Benefits of Healthy Soil |
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Soil health is very important to an overall healthy landscape or garden, and compost is a critical component of achieving soil health. Landscapes and gardens existing in healthy soil will require less energy, money, and time to maintain. Nature's own system of checks and balances will help to control pests and diseases. This page describes healthy soil and explains how the addition of compost, aeration, and water can build the health of the soil.
Healthy soil smells sweet, is loose, friable, well-drained, rich in organic matter. It feels moist because it is able to hold moisture. Soil will be aggregated into particles with lots of air around them. Air and water move freely through the soil because air space exists around aggregated soil particles. Healthy soil will have about 24% air, 25% water, 45% minerals, 3 - 5% humus, and up to 1% living organisms.
Aeration is critical for microorganisms, macroorganisms, and vegetation to provide natural ecological balance in soil. These living plants and animals need oxygen to survive, as well as other gases found in air.
Water is also essential to the survival of microorganisms, macroorganisms, and vegetation. While too much water is a problem, these living plants and animals must have enough water to live. Healthy soil provides water retention ability as well as good drainage, so the proper amount of water is held in the soil. "A 5% increase in organic material quadruples the soil's ability to store water" according to A Green Guide to Yard Care by the Texas Natural Resource Conservation Commission.
Healthy soil will have a pH between 6.2 and 6.5. This is well within the 5.5 to 7.5 pH range in which essential nutrients are available to plants. Outside this range, they become bound and cannot be absorbed by plants and microorganisms. Calcium, magnesium, potassium, sodium, and other trace elements can be found in their proper relative proportions if the soil is healthy.
Humus contains lignin, protein, and complex sugars. Microorganisms transform humus into enzymes, acids, and minerals which are the slow-release foods for vegetation. Humus is constantly being consumed by the microorganisms and so must constantly be replaced. In the forest, this process is natural as each fall adds a fresh layer of leaves to animal wastes, carcasses, and other organic wastes on the forest floor. In our less natural lawns and gardens, adding compost and other organic material is required to maintain the constant supply of decomposed matter.
Healthy soil serves as a home to insects, earthworms, and microscopic plants and animals. Their presence indicates that soil contains materials which are being decomposed, releasing nutrients into the soil. The balanced ecology extends to the micro and macroorganisms so that pests and diseases may be kept in check through nature's system of checks and balances.
Compost can help create healthy soil out of every kind of soil, silt, clay, or sandy dirt. The two things sick soils lack are microorganisms and organic matter. By adding nutrients to soil, vegetation becomes healthier and micro and macroorganisms are attracted to the ecosystem. The most beneficial organism is the earthworm, but there are many others. Once this ecosystem becomes balanced in the way nature intended, every aspect of the system works to create a good environment for vegetation. The benefits brought about by this healthy ecosystem are:
We explain how most of these results are obtained using the earthworm as an example.
- Encourages the formation of appropriately-sized aggregates which protect soil from erosion and compaction
- Eliminates (some say reduces) the need for chemicals which may pollute ground water
- Conserves water as penetration and retention are improved, erosion and run-off are reduced.
- Stabilizes and regulates pH at optimum level for nutrient availability
- Allows better root penetration in clay soils.
- Improves moisture retention in sandy soils so water loss and leaching are reduced or eliminated.
- Improves drainage in clay soils
- Promotes fertility through higher quantities of macro and micro nutrition, as well as improving the availablity of the nutrition
- Stimulates plant root development. Overall root environment is improved due to better structure, porosity, and density of the soil.
- Soil-borne plant pathogens are controlled or suppressed.
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A good indicator of soil's health is the presence of earthworms. Earthworms migrate to and inhabit healthy soil, then help to maintain that health. To increase your earthworm population, feed them organic foods and composted manures, avoid over tilling, mulch all bare soil and avoid high nitrogen fertilizers and chemical pesticides. Earthworms will repopulate naturally if they aren't poisoned.
Earthworms tunnel through the earth, excreting polysaccharides. Polysaccharides are sugars that act like glue to line the pencil-size tunnels, preserving them for years. As they move through the earth both horizontally and vertically earthworms drag bits of organic material around, helping to mix organic matter into the soil. As they eat the organic material, they turn it into rich nutrients by leaving castings everywhere they go. There are also compartments within the worm's body in which microorganisms multiply and are then released into the soil.
This simple activity of the earthworm provides numerous benefits:
- Web of tunnels aerates the soil so that plants and organisms can breathe. They break up soil hardpans and compacted soil.
- Web of tunnels allows moisture to move to and through the soil, so that plants and organisms receive the water they need, but have good drainage too.
- Having a tunnel built for them rather than pushing through compacted soil means that roots can grow up to 7 inches a day through the tunnels. Plants can root more deeply. Castings provide nutrition right at the root.
- Converting humus to castings provides nutritional value to plants and organisms. As plants decay, they form phenols and formaldehyde which can inhibit growth in plants. Earthworms reduce these substances and generate auxins and cytokinins instead, which stimulate plant growth. Castings contain as much as 10 times the soluble, plant-available nutrients as the original soil.
- Increased water absorption means that there is less run-off to (1) wash away topsoil and (2) prevent rain from reaching plant roots.
- Polysaccharides left by the earthworms help the aggregation of the soil. Sandy soil has large particles with large air pores, causing these soils to drain rapidly without adequate water retention. In sandy soil, compost helps to form larger aggregates from unconnected particles so that water and nutrients are retained. Clay soils have small particles which have small air pores. They drain poorly, retaining so much water that the soil cannot hold adequate air for vegetation. In clay or silt, compost breaks up the compacted particles to form aggregates so that water and air can move through the soil. Root systems can also forge their way through the soil more easily.
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Soil health is very important to an overall healthy landscape or garden, and compost is a critical component of achieving soil health. Others are aeration of the soil and covering all bare soil with mulch. This web site focuses on compost, but we will give a capsule of the logic behind these two critical steps.
Aeration allows oxygen to reach microorganisms that break down the organic matter. Methods of aeration range from simply punching holes in the ground with a pitchfork or pole to rototilling.
Covering all bare soil with mulch prevents rain from washing away top soil It also buffers the soil from temperature extremes, controls weeds, and helps to retain moisture.
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