Natural Soil Building and Amendments for Gardens
Soil – the gardener's most valuable resource is right under our feet. It is wisely said that a garden will thrive when the caretaker ceases to nurse the plants and focuses on tending to the soil. A garden that is grown on the foundation of fertile soil will be more bounteous, have increased resistance to pests and disease, and, perhaps most importantly of all, will be stocked with abundant nutritional value.
The importance of building healthy soil cannot be overstated; the health of the soil is directly responsible for the vitality of the plants that are growing in it. Building soil is an ongoing process, one that will be successful if we understand the five components of healthy soil, and how to keep them active and in balance.
Building healthy soil does not happen overnight. But with patience and good practices, a gardener can create a living soil that holds water, cycles nutrients, prevents disease and supports the growth of healthy, nutritious plants. Here are some ways to build soil and keep it healthy.
1. Understand the Components of Healthy Soil
The first, and perhaps the most obvious ingredient is dirt, which is granulated rock that contains many of the micronutrients and minerals that are necessary to plants. The second ingredient, organic matter, consists of fallen leaves, sticks, mulch and other decomposed materials that turn plain dirt into soil and give it a fresh, earthy smell.
In order to sustain plants, soil also must contain the third and fourth ingredients, which are air space and water. When soil becomes compacted, air spaces collapse and plant roots are smothered and stunted. Water carries nutrients and supports life; not only plant life, but also other organisms that live in the soil.
The fifth component of healthy soil is the presence of these living organisms, both visible and microscopic. Though mentioned last, they may be the most vital component of all. Without the presence of worms, bugs, bacteria and fungi, it is impossible for a garden to flourish. But when these organisms are in balance, nutrients are made available to plants, disease organisms are kept in check, and the plants themselves are tastier and more nutritious to eat.
2. Avoid Damaging Cultivation Practices
Two of the most damaging common practices are repeated tilling and the use of chemical fertilizers and pesticides. Though tillage and the application of chemical fertilizers, fungicides and pesticides promise a quick remedy to a troubled garden, repeated use damages soil life and encourages dependency on such practices. In effect, the productivity of the garden is sustained by commercial products and fossil fuels rather than by the free energy of the sun and the soil food web. This is costly to the health of the plants, to the planet and to the gardener’s budget.
When starting a brand new garden, tilling with a shovel or rototiller may be necessary in order to remove weeds, loosen soil and incorporate organic matter into the garden bed. But once the garden is established, repeated tilling may damage the soil food web. When you add organic material to a garden bed and begin to water it, the soil comes alive with macro- and microorganisms that feed on the materials. These organisms begin to multiply rapidly, aerating and enriching the garden soil. Undisturbed soil teems with microorganisms and larger creatures, such as earthworms, which aerate and enrich the soil. Tilling can disturb or even destroy this complex ecosystem, collapsing tunnels and damaging the structure of the soil. Additionally, tilling disrupts the immense networks created by bacteria and fungi that enable beneficial, symbiotic relationships with plant roots.
Chemical fertilizers and pesticides are also detrimental to the soil food web. When a chemical fertilizer is repeatedly applied, plants are not motivated to form beneficial relationships with bacteria and fungi, and the food web populations begin to dwindle. Without these beneficial relationships, the plants are less able to obtain water and nutrients, causing them to become dependent on high applications of fertilizer and water. The plants weaken, becoming less and less tolerant of nutrient and water shortages, and the garden suffers unless both are continually supplied.
Additionally, when there is no longer any organic material for beneficial organisms to eat, they may become outnumbered by the pathogenic organisms that feed on the plants themselves. This problem is compounded by the use of pesticides that kill beneficial insects as well as pest species.
3. Add Organic Material: Compost
Compost is decomposed organic materials that are tilled into the soil at the establishment of a garden, and regularly dressed to the top of the soil as a mulch. The addition of compost to the garden is a food source that attracts beneficial soil life. Compost breaks down quickly in the garden, and must be reapplied several times each year, so many gardeners choose to make their own compost in order to avoid purchasing and transporting bagged products. It is very easy to create healthy compost, and there are many tutorials online that will show you how to do it.
