Soil feel test for when to water

Knowing when to water is critical in these days, when West Texas is in an extended drought. The soil can tell us.

There is specialized equipment and there are many devices that determine when a soil should be irrigated. Most are highly technical, complex and expensive, and for the home gardener such devices are impractical.

Most gardeners are “hands-on” people who aren’t against getting into the soil. The method explained below is for just those kinds of gardeners. It is called the “feel” test.

There are four soil types, each with its own characteristic particle size and structure that affects how that soil feels at specific moisture levels. The soil types range from the type with largest particle size—the sandy soils with the coarsest particles—to the soil type with the smallest particles, the clays, which are heavy soils. In between these two extremes are the silts and clay loams, with a mixture of predominantly silt and clay with small amount of sand that would be called a “medium” soil type, and the sandy loams that are predominantly sand with some silt or clay mixed in with the sand and would be called a “light” soil type.

Soil can hold only a certain amount of water. Sandy soils hold the least; next are the sandy loams, then the silt and clay loams, and the fourth type, clay soils, hold the most.

The following is a comparison of how each type feels when dry and when it has “just right” moisture.

Sandy soil. When dry, with no remaining moisture particles are loose, single-grained, and flow easily through fingers; a ball cannot be formed. Upon squeezing this soil with adequate moisture, particles stick together.

Sandy loam. When dry, loose particles flow through fingers easily. When squeezed, a loose ball is formed that easily falls apart.

Silt and clay loam. When dry, particles are powdery if there are clumps they are easily broken into powder. Upon squeezing, particles form a ball that is pliable; particles may feel slick if clay content is high.

Clay. Particle surface is hard, cracked; there may be a few loose particles on the surface. Upon squeezing, moist soil can make a slick ball that keeps its integrity.

Some information from New Mexico State University Guide 400 A-111

Ellen Peffley Harp, a retired professor of horticulture at Texas Tech University, writes about gardening for several Texas newspapers.