Weed-out and soil-up! Weed Management without soil disturbance in organic agriculture (EMERGE)

The European Union has a target of having 25% of its agricultural land in organic production by 2030. Weed management is one of the main challenges in organic agriculture and a key challenge to increase organic area and yields in these systems. Weeds in organic systems are mainly managed through tillage, which has known detrimental effects on soil structure and increases the risk of erosion. So there is a need to find solutions based on nature to address the dual goal of high weed suppression and soil conservation. Cover crop and organic mulch-based no-tillage strategies (MBNT) are proposed as an alternative to manage weeds and decrease soil tillage in organic field crops and vineyards in Spain. This approach can help address ecological transition goals by (i) helping mitigate climate change through a reduction in tillage; (ii) preserving and regenerating natural resources like soil and (iii) promoting circular economy through the use of by-products. To test the applicability and efficacy of MBNT on both weeds and system sustainability, an experiment in field crops and two in vineyards will be implemented in organic fields close to Lleida. In field crops (experiment 1), two grass cover crop species (cereal rye and black oats) will be sown at two different times to assess species adequacy to the system and best sowing time. Cover crops will be terminated with a roller-crimper to create a weed suppressive mulch before soybeans and weed density, weed biomass and crop yield will be measured and compared to a tilled control situation. In vineyards (experiment 2), two cover crop species (Triticale and Phacelia) will be sown between the vine rows and will be terminated using either a roller-crimper or a shredded. A no-cover crop control, where weeds will be managed with tillage, will also be added. Finally, in the line underneath the vines (experiment 3), two different types of organic mulches (almond husk and vine “orujo”) will be installed to prevent weed growth and compared to an in-row tilled control. Vine “orujo” is currently a residue from wine production that contains grape skin and seeds and the rachis. The use of this by-product as a mulch may help close the nutrient cycle by returning to the soil part of the nutrients extracted with the grapes as well as managing weeds. Also, it will contribute to create a circular economy where the residues of one process are an asset to another. Experiments will be repeated in two locations for two years. Light Detection and Ranging (LiDAR) will be used to estimate vine vigour and growth and, for the first time, cover crop living and rolled biomass. The project will test if this technology can readily estimate cover crop biomass and correlate it to mulch weed suppression potential, thus increasing the digitalization and resource optimization in agricultural production. Finally, organic matter, water retention, soil structure and chemical soil analysis; as well as a carbon footprint analysis will be performed to measure the environmental impact of MBNT strategies and to compare them to the tilled option. The results of this project are expected to reduce the environmental impact of organic agriculture and move us toward climate change mitigation goals while conserving and regenerating soils. Results of the project will be disseminated through scientific publications and conferences, science magazines, extension seminars, social media and transfer activities to the sector and social media.