New synergies between agriculture and the energy sector making use of agricultural residues for bioenergy production and recycling recalcitrant residuals to soil may offer climate change mitigation potential through the substitution of fossil fuels and soil carbon sequestration. However, concerns have been raised about the potential negative impacts of incorporating bioenergy residuals (biochar) in soil and increasing the removal of crop residues such as straw, possibly reducing important soil functions and services for maintaining soil quality. Therefore, a combination of incubation studies and pot and
field experiments was used to study the effect of straw and wood biochar on carbon sequestration, soil quality and crop growth. Overall, the biochar amendment improved soil chemical and physical properties and plant growth and showed a potential for soil carbon sequestration without having any negative impact on soil biota. However, the effects of biochar on soil quality and plant growth differed according to the biochar properties and the soil type used. Furthermore, the positive impact on some soil structural properties observed after straw incorporation was not achieved with biochar amendment. In
conclusion, recycling gasification biochar to agricultural soils has the potential for development into a system that combines bioenergy generation and food production while maintaining soil quality.
However, annual straw removal needs to be carefully considered in order to avoid soil degradation and the risk of soil compaction or erosion.