Assessing the climate impacts of oat straw as a raw material
2022
Leppäkoski, Lauri | Uusitalo, Ville | Horn, Susanna | Levänen, Jarkko | Kasurinen, Heli | Härri, Anna | Suomen ympäristökeskus | The Finnish Environment Institute | 0000-0001-8138-0209
Straw is an interesting renewable feedstock for various high-value products, such as textile fibers. However, straw encompass to soils maintains a good soil structure, fertility, and carbon storage. Despite the availability of previous research on this topic, uncertainties remain regarding the climate and soil impacts of straw collection. This study aims to show the carbon footprint (CF) of straw collection compared with that of soil encompass. The goal is to demonstrate uncertainties related to initial data and methodological assumptions on whether straw is regarded as a waste or a coproduct and illustrate where more measured data is needed. Life cycle assessment method was used to conduct this study and the data therein were gotten from literature. The results show that straw removal can lead to reduced greenhouse gas emissions in comparison to soil encompass because of reduced nitrogen fertilizing needs and subsequent N2O emissions. However, there is high uncertainty related to soil organic carbon (SOC) and N2O emission changes because of straw removal. It is also possible that greenhouse gas emissions increase due to straw removal. Straw seems to have a relatively low CF, especially when it is regarded as a waste. Coproduct interpretation significantly increases the emissions allocated for straw. Straw also stores carbon, and its total CF can be negative. The life cycle length of the straw-based end products determines how long carbon can be stored before it is released back into the atmosphere. Total greenhouse gas emission balance at a system level can be defined only when also straw refining and manufacturing of replaced final products are considered. Additional information is needed, especially on soil emissions (N2O and CH4) and impacts on SOC storage, to ensure the sustainability of straw-based products.
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