Effects of Organic Amendments and Commercial Mycorrhizal Fungi on Switchgrass Biomass Production in Degraded Soils

Ekundayo O Adeleke, Tennessee State University


Bioenergy feedstock production on degraded land can serve as a means for modulating land competition for food versus energy. However, as farmers struggle to rejuvenate their degraded land, there is a need for a quick screening strategy to select the best method of enhancing cellulosic (switchgrass, SG) biomass production in degraded soil as well as understand the effect of method of enhancement on soil and water quality. Therefore, the goal of this study is to evaluate the effects of soil amendment and inoculation strategies on biomass productivities of SG in degraded soil. First, experiments were conducted in the greenhouse using moisture replacement microcosms (MRM) to screen strategies for enhancing biomass productivities of SG in degraded soils. Second, critical drivers of organic nutrients decomposition in the soil are soil microbial communities and understanding their role in plant-soil-microbe interaction for enhancement of plant productivity is mostly unstudied. Mesocosm experiment was set up using the top five treatment (commercial mycorrhizal fungi - AMF, paper mill sludge with nitrogen - PMS+N, vermicompost - VC, AMF +VC, and AMF + PMS) from the microcosm experiment. The mesocosm experiment was set up to investigate the response of soil microbial communities (SMCs) and SG productivity to the application of organic amendments, AMF inoculation and their combined applications in degraded soils. Rhizospheric soil samples were collected from each SG shoot harvested. Canonical correlation analysis indicated that most probable number was associated with increased total nitrogen, soil organic carbon and large macroaggregate. The SMCs in mesocosm experiment correlated positively with physicochemical properties. Lastly, metabarcoding analysis of SMCs in rhizospheric soil samples using methods ranging from DNA extraction, PCR-based amplification to next-generation sequencing was carried out for bacterial and fungal diversities. The 16S rRNA and ITS profiling of the extracted gDNA showed higher microbial diversity in reclaimed surface-mined soil than McBribe soil. The SMC was positively correlated with the root productivity and heavy metal concentrations in soil leachate. In conclusion, the effect of organic amendments increased the SG root productivity in degraded soil and trace elements in the leachate. Assessing the economic, environmental, and agricultural impact, the treatment AMF + PMS+N was the best treatment that improved the soil.

Subject Area

Agriculture|Microbiology|Molecular biology

Recommended Citation

Ekundayo O Adeleke, "Effects of Organic Amendments and Commercial Mycorrhizal Fungi on Switchgrass Biomass Production in Degraded Soils" (2020). ETD Collection for Tennessee State University. Paper AAI28026358.