Recently, a research team in the Hefei Institutes of Physical Science of the Chinese Academy of Sciences has introduced a soil amendment, humic acid-modified bentonite (HAMB), that effectively enhances soil's ability to hold onto ammonium while significantly reducing harmful nitrogen losses.
The research results were published in Journal of Soils and Sediments.
Nitrogen is an essential nutrient for crop growth, but a major challenge in agriculture lies in retaining this valuable resource. A significant portion of soil nitrogen is lost through two key pathways: ammonium leaching and ammonia volatilization. These losses not only waste agricultural inputs but also threaten environmental quality and human health. Traditional soil systems often lack the capacity to retain sufficient ammonium.
In this study, the research team found that HAMB application enhanced soil's ammonium adsorption capacity while suppressing its desorption, with these beneficial effects lasting 6-7 months. Importantly, the amendment's impact extended vertically to subsoil layers below the application zone, a key advantage for reducing deep nitrogen leaching.
Over a three-year field experiment, HAMB substantially reduced both potential ammonium leaching and ammonia volatilization compared with untreated soils, demonstrating its strong and sustained ability to mitigate nitrogen loss.
Further analysis showed that HAMB significantly enhanced the soil’s maximum ammonium adsorption capacity (Qmax) and buffering capacity (MNBC) for several months. These improvements were identified as the key factors driving long-term ammonium retention in soil.
This innovative soil amendment provides a promising strategy for improving nitrogen use efficiency and promoting more sustainable agricultural practices,
Placement of HAMB in the soil layers and the sampling time (Image by YANG Yang)
