Background and Objective

Soil organic carbon in agricultural soils is of great importance for central functions such as biodiversity, soil fertility, water balance, nutrient availability and erosion reduction. In addition, humus binds large amounts of carbon in the soil, so that by maintaining or increasing the SOC content, a contribution can be made to climate mitigation. Against this background, there are various political and private initiatives to increase the humus content in arable land. In order to achieve a positive climate impact, however, it is necessary that soil organic carbon sequestration can be reliably proven, is permanent and does not lead to a reduction on other areas. Therefore the following questions arise:

• Which measures can be used to achieve soil organic cabron enrichment?
• How much do these measures cost?
• What additional benefits do they bring to farms?

In order to answer these questions, measures to build up humus in arable land are being tested in the HumusKlimaNetz on 150 organically and conventionally farmed farms in ten different regions across Germany. The network is coordinated by the German Farmers' Association (DBV) and the Bund Ökologische Lebensmittelwirtschaft (BÖLW). The Thünen Institute accompanies the project scientifically and evaluates impacts of climate mitigation and the costs of the measures carried out.

Approach

• Based on previous scientific knowledge, we first create a catalog of measures from which farmers can select the measures implemented on their farms. Furthermore, we derive flat rates for the financial compensation of the measures on the basis of the existing literature and data.
• In order to be able to evaluate the crop production and economic effects of the measures, we are developing a user-friendly database in which the participating farmers can enter their data for the scientific evaluations on a field-specific basis.
• Based on the recorded data, we create field and product-specific as well as overall farm-gate greenhousegas balances. In this way, we can identify possible spillover effects and take yield reductions into account (product-related greenhouse gas balances).
• We evaluate several thousand soil data samples collected at the beginning of the project on the areas covered by the 150 farms, as well as samples from a second inventory at the end of the project.
• We model the soil carbon changes for all farm areas on the basis of the management data.
• In order to find out which barriers and challenegs the farmers experience when implementing the measures, we conduct surveys with the participating farms.
• We discuss the results with farmers at reflection workshops.

Links and Downloads

humus-klima-netz.de