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.土壤水交换（Soil water exchange）是评估土壤作为非吸收性物质过滤介质的特征指标，可表征非吸收性或难吸收性物质（如硝酸盐）的迁移风险，即硝酸盐淋失风险（nitrate leaching hazard）。养分几乎完全以溶解态留存于土壤水中，并随入渗过程发生运移，这一过程即为土壤水交换。在保水能力弱、降雨量高且蒸散量低的土壤中，物质迁移风险较高。迁移风险越高，土壤水交换强度也越大，因为参与交换的土壤水会携带着溶解其中的硝酸盐一同渗漏流失。 土壤水交换依据德国联邦土壤保护法（Bundesbodenschutzgesetz，缩写BBodSchG）第2条第2款评估土壤的自然功能，具体对应第1点c项，即作为因过滤、缓冲和物质转化特性而产生的物质影响的消解、平衡与构建介质，尤其可用于地下水保护。本次评估选取的量化标准为土壤对非吸收性物质的滞留能力，以土壤水交换特征值作为评估依据。 以下比例尺等级的配套地图已发布： — 1:1,000 – 10,000：适用于高精度或地块级精细规划 — 1:10,001 – 35,000：适用于市级规划 — 1:35,001 – 100,000：适用于较大区域规划 — 1:100,001 – 350,000：适用于全国差异化规划 — 1:350,001 – 1,000,000：适用于全国范围乃至跨区域规划 本示例中，土壤水交换已按区域进行分级。在标题为"土壤评估——硝酸盐淋失风险/土壤水交换（NAG）全国评估"的板块中，还设有一套土壤水交换分级方案，该方案基于自然空间边界，实现了全国范围内的土壤水交换统一评估。