Tuesday, June 24, 2008


Throughout history, the story has repeated itself: Great civilizations have grown where soils were fertile enough to support high-density human communities, and fallen when soils could no longer sustain our rough treatment. Soil directly and indirectly affects agricultural productivity, water quality and climate. From the food we eat to the clothes we wear to the air we breathe, humanity depends on the very dirt beneath our feet. Biodiversity in the soil ranges in size from microscopic one-celled bacteria, algae, fungi and protozoa, to larger nematodes, arthropods, earthworms, insects, plant roots and small animals. This community of organisms help to break down and incorporate organic materials into the soil, convert nutrients into useable forms for plants, and help to hold carbon which might otherwise enter the atmosphere, potentially contributing to global warming. Healthy soils also contain an abundance of minerals, air, water and organic materials, all which are essential for healthy plant growth. We must learn to understand, respect and rebuild our soils, before this precious commodity degrades beyond repair.

The major threats to our soil, and ultimately our water is: over-intensive farming and gardening practices that arise from tilling, heavy machinery and the use of harsh chemical pesticides and fertilizers. Soil compaction from heavy equipment reduces the soils air space and ability to take in water and nutrients. Compacted soils become hard when dry, and can restrict root growth and the activity of soil organisms. Deep tilling accelerates soil erosion, which ends up washing into our streams, rivers and eventually the ocean. When excessive nutrients from eroded soil enters waterways, algal bloom is stimulated to grow in abundance, and suck up most of the available oxygen as it breaks down. This process known as eutrophication, leads to death of aquatic life, and has created a “dead zone” in the mouth of the Mississippi river larger than the size of New Jersey. In addition to water degradation, a 1995 study published in Science concluded that in North America alone, the loss of soil from croplands in the form of erosion decreases agricultural productivity by about $27 billion per year. Lastly, the use of chemical pesticides and fertilizer can not only over acidify the soil, but also destroy the very soil organisms that support healthy plant growth. Soil is being lost faster than it can naturally replenish itself, but the good news is that we can rebuild our soils and revitalize soil life.

Soil is the skin of our planet, and a vital living system. Too often we forget that soil sustains all life, and is arguably the most important natural resource we have. The more abundant, diverse forms of life we can nurture in the soil, the more fruitful and self-sustaining our crops and landscapes will be. Harvey Blatt, author of the 2004 book, America’s Environmental Report Card, points out that one heaping tablespoon of healthy soil contains up to nine billion living microorganisms, which is more than the human population of earth. Better known as the soil food web, this complex group of organisms bear the important task of breaking down toxic pollutants and purifying water as it passes through the soil. Other roles include increasing the soils porosity, which improves air and water movement, as well as increasing the soils ability to bind, which can lessen the damaging affects of soil erosion. There is constant interaction among the organisms living in the soil. The few “bad” soil organisms are kept in check by the vast diversity of beneficial organisms, wherein keeping healthy soils in balance for optimum plant growth with the least amount of effort to upkeep them. If we do our part to encourage healthier soils, the organisms of our soils will flourish, and work even harder to help us build more nutrient rich crops, cleaner water and bigger, brighter blooms in our gardens.

We can increase the health of our soils, and ultimately the productivity of landscape plants and crops with a few simple techniques. Most soil organisms like cool, moist conditions, which are enhanced by the addition of mulch, plants of all sorts or lawns. Such groundcovers also help to hold soil, which lessens the affects of soil erosion. Also, the addition of well-aged compost can add organic matter back into the soils. The more diverse the ingredients that are incorporated into a compost pile results in a greater diversity of nutrients and soil organisms in the end product that is ready to be applied to your lawn and garden areas. Compost ingredients such as plant debris and manure should be aged for at least one year before being applied to such areas. Reducing the amount of tilling in one’s garden areas also help to reduce the loss of organic matter. Leave all landscape plant and crop residues in your bed areas through the winter to help reduce erosion in otherwise barren areas, as well as providing habitat for over wintering beneficial insects. Such plant debris can be removed in the spring to encourage soil temperatures to warm faster, which can increase early season plant growth. All over the world, a great portion of our useable soils are worn out, depleted and close to death. These soils possess the ability to be restored to maximum productivity. We need to continue to work together to enrich our soils and treat them as living communities of organisms that can enrich all life that stands a top them. Only when we stop treating our soils like dirt, will civilizations such as ours be able to sustain themselves permanently.

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