▎ 摘　　要

NOVELTY - Preparing a carbon nanomaterial comprises: (i) providing a mass of cellulosic plant fibers; (ii) treating the mass of cellulosic plant fibers with a base at a temperature of less than 100 ° C to form a treated mass of fibers; (iii) recovering the treated mass of fibers from the base; and (iv) heating the recovered mass of fibers to form the carbon nanomaterial. USE - The method is useful for preparing a carbon nanomaterial (claimed), which is used in agriculture for treating the soil. ADVANTAGE - The method is environmentally friendly, economical and straightforward to perform while providing good material properties.