Journal of Agronomy and Field Innovations

Background: Microorganisms in soils are vital to the ecosystem, nutrient cycles, and carbon processes. Although we know that conservation agriculture enhances soil biology, there has yet to be a complete understanding of how communities of microorganisms in soils change.
Objective: The study aims to investigate the diversity of soil microorganisms and how communities differ under the effects of different conservation agricultural practices, including the 16S rRNA gene sequencing method, and to find out which bacteria enhance soil health.
Methods: A randomized complete block design was used for the field experiment at research in northern India with the land consisting of silty clay loam soil. Five treatments were tested: conventional tillage (CT), minimum or reduced tillage (MT), zero tillage (ZT), residue retention (RR), and integrated conservation agriculture (ICA). Soil samples were taken at the depth of 0–15 cm from replicated plots for extraction of DNA, amplification of the 16S rRNA gene, and sequencing by Illumina MiSeq. Bioinformatics evaluation involved the use of QIIME2 and DADA2 pipelines and resulted in the generation of amplicon sequence variants (ASVs). The indices of diversity and composition were evaluated using analysis of variance (ANOVA) and PERMANOVA tests (p < 0.05).
Results: Application of conservation agriculture methods induced considerable elevation in Shannon indices (4.2–4.8) compared to conventional tillage methods (3.9). Use of zero tillage methods and integrated conservation agriculture brought about maximum bacterial species richness (Chao1 ≥ 2,450 ASVs). Phyla with the highest abundance included Proteobacteria (28%–35%), Actinobacteria (22%–28%) and Acidobacteria (15%–19%). The processes of ammonia oxidation were significantly enhanced under conservation agriculture methods with large spiking of Nitrospirae and Nitrospina. Strong correlation between organic carbon contents and Shannon diversity indices was established (r = 0.78, P < 0.01). Results of function prediction suggest improved capabilities with respect to N cycling and C sequestration.
Conclusion: The application of conservation agriculture techniques will enhance the diversity of soil microbes further increasing the number of organisms which are engaged in nutrient cycling including carbon sequestration processes. The use of 16S rRNA sequencing allows comprehensively studying microflora responses to the application of conservation agriculture techniques.