Facts About Soil Texture

Sandy Soils

• Sandy soils are made up primarily of particles that can be seen without a magnifying glass. These will feel gritty when you rub the soil between your fingers. Sandy soils drain and dry out quickly, an advantage when growing many drought-tolerant plants. Unfortunately, the water leeches minerals and nutrients away from the root zone of the plants, so sandy soils tend to be infertile and need more frequent fertilizing. Watering needs to be done more frequently with smaller amounts.

Silt Soils

• Silt particles are so small that you need a microscope or magnifying glass to see them. They are floury when dry and feel smooth when wet, but not sticky. If you compress a handful of silt, it will hold that shape until pushed firmly. Silt will hang on to water through capillary action and needs less frequent soakings than sand. It also holds nutrients fairly well, though additions of organic matter can improve this. When compacted, silt soil can be quite dense and hard to dig.

Clay Soils

• Clay soil is one of the most difficult soils to garden in. The tiny particles of clay, so small they can only be seen with a strong microscope, are flat and they stack together solidly if compressed. Wet clay is sticky and gummy, dry clay is powdery. As clay dries, it becomes hard and difficult to break, but the surface of a dried clay soil will crack into irregular pieces. Clay holds water tightly and roots sometimes have difficulty extracting it as the soil dries. Decayed organic matter produces a sticky substance called humus that can bind clay particles together into larger, sand or silt-sized grains, increasing pore space and improving drainage.

Loam Soils

• A soil with a combination of clay, silt and sand is called a loam. If clay predominates, it is a clay loam, if sand predominates, a sandy loam. There are also silt loam, sandy clay loam and silty clay loam soils, named according to the primary mineral sizes. Loam soils are usually easy to garden in, with enough small particles to hold water and nutrients but enough larger ones to drain well. A clay loam, however, due to the strong characteristics of clay, may be quite sticky and will compact easily. All loams are improved by adding organic matter to improve the nutrient content and water-holding capacity.