SOIL MICROBIAL ACTIVITY AS BIOINDICATORS DURING THE DECOMPOSITION OF GRASS RESIDUES IN SANDY CLAY LOAM SOIL

Abstract

Assessing the quality of the soil is an important method in determining the sustainability and environmental impact of agricultural ecosystems. Soil microbial indices like microbial biomass and microbial activity are important criteria for the determination of soil quality. Laboratory incubation study was undertaken to examine the influence of 2 grass residues on changes in soil microbial indices {(microbial (Cmic: Corg), metabolic (qCO2), carbon mineralization (qM) and microbial biomass change rate (qC) quotients)} in a sandy clay loam soil. Both P.maximum and D.horizontalis amended soil showed maximum soil respiration rate (11.90 mgCO2-C g-1 soil) while P.maximum had maximum cumulative respiration rate (199.90 mgCO2-C g-1 soil) .Microbial biomass C was significantly improved by both P.maximum and D.horizontalis residues under study (158.08 and 162 mg/g respetively). The qCO2 among different grass residues ranged from 1.23 to 1.24μg CO2- C μg-biomass-C -1 on the 82nd day. The results showed that incorporation of both grass residues impacted a positive effect on microbial flora and their activity. The study suggests that the despite the high C:N ratio of grasses, its seems to be of advantage in the maintenance of soil quality in a sandy clay loam soil.