Soil properties include texture and color. Soil contains minerals which in turn, determine its texture. Sand contains the largest particles, silt is finer and clay is the finest of particles in terms of size. Ideally, soil that is called a loam contains 40 percent sand, 40 percent silt and 20 percent weight. This is a good soil for growing crops and retaining moisture for the plants. A sandy soil contains rock fragments with particles ranging from 2.0mm to .05 mm. Silt particles are .05mm to .002 mm in size. Clay particles are .002mm or less. The color of soil is due to the minerals it contains. Therefore, if it is high in iron, it may appear yellow or reddish. Soil containing high organic matter known as humus, usually looks black or brown. Maganese, sulfur and nitrogen form black mineral deposits. Aerobic environments produce gradual color changes while anaerobic can result in rapid color flow with mixed up patterns, in a soil profile.
The physical properties of a soil are those characteristics which can be seen with the eye or felt between the thumb and fingers.
Texture refers to the relative amounts of differently sized soil particles, or the fineness/coarseness of the mineral particles in the soil. Soil texture depends on the relative amounts of sand, silt, and clay. In each texture class, there is a range in the amount of sand, silt, and clay that class contains. When soil is examined, color is one of the first things noticed. It indicates extremely important soil conditions.
In general, color is determined by: (1) organic matter content, (2) drainage conditions, and (3) degree of oxidation. Surface soil colors vary from almost white, through shades of brown and gray, to black. Light colors indicate a low organic matter content and dark colors can indicate a high content. Light or pale colors in the surface soil are frequently associated with relatively coarse texture, highly leached conditions, and high annual temperatures. Dark colors may result from high water table conditions (poor drainage), low annual temperatures.