ABSTRACT
Soils undergo intensive changes in their physical, chemical and biological properties during natural soil development and as a result of anthropogenic processes such as plowing, sealing, erosion by wind and water, amelioration, excavation and reclamation of devastated land. In agriculture, soil compaction as well as erosion by wind and water are classified as the most harmful processes which not only end in a reduction of the productivity of the site, but are also responsible for groundwater pollution, gas emissions and higher energy requirements to obtain a comparable yield. In forestry, normal plant and soil management, tree harvesting and clear cutting affect site-specific properties including organic matter loss, groundwater pollution and gas emissions, which have the potential to cause global changes. Furthermore, soil amelioration, especially by deep tillage prior to replanting, often causes irreversible changes in properties and functions. These interrelationships have been described by Soane and van Ouverkerk (1994) and quantified by Hakansson et al. (1987). Oldeman (1992) showed that about 33 million ha of arable land are already completely devasted by soil compaction in Europe alone while the total area of degraded land worldwide exceeds about 2 billion ha. Physical (soil erosion and deformation) and chemical processes are responsible for about 1.6 and 0.4 billion ha of degraded soils, respectively. Worldwide population growth will reduce the average area per person for food and fiber production from 0.27 ha today to < 0.14 ha within 40 years. Consequently, a more detailed analysis of soil and site properties is needed to manage soils in accordance with their potential properties.
