How is the majority of carbon transferred from plants and animals to the soil

Answer 1

The majority of carbon transfer from plants and animals to the soil occurs through two main processes: decomposition and root exudation.

1. Decomposition: When plants and animals die, their organic matter undergoes decomposition by soil microorganisms such as bacteria and fungi. These microorganisms break down the organic matter, including carbon-rich compounds, into simpler forms, releasing carbon dioxide (CO2) as a byproduct. This process is known as microbial respiration. The CO2 can either be released into the atmosphere or be dissolved in water and transported to the soil.

2. Root exudation: Living plants continuously release organic substances known as root exudates into the soil through their roots. These exudates include sugars, amino acids, organic acids, and enzymes, which are rich in carbon. These substances actively support microbial activity in the rhizosphere, the region of soil directly influenced by the roots. Soil microorganisms break down these root exudates, releasing carbon dioxide as a byproduct through microbial respiration.

In both decomposition and root exudation processes, some of the carbon can be retained in the soil as stable organic matter, such as humus. Humus is a complex mixture of decayed organic matter that serves as a long-term carbon storage pool in the soil.

Overall, the combination of decomposition and root exudation processes drives the transfer of carbon from plants and animals to the soil. This carbon contributes to the replenishment of soil organic matter and plays a crucial role in soil fertility, nutrient cycling, and carbon sequestration.