Browsing by Author "Morgan, Hayden"

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    Data - Immobilisation of anaerobic digestate supplied nitrogen into soil microbial biomass is dependent on lability of high organic carbon mat
    (Cranfield University, 2024-03-11 09:09) van Midden, Christina; Harris, Jim A.; Shaw, Liz; Sizmur, Tom; Morgan, Hayden; Pawlett, Mark
    Research data for a 150 day incubation study to determine the effects of mixing high organic carbon materials into anaerobic digestate on soil microbial immobilisation of digestate supplied nitrogen and on soil microbial communities. This dateset contains raw data on microbial biomass carbon and nitrogen, soil available nitrogen (ammonium-N and total oxides of nitrate-nitrite), total soil nitrogen, and PLFA biomarkers.
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    Glycerol immobilises anaerobic digestate supplied nitrogen
    (Springer, 2025-01-01) van Midden, Christina; Shaw, Liz; Harris, Jim A.; Sizmur, Tom; Morgan, Hayden; Pawlett, Mark
    Anaerobic digestate, a nutrient rich by-product of the biogas industry, is frequently applied to agricultural land as a fertiliser. However, nitrogen losses from its application negatively impact air and water quality. Therefore, methods are needed to reduce these losses. The aim of this study was to test the efficacy of applying digestate with glycerol, an organic carbon rich by-product of the biodiesel industry, on microbial nitrogen immobilisation and the soil microbial community. Soil was incubated with digestate, applied at a rate equivalent to 250 kg-N ha-1, in a laboratory experiment over 50 days with glycerol additions at either 0, 12, 24 or 36 kg-C m3 of digestate. The addition of glycerol resulted in significantly higher microbial biomass carbon and increased the relative abundance of Gram-negative bacteria. The 24 and 36 kg-C m3 doses of glycerol resulted in similarly greater and longer lasting effect on microbial biomass carbon, indicating that beyond 24 kg-C m3 digestate that nitrogen (or other essential nutrients) became the limiting factor for microbial growth instead of carbon. Soil available nitrogen decreased throughout the study and remained at lower concentrations in glycerol treatments than the digestate only treatment by the end of the study. These results demonstrate that glycerol has the potential to reduce nitrogen losses from digestate application by immobilising nitrogen in the microbial biomass. Therefore, the co-application of digestate and glycerol to soil is a potential mechanism for the biogas and biofuel industries to valorise their respective by-products. Further research is needed to verify that this method is viable under field conditions.
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    Immobilisation of anaerobic digestate supplied nitrogen into soil microbial biomass is dependent on lability of high organic carbon materials additives
    (Frontiers, 2024-03-22) van Midden, Christina; Harris, Jim A.; Shaw, Liz; Sizmur, Tom; Morgan, Hayden; Pawlett, Mark
    Anaerobic digestate is a nutrient rich slurry by-product derived from biogas production, often used as a fertiliser due to its high nitrogen content. However, nitrogen losses from its application can lead to environmental pollution. In a laboratory experiment, the addition of high organic carbon materials to digestate-amended soil as a potential means to stimulate microbial immobilisation of digestate supplied nitrogen was investigated. Soil was incubated in pots for 5 months with digestate (equivalent to 250 kgN ha−1). The impact of adding carbon into the digestate (equivalent to 540 kgC ha−1) as either glycerol, straw, woodchip, or biochar on soil microbial and chemical parameters was quantified. Glycerol amended soils had significantly higher microbial biomass compared to digestate alone during the first month and at 30 days after application had a 4x higher on average microbial N. The digestate + straw treatment resulted in a 2.5x significantly greater nitrogen immobilisation compared to digestate alone after 3 months of incubation. The digestate + woodchip had a 2× higher mean microbial N after 5 months, whilst the biochar amendment did not stimulate significant nitrogen immobilisation at any time. These results suggest that mixing a labile to moderately labile organic carbon amendment, such as straw, with digestate has the greatest potential to reduce nitrogen losses following digestate application through microbial immobilisation.