No-dig gardening

No-dig gardening is an approach to cultivation favored by many organic gardeners. No-dig gardening was developed by Australian Esther Deans and became an important tool in the Permaculture movement.

Function

While digging can damage soil life, not digging can preserve it, but requires that we entice micro organisms to the surface where they will excrete and aerate the soil by burrowing to keep the dynamic relationship between surface and depth. Adding organic matter and weather protection can entice them to the surface: this is what no-dig gardening does.

Digging history

The primary reasons for digging the soil are to remove weeds, to loosen and aerate the soil and to incorporate organic matter such as compost or manure. In countries with thin soil and high erosion there is a strong case against digging, which argues that in the long term it can be detrimental to the soil's health. While digging is an effective way of removing perennial weed roots, it can also cause dormant seeds (some dormant seeds are decades old) to come to the surface and germinate. Digging can also damage soil structure, cause problems like compaction, and disturb and damage balances among soil life. Also, by exposure to the air, digging tends to use up nutrients which then need to be replenished. Digging is practiced traditionally in countries with deep rich, old soils such as Western Europe, however this is followed by the tradition of periodically resting the soil (fallow period). Digging allows farmers and gardeners to kill the micro organisms and use their bodies as fertiliser.

Methods

No-dig methods rely on nature to carry out cultivation operations. Organic matter such as well rotted manure, compost, leaf mold, spent mushroom compost, old straw, etc, is added directly to the soil surface as a mulch at least 2 or 3 inches deep, which is then incorporated by the actions of worms pulling it downwards. Worms and other soil life also assist in building up the soil's structure, their tunnels providing aeration and drainage, and their excretions bind together soil crumbs. No-dig systems are said to be freer of pests and disease, possibly due to a more balanced soil population being allowed to build up in this comparatively undisturbed environment, and by encouraging the buildup of beneficial rather than harmful soil fungi. Moisture is also retained more efficiently under mulch than on the surface of bare earth.

Another no-dig method is Sheet mulching wherein a garden area is covered with wetted paper or cardboard, compost and topped off with landscape mulch.

Converting to a no-dig system is easier than digging. It is a long term process, and is reliant upon having plentiful organic matter to provide mulch material. It is also necessary to thoroughly remove any perennial weed roots from the area beforehand, although their hold can be weakened by applying a light-excluding surface layer such as large sheets of cardboard or several thicknesses of spread out newspaper (overlapped to provide thorough cover) before adding the compost mulch. When using newspaper, avoid shiny, glossy paper (usually advertisements). These do not break down readily. The newspaper or cardboard should be thoroughly wet as well. A popular book, Lasagna Gardening by Patricia Lanza (Rodale Press, Inc.) provides excellent instructions for the novice user.

Benefits

No-dig is not a technique that is appropriate in all situations, but organic gardeners and farmers should at least consider minimizing soil-disturbing practices if they are to reverse soil damage and erosion.

No-dig gardening systems are strongly recommended by Dr. Shewell Cooper of the Good Gardeners Association. You can see a full description on how to make a no-dig garden at http://www.permaculturevisions.com/no-dig.html.

References

Deans, Esther (1977). Esther Deans' Gardening Book: Growing Without Digging. Harper and Row.
Deans, Esther (1994). No-Dig Gardening & Leaves of Life. HarperCollinsPublishers. ISBN 0-7322-7099-5.
Gillbert, Allan (2003). No-Dig Gardening. ABC Books. ISBN 0-7333-0941-0.