Light and Heavy Soils
The presence of silt and especially clay in a soil imparts to it a fine texture, and a slow water and air movement. Such a soil is highly plastic becoming sticky when wet, and hard and cloddy when dry unless properly handled. The expansion and contraction on wetting and drying, usually are great. And the water holding capacity sf clayey and silty soils generally is high. In farming parlance, such smooth soils are known as heavy soils and the coarse sandy and gravel soils as light. This does not refer to their mass per unit volume, which may be greater for a sandy soil than a clay one, but to the power required to draw agricultural implements through the soil. This property is, therefore, a measure of cohesion between the soil particles, and although this is dependent on the pmicle size distribution in the soil, it is also dependent on the kind of particles present.