component, parts, soils
Soils are composed of solid, liquid and gaseous components. Materials in a solid state, soil minerals and organic matter constitute the soil itself; the liquid and gaseous components — water and air change continually with conditions independent of the soil. Organic soils are not so important as mineral ones. The mineral constituents are different in size, shape and chemical composition. The size of particles is one of the most important characteristics. Water absorption, air movement, and rate of solution depend on the particle size. Mechanical analysis divides the particles into size groups, but the results of the mechanical analysis do not include organic matter or particles larger than two millimeters. Each group is characterized by definite physical properties which depend on the size of the particles composing it. Every soil is a mixture of such groups, so the physical properties are determined by their proportions. For practical purposes, soils of the usual classes can be grouped as follows: coarse textured soils: the sand and sandy loams; medium textured: the loams and silt loams; fine textured: the clay loams and clays.
