Erodibility assessment of compacted biochar amended soil for geo-environmental applications

Biochar amended soil (BAS) has been explored as a cover material for geo-environmental applications such as landfill cover due to its vegetation potential. Soil erosion in these infrastructures can progressively lead to failure and hamper the workability of the system. BAS is compacted for geo-environmental applications, unlike agricultural soil, which are loose in nature. Furthermore, the love-hate relationship of biochar with water can potentially affect the functioning of compacted cover system. Thus, the performance of compacted BAS in the context of erosion potential is not well understood. The major objective of this technical note was to explore the erosion potential of compacted BAS sourced from four distinct biochars. Biochar were produced in-house and mixed with soil at 5% and 10% by weight. In total, 81 pinhole erosion tests were performed to gauge the erosion rate of bare soil and BAS at three different compaction states at same compaction energy. It was revealed that the erosion rate decreased with gradual increment in water content for BAS, which was mainly attributed to the change of particle orientation from flocculated to dispersed along the compaction curve. Addition of biochar to soil resulted in decrease of erosion along the dry state whereas the opposite was observed for wet state. This was attributed to the surface functional groups as well as particle gradation of biochar. Erodibility coefficient and critical shear stress plot of soil and BAS revealed that addition of biochar had minimal effect on erosion of compacted silty sand.