The molecular structures of the humic substances are still not known. There is much controversy and little consensus on the structural conception of these substances. Two main issues are considered: the accumulation of experiences and the methodological challenges. This review aimed to gather information on the nature of humic acids and their roles in natural and agrarian ecosystems, seeking their management and conservation, as well as technological opportunities for the development of new inputs for tropical agriculture.
soil organic matter; humic substances; management and conservation of natural and agrarian ecosystems
