Carbon is a key component of soil organic matter, derived from decaying plant and animal residues, as well as root exudates, and organic matter is a source of essential nutrients for plants, such as Nitrogen, phosphorus, sulfur and micronutrients. The microbes are responsible for the degradation of organic matter and for the mineralization of nutrients that are available to plants.

Dr Léo Adriano Chig thank you for your contribution to the discussion

Soil holds the largest portion of active carbon on earth. Plants take carbon from the air and convert it to plant tissue, some of which returns to the soil as plant residue. Carbon is critical to soil function and productivity, and a main component of and contributor to healthy soil conditions. The work is important because soil carbon is a major reservoir in the global carbon cycle, storing about three times the amount of carbon contained in the atmosphere as carbon dioxide. Some soil processes promote carbon storage, locking it away in stable forms, resistant to decay. Microbes are critical in the process of breaking down and transforming dead organic material into forms that can be reused by other organisms. This is why the microbial enzyme systems involved are viewed as key 'engines' that drives the Earth's biogeochemical cycles.Upon the death of plants and animals, microbes assume a dominant role in carbon cycle. The dead tissues are degraded and transformed into microbial cells and humus or soil organic fraction. Further decomposition of these materials leads to the production of CO2 and once again it is recycled.Microbes thrive under no-till conditions and winter cover crops. Cover crops and manure can be used to feed soil microbes and recycle soil nutrients. As soil microbes decompose organic residues, they slowly release nutrients back into the soil for the winter cover crops or for the preceding crop. Decomposers break down organic carbon compounds and release carbon back into the atmosphere as carbon dioxide where is can again be used by plants and other photosynthetic organisms to produce organic carbon. Microbes are critical in the process of breaking down and transforming dead organic material into forms that can be reused by other organisms. This is why the microbial enzyme systems involved are viewed as key 'engines' that drive the Earth's biogeochemical cycles. Microorganisms and fungi break down wood and return carbon to the biogeochemical cycles. If these organisms become absent, carbon would accumulate in the wood, where it could not be recycled into the environment. The fixation of nitrogen is dependent on microorganisms mostly through biological nitrogen fixation. Soil bacteria perform recycling of soil organic matter through different processes, and as a result they produce and release into the soil inorganic molecules (PO 4 3 − , CO2) that can be consumed by plants and microorganisms to grow and perform their functions. During the decomposition process, microorganisms convert the carbon structures of fresh residues into transformed carbon products in the soil. There are many different types of organic molecules in soil. Some are simple molecules that have been synthesized directly from plants or other living organisms. Plants absorb carbon dioxide during photosynthesis and much of this carbon dioxide is then stored in roots, permafrost, grasslands, and forests. Plants and the soil then release carbon dioxide when they decay. Other organisms also release carbon dioxide as they live and die. Soil microorganisms decompose these materials into inorganic nutrients and humus and are termed as mineralization and humification, respectively. The released nutrients further get chelated as organo-metal-complexes or leached through the soil or immobilized or become available to the plants. Bacteria sustain life by their ability to decompose plant and animal bodies, replenishing the limited amount of carbon dioxide needed for photosynthesis. As a result, they act as carbon decomposers in the carbon cycle. Bacteria are mostly decomposers in the carbon cycle.