Soil Health = Plant & Food Health = Human Health
Soil is an ecological system that functions to… serve as a media for plant growth, serve as a regulator of water supplies, serve as a recycler of raw materials, serve as a modifier of the atmosphere and serve as habitat for soil organisms. Most importantly soil serves as an environmental interface of other natural bodies: worlds of rock (the lithosphere), air (atmosphere), water (hydrosphere), and living things (biosphere).
Based on our observations from growing a garden for over twenty years, from delving into an education in soil science, and exploring multiple methods of managing soil tilth, the following are our recommendations for what you can do to improve soil health. Based on what we have learned, we use no-till growing bed methods with on-farm composting that make zero use of synthetic chemicals. We focus on protecting and feeding a robust soil microbiology and the returns in diverse healthy food is astounding.
A concept to consider is that what we might “do to fix the soil” will more likely harm it, than improve it. The most healthy and productive soils are found in the forests and in grassy plains where our interference is absent. Soil is destroyed where we determine to “do something to improve the site.” However, with close observation of ecology and nature’s cycles of life, death and decomposition, we can begin to understand what actions we might avoid and what actions we might take to assist nature and protect and improve the soil. In healthy conditions, soil is the medium in which we productively grow healthy food.
- Protect Soil Structure. Don’t plow or till. Important healthy soil peds, clods and particle aggregates can only be created by nature, and tillage can only destroy them. Good soil structure is characterized by ideal pore space of 50% of the total volume of soil. It can take on water without slaking and cogging pores.
- Protect the Pore Space in the natural soil structure. Do this by protecting the soil structure and avoiding compaction. Don’t walk on nor work the soil when it is wet. Maximum pore space consisting of a balance of macropores (diameter range of 0.08 – 5+ mm), mesopores (0.03 – 0.08 mm), and micropores (0.005 – 0.03 mm). A healthy balance allows for the soil to soak up and hold water, and cycle air through the soil allowing the soil microbiology to breathe.
- Keep Soil Covered. Direct contact with sun dries out soil, drastically reducing the abundance of soil microbiology. Direct contact with wind and rain causes abrasion, structure destruction, compaction, slaking, water runoff, and topsoil erosion.
- Use Cover Crops and Plants. Beyond the benefits of keeping the soil covered, roots in the soil help create, repair, and protect soil structure. Roots serve to feed and enhance the life and decomposition cycle of soil microorganisms. Certain plants improve nutrient content and improve nutrient cycling in the soil. Certain plants exude an allopathic substance that discourages the growth of weeds. Even what most would consider weeds are better left in place than tilling out and serve to protect soil and feed soil life. Crop rotation of annuals is an important element of preventing imbalanced deficiencies in nutrients or imbalanced presence of disease or pests.
- Use Compost. Collect and compost carbon sources such as leaves, nitrogen sources such as kitchen waste and grass clippings, and other dying plant biomass. This adds cover, and organic matter to the soil to feed the soil microbiology. Compost can be added on like mulch on top of soil and does not need to be tilled into it. The added nutrients from this decomposition process feeds new plant and soil life. The effects of soil organic matter on soil functions are profound.
- Keep Soil Life Healthy. Soil microbiology is both flora and fauna creating a diverse complex web of life and decomposition. According to Kathy Merrifield, a retired nematologist at Oregon State University, beyond the visible bugs, ants, earthworms and other organisms we can see, “a single teaspoon of rich garden soil can can hold up to one billion bacteria, several yards of fungal filaments, several thousand protozoa, and scores of nematodes. The overwhelming majority of soil life is beneficial to soil and plant health when they are in a collective and robust decomposition cycle. There are always bad actors such as specific nematodes of the genus Heterodia, which can infest the roots of practically all plants, stunting them. However, considering there are some 20,000 species of nematodes of the 100,000 nematode species that are thought to exist, some of which kill and feed on the Heterodia nematodes, it would be detrimental to use a nematicide, which would kill them all and risk putting the web out of balance.
- Don’t use synthetic chemicals, pesticides or herbicides. They are toxic and cause damage to the health of soil, soil microbiology, air, water, plants, animals and people, much of which has been demonstrated through scientific study, more of which we don’t fully understand yet. If you must use a natural pesticide or herbicide, one that nature knows how to digest, do so judiciously only to correct an observed imbalance where a bad pest or disease is overwhelming. Err on the side of less than you believe you might need. Even natural pesticides, herbicides, fungicides attack the good fauna and flora as well as the bad.
- Plus one… Get an annual soil test. While standard soil tests sorely lack important information and consideration of the ecological elements of soil health, they do give us basic information about soluble macro and micro nutrient status and pH. The seven steps above usually result in healthy nutrient cycling eliminating the need to add nutrients into the ecological system. However, the soil pH measurement (negative logarithm of the hydrogen ion activity/concentration) determines much about the natural chemical and biological conditions in the soil. For example most plants need a pH between 6.0 and 7.0. to take up available nutrients. Where a soil is too acidic (low pH), we can assist it by applying lime (calcitic limestone or dolomitic limestone), or gypsum (calcium sulfate), or a combination of both of these natural substances. Learn how to measure, use and apply. Applying them when they are not needed, i.e. the soil measures a higher pH (more base, less acidic), will further worsen the balance and be slow and difficult to correct.
Endnote: some of the concepts and soil facts are credited to Elements of The Nature and Properties of Soils, Third Edition; by Nyle C. Brady and Ray R. Weil.