Soil Health
What is
soil health?
Plants grown in lifeless dirt need humans to perform many functions like fertilizing, aerating, correcting soil acidity, and controlling pest populations. But soil organisms fed and sheltered by plants can perform all these services, if those organisms are abundant and diverse.
Soil health is the result of all the processes of diverse and abundant life in the soil. A healthy soil will be on an "upward spiral" – increasingly being enriched, becoming resilient against stresses, and sequestering carbon underground, where it's often desperately needed.
Who creates soil health?
Soil health is created by aerobic soil biology: plants, bacteria, fungi, protozoa, nematodes, earthworms, microarthropods, and many other organisms. Healthy soils require that this diverse biology is abundant and that we're not managing against it. Because they make foods through photosynthesis, plants are the engine that powers the entire soil ecosystem, feeding aboveground and belowground organisms with
decaying plant parts, as well as with root exudates – sugary substances that plants leak from their roots to attract and feed beneficial microbes. From there, diverse soil organisms play their roles; for example, fungi that mine minerals for nutrients on behalf of plants, earthworms that develop soil structure, and predatory nematodes that cycle nutrients and keep pest populations from exploding.
What destroys
soil health?
Because soil health happens when living plants are feeding and housing a thriving community of soil organisms, that health can be lost whenever farmers, gardeners, and other land managers remove or damage that community or the plants that feed and house it. This occurs when the soil is not covered with living plants and their residues (e.g. fallowing), when we disturb soil (e.g. tilling), and when our soil ecosystem lacks bio-diversity (e.g. using nonselective pesticides).
In the Mid-Atlantic, one of our biggest barriers to soil health is compaction – where pore spaces that should hold air, water, roots, and micro-
organisms, are crushed. This creates a situation in which air and water cannot move through the soil, roots have trouble penetrating the hard ground, water stuck at the compaction layer suffocates roots below that point, and disease-causing microorganisms are increased while beneficial ones are starved of oxygen and foods.
Managing for soil health:
We can manage for the soil ecosystem by applying the USDA's soil health principles on cropfields, gardens, lawns, orchards, and pastures:
(1.) Maximize biodiversity. For example: inoculate soils with diverse beneficial micro-organisms by applying actively aerated composts or compost teas, use crop rotations to incorporate additional plant species, introduce livestock, and limit pesticide use.
(2.) Maximize soil cover. For example: apply mulches, mow fallen tree leaves to decompose in-place rather than removing them, and leave significant plant residues from the previous crop.
(3.) Minimize disturbance. For example: practice no-till seeding, use less tillage and fast-acting fertilizers, rotationally graze livestock, and mow lawns and hayfields at a higher height.
(4.) Maximize living roots. For example: use cover crops, incorporate perennials into your crop rotation, and apply agroforestry.