The Innovation Team of Fertilizer and Fertilization Technology of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) has researched the mechanism of strengthened cadmium (Cd) adsorption by iron-modified biochar through the co-decomposition of Chinese milk vetch and rice straw, which produces dissolved organic matter (DOM). The related findings have been published under the title "The dissolved organic matter from the co-decomposition of Chinese milk vetch and rice straw induces the strengthening of Cd remediation by Fe-modified biochar" in the international journal "Biochar" (IF = 12.7).

China's scarce arable land resources and the difficult trend of soil degradation pose a serious threat to the country's food security due to severe cadmium (Cd) contamination in agricultural fields. Establishing a path for the coordinated cultivation of farmland soils and ecological governance aligns with China's agricultural security production concept. The application of biochar is an effective measure for the remediation of Cd-contaminated paddy fields, and the co-utilization of green manure and rice straw is a commonly used measure for soil fertility and yield enhancement in paddy fields. Previous studies by this group have indicated that the co-utilization of green manure and rice straw combined with biochar can strengthen the control of Cd uptake by rice, but the mechanism of this strengthening was not yet clear.

Through pot, decomposition, adsorption, and other experiments, and employing techniques such as three-dimensional fluorescence, Fourier transform ion cyclotron resonance mass spectrometry, and X-ray photoelectron spectroscopy, this study investigated the mechanism of the strengthened Cd adsorption by iron-modified biochar through the co-decomposition of Chinese milk vetch and rice straw. The results indicate that the DOM produced by the co-decomposition of Chinese milk vetch and rice straw enhances Cd adsorption by increasing the specific surface area, negative charge numbers and functional groups of iron-modified biochar. Furthermore, the combination of iron-modified biochar and DOM obtained by the co-decomposition of Chinese milk vetch and rice straw exhibits higher aromaticity, molecular diversity, and complexity, with its main compound components being lignin/carboxylic-rich alicyclic molecules and proteins/amino sugar, which promotes Cd adsorption. In general, the co-utilization of Chinese milk vetch and rice straw primarily strengthens the Cd adsorption performance of iron-modified biochar through the co-decomposition-produced DOM, enhancing the remediation effect of Cd-contaminated farmland, making it a promising technology for the management of Cd-contaminated agricultural fields.

Dr. Liang Ting from the IARRP and Professor Zhou Guopeng from the College of Resources and Environment at Anhui Agricultural University are the co-first authors of the paper, with Researcher Cao Weidong and Professor Zou Chunqin from China Agricultural University as the co-corresponding authors. The research was supported by the "14th Five-Year" National Key Research and Development Program of China (2021YFD1700200), the National Green Manure Industry Technology System (CARS-22), and the China Agricultural Science and Technology Innovation Program.

Citation: Liang, T., Zhou, G., Chang, D., Ma, Z., Gao, S., Nie, J., Liao, Y., Lu, Y., Fan, H., Zou, C*., Cao, W*. 2024. The dissolved organic matter from the co-decomposition of Chinese milk vetch and rice straw induces the strengthening of Cd remediation by Fe-modified biochar[J]. Biochar, 6:27.

Original paper link: https://doi.org/10.1007/s42773-024-00313-6