Effects of bamboo nano-biochar on sandy loam nitrogen and phosphorus leaching loss and water infiltration capacity

Biochar has emerged as a promising soil amendment for improving soil quality and mitigating environmental impacts, such as nutrient leaching. This study evaluated the impacts of ball-milled bamboo nano-biochar on water infiltration dynamics, retention capacity, and nitrogen‑phosphorus leaching in sandy loam soil using controlled column experiments and leaching experiments with five application doses alongside bulk biochar and untreated controls. Experimental results demonstrated that nano-biochar application significantly enhanced soil water retention capacity compared to the raw soil. Soil column experiments demonstrated that nano-biochar significantly delayed wetting front advancement, prolonging the time required for vertical penetration compared to the raw soil. The nanoscale biochar exhibited superior performance to bulk biochar, attributable to its substantially higher specific surface area (523 m²/g) and enriched oxygen-containing functional groups. Nano-biochar amendments reduced total nitrogen leaching by 8.90-23.40 % and total phosphorus leaching by 63.27-67.56 %, representing marked improvements over bulk biochar treatments. These effects correlated strongly with the material's enhanced pore structure and cation exchange capacity. The findings demonstrate that nano-biochar can serve as an effective soil amendment for enhancing water conservation and reducing nutrient losses in sandy agricultural soils.