Microbial and Enzyme Activities and Carbon Stock in Unique Coastal Acid Saline Soils of Goa

Abstract

The aim of the present investigation was to study the effects of salinity under low soil pH conditions on soil microbial and enzyme activities and to quantify soil organic carbon (SOC) stocks in coastal saline soils of Goa, India. Global positioning system based replicated soil samples collected from fifteen different locations showed characteristic variations in electrical conductivity (0.09–6.29 dS m−1), soil pH (4.11–6.57), exchangeable sodium (Na) (7.40–23.2 meq 100 g−1) and exchangeable sodium percentage (48.3–85.7 %). Exchangeable Na was the most dominant cation among all the cations analyzed at all the sites. The total SOC stock of the study sites varied significantly (p < 0.05) and ranged from 4.27–24.3 Mg C ha−1. The soil microbial activity measured in terms of basal soil respiration, soil microbial biomass carbon (Cmb), Cmb as a fraction of SOC and enzyme activities related to dehydrogenase, phosphatase and urease showed a decline with increasing salinity levels. On the contrary, metabolic quotient increased with increasing salinity. The results of the study suggest that salinity under low soil pH has a depressive effect on the soil microbial and enzyme activity. Alleviation of the depressive effect of salinity on microbial activity needs to be addressed through suitable interventions and countermeasures for sustainable crop production in coastal acid saline soils of Goa.