Comparative performance of conservation agriculture vis-a-vis organic and conventional farming, in enhancing plant attributes and rhizospheric bacterial diversity in Cajanus cajan: A field study
Upma Singha, Anil K.Choudharyb,1, Shilpi Sharmaa
Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.
The intensification of agriculture to meet the ever-increasing demand for food has exerted a negative impact on the ecosystem. Conservation agriculture has been highlighted as a comprehensive approach to sustainability. The present study aimed to assess the performance of conservation agriculture (CA) on plant growth, and its impact on bacterial community composition, specifically guilds involved in nitrogen (N) cycling, in comparison to conventional (CT), and organic agriculture (OA). A field experiment was set up with Cajanus cajan (pigeonpea) under the three agricultural practices with a total of nine modules. The rhizospheric bacterial community composition was examined using Illumina sequencing with the 16S rRNA gene as a marker. The bacterial community involved in nitrogen cycling was examined by analysis of key genes involved in pathways, viz. nitrogen fixation (nifH), nitrification (amoA), and denitrification (narG and nirK) by qPCR. Plant growth parameters and grain yield of C.cajan were relatively higher in CA-based modules. Enhanced abundances of genes involved in the N cycle were observed under CA compared to CT and OA. CA had the highest alpha diversity at the phylum level, while CT had the lowest. Proteobacteria (28%), Planctomycetes (15–19%), Acidobacteria (10–12%), and Bacteroidetes (10–15%) were the dominant phyla across the three agricultural practices. A significant correlation could be drawn between the performance of agricultural management practice, and bacterial community structure and function. The research adds to our understanding of the various mechanisms involved in the promotion of plant growth and soil diversity under sustainable means of agriculture. Besides it emphasizes the significance of rhizospheric bacterial communities as ecological indicators for soil health in arable land.
Keywords: Conservation Agriculture, Conventional agriculture, Organic agriculture, Next generation sequencingq, PCR, Nitrogen cycle.