Removal takes place by leaching , as dissolved material is carried away in percolating soil water, and by erosion. Humification is an important transformation process in which organic material is decomposed to humus . Soil classification systems are used to study the distribution of soils and their relationship to a variety of environmental factors. The U.S. Comprehensive Soil Classification System groups the soils of the world into 11 soil orders that are distinguished primarily by the presence of diagnostic horizons. One soil order, Histosols , includes soils with a large proportion of organic matter.
Colloids play an important role in determining soil base status and fertility.
Identify two important classes of secondary minerals produced by mineral alteration and give an example of each. Sketch a diagram to illustrate the concept of the soil water balance. Your diagram should show the important inputs, outputs and storage components of the soil column. Define water use and water need and discuss how they affect the soil water balance. Describe each of them.