Carbon travel, destination: Soil

The general flow of the carbon to be transferred from the air to the soil is illustrated bellow:

The photosynthesis is a vital procedure for the plants that ensures a carbon sequestration in the terrestrial and aquatic environment up to 60 Pg-C for both (Cramer et al. 2001).

The plants capture CO₂ from the atmosphere using the mechanism of photosynthesis. This procedure secures the food supply for the plant and reduces the carbon dioxide as we saw in the previous post.

Photosynthesis 

Following the life cycle of the plants, the dead plant material in the soil gives organic matter that stats to decompose. This biological process is affected by (Bot & Benites, 2005):

1. Soil organisms,
2. The physical environment, and
3. The quality of the organic matter

The decomposition of the organic matter is a biochemical process that soil organisms use to produce food by converting the plant residues into humus (giving a black colour in the soil as illustrated below) with the process called humification. That releases useful nutrients in a form that the plants can absorb back. Other product of the decomposition is the carbon dioxide that goes back to the atmosphere(Bot & Benites, 2005).

Soil rich in humus (left) and no humus rich soil (right)

The following figure illustrate the carbon cycle in the soil:

Soil Carbon Cycle

The humus produced by the metabolism of the soil organisms is the most common carbon compound in the terrestrial ecosystem and it is very stable as it cannot be used further by the micro-organisms (Bot & Benites, 2005). 

Thus, the carbon starts to be sequestrated in the soil, reducing the CO₂ concentration in the atmosphere. 

Next in our trip we will examine where the carbon in the soil is and what it is doing there!

See you!