Climate plays a significant role in the dynamics of soil organic carbon (SOC) and its relationship with soil organic matter (SOM). Certain climate factors, such as temperature, rainfall, and vegetation cover, can influence the amount and composition of SOC in soils.

1. Temperature: Climate directly affects temperature, which influences the rate of organic matter decomposition and SOC turnover in soils. Warmer temperatures generally accelerate decomposition processes, leading to faster mineralization of organic matter and a decrease in SOC levels. Conversely, cooler temperatures slow down decomposition, favoring the accumulation of SOC.

2. Precipitation: Climate conditions, particularly rainfall patterns, affect soil moisture content, which in turn affects SOC dynamics. Adequate moisture availability facilitates microbial activity and decomposition processes, leading to the release of carbon dioxide and subsequent loss of SOC. In areas with limited precipitation, organic matter decomposition is slowed, favoring the accumulation of SOC.

3. Vegetation and Land Cover: Climate also influences vegetation growth patterns, which can indirectly impact SOC levels by affecting the input of organic matter into the soil. Different types of vegetation produce varying amounts and qualities of organic residues, which directly impact SOC accumulation or loss. In addition, land cover changes, such as deforestation or afforestation, driven by climate factors like temperature or precipitation patterns, can impact SOC stocks due to altered organic matter input or soil disturbance.

The relationship between soil organic matter (SOM) and organic carbon (OC) is close, as SOC is a major component of SOM. SOM includes both the organic and inorganic components of the soil, including plant and animal residues, microbial biomass, and associated substances. SOC refers specifically to the carbon contained within the organic fraction of SOM.

SOM represents the entire pool of organic materials in the soil, whereas SOC focuses solely on the carbon component. SOC is typically estimated as a proportion of the total organic matter content, which can vary depending on soil type and management practices. Although SOC is a critical component of SOM, changes in SOM composition, such as shifts in microbial biomass or other organic compounds, can occur without directly affecting SOC levels.

Understanding the relationship between climate and SOC is crucial for predicting and managing carbon cycling in ecosystems. Climate change can alter the balance between SOC production and decomposition rates, potentially leading to the release of carbon dioxide into the atmosphere and exacerbating global warming. Proper land management practices, such as implementing conservation agriculture, managing land cover, and optimizing organic matter inputs, can help sustain SOC stocks and mitigate climate change effects on soils.

Dr Godwin Sabah thank you for your contribution to the discussion

Increased carbohydrate and decreased lignin reduce aggregate stability under warming. Warming affects soil organic carbon stabilization by physical protection of particulate organic matter. Warming affects soil organic carbon stabilization by chemical protection of mineral association. Soil organic carbon is a component of soil organic matter. Organic matter is primarily made up of carbon (58%), with the remaining mass consisting of water and other nutrients such as nitrogen and potassium. Because soil organic matter contains around 60% carbon, it is the defining factor in soil's influence on the global carbon cycle. With around 1 500 billion tonnes of carbon found in the organic matter in soil worldwide, soils are the second largest active store of carbon after the oceans (40 000 billion tonnes). So, soil organic matter is critical for forming aggregates, and aggregates are critical for holding water. Because of that link, there is definitely a positive relationship between organic matter and water-holding capacity. How much water-holding capacity increases depends on your soil type. Soil type, climate and management influence organic matter inputs to soil and its turnover or decomposition. Rainfall is a major driver of plant growth (biomass) and biological activity which results in the decomposition of organic matter that enters soil.

You are welcome Dr Naresh

Climate plays a significant role in influencing soil organic carbon (SOC) levels and its relationship with soil organic matter (SOM). SOC is a crucial component of SOM, accounting for about 40-60% of its total mass. SOM, in turn, is a vital component of healthy and productive soils, contributing to essential soil functions such as nutrient retention, water infiltration, and soil structure maintenance.

Impact of Climate on SOC

Climate variables, particularly temperature and precipitation, exert a profound influence on SOC dynamics. Warmer temperatures generally accelerate microbial decomposition, leading to increased SOC mineralization and reduced SOC stocks. Conversely, cooler temperatures tend to slow down decomposition processes, promoting SOC accumulation.

Precipitation patterns also play a critical role in SOC dynamics. Adequate rainfall supports plant growth and biomass production, which provides the primary source of organic matter for SOC formation. However, excessive rainfall can lead to soil erosion and the loss of SOC-rich topsoil.

Relationship between SOM and SOC

SOM is a complex mixture of organic compounds, including plant residues, animal manure, and microbial biomass. SOC, a key component of SOM, represents the carbon stored in these organic compounds. The relationship between SOM and SOC is generally positive, meaning that higher SOM levels typically correspond to higher SOC concentrations.

However, the exact relationship between SOM and SOC can vary depending on soil type, land management practices, and climatic conditions. For instance, clay-rich soils tend to have higher SOC content than sandy soils due to their greater capacity to retain organic matter. Additionally, no-till farming practices can enhance SOM accumulation and, consequently, SOC sequestration.

Climate Change and SOC

Climate change poses a significant threat to SOC stocks globally. As temperatures rise and precipitation patterns become more erratic, SOC mineralization is expected to increase, leading to a decline in SOC levels. This loss of SOC can further exacerbate climate change by releasing carbon dioxide back into the atmosphere.

Therefore, maintaining and enhancing SOC stocks is crucial for mitigating climate change and promoting soil health. Practices such as cover cropping, reduced tillage, and compost application can help increase SOM and SOC content, thereby improving soil carbon sequestration and resilience to climate change impacts.

Dr Murtadha Shukur thank you for your contribution to the discussion

Recalcitrant carbon fraction in macro-aggregates is sensitive to climate warming. Increased carbohydrate and decreased lignin reduce aggregate stability under warming. Warming affects soil organic carbon stabilization by physical protection of particulate organic matter. The concentration of carbon (oxide in the atmosphere which encourages climate change is greatly influenced by the balance between soil organic carbon (SOC) inputs and outputs. Normally, the carbon pool in the soils is approximately twice as that in the atmosphere. Soil organic matter levels commonly increase as mean annual precipitation increases. Conditions of elevated levels of soil moisture result in greater biomass production, which provides more residues, and thus more potential food for soil biota. Soil biological activity requires air and moisture. Increases in atmospheric CO2 concentration and temperature are expected to increase net primary production in areas where nutrients and water are not limiting because photosynthesis is limited by atmospheric CO2 concentration. Soil organic carbon is a component of soil organic matter. Organic matter is primarily made up of carbon (58%), with the remaining mass consisting of water and other nutrients such as nitrogen and potassium. While carbon is the primary component, soil organic matter also contains hydrogen and oxygen and is an important source of nutrients; nitrogen, phosphorus, sulphur and trace elements. While carbon is the primary component, soil organic matter also contains hydrogen and oxygen and is an important source of nutrients; nitrogen, phosphorus, sulphur and trace elements. Soil type, climate and management influence organic matter inputs to soil and its turnover or decomposition. Rainfall is a major driver of plant growth and biological activity which results in the decomposition of organic matter that enters soil. Warming might affect the decomposition rate of soil carbon and the soil DOC content probably increases when the decomposition rate of soil labile carbon is lower than that of recalcitrant organic carbon.