Field Techniques: Soil Systems

This article deals with the principles of soil formation and shows the problems to recognize and visualize the many effects of man made stress in soils. Soils are transformation products of minerals and organic matter with a defined organization, morphology and structure. They are closely related to site factors and for this, the soil properties vary considerably in time and space. Due to many buffer reactions, the time needed to produce visible changes in a soil is, on a human time scale, usually very long. Nevertheless, a careless treatment of soils by inappropriate techniques and the impact of excessive deposition of chemical compounds have an adverse effect on soil properties and functions. The article highlights the effects of deposition with nitrogen, acidifying substances, inorganic trace elements and organic pollutants on the soils. It also discusses the role of soils in global changes. Special attention is given to the fact that most of the elements considered as pollutants appear as natural weathering products in soils. The same is true for the acidification which is a natural process in soils of cool-humid climates where the amount of precipitation exceeds the amount of evapotranspiration. To detect pollutants in soils, usually laboratory analyses are needed. Appropriate sampling strategies and tools, which are discussed in this section, are a prerequisite to find a correct answer.