Effect of soil particle size and biochar on plant–soil interaction and carbon accumulation

Soil texture and organic amendments, such as biochar, are essential for soil quality and plant production in environmental geotechnics. This study investigates the coupled impact of soil particle size and biochar application on plant–soil interactive systems. The soil conditions examined included finer soil with particle sizes less than 2 mm and coarser soil with sizes ranging from 2 to 5 mm. Biochar derived from peanut shells was applied at a dosage of 3% (w/w). Compared with coarser soil, finer soil led to up to a 34% significant increase in plant biomass accumulation when biochar was added. This was attributed to higher organic carbon levels and enhanced soil enzyme activity. Biochar considerably boosted plant carbon assimilation, increasing 130% for pak choi and 184% for lettuce, primarily due to higher biomass accumulation. The most significant levels of plant carbon assimilation were found when biochar was added in finer soil, increasing up to 148% for pak choi and 192% for lettuce compared with other conditions. The maximum plant production and carbon assimilation were observed in finer soil treated with biochar. This research offers valuable insights for land development and plant production through the application of biochar in sustainable eco-geotechnical practices.