Heading outside with a shovel, a gardener must consider this: Dirt is what he sweeps off of the floor. Plants grow in soil. The Soil Science Society of America defines the growing medium as "complex mixtures of minerals, water, air and organic matter (both dead and alive), forming at the surface of land." Soil formation refers to five factors scientists consider to describe how different soil types are created, and where those types may be found. For a backyard gardener, it is important to understand soil components and how the soil in the garden space is structured.
The texture of garden soil describes content and size of three particles: silt, sand and clay. Most soils are structured with a combination. Clay particles are the smallest component. Sand particles are the largest. Silt falls somewhere in between. Good garden soil also contains plenty of organic matter..
Clay particles are microscopic in size, packed tightly together. Thus, the spaces between those particles where air and water reside are also extremely small. This structure creates a high concentration of available nutrients but prevents adequate drainage and keeps roots wet for longer periods. Amend clay soils with sand and organic matter to increase your chances of a prosperous garden.
Soils structured with a high proportion of sand possesses the largest pore spaces for air and water. Beneficial nutrients are few and far between because water drains out quickly, taking those nutrients with it. Therefore, water a sandy garden frequently and fertilize it often. Add plenty of organic material to a sandy garden space.
Gardeners who tend a space containing a "sandy loam" soil structure should consider themselves very lucky. Loam is an ideal mixture of clay, sand and organic matter. It drains moderately and supplies adequate air space and nutrient content, so that plants can thrive. Add compost to loam soils each year to maintain this healthy structure. Water loam soils only when necessary, and keep additional fertilizing to a minimum.