Soil assessment – nutrient availability in the effective root space, evaluated regionally

The so-called S-value is a characteristic value for evaluating the soil as a component of nutrient retention and is evaluated by nutrient availability. The S-value is the amount of nutrients (cations, not e.g. nitrate) that a soil can interchangeably bind or absorb to clay, humus particles, oxides and hydroxides (cation exchange capacity). The S-value is therefore well suited to describe the nutrient availability. Similar to the field capacity in the effective root space (FKwe), high levels of clay, humus, as well as a large effective root space require a high S-value and vice versa. The pH value also has a great influence on the S-value. The pH may fluctuate in a wide range depending on the use. The higher the S-value, the more nutrients the soil can bind to exchangers. Nutrient inputs via air or fertilisation are thus protected against discharge with the leachate water. At the same time, this ensures a more uniform supply of nutrients to the plants. The S-value evaluates a natural soil function in accordance with § 2(2) of the BBodSchG, namely in accordance with point 1.b) as part of the natural balance, in particular with its water and nutrient cycles. The criterion chosen for this purpose is the nutrient availability with the characteristic value S-value. 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 presentation, the S-value is classified regionally. Under the title “Soil assessment – nutrient availability in effective root space (SWE), evaluated nationwide”, there is still a classification of the S-value, which represents the S-value uniformly across the natural space boundaries.