SOIL FERTILITY PROBLEMS - AN AGRICULTURE AND FORESTRY PERSPECTIVE

The loss of soil fertility is an important problem in large areas that have been utilised for agricultural production during the last 20 years. Enhanced concentration, intensification and specialisation of crop and livestock production without sufficient consideration of the natural site specific soil and climate conditions caused pronounced degradation and partly irreversible damage of the soil including such processes as soil compaction, water and wind erosion, water logging, chemical degradation and humus loss. With regard to Germany the sandy and loamy to sandy soils in the northern part of the country are more impacted than the naturally loamy soils in southern Germany. Clearly, damaged soils cannot accomplish their ecological 'tasks' (e.g. buffer, filter, storage function) in the various ecosystems of the landscape. In addition, man's activity particularly in highly industrialized nations brought about severe problems with regard to forest ecosystem health. For example, in Germany and elsewhere new types of forest decline are occurring since the mid 1970s. This damage is related to air pollution and other factors. Despite much controversy there exists no doubt that air pollution stresses like 'acid rain' and enhanced N deposition affect forest soils by e.g. accelerating soil acidification. This process increases the loss of cationic nutrients such as Mg, Ca and K from the ecosystem. Therefore it is not surprising that various types of this new damage involve Mg and K deficiencies. In this context fertilizer and lime applications have proven useful mitigation tools. However, when these practices are conducted improperly, i.e. not related to site and stand conditions, ecological hazards may arise. It is therefore necessary to develop new solutions to restore soil fertility and to improve soil protection in agricultural and forest ecosystems.