Nitrate retention capacity

The displacement of nitrate with leachate is to be regarded as a decisive factor of a groundwater hazard. It increases with the leachate rate, which results mainly from the annual water balance surplus, and decreases with the duration of the water in the soil and the resulting increased nitrate deprivation by the plants. The residence time depends mainly on the field capacity, which is determined for the rootable soil space. The discharge risk is particularly influenced by potential denitrification, longer retention time of the dam water in the root space (increased removal by the plants) and an unquantifiable lateral nitrate input or output by Interflow. Sites affected by backwater are therefore marked separately. In clay-rich soils, which tend to form dry cracks, nitrate displacement can occur after prolonged dry periods despite high field capacity during precipitation events. Such soils (pelosols, Terrae Fuscae) are also marked. Soils made of organogenic substrates are generally characterized by a high retention capacity. However, due to their increased mineralization potential, a hazard to groundwater (e.g. after melioration) cannot be ruled out. These locations are also marked separately. However, the increased mineralization potential is not taken into account in the classification. Site typing is carried out according to defined criteria of the FIS Soil/Soil Protection Method Bank. Further information on methodology and evaluation is available on request. Depending on the output purpose, the result is displayed as a complex map with overlapping subtopics or as a simple classification.