Quite honestly, I don&#x27;t have the numbers I&#x27;d like on this. But you&#x27;re talking about topsoil, which covers literally hundreds of millions of acres throughout the US, and probably on the order of billions of acres worldwide. And that for a depth of up to multiple meters. That&#x27;s a vast, vast resource. And soil depletion is about exhausting that -- both returning the carbon content to the atmosphere and washing away topsoil.<p>OK, here&#x27;s a Wikipedia stat:<p><i>Soil carbon is the generic name for carbon held within the soil, primarily in association with its organic content. Soil carbon is the largest terrestrial pool of carbon, containing 2,200 gigatonnes (Gt) of it.[1] Humans increasingly influence the size of this pool. Soil carbon plays a key role in the carbon cycle, and thus it is important in global climate models.</i><p>Citing: Batjes, N.H. (1996). &quot;Total carbon and nitrogen in the soils of the world&quot;. Soil Science 47 (2): 151–163. doi:10.1111&#x2F;j.1365-2389.1996.tb01386.x.<p>Continuing:<p><i>Although the figure is frequently being revised upwards with new discoveries, over 2,700 gigatonnes (Gt) of carbon is stored in soils worldwide, which is well above the combined total of atmosphere (780 Gt) or biomass (575 Gt), most of which is wood. Carbon is taken out of the atmosphere by plant photosynthesis; about 60 Gt annually is incorporated into various types of soil organic matter (SOM), including surface litter; about 60 Gt annually is respired or oxidized from soil.[2]</i><p>And I really <i>don&#x27;t</i>know how that is influenced by human activity, climate change, changes in biocover, etc.<p>There&#x27;s also loess, a high-carbon sediment covering 10% of the Earth&#x27;s surface, to depths of tens of meters, over 100 meters in parts of China.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Loess" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Loess</a><p>More on CO₂ in soils:
<a href="http:&#x2F;&#x2F;soilquality.org.au&#x2F;factsheets&#x2F;how-much-carbon-can-soil-store" rel="nofollow">http:&#x2F;&#x2F;soilquality.org.au&#x2F;factsheets&#x2F;how-much-carbon-can-soi...</a>