Healthy soil is crucial to all life on earth.
Soil is the foundation of life on earth. It is made up of mineral solids, water, air, and organic matter. Although it may appear unremarkable, soil is a complex ecosystem, teeming with microscopic life. It is the habitat of countless organisms, from microscopic bacteria to earthworms, that transform wastes into the food that nourishes plants, wildlife and humans. Soil supports plants that we rely upon for the air we breathe.
Our modern industrial society has left much of the Earth’s soil eroded, exhausted and polluted. Our actions have taken a heavy toll on the planet, causing large-scale habitat destruction, extinction of species, overexploitation of natural resources and pollution of the environment. We can help make a difference. The sustainable gardener can implement practices to mimic nature, supporting a diverse community of flora and fauna, without depleting the Earth’s natural resources.
What is a Healthy Soil?
A healthy soil is one that is not eroded, exhausted, or polluted. It is a habitat for countless organisms, from microscopic fungi and bacteria to larger creatures such as earthworms and millipedes. These organisms – and the organic matter that sustains them – are key to the long-term fertility and viability of soil. Healthy soils give us clean air and water, diverse wildlife, beautiful landscapes, bountiful crops and forests, and productive grazing lands. Therefore, knowing your current soil conditions and improving or maintaining healthy soils are vitally important in achieving your sustainable landscape.
Soil is a complex mixture of weathered rock and mineral particles, living organisms of the soil food web and the decaying remains of dead plants, animals and microorganisms. The living and dead organisms are known as organic matter. The contents of spaces between the solids — air and water — are also important components of healthy soil. Topsoil is the most biologically active and productive upper layer.
The Soil Food Web
The soil in your garden is an astonishingly complex ecosystem comprised of a wide variety of interacting organisms – producers, consumers, predators and prey. These include earthworms, ground beetles, ants, spiders, millipedes, centipedes and other creatures visible to the naked eye. They also include a diverse population of fungi, bacteria, and other tiny organisms, representing thousands of species. Protecting and nurturing their habitat is the key to growing healthy, beautiful plants.
These soil organisms perform a number of essential services for plants, and ultimately for us. They include:
- Nitrogen fixation – converting atmospheric nitrogen into a form usable by plants
- Aiding in the uptake of nutrients
- Aerating the soil through burrowing and other activities
- Breaking down toxic organic compounds such as pesticides
- Suppressing outbreaks of soil-borne diseases
- Decomposition of organic matter (dead plant and animal tissue).
Composting is the art and science of mixing various wetted organic materials in a pile and controlling the conditions so that soil organisms break down the raw organic matter into humus. Humus is the rich organic matter that will break down no further and, when added to soils, contributes to moisture and nutrient retention. The organic matter is broken down first by worms and fungi, then further decomposed by bacteria and other microorganisms.
Basically, composting mimics the natural humus-formation processes that take place in nature. More simply, it is the process of taking discarded organic matter (e.g. food scraps, dead plant material) and allowing it to decompose into humus over a period of time.
Mulching is a practice that imitates one of nature’s most fundamental processes. Deciduous forests, one of nature’s champion mulchers, shed leaves in the fall that are transformed by the soil’s natural food web into plant food and the rich organic matter called humus, which is the key to healthy soils.
Mulch is a layer of material (most commonly an organic material) applied to the surface of soil. When it is made from organic materials (e.g. leaves, bark, wood chips, pine needles, nutshells, compost), mulch can also contribute to soil fertility as it breaks down and decomposes.
In a landscape, mulch provides the following benefits:
- Conserves water by shading the soil and reducing evaporation
- Insulates roots by moderating soil temperatures
- Cushions the impact of pounding rainfall and helps prevent soil compaction
- Provides nutrients and a home for certain soil food web organisms
- Makes plants less vulnerable to pests and diseases
- Suppresses weeds and keeps the soil loose
- Creates conditions in which plants are less stressed, more vigorous and less vulnerable to pests and diseases