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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Commodity Utilization Research » Research » Publications at this Location » Publication #427809
Research Project: Sugar Crop Processing Improvement and Sustainable Co-product Development

Location: Commodity Utilization Research

Title: Sensitivity of aromatic carbon in sugarcane mill mud to photolysis within the visible range

Author
item Uchimiya, Sophie
item TAYLOR, KAITLYN - Oak Ridge National Laboratory

Submitted to: BioResources
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2026
Publication Date: 4/14/2026
Citation: Uchimiya, S.M., Taylor, K. 2026. Sensitivity of aromatic carbon in sugarcane mill mud to photolysis within the visible range. BioResources. 21(2). pg5057-5070.

Interpretive Summary: High molecular weight, aromatic chemical structures are used as ingredients in bio-stimulant, which is a newer variety of fertilizer for food crops. This study shows how natural sunlight and microorganisms affect the amount of those active ingredients. Results could be used to develop potting mix and and fertilizer with added benefits to stimulate and sustain the growth of plants for gardening or farming.

Technical Abstract: Direct and indirect photolysis are the primary fate pathways of natural organic matter (NOM) impacting the global carbon cycle. For dissolved organic carbon (DOC) of natural environments (soil, river, ocean), opposite trends in structural changes are often observed between photolytic and dark aerobic transformations. Industrial organic byproducts are generated under more controlled conditions than NOM, and their photochemical fate is largely unknown. This study traced the changes in conjugated structures of sugar processing byproduct (sugarcane mill mud) over 2 wk period. After an initial (˜1 wk) lag period, photolysis became dominant over dark reactions. Photolysis increased the aromaticity (higher emission wavelength peaks) and amount (higher fluorescence intensity) of chromophores, more so for pristine than aged mill mud. Those kinetic trends were observed regardless of the initial DOC content or whether the byproduct was aged. However, field aging of mill mud transformed reactive chromophores to stable aromatic structures with characteristic 400-400 nm emission that are resistant to photolysis or microbial decomposition. Factory mill mud showed similar fate pathways as NOM. Anaerobic incubation in dark formed 280 and 320 nm absorbance peaks typically observed in NOM. Slope ratios for those peaks decreased by photolysis, indicating the formation of aromatic structures. Absorption (UV/visible) spectra detected the reactive chromophores, while emission (fluorescence) spectra provided snapshots of structural changes at photosensitive excitation wavelengths. Those optical methods could be used to evaluate the stability of industrial byproducts as soil amendments.