A research team led by Dr. Zhang Huimin from the Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, has made significant progress in studying the effects of long-term fertilization on soil humus and iron-aluminum interactions, as well as the mechanisms of carbon sequestration and yield sustainability. 

The related findings, titled "Soil humus and aluminum-iron interactions enhance carbon sequestration and yield sustainability after long-term fertilization in three different soils," were published in the Journal of Agriculture and Food Research.

Subtropical farmland soils in China face issues such as acidification and declining organic matter due to long-term intensive cultivation and chemical inputs. Based on the long-term field experiment initiated in 1982 at the Qiyang Red Soil Experimental Station, the research team selected three typical soils developed from granite, Quaternary red soil, and purple sand shale to investigate the interaction between humus carbon components (humic acid carbon HA-C, fulvic acid carbon FA-C, humin carbon HU-C) and iron-aluminum forms under long-term fertilization and their impact on soil organic carbon sequestration and crop yield sustainability.

The results of the study showed that single fertilization with straw return (NPK-R) and single organic fertilizer with straw return (OM-R) significantly increased the content of HA-C and the concentration of amorphous aluminum oxide (Alo) and iron oxide (Feo) in granite and Quaternary red soil. This promoted carbon stabilization through chelation with amorphous iron-aluminum oxides (Alo, Feo). Treatment with single chemical fertilizer (NPK-T) and combined chemical fertilizer with straw return (NPK-R) significantly increased soil organic carbon content and carbon sequestration rate (CRS), while also improving soil structure and nutrient availability. The relationship between CRS and Sustainable Yield Index (SYI) differed among different soil types. In acidic granite and Quaternary red soils, the SYI of sweet potato was negatively correlated with CRS, while the SYI of broad bean increased with CRS. In contrast, in alkaline purple sand shale soil, the pattern was reversed. Humus carbon components (HA-C, FA-C, HU-C) also helped regulate soil pH and the forms of aluminum (Alo, Alp), iron (Fed, Feo), and organic-bound iron (Fep), thereby promoting nutrient absorption and increasing crop yield, especially evident in acidic soils like granite and Quaternary red soil. This study provides theoretical guidance for sustainable management of different soil types.

Philip T. Singbah, a doctoral student, and Associate Researcher Huang Jing are co-first authors of the study, with Dr. Zhang Huimin as the corresponding author. The research was supported by the National Key Laboratory of Efficient Utilization of Farmland in Arid and Semi-arid Areas, National Key Research and Development Program, and the Special Science and Technology Project of Jinggang Mountain Agricultural High-tech Industrial Demonstration Zone.

Original article link: https://doi.org/10.1016/j.jafr.2025.101995