Climate impact of alternative organic fertilizers using life cycle assessment

Anaerobic digestion is a common method for managing liquid manure and other biomasses, generating biogas as a renewable energy source. The resulting digestate can be processed into organic fertilizers to enhance nutrient recycling, but its environmental impact warrants investigation. In this study,...

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Main Authors: Xiaoyi Meng, Marie Trydeman Knudsen, Søren O Petersen, Henrik B Møller, Fatemeh Hashemi
Format: Article
Language:English
Published: IOP Publishing 2024-01-01
Series:Environmental Research Letters
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Online Access:https://doi.org/10.1088/1748-9326/ad8589
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author Xiaoyi Meng
Marie Trydeman Knudsen
Søren O Petersen
Henrik B Møller
Fatemeh Hashemi
author_facet Xiaoyi Meng
Marie Trydeman Knudsen
Søren O Petersen
Henrik B Møller
Fatemeh Hashemi
author_sort Xiaoyi Meng
collection DOAJ
description Anaerobic digestion is a common method for managing liquid manure and other biomasses, generating biogas as a renewable energy source. The resulting digestate can be processed into organic fertilizers to enhance nutrient recycling, but its environmental impact warrants investigation. In this study, a life cycle assessment was conducted to examine the impact of fertilizers derived from cattle slurry and grass–clover co-digestion on global warming (measured in CO _2 equivalents) compared to untreated cattle slurry (CA). The different treatments analyzed include CA, digestate, liquid fractions (LFs) from digestate separation, and an enriched liquid nitrogen–sulfur product derived from post-processing of biogas and drying of the solid fraction. The functional units of this study were 100 kg of total nitrogen in the final organic fertilizer (FU1) with the cradle-to-processing gate boundary, and the harvesting of 1 ton of spring barley dry matter (FU2) with the cradle-to-field application boundary. The carbon footprint ranged from 24% to 49% of the baseline scenario for FU1, and from −6% to 177% of the baseline scenario for FU2. The main contributors to the carbon footprint of fertilizers included greenhouse gas emissions from storage and field application. However, biogas production from anaerobic digestion, together with the concurrent mitigation of CH _4 emissions during storage, contributed most to a reduction in the overall global warming potential associated with anaerobic digestate and its LF. This study showed large climate prospects in replacing untreated slurry as organic fertilizer with alternatives resulting from its anaerobic digestion and post-treatment.
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spelling doaj-art-b2ae992b6b58415fb7621a14e4e4be062024-11-15T08:04:01ZengIOP PublishingEnvironmental Research Letters1748-93262024-01-01191212405010.1088/1748-9326/ad8589Climate impact of alternative organic fertilizers using life cycle assessmentXiaoyi Meng0https://orcid.org/0000-0003-0550-3478Marie Trydeman Knudsen1https://orcid.org/0000-0001-7905-0382Søren O Petersen2https://orcid.org/0000-0001-7524-6695Henrik B Møller3Fatemeh Hashemi4https://orcid.org/0000-0002-4756-9339Department of Agroecology, Aarhus University , Blichers Allé 20, 8830 Tjele, Denmark; Department of Agroecology, Aarhus University Interdisciplinary Centre for climate change (iCLIMATE) , Blichers Alle 20, 8830 Tjele, DenmarkDepartment of Agroecology, Aarhus University , Blichers Allé 20, 8830 Tjele, Denmark; Department of Agroecology, Aarhus University Interdisciplinary Centre for climate change (iCLIMATE) , Blichers Alle 20, 8830 Tjele, DenmarkDepartment of Agroecology, Aarhus University , Blichers Allé 20, 8830 Tjele, DenmarkBiological and chemical Engineering, Aarhus University , Blichers Allé 20, 8830 Tjele, DenmarkDepartment of Agroecology, Aarhus University , Blichers Allé 20, 8830 Tjele, Denmark; Department of Agroecology, Aarhus University Interdisciplinary Centre for climate change (iCLIMATE) , Blichers Alle 20, 8830 Tjele, DenmarkAnaerobic digestion is a common method for managing liquid manure and other biomasses, generating biogas as a renewable energy source. The resulting digestate can be processed into organic fertilizers to enhance nutrient recycling, but its environmental impact warrants investigation. In this study, a life cycle assessment was conducted to examine the impact of fertilizers derived from cattle slurry and grass–clover co-digestion on global warming (measured in CO _2 equivalents) compared to untreated cattle slurry (CA). The different treatments analyzed include CA, digestate, liquid fractions (LFs) from digestate separation, and an enriched liquid nitrogen–sulfur product derived from post-processing of biogas and drying of the solid fraction. The functional units of this study were 100 kg of total nitrogen in the final organic fertilizer (FU1) with the cradle-to-processing gate boundary, and the harvesting of 1 ton of spring barley dry matter (FU2) with the cradle-to-field application boundary. The carbon footprint ranged from 24% to 49% of the baseline scenario for FU1, and from −6% to 177% of the baseline scenario for FU2. The main contributors to the carbon footprint of fertilizers included greenhouse gas emissions from storage and field application. However, biogas production from anaerobic digestion, together with the concurrent mitigation of CH _4 emissions during storage, contributed most to a reduction in the overall global warming potential associated with anaerobic digestate and its LF. This study showed large climate prospects in replacing untreated slurry as organic fertilizer with alternatives resulting from its anaerobic digestion and post-treatment.https://doi.org/10.1088/1748-9326/ad8589life cycle assessmentcattle slurrygrass–cloveranaerobic digestionorganic farminggreenhouse gas emission
spellingShingle Xiaoyi Meng
Marie Trydeman Knudsen
Søren O Petersen
Henrik B Møller
Fatemeh Hashemi
Climate impact of alternative organic fertilizers using life cycle assessment
Environmental Research Letters
life cycle assessment
cattle slurry
grass–clover
anaerobic digestion
organic farming
greenhouse gas emission
title Climate impact of alternative organic fertilizers using life cycle assessment
title_full Climate impact of alternative organic fertilizers using life cycle assessment
title_fullStr Climate impact of alternative organic fertilizers using life cycle assessment
title_full_unstemmed Climate impact of alternative organic fertilizers using life cycle assessment
title_short Climate impact of alternative organic fertilizers using life cycle assessment
title_sort climate impact of alternative organic fertilizers using life cycle assessment
topic life cycle assessment
cattle slurry
grass–clover
anaerobic digestion
organic farming
greenhouse gas emission
url https://doi.org/10.1088/1748-9326/ad8589
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AT sørenopetersen climateimpactofalternativeorganicfertilizersusinglifecycleassessment
AT henrikbmøller climateimpactofalternativeorganicfertilizersusinglifecycleassessment
AT fatemehhashemi climateimpactofalternativeorganicfertilizersusinglifecycleassessment