Plants are like icebergs. So much is beneath the surface. Plants grow and thrive on the strength of their root system, what we don’t see. Roots both stabilize and nourish the plants above. To fulfill their role, roots need water, air, nutrients and room to burrow and to develop those delicate root hairs that are so important in absorbing nutrients and moisture. The nature of our soil determines whether they get what they need. If they don’t, the plants above the ground die or live stunted, disease-prone lives. As gardeners, we are constantly looking above ground to find out why some of our plants are not doing well, when the answer so often lies underground.

Good gardening starts with good soil. Healthy top soil, that uppermost layer of soil, provides the water, air and nutrients that roots needs. Some parts of the country have top soil many feet deep. Here in southern Idaho, we are lucky if we have 6 to 8 inches of topsoil, and, even then, it is often mediocre, alkaline and clay-heavy.

Roughly half of soil by volume is mineral content in the form of sand, silt or clay particles. The other half is comprised of air, water and organic matter. In an average soil sample, mineral content would be 48 percent, air 25 percent, water 25 percent and organic matter 2 percent. Sand, silt and clay are defined in terms of particle size. Sand is the largest, clay the smallest. If soil has a balance of sand, silt and clay particles with a good dose of organic matter, we call that loam soil. In such soil, all elements work together to hold and transport water, air and nutrients to plant roots. The sand and silt provide pore space for air and water movement, and the clay provides water and nutrient-holding…