Microbial C, N and P in dry tropical savanna: effects of burning and grazing

Abstract

(1) The effects of burning and grazing of dry tropical Indian savanna on the level of available nutrient pools and microbial C, N and P were assessed. (2) The maximum amounts of available nutrients and microbial biomass occurred in the dry period and minimum in the wet period. (3) Burning and grazing increased inorganic N by 54% and 15-49%, respectively and also increased bicarbonate-extractable inorganic P by 35% and 27-32%, respectively. (4) Mean annual microbial C varied from 361 to 466 μ g g^-1, microbial N from 35 to 44 μ g g^-1 and microbial P from 16 to 23 μ g g^-1 dry soil. The mean annual microbial C, N and P were positively related to each other. (5) Burning increased microbial C by 18%, microbial N by 26% and microbial P by 35%, and grazing increased microbial C by 15-18%, microbial N by 14-23% and microbial P by 19-29%.