4. Add Organic Material: Manure
Manure is another organic source of nutrient for the garden. When applied to the soil, it feeds the microbes, which in turn, feed the plants. It is recommended that, if manures are used in the garden, they be composted first in order to decrease pathogenic organisms and break down nitrogen into forms that are readily available to plants. Fresh manures may contain too much nitrogen, which kills seedlings and over-activates soil microbial activity causing the nutrients burn up before plants can use them. Additionally, fresh manures may contain weed seeds that can germinate in your garden.
Manures can carry human disease pathogens, such as E. coli, Listeria and Salmonella. To reduce the danger of introducing pathogens to our gardens, refrain from using any manure produced by a carnivorous animals. Instead, apply manures produced by herbivores, such as cows, horses, goats, rabbits and pet rodents. Manures should be applied after vegetables have been harvested, prior to planting the garden out for the next season, at least 120 days prior to your expected harvest. Once the garden is established and plants are in production, amending the soil with manure is ill advised.
Despite the risks, which are minimized by safe practices, manures are an excellent and inexpensive soil amendment that turns waste, a potential pollutant, into a valuable resource in the garden.
5. Grow Green Manures
The term green manures refers to cover crops that are planted to add biomass to the soil when a garden or field is not in use for growing market crops. Some green manures are also grown between crop rows during the growing season, which is called intercropping or interplanting.
Cover crops perform several functions: to cover the soil, block weeds, prevent erosion, and maintain soil moisture, while adding organic matter and nutrients to the garden. Grasses, grains, and legumes are employed, some of which grow long roots, pulling up nutrients from deep in the soil and making them available to plants with more shallow root systems. Others attract beneficial insects or fix nitrogen in the soil. Cover crops are cut and composted or turned directly into the garden bed at the end of the season.
6. Apply Mulch
Mulch is organic materials that are applied to the top of the soil, like a blanket. Compost, bark, wood chips, straw and hay are common mulching materials. Almost any organic material can be used as long it is large enough to stay relatively immobile, will break down slowly and is nontoxic. The application of several inches of mulch helps a garden in many ways. The materials provide the soil with protection from erosion and temperature extremes. Mulch slows water down, reducing runoff and increasing the amount of moisture that is absorbed by the soil during rain or irrigation. Additionally, mulch aids in nutrient and water retention, decreasing the evaporation rate of moisture and nitrogen.
Mulch breaks down over time, adding organic matter to the ground and feeding the soil food web. Worms and bugs come up to the surface to eat the materials, and subsequently transport them down into the earth where microbes and plants can use them. Be careful not to pile mulch up around plant stems or it may have a smothering effect. Additionally, when growing plants from seed, a thin layer of mulch material may be helpful to hold seeds down and retain moisture. But avoid burying seeds under a thick layer, especially small seeds that usually need light to germinate.
7. Rotate Crops
Crop rotation is a method of systematically moving crops around in the garden from one year to the next. Plant families have different nutritional needs; some are heavy feeders that deplete nitrogen and phosphorus, and others are light feeders. Legumes (beans and peas) add nitrogen to the soil, so it is helpful to follow them with plants that use nitrogen heavily, like tomatoes or corn.
Crop rotation can also help to decrease plant disease and pest problems. Some diseases persist in the garden and many pests overwinter in the soil, and planting varieties that are susceptible to them in the same place very year invites trouble. By rotating crops around, the gardener removes the food source from the area that attracts the pathogens or pests, thereby discouraging their proliferation.
A three- or four-year rotation is recommended to effectively deter diseases. One common rotation schedule is as such: beans, greens, fruits, roots. In a simple rectangular garden, the area can readily be divided into quadrants with plants rotating clockwise around the bed.
