Based on a systematic grid of 8 x 8 km, more than 3000 sampling sites on agricultural soils are examined all over Germany. The sampling sites are identified in a coincidence-based procedure, which is based on the distance between the points as well as on the land use (arable land, grassland, garden, special crop) identified by the basis-DLM (digital landscape model). According to several tests, the sampling-grid produced is representative for the distribution of agricultural fields in Germany and in the Bundesländer as well as for the respective soil-climate-regions.
In the course of a one-time sampling, soil samples are taken from a pit down to a depth of 100 cm following a standardised procedure. Further, the small-scale variability in a radius of 10 m around the sampling site is recorded via core sampling. Thereby, the sampling procedure relies on the German Forest Soil Inventory.
After the soil profile is described, the material sampled is analysed in the laboratory for the content of soil organic carbon and dry bulk density. Moreover, stone content, soil type and further explanatory parameters are determined in order to calculate the stock of soil organic carbon in agricultural soils.
The stock of soil organic carbon reflects the land-use and the cultivation history of each field. By the use of a questionnaire, these additional information on the site sampled are collected and used for the scientific data prosessing. All information are handled confidentially and processed anonymously, they are used only for the emission reporting and research aims.