On whether fertilizers are the source of carbon dioxide
In today's world, farming is prosperous, and the application of fertilizers is related to the harvest. However, there are different opinions on the source and flow of fertilizers and carbon dioxide, which should be explored in detail.

There are many types of fertilizers, including natural organic fertilizers and chemically synthesized inorganic fertilizers. Organic fertilizers, such as manure and green manure, are decomposed by microorganisms. During this process, carbon is metabolized by microorganisms, and most of them escape into the atmosphere in the form of carbon dioxide. Looking at the past, when farmers accumulated manure, on the fertilizer pile, there was sometimes warm gas rising, and there was no lack of carbon dioxide. Because of microbial fermentation, organic carbon in the fertilizer is converted and released.

Among inorganic fertilizers, nitrogen fertilizers, phosphate fertilizers, and potassium fertilizers perform their respective duties. Taking nitrogen fertilizers as an example, the common urea is applied to the soil and hydrolyzed in contact with water. Some products undergo a series of chemical reactions. Although carbon dioxide is not directly generated in large quantities, it affects soil microbial activities. Due to changes in the nitrogen fertilizer environment, when microorganisms decompose soil organic matter, their metabolic pathways or rates change, which is indirectly related to the generation and emission of carbon dioxide.

And the application of fertilizers affects plant growth. Plants are lush, photosynthesis is enhanced, and carbon dioxide absorption and carbon sequestration capacity is enhanced. However, if fertilizers are applied too much, plants are leggy, resulting in poor ventilation and light transmission in the field, soil microorganisms are hypoxic, anaerobic fermentation is intensified, and carbon dioxide emissions are increased. In addition, excessive fertilizer causes soil acidification and compaction, which affects plant root respiration and soil microbial ecology, and also has an impact on carbon dioxide emissions.

Overall, fertilizers are closely related to the source of carbon dioxide. Organic fertilizers directly release carbon dioxide through microbial action, and inorganic fertilizers are indirectly involved in the generation and emission of carbon dioxide by affecting soil ecology and plant growth. Therefore, in agriculture, rational use of fertilizers and consideration of their impact on carbon dioxide emissions are of great significance to the ecological environment and sustainable agricultural development.