Bio-associative influence of secondary metabolites of turmeric on microbial and biochemical changes in rhizosphere and non-rhizosphere soils under various nutrient management practices

Abstract

Field experiment was conducted using turmeric as test crop at farmer’s field, Byadamudlu village, Chamarajanagara district, Southern Dry Zone of Karnataka during 2016-2017 to determine the bio-associative effect of specific nutrient management practices recommended by different institutions and farmers’ practice. In addition to above recommendations, two microbial consortia i.e., Microbial consortia (MC) and Arka Actino Plus (AAP) were evaluated for their influence on microbial and biochemical changes in soils at three levels i.e., 100, 75 and 50% of nutrients recommended by University of Agricultural Sciences, Bengaluru. Both rhizosphere and non-rhizosphere soils were sampled to compare the associative influence on soil microbial and biochemical changes. Higher microbial population, enzymatic activity and soil microbial biomass carbon and nitrogen was observed in non-rhizosphere soils than rhizosphere soils of turmeric, due to its antimicrobial properties, secondary metabolites like curcumin. Nutrient management practice according UAS (B) recommendation (N150P125K250) + MC + AAP resulted in maximum bacteria, fungi, actinomycetes, phosphorus solubilising bacterial and N-fixers population (14 x 106, 11 x103, 31 x 104, 19 x 104 and 18 x 103 cfu g-1, respectively) compared to other treatments in non- rhizosphere soils, similarly higher enzymatic activity and soil microbial biomass carbon and nitrogen was recorded in same treatment.