A Chinese research team led by Prof. WU Zhengyan in the institute managed to develop a near-infrared light-responsively controlled-release herbicide for reducing pesticide loss and then to increase the utilization efficiency.
Pesticides have been contributing greatly to agriculture, since they effectively control diseases, pests, and weeds in farmland, which results in about one-third of the world’s food output. However, traditional pesticides can easily be lost into soil through leaching, causing serious pollution and low utilization efficiency (UE). Thus, numerous and substantial volumes of pesticides are utilized to ensure agricultural productivity, which leads to residual pesticides in agricultural products and severe hazard potential for human beings.
Therefore, the development of new pesticide formulations to reduce pesticide loss, increase UE, and decrease usage has become an hot focus of agricultural and environmental research.
In their work, near-infrared light (NIRL) responsively controlled-release herbicide particles (NCHPs) were fabricated using biochar, attapulgite (ATP), NH4HCO3, ethylcellulose (EC), silicon oil (SO), and glyphosate (Gly). The resulting complex was granulated and coated by EC and SO to form NCHPs.
According to the study, biochar acted as a photothermal agent, with a photothermal conversion efficiency of 38%, to convert light energy into thermal energy, thus triggering NH4HCO3 decomposition into CO2 and NH3 that broke through the coating and facilitated Gly release.
Additionally, NCHP showed a higher control efficacy on weeds than Gly alone.
The scientists believe their work may provide results for a promising method to control the release of Gly, increase utilization efficiency, and decrease environmental contamination.
This research was supported by the Science and Technology Service Programs of Chinese Academy of Sciences, the National Key R&D Program of China, the Key R&D Program of Ningxia Province, the Science and Technology Major Project of Anhui Province, and the Environmental Protection Project of Anhui Province.
Link to the paper: Near-infrared light-responsively controlled-release herbicide using biochar as a photothermal agent.

Schematic illustration of mechanism. (Image by LIU Bin)