Improving agroforestry and silvopastoral systems in Latin America by maximising species and genetic diversity of the multipurpose legume Inga

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Tropical forest soils in the Amazon and many other parts of Latin America are generally nutrient-poor and unsuited to long-term agricultural use. Land converted to agriculture by cutting and burning natural vegetation tends to remain productive for only a few years, necessitating continual advance of the agricultural frontier, with accompanying deforestation, and generating situations of food insecurity and poverty.Agroforestry and silvopastoral systems, which incorporate trees into crop and livestock systems, have been shown to make a dramatic impact on the maintenance and restoration of long-term productivity in agricultural landscapes, including degraded and abandoned land, and are well suited to use by poor rural smallholders. They can provide major benefits through enhanced livelihoods and food security, as well as to local economies.Inga is a diverse genus of trees from the legume family, found across the humid tropics of Latin America. These fast-growing trees are able to capture nitrogen from the atmosphere and fertilise the soil around them. They can be grown in poor, degraded soils, out-competing weeds and invasive species. The value of native trees, including Inga, within agroforestry systems, where they are planted to provide a nurturing environment for crops, has been amply demonstrated by a number of projects, and is gaining momentum. However, this has been insufficiently explored. Most such systems have been developed around a limited genetic stock of a single species, Inga edulis, yet it performs best under a limited range of conditions and other Inga species are likely to provide equal if not greater benefits outside of this range, which would expand the geographic and ecological scope within which these systems can be applied.Emerging techniques in genetics offer the potential for rapid identification of species and genotypes of Inga with similar ecological characteristics, thus facilitating fast-tracking of appropriate candidates into field trials and ultimately into more productive landscapes. The project will apply state-of-the-art genetic approaches to complete a thorough analysis of the genus, focusing primarily on species in the Brazilian Amazon, identifying the most suitable species for agroforestry and silvo-pastoral systems. Critically, this selection of species will be done in consultation with stakeholders and smallholders, to ensure uptake and use of the selected species.Targeted field collection of tissue specimens and seeds from these species will support ongoing genetic research, and will be used to establish early-stage field trials in Mato Grosso (southern Amazon), both in controlled contexts and in agroforest systems. These will be monitored to assess a range of characters including growth rate, biomass and tree form, all of which are important indicators of their suitability. Longer-term monitoring, using protocols developed by the project, will provide further indication of their potential value within these systems.The project will be delivered in Brazil through collaborative partnerships between UK and Brazilian scientists. It aims to develop and demonstrate the effectiveness of a methodological approach that can form the basis for improved agroforestry and silvopastoral systems across Latin America. In the course of the project, the team will build a network of scientists and practitioners within Brazil and across other Latin American countries, facilitating the development of further research in this field and communicating its findings to a range of academics, practitioners of agroforestry and silvo-pastoral systems and the lay public, in both Latin America and the UK.