Before gardeners spend time and money designing their landscapes and choosing their plants, they should first take care of their "dirty" business. Starting with and maintaining healthy soil is fundamental to good gardening, but too often it is overlooked in the frenzy to get those plants in the ground.
Since many plant problems can be traced to poor soil, compacted soil, depleted soil, or even the wrong type of soil, it is well worth the gardener's time to learn a few facts about soil science. Fall is an ideal time to take a soil test, start a compost pile, apply mulch to newly planted trees and shrubs, and add compost to the soil of garden beds.
Soil Components
Soil is made up of decomposed rock (mineral component), decomposed plants and animals (organic component), microorganisms (bacteria and fungi), air, and water. Soil particles come in all sizes, ranging from the largest (gravel) to the finest (clay), which cannot be seen even with an ordinary microscope. Soil particles have sides or edges that play an important role in creating soil structure. When tiny particles of soil are all jumbled together, they don't fit perfectly like a jigsaw puzzle. There are spaces between them where oxygen, water, and roots move. The more sides a particle has, the more space is created between particles. Healthy soil has many spaces. It has good structure.
Compacted Soil
What happens when heavy machinery runs back and forth across soil? Or when tools or feet tread on soil day after day? What happens when gardeners tamp down a moist planting area with heavy boots? The soil becomes compacted. The spaces collapse, squeezing out air and water, creating a solid brick-like mass where oxygen exchange cannot occur, water can't trickle through, and roots can't penetrate. Plants won't thrive in this situation. Construction, development, and home building all take their toll on the quality of urban soil.
Tips for Restoring the Soil
What can gardeners do to restore their soil?
Avoid working in the garden when the soil is wet.
This is especially important when planting valuable permanent trees and shrubs. The Midwest's classically wet springs make this difficult, so it may be beneficial to plant trees and shrubs in the fall instead of in March mud.
Try to keep an even supply of moisture throughout the garden beds.
Occasionally watering an established tree is not enough. Water deeply but infrequently. When the water goes deep, the roots will grow downward. If the water is always on the soil surface, roots will grow upward in search of the moisture, exposing themselves to fatal freezing when the temperatures drop.
Cut back on soil-applied herbicides and pesticides, if possible.
They seriously alter the chemistry, structure, and nutrition of soil.
If possible, bring in native topsoil to your garden.
This requires working with local nurseries to source out where they buy their topsoil and finding a nursery with soil that matches the native soil of your area.
When fertilizing plants, try to use organic fertilizers rather than synthetic ones.
Organic fertilizers are derived from once-living sources. They add more organic matter to the soil without drastically altering the soil chemistry. Examples are composted manure, leaf mold (ground-up leaves), fish emulsion, or homemade compost.
Compost your yard waste and add 2 inches of this rich amendment to your planting beds.
A cubic yard of space is all you need to get cooking. Use a commercial bin or make your own. Or just layer the following ingredients in a big pile away from the garden: one layer of ground-up leaves and twigs, one layer of grass clippings and disease-free plant material, and one layer of soil. As you repeat the layers, sprinkle each layer with moisture and a half-cup of granular 10-10-10 fertilizer. A cubic yard of compost requires 1 pound of fertilizer. Turn every two weeks in warm weather, not as often in cold weather. Dark, earthy, crumbling compost will be ready for your garden in four to six months. It's so easy, and it's the best thing you can do for your soil—and your plants.