Soil assessment – nitrate leaching hazard/soil water exchange (NAG), regionally assessed

Soil water exchange is a characteristic for evaluating the soil as a filter for non-absorbable substances and indicates the risk of displacement for non-absorbable or hardly absorbable substances such as nitrate (nitrate leaching hazard). The nutrients remain almost completely in dissolved form in the soil water and are shifted with it upon infiltration (soil water exchange). The risk of displacement is high in soils with low water retention capacity, high rainfall and low evapotranspiration. The higher the risk of displacement, the higher the soil water exchange is because the exchanged soil water leaks with the nitrates dissolved therein. The soil water exchange evaluates a natural soil functions in accordance with § 2(2) of the BBodSchG (BBodSchG), namely in accordance with point 1.c) as a dismantling, balancing and build-up medium for material influences due to the filter, buffer and material conversion properties, in particular also for the protection of groundwater. The criterion chosen for this purpose is the retention capacity of the soil for non-absorbable substances with the characteristic value of soil water exchange. The maps are available for the following scale levels: — 1: 1,000 – 10.000 for high-resolution or parcel-sharp planning, – 1: 10.001 – 35.000 for municipal level planning, – 1: 35.001 – 100.000 for planning in larger regions, – 1: 100.001 – 350.000 for nationally differentiated planning, – 1: 350.001 – 1000.000 for nationwide to nationwide planning. In this illustration, the soil water exchange is classified regionally. Under the title “Soil assessment – nitrate leaching hazard/soil water exchange (NAG), nationally evaluated”, there is still a classification of soil water exchange, which represents the exchange of soil water across natural space boundaries uniformly across the country.