Enhanced Yields in Organic Crop Production - a Role for Crop Diversification in Ecofunctional Intensification?.

Organic agriculture (OA) faces challenges to enhance food production per unit area and reduce environmental and climate impact, e.g. GHG emissions per kg product. Eco-functional intensification (EFI) is suggested as a means for enhancing yields in OA. EFI involves activating more knowledge and intensifying the beneficial effects of ecosystem functions, including agrobiodiversity (planned and associated) and soil fertility, and refocusing the importance of ecosystems services in agriculture. Organic farmers manage planned agrobiodiversity in time, for example by growing crops in rotation – a basic principle in OA. However, cultivating genetically identical plants in OA monocrops limits resource use efficiency and yield per unit area. Intercrops of annual species or cultivars, perennial polycultures of forage or grain crops and agroforestry are examples of spatial diversification, which based on eco-functional intensification can enhance yield by interspecies complementarity improving resource use. Intercropping of species is based on ecological principles such as competition, facilitation and complementarity and optimization of ecological functions. We show that intercropping of cereals and grain legumes in European arable OA systems is a strong tool for enhancing grain yields per unit area compared to the average yield of sole crops. Simultaneously, we show how eco-functional intensification by intercropping can be used as an efficient tool for weed management, enhanced product quality (i.e. grain protein concentration of cereal), efficient use of soil N sources and minimized losses of N by leaching during autumn and winter. We discuss barriers and suggest a roadmap for innovation and implementation of intercropping in organic agriculture.