Understanding the carbon cycle and the farming production system

The carbon cycle is an essential process in agriculture and with carbon becoming a mainstream topic, farmers need to understand it and how they can influence it.

The interaction between plants and soil are key to this process, as is looking after soil biology. By adapting farming systems, the process can work more efficiently, bringing benefits to your business.

Carbon's contribution to farming

Carbon is a word which seems to come up daily, whether through policy documents or industry reports – it certainly is a hot topic. The subject is not the easiest to understand and many of us wish we’d listened more in biology at school and soil science lectures at college!

What we need to know is:

  • Carbon drives the production cycle in agriculture.
  • Farmers need to understand the cycle to be able to manage it.
  • The interaction between plants and soil are key in building soil carbon.
  • Adapting a few on-farm practises can have significant benefits. 


Whether you farm livestock or crops, the carbon cycle sits at the very heart of your production system. Carbon is the energy source of life and helps farmers turn energy from the sun into an energy source in the soil which drives many other nutrient cycles, allowing crops to grow. These crops are then consumed by us directly or by animals, creating more complex protein sources for humans to eat.

Therefore, carbon must be a good thing? Yes, but we need to understand the stages in the carbon cycle to realise its importance to agriculture:

Stage 1: The plant

The plant takes in carbon dioxide (CO2) and releases oxygen through the process of photosynthesis. As the plant draws in CO2, it requires water from the soil to produce more complex compounds in green plant material above ground and roots below ground. As the roots grow, they produce root exudates, which are essentially complex carbohydrates, which are released by the plant into the soil.

Roots are extremely important in the function of your soil. They have the ability to carry carbon deeper into the soil profile, through the release of root exudates. They also have the ability for the plant to “talk” to the soil. For example, if a plant is growing vigorously and requires phosphate for this process, the plant releases an exudate which stimulates those bacteria and fungi which can mineralise phosphate making it more available to the plant.

Stage 2: The soil

In the soil, carbon enters from two main sources: root exudates and Bulky Organic Manures (BOMs) (chopped straw, plant residues, FYM, slurry etc). These sources are broken down by a multitude of living organisms including insects, bacteria and fungi, into organic matter. In the process, they produce two types of carbon pool:

  • Short-term carbon pool, consisting of the living organisms in the soil. It is easily cycled and as this pool is living, it also respires and releases CO2 into the air.
  • Long-term carbon pool, consisting of humus, the end product of decomposition. This is a more stable pool which can be held in the soil for a number of years, stores plant nutrients, holds moisture and improves soil structure.


The two stages are fundamentally linked with the success of the plant relying on the soil.

5 top tips to make the carbon cycle work harder for you:

  1. Harness as much of the sun’s energy as you can using plants and capture it in your soil.
  2. Allow plants to do a lot of the hard work for you such as breaking compaction and protecting the soil.
  3. Look after the living organisms in your soil, your “soil livestock”, feed them with bulky organic manures regularly.
  4. Minimise the amount of soil disturbance to create the ideal habitat for soil biology.
  5. Diversify rotations (perhaps introduce cover crops) as different crops encourage different soil organisms.


Understanding the carbon cycle underpins your production system and adapting your system to take this into account can have a significant impact on your business.

More Insights

field after harvest with round haybales and trees on the verge
Agrecalc welcomes new CEO

Agrecalc is delighted to announce the appointment of its new Chief Executive Officer.
Hailing from the private sector, Scott Davies brings a wealth of production and managerial leadership experience from a career in developing and growing successful technology-backed businesses.

Read More
soil being dug up in the field to admire the biodiversity richness
Mitigating the climate impact of farming

In today’s uncertain environment, which is coupled with ambitious legislative net zero targets (in Scotland by 2045), the agri-food sector is facing increasing demands to measure and monitor progress against carbon equivalent (CO2e) reduction targets.

Read More