Catch crop upheaval and nitrogen cycle (CIRCLE) 2022 - 2025

The project is the first research topic to be developed jointly with the farmers involved in the Hesse Practical Research Network in the specialist group for arable farming. The expert group consists of organic arable farms, advisors from the Hesse State Agricultural Office (LLH) and the Naturland association, and the Department of Organic Crop Production at the University of Kassel. The influence of different intercropping methods on the fate of the nitrogen that the intercrops have absorbed into their shoot mass before winter is being investigated. Farmers want to direct their measures in such a way that the nitrogen does not escape in liquid or gaseous form, but enters the soil in organically bound form. As various studies have shown, this is only partially achieved by the classic method of incorporating the soil with a plow before winter. Two possible alternatives are shallow incorporation, e.g., with a tiller only in spring, or stalk bending followed by windrowing and soil accumulation in fall and incorporation of the intercrop biomass in spring. These methods promise rapid microbial decomposition of the crop and root residues of the intercrops only in the spring and can thus potentially mitigate liquid and gaseous losses. In the project applied for here, the influence of all three tillage methods on the N cycle in soil, plant and atmosphere is to be tested in field trials on the Frankenhausen domain and on the participating practical farms. The results should help the farmers involved and others to optimize their intercropping with regard to the contribution to humus build-up and the preservation of nitrogen in the soil-plant system.