decompose into lower layers, and therefore must be replaced periodically. When the soil is amended and sheet mulch applied properly, you will never need to turn the soil, as earthworms will do the work. Simply keep the soil covered by replenishing the mulch.

Mulching Around Trees

  1. Plant tree.
  2. Amend soil around tree in a wide ring shape from a few centimeters from trunk out to 1 meter (3 feet) with a light layer of nitrogen fertilizer, such as chicken manure, and other amendments if necessary. Rake or water in.
  3. Spread a layer of permeable weed barrier around the tree in a ring shape, leaving about 15 cm (6 inches) diameter around the trunk of the tree for it to “breathe.” Make certain there are no gaps in the ring shape through which weeds can emerge. Water the weed barrier layer thoroughly before the next step.
  4. Spread compost and/or mulch about 15 cm (6 inches) thick over the weed barrier, again making sure it is several centimeters away from the trunk of the plant.

The Ongoing Process

To make mulching as efficient and easy as possible, use mulch materials which are readily available. With good planning, mulching of gardens and orchards can become a regular part of maintenance-just mulch with handy materials such as grass clippings, plant prunings (chipped or roughly chopped), animal bedding, etc.. Eventually, other tasks such as watering, fertilization and weeding will be reduced. The overall maintenance burden in mulched conditions, when properly executed, is far less than in conventional systems.

Once a plant is properly mulched, its own leaf drop will constantly add to that mulch. But is natural leaf drop enough to maintain the mulch? The answer to this depends on the plant species and also how the plant is growing in relation to other plants. Certain trees produce tremendous amounts of leaf matter which decomposes rather slowly; examples are: avocado, macadamia, lychee, as well as many others. These trees can be expected to generate sufficient mulch for themselves once vigorous growth is attained. Unfortunately, under most conditions many trees do not create enough long lasting mulch for maintenance of their needs. To explain this apparent deficiency, look once again at the forest. Here, plants are “stacked” in the vertical direction in ground-level, middle, and tall vegetation. This means that the ground under each plant receives organic matter from several plants.

There are many ways to produce sufficient mulch at your site. Grass clippings, comfrey, various bunch grasses, nitrogen-fixing tree varieties, and other prolific producers of biomass work well. Also, many water plants such as water hyacinth are good mulch materials. However, many plants (like comfrey) can be invasive and more trouble than they are worth if not managed very carefully. Proceed with caution before planting something that may spread widely in your garden.