Microbial diversity of tropical Andean soils and low-input sustainable agriculture development

The Tropical Andes spans over 1,540,000 km² from western Venezuela to northern Chile and Argentina and is currently considered the most biologically rich and diverse region on Earth. The rural populations from the Andean highlands depend largely on agriculture and related activities for their livelihoods. In spite of a long history of agriculture in the region, crop production in these highlands is constrained by adverse natural factors such as low soil fertility, rugged terrains, water deficit, and cold climates. In the last decades, a better understanding of the functioning of microbial communities in agricultural soils has led to the development of technologies that could alleviate some of these natural constraints and increase productivity sustainably. A promising approach to take advantage of the functioning of these microbial communities is the development of bioinoculants, products containing live or latent cells of agriculturally beneficial strains of microorganisms. When applied to seeds or soils, these bioinoculants boost the populations of beneficial microorganisms in the rhizosphere and accelerate certain microbial processes that result in increased nutrient acquisition by plants and in augmented antagonism to pathogens. A key step in the process of developing this kind of bioinoculants is the study of the indigenous microbial biodiversity of the agricultural and natural ecosystems in which these inoculants will be applied, in order to select microbes that are well adapted to the particular conditions of these ecosystems. Here we review the most recent descriptions of the microbial diversity of Tropical Andean soils, the potential use of these microbes for improving the functioning of crop production systems, and important experiences in the development of inoculant technologies in the region.