Grain legume decline and potential recovery in European agriculture: a review

摘要

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 system-internal outputs of legumes such as the nitrogen fixed, of 130 to 153 kg N ha(-1); 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 N2O, 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.