Digging up the dirt on agricultural soils: using NMR to differentiate between macromolecules and small molecule metabolites accumulated in anaerobic disinfested soils

Authors: GRANT, AUSTIN - Miami University - Ohio; Rosskopf, Erin; Hong, Jason; Turechek, William; Burelle, Nancy; FINLEY, NATOSHA - Miami University - Ohio

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/20/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary: Anaerobic soil disinfestation has been adopted as an alternative to chemical fumigation to control soil plant pathogens. Anaerobic soil disinfestation consists of applying soil amendments, working them in, saturating the soil with water, and covering the soil with a plastic mulch. This technique has proven to be effective in controlling soil plant pathogen and increasing fruit yield, however the mechanism behind anaerobic soil disinfestation is not well understood. In this study, nuclear magnetic resonance was used to analyze macromolecules and small aromatic compounds between soils treated with anaerobic soil disinfestation and not-treated soils. We showed that nuclear magnetic resonance analysis could distinguish between anaerobic soil disinfestation treated and not-treated soils, and that nuclear magnetic resonance will aid in characterizing the soil and helping us understand the mechanism behind anaerobic soil disinfestation.

Technical Abstract: Water soluble compounds extracted from agricultural soils are complex mixtures varying in composition based on sample origin. The presence of macromolecules, such as proteins and complex carbohydrates, can complicate the nuclear magnetic resonance analysis of soils subjected to anaerobic soil disinfestation, which are known to be abundant in small molecule metabolites. Anaerobic soil disinfestation, adopted as an alternative to chemical fumigation in crop management, involves the introduction of labile carbon sources into the soil, saturating soil pores by irrigation, and limiting oxygen availability with tarps. Under these conditions, anaerobiosis is achieved, organic compounds accumulate, and soil-borne pathogens are suppressed. The anaerobic soil disinfestation mechanism remains unclear, due in part, to an incomplete understanding of the biochemical profiles of these soils. Here, we evaluate the efficacy of chemical precipitation and relaxation filtered nuclear magnetic resonance spectroscopy in the characterization of extracts from non-treated and anaerobic soil disinfestation-treated soil samples. These approaches decrease the complexity of nuclear magnetic resonance spectra and facilitate compound identification in soil extracts. We provide evidence that the composition of macromolecules and small aromatic compounds varies between non-treated and anaerobic soil disinfestation-treated soils, an observation which is critical in determining the identity of compounds that may influence disease resistance in agricultural soils. These findings support the promise of nuclear magnetic resonance in differentiating anaerobic soil disinfestation-treated soils from controls based on biochemical profiles, information which is essential to the further development of sustainable agricultural practices.