Mechanical properties of freshly amended soils with miscanthus biochar

Biochar has been shown to have multiple, positive benefits on soil physico‐chemical and biological properties. However, mechanical behaviour of biochar‐amended soils has been given relatively less attention. Therefore, in this study, we aimed to describe these properties of freshly amended soil with Miscanthus biochar in the context of compaction mitigation through a comprehensive laboratory study. In particular, for the first time, we evaluated the short‐term loading and unloading responses of replicated biochar‐amended soils using a modified oedometer, using different rates of application of biochar (2, 6 and 10% w/w, dry weight basis), in two types of soil (humus free loam and field loam) prepared at two different (10 and 22% w/w) soil moisture contents. From the experiment, dry density (ρd), void ratio (e), compression index (Cc) and relaxation ratio (R) were derived and statistically analysed. The addition of biochar was shown to reduce ρd while e increased with the amount of added biochar. The addition of biochar increased Cc and R. The effect of soil moisture content and soil types were also found to be statistically significant on the above parameters. However, field studies are needed to understand the long‐term mechanical behaviour of biochar‐amended soils and further studies are required to examine the performance of different biochar types and soil types.