<Tr> <Td> </Td> <Td> This article needs more links to other articles to help integrate it into the encyclopedia . Please help improve this article by adding links that are relevant to the context within the existing text . (October 2012) (Learn how and when to remove this template message) </Td> </Tr> <P> Soil respiration refers to the production of carbon dioxide when soil organisms respire . This includes respiration of plant roots, the rhizosphere, microbes and fauna . </P> <P> Soil respiration is a key ecosystem process that releases carbon from the soil in the form of CO . CO is acquired from the atmosphere and converted into organic compounds in the process of photosynthesis . Plants use these organic compounds to build structural components or respire them to release energy . When plant respiration occurs below - ground in the roots, it adds to soil respiration . Over time, plant structural components are consumed by heterotrophs . This heterotrophic consumption releases CO and when this CO is released by below - ground organisms, it is considered soil respiration . </P> <P> The amount of soil respiration that occurs in an ecosystem is controlled by several factors . The temperature, moisture, nutrient content and level of oxygen in the soil can produce extremely disparate rates of respiration . These rates of respiration can be measured in a variety of methods . Other methods can be used to separate the source components, in this case the type of photosynthetic pathway (C3 / C4), of the respired plant structures . </P>

Where does the co2 that plant roots release come from
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