SummaryIntercropping is a farming practice involving two or more crop species, or genotypes, growing together and coexisting for a time. On the fringes of modern intensive agriculture, intercropping is important in many subsistence or low-input/resource-limited agricultural systems. By allowing genuine yield gains without increased inputs, or greater stability of yield with decreased inputs, intercropping could be one route to delivering 'sustainable intensification'. We discuss how recent knowledge from agronomy, plant physiology and ecology can be combined with the aim of improving intercropping systems. Recent advances in agronomy and plant physiology include better understanding of the mechanisms of interactions between crop genotypes and speciesfor example, enhanced resource availability through niche complementarity. Ecological advances include better understanding of the context-dependency of interactions, the mechanisms behind disease and pest avoidance, the links between above-and below-ground systems, and the role of microtopographic variation in coexistence. This improved understanding can guide approaches for improving intercropping systems, including breeding crops for intercropping. Although such advances can help to improve intercropping systems, we suggest that other topics also need addressing. These include better assessment of the wider benefits of intercropping in terms of multiple ecosystem services, collaboration with agricultural engineering, and more effective interdisciplinary research.

There is a great demand for high-protein materials for livestock feed in Europe and European agriculture has a deficit of about 70% high protein materials of which 87% is met by imported soybean and soy meal. This reflects the fact that grain legumes are currently under represented in European agriculture and produced on only 1.5 % of the arable land in Europe compared with 14.5% on a worldwide basis. Several grain legumes have the potential to replace at least some of the soya currently used in the diets of monogastric animals, ruminants and fish. There are also opportunities for greater use of legumes in new foods. Here we review the contribution of ecosystem services by grain legumes in European agriculture starting with provisioning services in terms of food and feed and moving on to the contribution they make to both regulating and supporting services which are in part due to the diversity which these crops bring to cropping systems. We explore the need to understand grain legume production on the time scale of a rotation rather than a cropping season in order to value and manage the agronomic challenges of weed, pests and diseases alongside the maintenance or improvement of soil structure, soil organic matter and nutrient cycling. A review of policy interventions to support grain legumes reveals that until very recently these have failed to make a difference in Europe. We contrast the European picture with the interventions that have allowed the development of grain legume production in both Canada and Australia. Whether farmers choose to grow more legumes will depend on market opportunities, the development of supply chains and policy support as well as technical improvements of grain legume production such as breeding of new varieties and management development to improve yield stability. However, to really increase the production of grain legumes in Europe the issues are far more wide reaching than agronomy or subsidy and require a fundamental rethinking of value chains to move grain legumes from being niche products to mainstream commodities.

Abstract. 12Complex relationships exist between different components of the organic farm and 13 the quantity and quality of the end products depend on the functioning of the whole 14 system. As such, it is very difficult to isolate soil fertility from production and complex interactions between different system components, fertility management in 1 organic farming relies on a long-term integrated approach rather than the more short-2 term very targeted solutions common in conventional agriculture.

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Sustainable development of agriculture is at the core of agricultural policy debates in Europe. There is a consensus that diversification of cropping would support sustainable development. However, a reduction in legume cultivation has been observed in the EU during the last decades. This decline has induced, in turn, a deficit of proteins and a reduction of ecosystem services provided by legumes. Therefore, we analysed the mechanisms that shape agricultural systems to identify leverage points for reviving European legume production. Specifically, we reviewed the factors that affect the market and non-market value of legumes and the relevant agricultural policies. We characterized the decline in legume cropping as an outcome of the dominance of economic forces that favour specialization of production systems over diversification. We found that the value of market outputs of legumes per unit area is relatively low and volatile, with a 25-78 % variation in pea gross margins, which reduces market competitiveness. We observed that the value of systeminternal outputs of legumes such as the nitrogen fixed, of 130 to 153 kg N ha; crop protection services that reduce agrochemical costs, by 20-25 % in cereals; and yield enhancements of subsequent crops, of 0.2 to 1.6 t ha −1 in cereals, are often underestimated. In addition, markets fail to translate external effects of legumes such as biodiversity enhancement, reduction in emissions, of up to 50 % in N 2 O, and soil improvements into economic benefits. Current policies support legumes through selected mechanisms such as ecological focus areas, agri-environmental programmes and sparse coupled support measures. Domestic cultivation of legumes could be supported through trade policies such as import restrictions on genetically modified soybean or new mechanisms to appreciate non-market outputs including payments for ecosystem services and carbon markets. In addition, development of new value chains, niche markets, scaling-up of plant breeding efforts and dissemination of information is required.

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Sustainable farming systems strive to minimise the use of synthetic pesticides and to optimise the use of alternative management strategies to control soil-borne pathogens. Arbuscular mycorrhizal (AM) fungi are ubiquitous in nature and constitute an integral component of terrestrial ecosystems, forming symbiotic associations with plant root systems of over 80% of all terrestrial plant species, including many agronomically important species. AM fungi are particularly important in organic and/or sustainable farming systems that rely on biological processes rather than agrochemicals to control plant diseases. Of particular importance is the bioprotection conferred to plants against many soil-borne pathogens such as species of Aphanomyces, Cylindrocladium, Fusarium, Macrophomina, Phytophthora, Pythium, Rhizoctonia, Sclerotinium, Verticillium and Thielaviopsis and various nematodes by AM fungal colonisation of the plant root. However, the exact mechanisms by which AM fungal colonisation confers the protective effect are not completely understood, but a greater understanding of these beneficial interactions is necessary for the exploitation of AM fungi within organic and/or sustainable farming systems. In this review, we aim to discuss the potential mechanisms by which AM fungi may contribute to bioprotection against plant soil-borne pathogens. Bioprotection within AM fungal-colonised plants is the outcome of complex interactions between plants, pathogens and AM fungi. The use of molecular tools in the study of these multifaceted interactions may aid the optimisation of the bioprotective responses and their utility within sustainable farming systems.