Question: where does the co2 that plant roots release come from

title: Soil respiration
text: 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 . 

Answer: answer: Soil respiration is a key ecosystem process that releases carbon from the soil in the form of CO.
When plant respiration occurs below-ground in the roots, it adds to soil respiration.
answer: CO is acquired from the atmosphere and converted into organic compounds in the process of photosynthesis.  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.