While this model is simple and helpful, a familiarity with botanical plant families will help the gardener avoid mistakes. For example, though tomatoes are a fruit and potatoes are a root, they are actually members of the same plant family, Solanaceae, and are susceptible to the same fungal diseases. Without this knowledge, the gardener may inadvertently plant one following the other. If disease pathogens are present, both crops may fail.
There are many methods of crop rotation that can be found in gardening books and on the web, so do a little bit of research to find one that will work for your garden. Map out your plan in advance. Keeping careful records of crop placements will help you to organize sequences. Apply observation skills and record the results of your rotations, including the presence of pests, signs of disease, germination rates, yields and other relevant factors. By maintaining these kinds of records, you will be able to make adjustments that will improve your garden’s success over time.
8. Use Organic Fertilizers
Occasionally, organic fertilizers may be necessary to overcome nutrient deficiencies in new gardens or soil that has been grown heavily. Use an organic source that feeds the soil microbes, which in turn feed the plants and improve the soil. Over the course of time, well tended and amended soils are generally able to supply plants with the nutrients that they need without fertilizer applications.
Consider what the specific nutrient deficiency might be, and find natural solutions before applying any fertilizer, even from organic sources. As an example, tomatoes that exhibit blossom end rot signal the absence of bioavailable calcium in the soil. Burying crushed eggshells or alfalfa pellets in a trench between rows of tomatoes will likely solve the problem, providing a slow-release source of calcium that builds the soil and does not damage microbial life. If you have laying hens or animals that eat alfalfa pellets, you will have eggs and alfalfa pellets handy, eliminating the need to visit the nursery to buy a fertilizer product. Explore the web for more natural fertilizers that you may already have in your home.
Balanced organic fertilizers provide plants with all of the macronutrients and some of the micronutrients that plants need to thrive. Their application is simple, covering all of your bases at once. The downside is waste, applying nutrients that are not necessary and which may actually cause harm to the garden. Familiarizing yourself with the signs of nutrient deficiency in plants and testing your soil to find out what specific nutrients need to be amended will help you to apply only what is lacking. This is in line with an important Permaculture strategy: making the least change for the greatest possible effect.
9. Control Pests Naturally
Finally, if pests are present in your garden, apply observation before taking action. Ask yourself the following questions:
Are the pests killing the crop, or only doing a small amount of cosmetic damage?
Is the crop at the end of its lifecycle?
Do you see any signs of predatory insects that feed on the pests in the garden?
Often, the solution is to simply wait and see. Pests will never be eliminated, but nature has a way of balancing itself out. When pests, like aphids, show up in your garden, look for the presence of their predators. Lacewings, ladybugs, mantises and other pest predators are a sign that the ecosystem is coming to the rescue.
Some insects that gardeners consider pests are actually carrying out important functions, such as breaking down plants that are diseased or dying for decomposition. A problem for the gardener occurs when the bugs think it is time to act before the harvest is complete, as in the case of aphids that attack kale when the weather warms before the farmer is ready to remove it from the garden. Soapy water sprayed directly on the bugs may deter them enough to extend the life of the crop, but it may be more prudent to harvest the plants, discarding the infested material, and planting something new in its place.
When pests attack plants in mid-production, action may be necessary if the cost to control the insect outweighs the cost of the damage. For example, if a farmer expects the crop to yield $200 worth of vegetables for sale at market, and the cost to control the pest is only $50, then it makes financial sense to take action. Start with a hard spray of water, which will deter many insects without damaging any soil life. If that is not adequate, the next step may be an application of soapy water, applied directly to the pests to suffocate them and break down their exoskeletons. If that is not effective enough, perhaps the gardener may add some capsaicin to the soapy water. Finally, an organic pesticide may be required.
Keep in mind that even organic pesticides can damage pollinators, such as bees and butterflies, as well as soil organisms. Judicial use of any pest deterrent will prevent a decline in biodiversity and reduction of life that exists in the soil.