Structure of the system

Different reference soils (RefeSol) were defined according to before-established criteria and assigned to four levels (see illustration below). Samples of the soils were taken for a pedological and ecological characterization. The inclusion of eight arable and four greenland sites represents well the proportions of the presently used agricultural areas in Germany.

Level 1 (inside) represents one single soil which is very similar to the soils presently used for practical laboratory testing (e.g. LUFA 2.2 lysimeter soil). This soil is representative for agricultural areas in Germany and can be used for all tests performed according to procedures described in the Federal Soil Protection Ordinance.

At level 2, significant soil parameters, such as C organic content, pH, texture, etc., are varied as widely as possible considering the requirements of laboratory techniques.

The selection of additional soils included in levels 3 and 4 refers to other soil characteristics (sesquioxids and heavy metal contents etc.) and other significant parameters (utilisation, areal representativity, distribution in Germany, etc.). As the RefeSol system design allows further improvement, further soils, e.g. forest soils or town soils can be added on level 5.