Soil texture refers to the relative proportions of sand, silt, and clay particles which make up the soil mass. Figure 6 shows the percentages these soil fractions in the basic textural grades; definitions and discussion of this subject may be found in the Soil Survey Manual (Agriculture Handbook 18, U.S. Department of Agriculture, 503 pp., 1951).

Soil texture can be found exactly in a laboratory analysis. It can also be adequately classified in the field, after some experience, by sight and feel. On the opposite page is a key to the important textural grades. The first three – sandy loam, loam, and silt loam– are common surface soils, and may occur as subsoils. The rest are subsoils.