Field study of nitrification and denitrification in a wet savanna of West Africa (Lamto, Cote d'Ivoire)

Field experiments about denitrification and nitrification processes have been performed in a wet savanna of West Africa (Lamto, Côte d'Ivoire). Two scales have been chosen: (i) a topographic gradient including the main forest and savanna environments; (ii) a soil profile taking into account roots and fauna effects. Denitrifying potential activity was only recorded in the surface soil: it was higher under forest than under savanna. Within the shrub savanna soil profile, denitrification was low in the average soil, but high in the walls of the termite fungus comb chambers, in the soil collected very close to the roots and in the earthworm casts. Nitrifying activity was higher in the grass savanna than in the shrub savanna dominated by the graminaceae Hyparrhenia diplandra.