Recently, the Team of Agricultural Clean Watershed from the Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, studied the pathways influencing organic carbon mineralization on sloping farmland in the black soil region of Northeast China. The findings show that soil resource allocation and nutrient limitation regulates the mineralization of soil organic carbon by acting on extracellular enzymes, and play a critical role in the regulation of nutrient cycling in sloping farmland ecosystems. The related research findings have been published in the Science of the Total Environment .

Soil erosion is a main driver of soil organic carbon redistribution and mineralization, and soil extracellular enzymes (EEs) are involved in the regulation of organic carbon mineralization. Therefore, there is an urgent need to study the correlation between soil enzyme activity and carbon mineralization. This study analyzed the variation of soil organic carbon and different forms of nutrients at different positions of long gentle slopes in the black soil region under slop-ridge tillage (SRT) and cross-ridge tillage (CRT). At the same time, it measured the changes in enzymes acquiring four key elements, such as carbon, nitrogen and phosphorus, at different slope positions, and explored the response of EEs-mediated soil carbon mineralization to soil erosion based on indoor organic carbon mineralization culture experiments. The study indicated that under SRT, soil erosion increased soil carbon limitations, accelerating the organic carbon mineralization in the upper slope, while the physical protection mechanism of sediment deposition in the lower slope (e.g., at the toe-slope) inhibited soil organic carbon mineralization. CRT increased the soil carbon content, reduced the clay content in the lower slope, diminished the physical protection of organic carbon by sediment deposition, enhanced microbial and enzyme activity, and increased organic carbon mineralization. The study emphasized that CRT on sloping farmland in the black soil region was an effective tillage practice for mitigating the variability in the spatial carbon distribution and increasing carbon sequestration, and was of great significance to the prevention and control of soil erosion, the maintenance of soil productivity, and the sustainable development of agriculture on sloping farmland.

This work was supported by the National Natural Science Foundation of China, and the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences.

Linkage: https://www.sciencedirect.com/science/article/pii/S0048969724025634