Exploitation of crop residues for bioenergy: is it possible without harming the environment?
Although the use of crop residues for bioenergy production can play an important role in limiting climate change and reaching the goals set out in the Paris Agreement, it is often associated with negative environmental impacts. A recent publication by researchers from Utrecht University, the Leibniz Centre for Agricultural Landscape Research, and the University of Bonn suggests that integrated site-specific agricultural management enables crop residue use for bioenergy to contribute to climate change mitigation goals while also respecting soil and water quality.
Crop residues, materials like straw which remain after a crop has been harvested, can be a valuable resource for bioenergy production, assisting climate change mitigation efforts without jeopardising food security. But the removal of excess crop residues from agricultural fields is often associated with a decline in soil organic carbon stocks, which are essential for long term soil fertility and climate change mitigation. When interviewed about the prospects of crop residue exploitation for bioenergy in their region, stakeholders from North Rhine-Westphalia in Germany expressed concern about this soil organic carbon decline.
Importance of an integrated approach for achieving sustainable intensification
It is therefore important that intensification of crop residue exploitation for bioenergy is sustainable – that residue harvests are increased without adversely affecting overall agricultural productivity and environmental sustainability. This means that climate change mitigation and other sustainability objectives such as soil and water quality must be taken into account in an integrated way when increasing the potentials of crop residues for bioenergy.
Integrated site-specific agricultural management can help resolve trade-offs between agricultural productivity and climate, soil and water quality.
Possible to avoid adverse environmental impacts
Research carried out by Ioanna Mouratiadou and colleagues in North Rhine-Westphalia has found that the adoption of integrated site-specific agricultural management can help resolve trade-offs between agricultural productivity and climate, soil and water quality. Such management is tailored to the characteristics of agricultural fields, such as soil type and land use, and considers the interaction of different aspects of agricultural management.
Using a spatially explicit approach, the researchers find that a strategy integrating adaptation of residue removal to the humus balance, optimised fertilisation, and winter soil cover performs better than agricultural management measures implemented in isolation or not tailored to the characteristics of agricultural fields. This integrated site-specific approach simultaneously increases residues available for bioenergy while reducing soil organic carbon losses, greenhouse gas emissions and nitrate leaching.
If we want to exploit crop residues for bioenergy while enhancing environmental co-benefits and increasing agricultural productivity, we need to carefully tailor agricultural management to its natural environment and land use.
Tailoring agricultural management to natural environment and land use
“But we need to be cautious,” says Mouratiadou. Tapping into crop residues for bioenergy is challenging in areas prone to soil organic carbon decline. “If we want to exploit crop residues for bioenergy while enhancing environmental co-benefits and increasing agricultural productivity, we need to carefully tailor agricultural management to its natural environment and land use.” Residue removal strategies must also be designed according to explicit policy targets for soil organic carbon conservation.
Further reading
Mouratiadou et al. (2020). Sustainable intensification of crop residue exploitation for bioenergy: opportunities and challenges. Global Change Biology Bioenergy, 12, 71–89.
Stella et al. (2019). Estimating the contribution of crop residues to soil organic carbon conservation. Environmental Research Letters, 14, 094008.