Assessment of Soil Microbial Diversity under Organic and Conventional Farming Systems

Abstract

Soil microbial diversity is one of the most important indicators of soil health and agricultural sustainability. Soil microorganisms, including bacteria, fungi, actinomycetes, algae, archaea, protozoa, and other beneficial microbes, regulate essential ecological processes such as nutrient cycling, organic matter decomposition, nitrogen fixation, phosphorus solubilization, soil aggregation, and disease suppression. Agricultural management practices strongly influence the abundance, diversity, and functional activity of these microbial communities. Organic farming systems generally promote higher microbial diversity through the application of organic manures, compost, crop residues, green manures, biofertilizers, and diversified crop rotations, whereas conventional farming often depends on intensive tillage and synthetic fertilizers and pesticides that may alter microbial populations and ecosystem functions. Assessing soil microbial diversity is therefore essential for evaluating the sustainability and long-term productivity of agricultural systems. Modern assessment techniques such as microbial biomass estimation, enzyme activity analysis, DNA sequencing, metagenomics, polymerase chain reaction (PCR), phospholipid fatty acid (PLFA) analysis, and next-generation sequencing have greatly improved the understanding of soil microbial communities. Numerous studies indicate that organic farming enhances microbial biomass, functional diversity, enzymatic activity, and beneficial microbial populations compared with conventional farming, leading to improved soil fertility, nutrient availability, and crop resilience. However, microbial diversity is also influenced by climate, soil type, crop species, and management intensity. This paper evaluates soil microbial diversity under organic and conventional farming systems, highlighting assessment methods, ecological significance, challenges, and future research directions for sustainable agricultural development.