Mechanical properties of soil freshly amended with Miscanthus biochar

Abstract 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 soil freshly amended 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 ( ρ d ), void ratio ( e ), compression index ( C c ) and relaxation ratio ( R ) were derived and statistically analysed. The addition of biochar was shown to reduce ρ d , while e increased with the amount of added biochar. The addition of biochar increased C c and R . The effect of soil moisture content and soil types was 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.