Developing Organic Minimum Tillage Farming Systems for Central and Northern European Conditions

Organic farming in temperate climatic conditions usually relies on intensive soil tillage to mineralize nutrients and suppress weeds in order to compensate for the lack of herbicides and synthetic fertilizers. In the long term, this may reduce soil organic carbon contents, and by this, soil fertility. Consequences are deterioration of soil structure and increased risks of water and wind erosion. For long-term sustainability, organic minimum tillage practices are needed that are based on strategies that circumvent problems with nutrient limitations and weed infestations. In three case studies, we demonstrate how the intensive use of cover crops, compost, and/or mulch help to improve soil structure and fertility and thus, enable the establishment of organic minimum tillage. This includes an example of practical research in a vegetable farm developing innovative, soil improving cultivation strategies. Traditional as well as participatory and on-farm research can be supported by a visual spade-based diagnostic method to determine the Soil Structure Index (SSI) that helps generate highly informative data. The success of organic minimum tillage hinges on (i) Organic amendments for balanced nutrient supply and increased crop performance while stimulating and enhancing the soil and rhizosphere microbiome; (ii) Effective cover crop and crop residue management for nutrition, weed suppression, prevention of pests and pathogens and climate resilience; (iii) Technical solutions and professional support, especially for direct planting and mulching. For organic farming, soil fertility is not the result, but rather the prerequisite, for no- or minimum tillage. Further research should focus on crop rotations, efficient cover crops, tillage strategies, and crop species adapted fertilization.