Defining anaerobic soil disinfestation through changes in the microbiome

Authors: Hong, Jason; DI GIOIA, FRANCESCO - Pennsylvania State University; JONES, JEFFREY - University Of Florida; Turechek, William; JOHNS, CHRISTIAN - Miami University - Ohio; FINLEY, NATOSHA - Miami University - Ohio; OZORES-HAMPTON, MONICA - University Of Florida; McCollum, Thomas; Rosskopf, Erin; Burelle, Nancy

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2019
Publication Date: 2/27/2020
Citation: Hong, J.C., Di Gioia, F., Jones, J.B., Turechek, W., Johns, C.W., Finley, N.L., Ozores-Hampton, M., Mccollum, T.G., Rosskopf, E.N., Burelle, N.K. 2020. Defining anaerobic soil disinfestation through changes in the microbiome. Acta Horticulturae. https://doi.org/10.17660.
DOI: https://doi.org/10.17660

Interpretive Summary: Anaerobic soil disinfestation (ASD) manipulates the soil microorganisms, also known as the soil microbiome. This is accomplished by working in soil amendments to the soil, composted poultry litter and sugar cane molasses, tarping the soil with a plastic sheet, and saturating the soil with water. After this procedure, the microbiome in the treated soil quickly changes to an anaerobic, lacking oxygen, population. These microbes produce acids and other secondary metabolites that lower the soil pH. Because of the lack of oxygen, lower pH, and most likely other factors, ASD inhibits the growth of soil plant pathogens. In this study we looked at what types of acids were produced during this soil treatment. We also looked at changes in microbiome over time.

Technical Abstract: The main driver of anaerobic soil disinfestation (ASD) is manipulation of the microbiome. This is achieved by introducing soil amendments and depleting the soil of oxygen by saturating with water under a plastic tarp. The current standard ASD method in Florida, USA, consists of applying composted poultry litter (13 Mg ha-1), feed grade sugar cane molasses (13,900 L ha-1), tarping with totally impermeable film (TIF), and saturating the soil with 5 cm of water. ASD is applied three weeks prior transplanting. Herein, we report on impacts of modifications of the ASD treatment regarding the soil microbiome. The study was conducted in the greenhouse and field, in which standard ASD, ASD with double application of molasses (ASD 2×), and soil covered with TIF (control) were compared. Spatial and temporal soil samples were taken at 0-15 cm and stored at -80° C. Total DNA was extracted and microbial populations were identified using length heterogeneity polymerase chain reaction (LH-PCR) and next generation sequencing of the 16s ribosomal deoxyribonucleic acid (DNA). Based on the redox potential data, ASD 2× was more anaerobic than ASD in the greenhouse, and both were statistically more anaerobic than control at both locations. Using LH-PCR, shifts in the microbiome were observed and both ASD treated soils differed from the control in both the greenhouse and field experiments. Based on 16s rDNA, members of the Firmicutes and Proteobacteria phyla increased compared to the control. From a panel of seven different organic acids, only isobutyric acid was detected in the control samples, while all six of the seven acids were detected in the ASD treated soils. ASD 2× had a greater quantity of each organic acid than ASD.