Ground map of Lower Saxony 1 : 50 000 - Denitrification potential of soil
Description
The denitrification potential describes the ability of the soil to convert part of the nitrate back into air nitrogen (sometimes nitrous oxide) by microbial reactions and under anaerobic conditions. Prerequisites for nitrate degradation are the presence of nitrate, the absence of oxygen and the presence of oxidizable organic matter.
The denitrification potential is derived from the Lower Saxony-wide soil map (BK50, Gehrt et al 2021) and applies to a depth of two metres. The methodology is described in Georeport 19 (Bug et al. 2020) is presented. Each soil type is assigned a denitrification level with an average annual rate, depending on the groundwater or backwater influence.
In total, there are five denitrification stages characterized by mean denitrification rates of 5, 20, 40, 60 and 100 kg N/ha*a (150 kg N/ha*a in peat-containing substrates at high groundwater levels). The lowest denitrification rates have low humic locations in which water saturation of the soil body is excluded all year round. The denitrification potential of soils increases with an increase in humus content or the occurrence of temporary wetness under the influence of groundwater or reservoir water. The second denitrification level represents an average denitrification rate of 20 kg N/ha*a. In principle, the highest denitrification rates are to be expected as soon as groundwater is in soil layers containing humus or sulphur. At denitrification level 5 (>> 150 kg N/ha*a), the denitrification rate can be up to 3 000 kg N/ha*a. Such rates are mainly found in bogs and humus-rich soils, where the groundwater surface is at = 6 dm and GOK in the peat body all year round. Since denitrification degrades organic matter in water-saturated soil layers, it can be assumed that the rate of denitrification decreases over the decades and centuries, especially for mineral horizons. Groundwater subsidence can also significantly reduce denitrification performance in the soil zone of a site (Wienhaus et al., 2008).
References:
BUG, J., HEUMANN, S., MÜLLER, U. & WALDECK, A. (2020): Evaluation methods in soil protection - documentation on the method bank of the Lower Saxony Soil Information System (NIBIS®). – GeoReports 19: 383 pp. Hannover: LBEG
GEHRT, E., BENNE, I., EVERTSBUSCH, S., KRÜGER, K. & LANGNER, S. (2021): Explanatory note on BK 50 of Lower Saxony. – GeoReports 40: 282 pp., 125 fig., 100 tab.; Hanover (LBEG).
WIENHAUS, S.,HÖPER, H., EISELE, M.,MEESENBURG, H. & SCHÄFER,W. (2008): Use of soil and hydrogeological information for the designation of target areas for groundwater protection - Results of a model project (NOLIMP) for the implementation of the EC Water Framework Directive. – GeoReports 9: 56 p., 13 fig., 5 tab., annex; Hanover (LBEG).
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https://nibis.lbeg.de/net3/public/ogc.ashx?NodeId=2256&Service=WMS&Request=GetCapabilities& |