Abstract: Photosynthetic carbon is an important component in the carbon cycling of atmosphere-plant-soil system, and the main source of soil organic carbon. In farmland ecosystems, the fate and metabolic mechanism of photosynthetic carbon in belowground part of crops during their growth period are usually ignored, but are indispensable for understanding the plant-soil-microbe interaction, change of soil quality, and global carbon cycling. In this paper, the allocation of photosynthetic carbon in belowground part of crops during their growth period, the contribution of this allocation to soil organic carbon, and the roles of soil microbes in the turnover of the photosynthetic carbon, as well as carbon-labeling technology, were reviewed. It was proposed that the study of photosynthetic carbon in typical soil types should be strengthened, and the contribution of photosynthetic carbon to different components of soil organic carbon should be defined, with the focuses on the allocation pattern of photosynthetic carbon in the belowground parts of soybean and maize, the relationships between the carbon compounds released from roots and their utilization by soil microbes, and the effects of climate factors and agronomic practices on the carbon allocation.

Key words: Peanut hull, Biosorption, Anionic dye, Amaranth, Sunset yellow, Fast green FCF