Understanding your garden's soil type helps you care for your garden effectively and enjoy its full potential. Backyard soil science is simpler than you may think. Soil falls into three main types -- clay, sand and loam -- each with distinct characteristics. You may find all three types in the same garden soil in differing proportions. Close examination of your garden soil holds the clues to the soil type your garden has.
Particles and Properties
To understand the differences among clay, sand and loam soils, look deeper into the types. Three basic particles -- sand, silt or clay -- compose all soils. Wide size variations among these particles affect the properties of your garden. Coarsest and largest, sand particles are clearly seen and felt in your hand. Smaller silt particles have smooth, flourlike texture. Smallest of all, clay particles can only be seen through a microscope. The amounts of these different particles determine whether your soil type is primarily clay, sand or loam.
Often called heavy soil, clay soil combines ultra-fine particles with small spaces between them. Squeezed in your hand, wet clay soil forms a tight, slick ball. The closely packed particles make it hard for water to permeate the surface. Once absorbed, it takes longer to dry out. What delays spring gardening helps in drought situations, but it also makes overwatering easy. Small pores between particles leave little space for air, but they do hold nutrients well. Allow clay soil to dry out slightly between waterings, and water slowly to minimize runoff. One inch of water reaches a depth of 4 to 5 inches in clay soil.
Sandy soil, often called light soil, contains large, coarse particles with large spaces for air and water between them. Wet sand crumbles in your hand when squeezed. Water permeates sandy soil quickly and easily, and sand doesn't stay waterlogged. But sand dries out faster and needs watering more often. What helps in spring at cultivating time hurts during times of drought. Sand soil doesn't hold water well, but water does penetrates farther down. Each 1 inch of water on sand soil travels 1 foot deep. Sandy soil often needs more fertilizer in lighter applications, because water rinses the nutrients through the soil.
Loam soil is the gardening sweet spot between extremes of clay and sand. It holds roughly equal amounts of sand, silt and clay particles. Wet loam holds a shape, but crumbles easily when squeezed. Water permeates loam evenly, not running off or running through. Loam retains moisture but releases it freely, creating the perfect balance of water and air for plant roots. Each 1 inch of water applied to loam soil reaches about 7 inches deep. Soils may lean toward sandy loam, clay loam, silt loam or other soil-type combinations, depending on the predominant particle.