EVALUATION OF POPULATION DENSITY AND PHYSICOCHEMICAL ATTRIBUTES OF FIELD SOIL FROM MAHADEVAPATTINAM, THIRUVARUR DISTRICT

Abstract

This research presents an analytical investigation of field soil samples collected from Mahadevapattinam village and surrounding areas of Thiruvarur District. The study focused on assessing the population density of soil microbes along with their physicochemical and biochemical parameters. Soil, a heterogeneous matrix composed of both organic and inorganic components, serves as a vital and nutrient-rich medium supporting microbial diversity. A total of six bacterial strains—Bacillus subtilis, Azotobacter chroococcum, Azospirillum brasilense, Enterobacter cloacae, Rhizobium leguminosarum, and Pseudomonas fluorescens—were isolated using the dilution plating technique and identified with reference to standard microbial manuals. Physicochemical properties such as soil texture, pH, electrical conductivity, and microbial populations including bacteria, fungi, actinomycetes, and diazotrophs were analyzed.Further, Fourier Transform Infrared (FTIR) spectroscopy revealed the presence of major functional groups such as hydroxyl (–OH), carbonyl (C=O), and amide linkages, indicating the abundance of organic matter and microbial metabolites. Gas Chromatography–Mass Spectrometry (GC–MS) profiling identified several bioactive compounds including fatty acid methyl esters, alkanes, and phenolic derivatives, signifying active microbial decomposition and complex organic composition of the soil. The findings suggest that the bacterial isolates from paddy field soils, supported by rich organic signatures revealed through FTIR and GC–MS analyses, can serve as potential biofertilizers and biocontrol agents. Collectively, these rhizosphere-associated microbes and their metabolites play a crucial role in nutrient cycling, nitrogen fixation, and sustainable soil fertility management.