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Project Topic
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Sown forage mixtures have shown advantages compared to monocultures in terms of goods and services. Among the most relevant benefits researchers have tested are: high productivity and quality forage, enhanced yield stability, lower susceptibility to pests and diseases, reduced nitrogen need, decreased greenhouse gas emissions (GHG). As major outcome, mixtures were shown to increase soil fertility, and water and nutrient use efficiency, and therefore are expected to have positive effects on soil biodiversity and function. However, a better understanding under extreme conditions and drought is still needed in vulnerable climates including the Mediterranean. This is particularly important as, despite the known benefits of forage mixtures, there is a trend in loss of mixtures in favour of grass monocultures in all Mediterranean areas. Furthermore, there is a lack of information about the effects of grazing on soil carbon and fertility conservation in mixed polycropping-livestock systems, yet grazing systems are key in many Mediterranean countries. Here, they are expected to provide numerous ecosystem services and high biodiversity to human livelihoods in rural areas, sometimes remote. Nonetheless, despite known productive and environmental advantages, there might be barriers to the implementation and spread of sown mixtures, and those could range from management difficulties over seed availability to market demands. To this purpose, SUSFORAGE asks the following questions: a) Are sown mixtures advantageous in dry Mediterranean areas in terms of yield productivity, quality, resilience and stability, moreover for soil fertility, health and carbon sequestration? b) Do sown mixtures combining different plant traits ameliorate soil function and microbial processes to deliver mixture benefits? c) Do the benefits of sown mixtures hold under grazing conditions in water-limited areas? d) What are the most important perceived benefits and constraints of sown forage mixtures by local growers? To answer those questions, SUSFORAGE proposes the establishment of 5 Case-Study Regions across a climatic gradient, where socio-ecological surveys will be carried out and 4 experimental forage swards will be established. The swards will include a range of sown proportions and monocultures of the most commonly used local forage species to develop models of optimal adaptive mixture proportions under given climatic conditions. Several ecological indicators will be measured at all sites during the development of the systems: yield; forage quality; water and nitrogen use efficiency by chemical and isotopic techniques; soil fertility; GHG fluxes; soil organic carbon storage; soil microbial activity, diversity and function by phospholipid fatty acids (PLFAs), exoenzymes and metagenomics; system stability by comparing benefits throughout time. Simultaneously, surveys and socio-ecological multi-actor workshops will be carried out with stakeholders to determine local perceptions on sown mixtures. Overall the SUSFORAGE project will contribute to enlarge the information of the benefits of sown mixtures, particularly in Mediterranean dry areas and under grazed conditions, in a vulnerable region with climate extremes. We will provide a model to determine the optimal proportions of different functional types of forage species locally adapted to the specific climate scenarios. In addition, we will elaborate a socio-ecological model including perceived benefits and constraints by local populations, and design with multi-actor stakeholders how to implement the tested sown systems at large scales in the Case-Study regions. We will derive general recommendations applicable to wider regions in the Mediterranean. Combining innovative methodologies, we will demonstrate if sown mixtures are indeed a solution for mitigation and adaptation to climate change in Mediterranean areas as expected, and the limits and constraints to their widespread distribution.
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