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ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Publications at this Location » Publication #397601

Research Project: Developing and Evaluating Strategies to Protect and Conserve Water and Environmental Resources While Maintaining Productivity in Agronomic Systems

Location: Soil and Water Management Research

Title: No/low-cost chipped woody debris nutrient composition benefits and tradeoffs for denitrifying bioreactors

item CHRISTIANSON, LAURA - University Of Illinois
item WICKRAMARATHNE, NIRANGA - University Of Illinois
item JOHNSON, GABRIEL - Iowa State University
item Feyereisen, Gary

Submitted to: Bioresource Technology Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2022
Publication Date: 10/6/2022
Citation: Christianson, L.E., Wickramarathne, N., Johnson, G.M., Feyereisen, G.W. 2022. No/low-cost chipped woody debris nutrient composition benefits and tradeoffs for denitrifying bioreactors. Bioresource Technology Reports. 20. Article 101237.

Interpretive Summary: Agricultural tile nitrate losses can be reduced by woodchip denitrifying bioreactors. However, woodchip source supply and cost can be impediments to scaling up this conservation practice. This study reviews the pros and cons of using free/low-cost chipped debris as the media rather than woodchips. Concentrations of key constituents were compared between 16 purchased woodchip lots and 6 chipped debris samplings. The carbon and cellulose concentrations were similar but the debris media had higher nitrogen and phosphorus concentrations, which can be a leaching concern during bioreactor start up. In conclusion, if chipped media is coarse and does not contain fines or soil, it may be considered for bioreactor use in areas that do not outlet to sensitive waters. These findings provide insight into media choices for denitrifying bioreactors and are pertinent to practitioners, researchers, agency personnel, and academics with interest in using denitrifying bioreactors to remove nitrate-N from water.

Technical Abstract: Woodchip cost and sourcing availability may be barriers for denitrifying bioreactor implementation. This survey comparison of nutrient composition improves understanding of the spectrum of widely available wood media possible for use in bioreactors. Sixteen new woodchip types purchased from bulk suppliers and six chipped debris media sourced for free at the supplier were analyzed for carbon (C), nitrogen (N), phosphorus (P), cellulose, and lignin. Results were presented in context of woodchips harvested from saturated and unsaturated portions of operational bioreactors. The municipal debris was not significantly different from the bulk woodchips in C or cellulose but had significantly greater N and P concentrations. The lower C:N, C:P, and lignin:N ratios of the chipped debris highlighted that the role of macronutrients in supporting a diverse “bioreactor ecosystem” (e.g., decomposers who make C available) is not fully understood. Useful ranges of nutrient and fiber composition were provided for future modeling efforts.