Grassland N fertilization in humid tropics : production, organic matter decomposition and uptake

Under tropical humid conditions at low altitudes in La Reunion island an experiment was conducted in 1995 to examine the effects of mineral and organic N fertilisation on regrowth of #Chloris gayana#. Mineral fertilisation stimulates the production of leaves for the first 20 days of regrowth. Dry master production was increased of 181 % with the combination of manure plus ammonium nitrate and only 147 % with ammonium nitrate alone. The soil microbial biomass activity, measured after 50 days of regrowth, was increased of 31 % by application of manure, 41 % by ammonium nitrate and 50 % by manure + ammonium nitrate. With organic fertilisation the uptake of N is more important in leaves than in stems. (Résumé d'auteur