Microbes are critical in the process of breaking down and transforming dead organic material into forms that can be reused by other organisms. Microbes are play a pivotal role in carbon cycling within soil systems and contribute to the stabilization of organic carbon, thereby influencing soil carbon storage and turnover. Soil microorganisms are responsible for most of the nutrient release from organic matter. When microorganisms decompose organic matter, they use the carbon and nutrients in the organic matter for their own growth. They release excess nutrients into the soil where they can be taken up by plants. The carbon cycle in soil is a dynamic balance between photosynthesis, the respiration of decomposing organisms, and the stabilization of carbon.

https://www.researchgate.net/post/What_is_the_role_of_carbon_cycle_in_soil_fertility_and_role_of_microbes_in_soil_nutrient_cycling_and_transformation_of_carbon_in_soil

Dr Prem Baboo thank you for your contribution to the discussion

Soil microorganisms, by actively participating in the decomposition and transformation of organic matter through diverse metabolic pathways, play a pivotal role in carbon cycling within soil systems and contribute to the stabilization of organic carbon, thereby influencing soil carbon storage and turnover. Microorganisms help return minerals and nutrients back to the environment so that the materials can then be used by other organisms. As the bacteria and fungi decompose dead matter, they also respire. 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. Microorganisms play a crucial role in nutrient cycling in soil. The composition and activity of microbiota impact the soil quality status, health, and nutrient enrichment. Microbes are essential for nutrient mobility and absorption. Microorganisms are responsible for the degradation of organic matter, which controls the release of plant nutrients, but is also important for the maintenance of soil structure and sustainability of soil quality for plant growth. Soil microorganisms are responsible for most of the nutrient release from organic matter. When microorganisms decompose organic matter, they use the carbon and nutrients in the organic matter for their own growth. They release excess nutrients into the soil where they can be taken up by plants. Soil microorganisms, by actively participating in the decomposition and transformation of organic matter through diverse metabolic pathways, play a pivotal role in carbon cycling within soil systems and contribute to the stabilization of organic carbon, thereby influencing soil carbon storage and turnover. The soil biomass serves both as a sink (immobilisation) and source (mineralisation) of nutrients playing a key role in influencing the availability of nutrients for NPP and NSP. Plants also influence the cycling of nutrients by competing directly for nutrients through root and mycorrhizae-mediated uptake.

Microorganisms play a crucial role in the cycling of carbon and other minerals, significantly contributing to soil fertility and ecosystem sustainability. Here's a comprehensive and detailed overview of their roles:

1. Role of Microbes in Carbon Cycling

a. Decomposition and Organic Matter Breakdown

• Decomposers: Microorganisms such as bacteria, fungi, and actinomycetes break down dead organic matter, including plant residues, animal remains, and other organic materials. This process, known as decomposition, converts complex organic compounds into simpler substances.
• Release of Carbon Dioxide: During decomposition, microbes metabolize organic carbon compounds, releasing carbon dioxide (CO2) into the atmosphere through respiration. This is a crucial step in the carbon cycle, as it returns carbon from the biosphere to the atmosphere.

b. Soil Organic Carbon (SOC) Formation

• Humus Formation: The breakdown of organic matter leads to the formation of humus, a stable form of organic matter that enhances soil structure, water retention, and nutrient availability.
• Carbon Sequestration: Some carbon is stored in the soil as soil organic carbon (SOC). Microbes play a role in stabilizing this carbon, reducing the amount of CO2 released into the atmosphere, and mitigating climate change.

c. Methanogenesis and Methane Oxidation

• Methanogens: In anaerobic environments (e.g., wetlands, rice paddies), certain archaea known as methanogens produce methane (CH4) from carbon compounds. Methane is a potent greenhouse gas, contributing to global warming.
• Methanotrophs: Conversely, methanotrophic bacteria oxidize methane to CO2 in aerobic environments, thus reducing the amount of methane released into the atmosphere.

2. Role of Microorganisms in Mineral Cycling

a. Nitrogen Cycle

• Nitrogen Fixation: Symbiotic bacteria (e.g., Rhizobium spp.) and free-living bacteria (e.g., Azotobacter spp.) convert atmospheric nitrogen (N2) into ammonia (NH3), a form that plants can assimilate.
• Nitrification: Nitrifying bacteria (e.g., Nitrosomonas and Nitrobacter spp.) convert ammonia into nitrate (NO3−), another form of nitrogen that plants can absorb.
• Denitrification: Denitrifying bacteria (e.g., Pseudomonas spp.) convert nitrate back into N2 gas, releasing it into the atmosphere and completing the nitrogen cycle.

b. Phosphorus Cycle

• Mineralization: Microorganisms decompose organic matter, releasing inorganic phosphate (PO43−) from organic phosphorus compounds.
• Solubilization: Phosphate-solubilizing bacteria (e.g., Pseudomonas spp., Bacillus spp.) convert insoluble phosphates into soluble forms, making phosphorus available to plants.

c. Sulfur Cycle

• Mineralization: Microbes decompose organic sulfur compounds, releasing inorganic sulfate (SO42−) into the soil.
• Oxidation and Reduction: Sulfur-oxidizing bacteria (e.g., Thiobacillus spp.) convert sulfide (S2−) to sulfate, while sulfate-reducing bacteria (e.g., Desulfovibrio spp.) convert sulfate to sulfide in anaerobic conditions.

d. Potassium and Micronutrient Cycling

• Weathering: Certain bacteria and fungi produce organic acids that help in the weathering of minerals, releasing potassium and micronutrients (e.g., iron, manganese, zinc) into the soil.
• Chelation: Microbes can produce chelating agents that bind to micronutrients, increasing their availability to plants.

3. Role in Soil Fertility

a. Nutrient Availability

• Mineralization and Solubilization: By breaking down organic matter and solubilizing minerals, microbes increase the availability of essential nutrients (e.g., nitrogen, phosphorus, sulfur) for plant uptake.
• Mycorrhizae: Mycorrhizal fungi form symbiotic relationships with plant roots, enhancing nutrient uptake, especially phosphorus, and improving plant growth.

b. Soil Structure and Stability

• Organic Matter Decomposition: The decomposition process leads to the formation of humus, which improves soil structure, water retention, and aeration.
• Exopolysaccharides: Microbial secretions, such as exopolysaccharides, help bind soil particles into aggregates, enhancing soil stability and preventing erosion.

c. Disease Suppression

• Biocontrol Agents: Certain soil microbes (e.g., Trichoderma spp., Bacillus spp.) can suppress plant pathogens by producing antibiotics, competition, or inducing plant resistance mechanisms.
• Microbial Diversity: A diverse microbial community can outcompete and inhibit the growth of harmful pathogens, promoting a healthy soil ecosystem.

Dr Qasim Ali thank you for your contribution to the discussion