Potential for developing low-input sustainable agriculture in the tropical andes by making use of native microbial resources

The Tropical Andes, a vast region spanning over 1,540,000 km2 from Western Venezuela to Northern Chile and Argentina, faces huge challenges. Among these are a rapid demographic change and an increasing demand of agricultural goods to satisfy the needs of both rural and urban population. Unfortunately, crop production in this mountainous region is severely constrained by adverse natural factors, among which low soil fertility and cold climates occupy the top positions in the ranking. Considering that agriculture intensification, following the traditional approaches that made possible the Green Revolution, may cause further disruption and degradation of Andean agroecosystems, new strategies are being explored by researchers and farmers to deal with that dilemma. It has been proposed that partial replacement of agrochemicals (fertilizers and pesticides) with bioinoculants-products formulated with living microorganisms with plant-promoting abilities-is one of the measures that might allow to intensify even more agriculture in the Andes, without seriously affecting the environment or threatening human health. In order to maximize profits following this approach, it is imperative to study in depth the microbial diversity present in the Andean ecosystems, to select microbes exhibiting the best plant growth-promoting traits, and optimal performances in the rhizosphere of crops. Here we review some of the recent advances concerning the description of the microbes colonizing the rhizosphere of some important Andean crops; we further highlight important local and regional experiences showing that the development of efficient bioinoculants may certainly contribute to intensify agriculture in the Tropical Andes and, subsequently, to create better life conditions for the Andean small farmers and their families.