The carbon needed by plants is to absorb carbon dioxide from the atmosphere, to provide nutrients through photosynthesis, and to make the main chemical components of the body (lignin, carbohydrates, proteins, etc.), rather than to provide carbon through artificial fertilisers. Therefore, the carbon element in any organic matter cannot replace or supplement the carbon in the atmospheric carbon dioxide (C). So humic acid contains carbon, but not "carbon fertilizer."
According to the regulations of China's fertilizer registration administration, humic acid is one of the technical indicators of fertilizer registration, while "carbon" is not included in the technical indicators of fertilizer. Understanding humic acid comes from soil, humic acid is the "core" material of soil fertility. However, in a strict sense, humic acid is not a nutrient, but a functional substance that combines nutrients, enhances efficiency, stabilizes nutrients, effectively constructs "soil fertilizer harmony", and comprehensively coordinates plant physiological activities.
Therefore, science must be respected. The carbon (C) necessary for the normal growth and development of plants mainly comes from carbon dioxide in the atmosphere, and a small amount of carbon comes from water-soluble organic carbon (including humic acid carbon) provided by soil.