Microbial respiration (soil respiration):
Microbial respiration (soil respiration) is defined as oxygen uptake or carbon dioxide evolution by bacteria, fungi, algae, and protozoans, and includes the gas exchange of aerobic and anaerobic metabolism. Soil respiration results from the degradation of organic matter (e.g. mineralization of harvest residues). This soil biological activity consists of numerous individual activities; the formation of C02 is the last step of carbon mineralization.
In undisturbed soils (no organic residues decomposition such as dead plant roots, and nutrient addition, etc.), thus under ecological balance between the organisms and their activities, a status called “basal respiration”. Upon a disturbance, e.g. through organic residues decomposition, or the addition of organic matter, and incorporated harvest residues, one can observe a change in the soil respiration due to more rapid plant growth, secretion of acids, and soil microbes- plant roots carbohydrates exchange, a process that leads to higher mineralization of the microorganisms. This increased respiration is characterized by an initial, an acceleration, an exponential, a delay, a stationary, and a decreasing phase. C02 evolution from the soil is thus a measure of the total soil biological activity.
Soils have no respiratory system. But soils “breathe” and are teeming with life through a process known as soil respiration. While plants receive the oxygen that is necessary for their growth and continued existence from the soil's respiration process.
Therefore, soil respiration is a measure of the carbon dioxide released from the soil by microbes decomposing soil organic matter and from the respiration of plant roots. Soil respiration indicates soil health (soil organic matter content, soil organic matter decomposition, and the level of microbial activity).
Soil respiration is a key ecosystem process that releases carbon from the soil in the form of CO2, which is acquired by plants from the atmosphere and converted into organic compounds in the process of photosynthesis. However, plants respire some of the carbon compounds which were generated by photosynthesis. When this respiration occurs in roots, it adds to soil respiration. Root respiration accounts for approximately half of all soil respiration.
Plants use these organic compounds to build structural components or respire them to release energy. The process is known as soil respiration, which is the process by which soil roots and microbes release carbon dioxide into the atmosphere. It is an essential part of the carbon cycle and plays a significant role in the process of regulating the climate on Earth.
The composition of soil consists of a wide variety of organic and inorganic components, as well as air and water. The pores in the soil make it possible for air and water to move freely throughout the soil, creating an environment that is favorable to the growth of plants and microorganisms.