<p>There are two ways carbon is released from soil.</p>

<p>The first is cellular respiration of plants that uses previously stored energy (visualized in this <a href="https://en.wikipedia.org/wiki/Cellular_respiration#/media/File:CellRespiration.svg" rel="nofollow noreferrer">chart</a>).</p>

<p>The second is when heterotrophs consume organic carbon below ground and respire carbon dioxide.</p>

<p>The sum of these is called soil respiration, which I think was the process you were asking about.</p>

CC BY-SA 3.0
2017-09-12T10:41:57.700Z
By the scientific process, I guess I was thinking what is meant by carbon is 'lost' when topsoils are altered significantly and why farmers try to 'trap' carbon to maintain fertility? I obviously have some science gaps of knowledge here.
Ronald Jees
CC BY-SA 3.0
2017-09-11T10:52:59.960Z
2017-09-11T10:52:59.960Z
Communisty
<p>Soil loses <em>net</em> carbon when disturbance stops carbon fixation but does not stop carbon respiration. </p>

<p>Carbon is fixed into organic material by photosynthesis, mostly by plants; carbon respiration is when organic material rots or is eaten, as described by communitys. Undisturbed soils have fluxes of carbon both in and out almost all the time. </p>

<p>Most human disturbances reduce photosynthesis, so "disturbed soils release carbon" is an adequate shorthand. For instance, plow agriculture that keeps soil bare of plants for a significant part of the year; or moving piles of soil around for construction, or diverting streams and groundwater so that plants die of drought, or simply paving over soil. Natural disturbances can do the same. </p>

<p>As ecosystems mature on undisturbed soil, they tend to become more efficient at capturing energy and retaining limiting nutrients and therefore gain biomass, including soil organic material (SOM). SOM not only literally contains nutrients, but is a micro-environment that buffers nutrients, buffers water, and supports microbes that help plant roots flourish, which is why agriculture benefits from increased SOM. </p>

<p>Even in wild environments, leaching eventually reduces the soluble nutrients and reduces total biomass (see <a href="http://www.hydrology.bee.cornell.edu/BEE3710Handouts/VitousekBS75.pdf" rel="nofollow noreferrer">Vitousek &amp; Reiners, 1975</a>, and a lot of Vitousek's later work). The leaching takes long enough that it's also an adequate shorthand to say that undisturbed soils will accumulate soil carbon. </p>

CC BY-SA 3.0
2017-10-12T21:21:51.657Z
2017-10-12T21:31:04.197Z
2017-10-12T21:31:04.197Z
cphlewis
<p>Is carbon lost from topsoil when it's degraded/removed? What is the scientific process?</p>

CC BY-SA 3.0
2017-09-11T08:20:53.573Z
The scientific process? Do you mean how scientists deal with this question and work in the field with measuring CO2 fluxes?
daniel.heydebreck
CC BY-SA 3.0
2017-09-11T09:11:44.407Z
Too short to be an answer: Oxidation.
David Hammen
CC BY-SA 3.0
2017-09-11T18:00:46.600Z
You also need to specify the form of carbon you mean.  Pure carbon, e.g. charcoal from fires, is pretty stable (from my own observations).  Carbon incorporated in organic materials - say the stuff I add to my compost pile - is eaten by various organisms, such as worms & bacteria.
jamesqf
<soil><soil-science>
Soil Science and the carbon cycle - is carbon released from soil into the atmosphere?
Ronald Jees
# Soil Science and the carbon cycle - is carbon released from soil into the atmosphere?

(Asked by: username_0 on 2017-09-11)

Is carbon lost from topsoil when it's degraded/removed? What is the scientific process?

**Tags:** soil, soil-science

> **Comments:**
> **username_1**: The scientific process? Do you mean how scientists deal with this question and work in the field with measuring CO2 fluxes?  
> **username_2**: Too short to be an answer: Oxidation.  
> **username_3**: You also need to specify the form of carbon you mean.  Pure carbon, e.g. charcoal from fires, is pretty stable (from my own observations).  Carbon incorporated in organic materials - say the stuff I add to my compost pile - is eaten by various organisms, such as worms & bacteria.  

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## 2 answers

### Answer by username_4 on 2017-09-11. Score: 2

There are two ways carbon is released from soil.

The first is cellular respiration of plants that uses previously stored energy (visualized in this [chart](https://en.wikipedia.org/wiki/Cellular_respiration#/media/File:CellRespiration.svg)).

The second is when heterotrophs consume organic carbon below ground and respire carbon dioxide.

The sum of these is called soil respiration, which I think was the process you were asking about.

> **Comments:**
> **username_0**: By the scientific process, I guess I was thinking what is meant by carbon is 'lost' when topsoils are altered significantly and why farmers try to 'trap' carbon to maintain fertility? I obviously have some science gaps of knowledge here.  

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### Answer by username_5 on 2017-10-12. Score: 0

Soil loses *net* carbon when disturbance stops carbon fixation but does not stop carbon respiration.

Carbon is fixed into organic material by photosynthesis, mostly by plants; carbon respiration is when organic material rots or is eaten, as described by communitys. Undisturbed soils have fluxes of carbon both in and out almost all the time.

Most human disturbances reduce photosynthesis, so "disturbed soils release carbon" is an adequate shorthand. For instance, plow agriculture that keeps soil bare of plants for a significant part of the year; or moving piles of soil around for construction, or diverting streams and groundwater so that plants die of drought, or simply paving over soil. Natural disturbances can do the same.

As ecosystems mature on undisturbed soil, they tend to become more efficient at capturing energy and retaining limiting nutrients and therefore gain biomass, including soil organic material (SOM). SOM not only literally contains nutrients, but is a micro-environment that buffers nutrients, buffers water, and supports microbes that help plant roots flourish, which is why agriculture benefits from increased SOM.

Even in wild environments, leaching eventually reduces the soluble nutrients and reduces total biomass (see [Vitousek & Reiners, 1975](http://www.hydrology.bee.cornell.edu/BEE3710Handouts/VitousekBS75.pdf), and a lot of Vitousek's later work). The leaching takes long enough that it's also an adequate shorthand to say that undisturbed soils will accumulate soil carbon.


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