Defining anaerobic soil disinfestation through changes in the microbiome

Authors: Hong, Jason; DI GIOIA, FRANCESCO - University Of Florida; 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

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/5/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary: Anaerobic soil disinfestation (ASD) manipulates the soil microorganisms, also known as the soil microbiome. In return, the adjusted microbiome under this treatment creates metabolites that control plant pathogens that causes plant diseases. This non-chemical soil fumigant controls plant pathogens as well as its chemical counterparts. Crops treated with this technique typically have a 17-35% greater yield. While the techniques work, little is known about the microbiome and the metabolites they produce. This study was conducted in the greenhouse and in the field. ASD and ASD with two times the carbon source were applied to the soil. The microbiome was characterized by using deoxyribonucleic acid extraction and sequencing techniques. Using high-performance liquid chromatography and nuclear magnetic resonance spectroscopy various metabolites were detected. This study showed that the microbiome was different from the ASD treated soils compared to the non-treated soil, and the metabolites differed. The quantity organic acids detected was greater for the soil treated with two times that amount of carbon than the other treatments.

Technical Abstract: Successful implementation of anaerobic soil disinfestation (ASD) is dependent upon manipulating the microbiome by introducing labile carbon and depleting the soil of oxygen by saturating the soil under a plastic tarp. The current standard ASD method in Florida, United States consists of applying composted poultry litter (22 Mg ha-1), feed-grade sugarcane molasses (13.9 m3 ha-1), tarping with totally impermeable film (TIF), and saturating the soil with 5 cm of water. ASD is applied three weeks prior transplanting (ASD1). Current research investigates how the microbiome is affected when elements of the ASD technique were manipulated. Greenhouse and field experiments in which ASD1, ASD with double application of molasses (ASD2), and soil covered with TIF but without amendments or water as untreated control (UTC) were compared. Spatial and temporal soil samples were taken at 0-15 cm and stored at -20° C. Total deoxyribonucleic acid (DNA) was extracted and microbial populations were identified using length heterogeneity polymerase chain reaction(LH-PCR), a deoxyribonucleic acid fingerprint method, and next generation sequencing of the 16s ribosomal ribonucleic acid (RNA) genes. Based on ORP probe data, ASD2 accumulated more mVh under anaerobic conditions than did ASD1, and both were statistically more anaerobic than UTC. Using LH-PCR, shifts in the microbiome were observed and the ASD-treated soil differed significantly from the(UTC) in both the greenhouse and field experiments. Based on 16s ribosomal ribonucleic acid, members of the Firmicutes and Bacteroidetes phyla increased compared to UTC. For both greenhouse and field trials, only isobutyric acid was detected in UTC samples from a panel of seven different organic acids using high-performance liquid chromatography, while all six of the acids were detected in ASD treated soil. The ASD2-treated soil had a greater quantity of each organic acid than ASD1. Nuclear magnetic resonance spectroscopy detected metabolites in ASD treated soil from the field study, which were not present in UTC.