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NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.

2024

Sammendrag

To increase soil organic carbon (SOC) storage, we need to improve our understanding on how to make best use of available plant biomass. Is it better to leave harvest residues on the field, or can we achieve higher SOC storage after processing biomass through, for instance, composting or pyrolysis to produce biochar? In the present study, we developed new parameters for different types of exogenous organic materials (EOMs), which allowed us to estimate the long-term effect of EOM addition on SOC storage using the soil carbon model RothC. For this purpose, we used a model version that included two additional EOM pools. First, we simulated the SOC evolution after addition of equal amounts of C in plant material and different EOMs (manure, compost, digestate, biochar) for a 38-year cropland trial in Switzerland. As expected, biochar showed the greatest increase in SOC due to its high stability. Next, we estimated how much C would remain after subjecting equivalent amounts of plant material and other EOMs to different processes. Loss rates of C for different processes were obtained from the literature. Due to different decomposition rates, the amounts of C remaining in the EOMs ranged from 7 % for anaerobic digestion of animal excreta to 100 % for plant material added directly to soil. These amounts of C were then added to the soil in the model experiments. Although the largest amount of C is lost during processing to biochar, biochar would clearly lead to highest long-term SOC stocks. Based on these first results we conclude that the trade-off between off-site stabilization and in-soil mineralization does not compromise the use of biochar for soil C storage. This means that despite the high C losses of about 50 % during biochar production, higher amounts of C remain in the soil because biochar has very low decomposition rates. In terms of C sequestration efficiency, biochar thus clearly outperforms the other biomass processing pathways. However, for practical recommendations, additional factors should be considered, such as nutrient availability of EOMs and environmental effects during processing, storage and soil application like nutrient leaching or gaseous emissions. Furthermore, we suggest a full life cycle assessment that considers e.g. energy costs for transport of biomass and energy savings from fossil fuel substitution by natural gas.