Sheet Mulching is simply a way to eliminate unwanted weeds in a given area, using a protective layer of recycled materials such as newspaper or cardboard, covering the area with seedless organic materials (such as wormcastings, straw animal bedding (usually has few seeds) or simply sawdust) for seedless soil or mulch to be gardened in (most often edible perennials).
While most people understand a lot about weeding and even more about tilling, not too many people think about the prospect of never weeding, or simply avoiding tilling all together.
Sheet mulching however, can both make life easier and replenish soil without ever using chemical fertilizers, weed kill or tilling.
There really isnt much to sheet mulching, just think like a really big cold pile that is going to compost itself overtime, turning all the weeds, seed and other organic matter under it, into a nutrient rich soil base, that built itself onsite, usually over winter.
First of all, mow down, roll over, stamp down, cut with a scythe or machete, and pile on all the kitchen scraps, doggy/kitty wastes or yard debris you can, mixing all those nitrogens and carbons as they come, mother nature knows how to tend it on her own with microorganisms and worms.
Then, over that, layer it with something that takes a long time to decompose and compost, like thick corrugated cardboard, newspaper (about ten sheets thick or so) or any recycled paper mattingmade specifically for sheet mulching, making sure to overlap about six inches between sheets, to be absolutely certain that none of those unwanted weeds/seeds and whatnot ever comeback in your grow bed.
Thirdly, backfill on top of your sheet with whatever organic mulch you wish, straw animal bedding with fewer or no seeds is great because it readily allows moisture and oxygen to accumulate, while sawdust or woodchips can also be wonderful, as long as this layer keeps out any unwanted weeds/seeds from seeping through, because if a single spot is missed, they will come back in force.
Lastly, simply place the plants in this mulch with enough soil to keep them healthy until everything breaks down (usually about six months or so is plenty of time), unless of course instead of mulch, worm castings or potting soils have been used in its place, in which case no extra soil is necessary, and there is also the risk of other kinds of seeds existing in this soil; so make sure it is seedless.
What is left within the year after sheet mulching? A raw boost of organic power that will supply your plants with enough food to last them years, and if they are the kinds of plants that search deep for more nutrients, they actually start to mend devastated soils.
Sheet Mulching video using a recycled paper product called ecocover in New Zealand as a barrier to cover the hard layer:
