Structuring of the soybean rhizosphere microbiome under application of potassium fertilizers

Abstract

The unconscious intensification of agricultural practices can result in the loss of soil quality, erosion and consequently a negative effect on plant development. Soil microbial communities, especially the rhizosphere, are closely linked to crop productivity and health. Thus, a better understanding of how agricultural management affects soil microbiota is necessary to promote sustainable agriculture. Among the different components of the agricultural production system, few studies seek to understand how the soil microbiota responds to the use of different sources of potassium (K) used as fertilizers. In this sense, this project aims to understand the changes in the taxonomic and functional profile, in the diversity and in the interaction networks of the microbial communities associated with the soybean rhizosphere, caused by the use of potassium fertilizers. For this purpose, the work will consist of 3 main experiments, which will aim to: (a) understand the changes caused in the microbial composition of the rhizosphere of soybean culture fertilized with different potassium sources (potassium chloride, potassium sulfate and phonolite rock) furthermore, to compare the composition of the microbial community between the rhizospheric soil and the bulk soil and, (b) how the presence of potassium fertilizers impacts the establishment and efficiency of inoculants (Azospirillum brasiliense and Bacillus sp.). The assays will be carried out in a greenhouse, and the evaluation will be performed using complementary techniques, covering enzymatic activity, metabolic profile of the community, pattern of colonization of the rhizoplane and anatomical alterations of soybean, DNA extraction and sequencing of specific regions (16S rRNA for identification of bacteria and ITS for fungi) of rhizospheric and bulk soil samples, as well as analysis of plant development, such as dry and fresh weight, plant height, shoot and root length, and productivity. Additionally, to understand the survival of inoculants, qPCR and microscopy methodologies will be used. With the results obtained during the project, it is expected to understand the functional and structural changes of microbial communities caused by the use of different potassium fertilizers, which will support the management with greater use and benefits of ecosystem services derived from the microbial ecology of the soil and of the rhizosphere. (AU)