Benefits and Detriments of “No-Dig” / “No-Till” Methods
“No-dig” or “no-till” methods date back centuries but have been increasing in popularity in recent years due to their simplicity and effectiveness. In fact, “no-dig” or “no-till” beds have so many benefits that it makes sense why they’re becoming a favorite of gardeners everywhere. While it’s true they don’t yield the same health and production as some other top-notch methods, like double-digging and spading, for especially deeply-rooted crops, they are much easier and work well enough, and just as well for lettuce, spinach, and others, that most gardeners will be thrilled with their plants’ health and production. Like any method, they have their possible detriments, but most of these stem from one particular site preparation technique and are easily solvable. All in all, “no-dig/till” methods provide gardeners with an incredible additional tool in their toolbox, especially one that allows them to start growing in an area even while smothering the existing vegetation.
Benefits
Doesn’t disturb the structure of the soil or soil life. Soil naturally develops structure—a combination of cracks, holes, and clumps of soil aggregates that create pore space. Healthy soil is 50% pore space filled equally with the air and water plants’ roots need to thrive. Healthy garden soil is also absolutely filled with soil life. Earthworms tunnel and eat organic matter, leaving nutrient-rich castings, in their wake. Stag beetles, sow bugs, spiders, and many other arthropods form an intricate food web. Tiny microbes break down organic matter and slowly release the perfect kinds and proportions of nutrients for your plants. And fungi transport minerals to plants in exchange for carbohydrates through a densely filigreed network. Tilling breaks up much of the soil structure and disturbs or kills at least some of this soil life. With the possible exception of burying some aerobic microbes too deeply, a “no-till” approach keeps all of these completely intact.
Doesn’t bring new weed seeds to the surface. Since many weed seeds stay viable in a dormant state in lower levels of the soil for years or even decades, most garden soil is filled with an almost incalculable number of weed seeds. Freeze-thaw cycles, erosion, tilling, and other cultivation are the mechanisms that bring new batches of weed seeds to the surface, where they’re finally triggered to germinate by the changes in temperature, moisture, oxygen, and/or light that break dormancy and signal they’ve finally found a suitable place to grow. One great advantage of a “no-till” or “no-dig” approach is that it avoids bringing weed seeds to the surface through tiling and other forms of cultivation. Plus, each method specifies adding additional materialon top of the soil—cured compost, mulch, piles of composting materials, or straw bales—further burying weed seeds, and continually adding to this depth each year—with more cured compost, mulch, or new straw—wise practices no matter the method used.
Adds crucial organic matter to the soil. Ideal garden soil is about five percent organic matter, which is largely responsible for the health of our soil and contributes the macro-and micro-nutrients our plants need for healthy and productive growth. Most of us, however, have soils that are far below this ideal. All “no-dig/no-till” methods add organic matter to the soil, and some of them, namely adding 6″ of compost and lasagna gardening, add about the maximum amount one should add initially, and then annually add just the right amount to get our soil back to that ideal five percent. Even if I were still gardening in several feet of rich, black, hummus-filled, midwestern loess and prairie soils—to which adding six inches of compost on top seems like dropping a swimming pool’s worth of water on a Lake Superior—I’d still be adding organic matter just to constantly replenish what my garden plants are using. It’s good to give back.
Allows a gardener to use the garden space of a prospective bed while the vegetation underneath is being smothered. If you’re smothering existing vegetation or sod during the growing season, you can use a preparation technique for these methods that allows you to grow vegetables in that spot at the same time (See “Option 2” in “Clearing Existing Vegetation for ‘No-Dig’/’No-Till’ Beds”). It has some significant downsides, discussed below, but even otherwise deeply-rooted garden plants do surprisingly well growing in 6″ of added compost or lasagna methods used on top of this preparation technique.
Most plants grow well. While you might not get the massive growth in tomatoes, peppers, and larger brassicas (broccoli, cauliflower, and cabbage) that you do from methods like double digging, garden plants do quite well in this method. And with plants like lettuce and spinach, you might not notice any difference at all.
Possible Detriments
Before you build a “no-dig/till” bed, it’s best to rid the area of its existing vegetation, so it doesn’t grow through your “no-dig/till” bed’s materials and become a weedy headache. One technique for doing this is to smother the vegetation under a five-to-ten-sheet layer of wetted newspapers laid down before the material of the “no-dig/till” bed—the cured compost, layers of composting material, mulch, or straw—is added. The first three of these detriments apply only to this preparation technique.
Not enough space for roots. If you smother the vegetation while building the bed, the layer of newspapers used to smother vegetation is more or less impenetrable by roots and shoots, and it takes months to break down to a more penetrable state. This is why it works so well to smother the existing vegetation. However, this same benefit of smothering weeds and sod gives your plants only the relatively thin added “no-dig/till” bed material (e.g. six inches of added compost) in which to grow most if not all of that first gardening season, keeping your plants from rooting as deeply as they otherwise would. Since, our garden plants have tremendous root systems, much bigger than we typically imagine, reaching four feet deep or deeper in their search for water and nutrients, even six inches in nowhere near the depth to which they usually grow, significantly limiting their ultimate potential for maximum health and production.
START EDIT: Most garden plants have large root systems, many reaching four feet or more deep and several feet wide. Loosened soil makes it much easier for these extensive networks of roots to expand to the depths and breadths need to find the necessary water and nutrients to fuel healthy planst and massive production. Even though traditional “no-till” and “no-dig” methods don’t loosen the underlying soil at all, most garden plants still do remarkably well due to the fact that their literally growing in pure cured compost. as deeply as methods like double digging, spading/forking, or even mounding tilled ground so plants are quite as healthy or productive maybe not as well as in double dug or spaded beds with even four inches of compost added but they grow remarkably well
Tends to compact the soil if use newspaper layer. What’s more the soil underneath newspapers or cardboard ends up quite compacted. We first noticed this when feeling the digging fork jar our hands repeated while harvesting potatoes at the end of a bed’s first year. Curious, we dug down and were surprised to see most of the wetted newspapers intact, some even readable. Wondering how it would fare over time, we tested again at the end of the next season, and the soil was still significantly compacted under the compost. It was as if the newspaper layer acted as a big snowshoe holding all of the weight of the compost above and compacting everything underneath it enough that it still hadn’t recovered by the end of the second year.
Dries out quickly. Cured Compost dries quickly. Plus, if a layer of newspapers or cardboard is used to smother the existing vegetation, the compost is cut off from the wicking action of water upwards from the water table. Both of these lead to gardeners having to water more often.
Is that much compost sustainable? I don’t know, but while there are relatively few of use looking to add it to our soils and it’s relatively inexpensive and easy to get or make, add as much of it as possible to get your soil back to five percent organic matter.
