Tropicultura (Jan 1991)
Gestion de la matière organique dans les sols tropicaux
Abstract
Organic matter management in the Tropical soils. Organic matter is the key of fertilization in tropical conditions and is closely associated with the cultural systems by/te dominant kinds of transfer : internal or external, vertical or horizontal. Although very complex by nature, organic material in the soils can be reduced to few transformation stages, accelerated in humid tropics compared with temperated environment, more particularly the mineralization of humus. Among the problems inherent to tropical ferrallitic soils, low cation adsorption capacity of the clay and low phosphorus availability to plant associated to high exchangeable and toxic aluminium content in strong acidity conditions constitute their main fertility constraints. So that reducing of exchangeable aluminium is the basis of the fertilizer effect of organic matter that can be compared with liming. This reducing is related to the formation of aluminium complexes with short chain di- and tri-carboxylic acids, characteristics of the freshly decomposed material rather than the humus. These data seem support the idea of the advantage of incorporating organic matter in soil before the humification in warm-humid tropics, according to many traditional cultural practices. The question of organic matter management is a good illustration of the necessity of a multidisciplinary approach with the agronomic and fundamental topics being treated in an integrated way.
