How to Build a Healthy Soil Community
By Tammi Hartung | Oct 21, 2020
Make beneficial wildlife part of your food-garden ecosystem. Tammi Hartung shares her successful methods for attracting pollinators, nourishing soil and deterring pests in The Wildlife-Friendly Vegetable Gardener (Storey Publishing, 2014). Learn how to build healthy soil in the following excerpt from “Encouraging Friends from the Underground.”
Purchase this book from the GRIT store:The Wildlife-Friendly Vegetable Gardener.
How to Build a Healthy Soil Community
How you choose to prepare the garden for planting will have an impact on the soil community, so it’s worth putting some careful thought into how you’ll proceed. If you have very compacted soil where you plan to put your garden, you’ll definitely need to use a more aggressive method to prepare it, such as double digging or rototilling. If you can accomplish your garden preparation using a no-dig method, however, you won’t disrupt the structure of the soil community, which will allow your plants to benefit more immediately from all the positive attributes soil-dwelling creatures have to offer.
Once the initial soil preparation has been completed, it’s equally important to keep the soil in good condition. Preventing soil from becoming compacted is crucial to how well and how quickly your plants will establish themselves and grow. Ensuring that your garden soil maintains a good level of organic matter will not only support the plants living in that soil, but will also foster the creatures and microorganisms that live in the soil as well. To that end, providing adequate moisture is something every gardener must have a plan for. Finally, mulching helps keep precious water in the soil, and smothers weeds at the same time.
Work the Soil Gently
Keep in mind that aggressive soil disturbance will cause damage or destruction to the soil community that may take a very long time, sometimes many years, to repair itself. Because of this, it’s wise to carefully consider how you’re affecting the soil when you prepare your garden beds.
Some gardeners feel that double-digging the soil when the garden is first prepared is the best way. This process — which involves digging a trench, placing the soil off to the side, then digging a second trench and filling the first trench with the topsoil from the second trench — may be helpful for dealing with compacted soil, but it also ends up inverting the layers of soil structure and puts organisms used to dwelling in the topsoil layer down in the subsoil.
Other gardeners prefer to use a rototiller to create new planting areas. A rototiller (i.e., an engine-powered tiller with rotary blades, or tines) is handy for preparing soil that has never been worked or has not been worked for a very long time. It saves time, not to mention wear and tear on your body. Rototiller tines typically do not work the soil as deeply as double-digging does, but rototilling does an acceptable job of breaking up soil so that it’s easy to work. You can also spread a layer of compost over the top of the soil about 1 inch deep and mix the compost into the soil as you till.
One word of caution, though: Frequent rototilling can damage soil structure that may have taken years to develop and that is essential for good drainage. Once I have done the initial preparation for a new garden space, I rarely ever till again. I do not want to disturb the healthy soil community of beneficial microorganisms and creatures, such as earthworms.
Using the No-Dig Method to Preserve Soil Structure
Another method of soil preparation — one less aggressive than both double-digging and -rototilling — has gained popularity in recent years: the no-dig method. For this technique, the soil is not dug deeply or turned over, and no tilling is done. Indeed, the only disturbance that happens to the soil comes from planting and weeding. Those who practice the no-dig method believe that an established, well-ordered soil community is functioning at a high level of good health and will support all the creatures and plants that live in that soil, both above and below the surface. After observing the health of my garden since I began using this approach several years ago, I’ve decided it makes the most sense for me.
I do disturb the soil as I am planting or weeding, but not aggressively, and no more often than is really needed to keep the garden in tidy order. I top-dress my soil with composted organic matter that earthworms, ants, and other organisms will mix into the soil for me. Some of the compost will soak into the soil with snowmelt, rain, or watering.
Avoid Compacting the Soil
In an ideal world, you should avoid walking on the soil where your plants are growing. Practically speaking, however, some gardening or harvesting tasks will require you to step in the bed where the plants are growing, so your garden should be designed to minimize soil compaction.
There are many reasons to avoid compaction. With dense soil, plants have difficulty establishing a strong root structure that can range far and wide to extract nutrients. The root structure also supports the portion of a plant growing above-ground. Water cannot easily soak into compacted soil, leaving plants under-hydrated and starved of waterborne nutrients. In addition, the soil community of microorganisms and other beneficial creatures will struggle if the soil they live and work in is hard-packed.
Provide Organic Matter
Organic matter is essential for maintaining soil health and integrity. It provides nutrition for the many kinds of wildlife that live in the soil, which, in turn, provide nutrition for the plants (when they excrete). Organic matter also keeps soil loosened up so that plants can form deep, strong root structures to support themselves. Keeping the soil stocked with organic matter will also help it soak up and retain moisture, like a sponge.
Organic matter can be compost, chopped leaves, and aged animal manure. You can till leafy green cover crops such as oats and winter rye into the soil as another excellent way to build up good levels of organic matter. Compost made in your own pile or barrel is a fantastic way to bring organic matter into the garden soil.
You can tell if soil is on the right track of having enough organic matter by its consistency. Take a handful of slightly moist earth and squeeze it into a fist. When you open your hand, the soil should crumble between your fingers rather than forming a tight ball. If you have sandy soil, this test may not work well, but you can still inspect the soil in your hand to see if it contains bits and pieces of composted material mixed with the sand.
You should strive for 4 to 5 percent organic matter. If you want to know the exact amount of organic matter present in your soil, pick up a soil sampling kit from your county extension office, follow its instructions on how to take a soil sample, and then take or send the sample to the extension office to have it tested. Be sure to write on the soil sample that you want it tested for the amount of organic matter present.
Maintaining abundant levels of organic matter in the soil is an ongoing process; it will never be a completed task. New areas in the garden may not have very much organic matter in the soil until you start to add it each year. Mix it into the soil during the initial garden-soil preparation, and then supplement with maintenance applications from that point onward. Once the garden is prepared and established, add your compost as a topdressing annually at the beginning of the growing season. It will soak in and nourish the soil as the garden is watered. In this way you will be building healthy soil and replenishing the organic matter as it gets used up by the tiny organisms that convert it to plant nutrients.
If your soil is sandy, if you garden in a hot climate, or if your soil seems to be low in organic matter, spread a second topdressing of compost at the end of the growing season. This extra application will break down over winter, when not much active growing is taking place. Even in regions where the climate allows for year-round gardening, the garden’s natural cycle slows down a bit in winter. As the garden soil approaches that ideal mark of 4 to 5 percent organic matter, you’ll see the evidence of it in how well your garden is growing and in the good yields you get from your food and herb plants.
More about garden health: Read another excerpt from The Wildlife-Friendly Vegetable Gardener in Beneficial Insects: Get to Know the Good Garden Bugs.
Excerpted from The Wildlife-Friendly Vegetable Gardener by Tammi Hartung, illustrations (c) Holly Ward Bimba used with permission from Storey Publishing. Purchase this book from our store:The Wildlife-Friendly Vegetable Gardener.
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