Soil Rating - Total Filter Effectiveness (GFW), uniform across the country

The overall filter effect is a parameter for evaluating the soil as a filter for sorbable substances and is evaluated using the mechanical and physico-chemical filter capacity. Sorbable substances include, in particular, groups of substances such as nutrient cations, heavy metals and organic matter, which are either dissolved in the soil water or adhere to small particles or are themselves present in particle form. In dissolved form, the substances mentioned are bound to the exchangers (soil material) and thus removed from the soil solution. In particulate form, they are filtered in the ground when they are forced through mechanical obstacles such as e.g. B. at the end of worm tubes, with the leachate can no longer be transported. The total filter effect can be estimated depending on the cation exchange capacity and the air capacity. The estimation result consists of a total of 11 levels, of which only 8 are relevant in Schleswig-Holstein. The higher the level, the higher the overall filter effect. It is greatest in fine-grained soil material with low air capacity, such as in the Marsh and Eastern Uplands, and lowest in coarse-grained soil material with high air capacity, such as B. in the Vorgeest. With the overall filter effect, a natural soil function is evaluated according to § 2 Para. 2 BBodSchG, namely according to point 1.c) as a degradation, compensation and build-up medium for material impacts due to the filter, buffer and material conversion properties, in particular to protect the groundwater. The criterion chosen for this is the mechanical and physico-chemical filtering capacity of the soil with the parameter total filter effect. The maps are available for the following scale levels: - 1 : 1,000 - 10,000 for high-resolution or plot-specific planning, - 1 : 10,001 - 35,000 for planning at community level, - 1 : 35,001 - 100,000 for planning in larger regions, - 1 : 100,001 - 350,000 for statewide differentiated planning, - 1 : 350,001 - 1000,000 for statewide to nationwide planning.