Editing Carbon sink (section)

=== Soils ===
[[Soils]] represent a short to long-term carbon storage medium and contain more carbon than all terrestrial vegetation and the atmosphere combined.<ref>{{cite journal |journal=Soil Science |volume=166 |issue=11 |pages=858–71 |last=Swift |first=Roger S. |title=Sequestration of Carbon by soil |date=November 2001 |doi=10.1097/00010694-200111000-00010 |bibcode=2001SoilS.166..858S |s2cid=96820247 }}</ref><ref>{{Cite journal |last=Batjes |first=N.H. |date=1996 |title=Total carbon and nitrogen in the soils of the world |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2389.1996.tb01386.x |journal=European Journal of Soil Science|volume=47 |issue=2 |pages=151–163 |doi=10.1111/j.1365-2389.1996.tb01386.x |bibcode=1996EuJSS..47..151B |issn=1351-0754}}</ref><ref>{{Cite journal |last=Batjes |first=N.H. |date=2016 |title=Harmonized soil property values for broad-scale modelling (WISE30sec) with estimates of global soil carbon stocks |url=https://linkinghub.elsevier.com/retrieve/pii/S0016706116300349 |journal=Geoderma|volume=269 |pages=61–68 |doi=10.1016/j.geoderma.2016.01.034|bibcode=2016Geode.269...61B }}</ref> [[Plant litter]] and other [[Biomass (ecology)|biomass]] including [[charcoal]] accumulates as [[Soil organic matter|organic matter]] in soils, and is degraded by [[chemical weathering]] and biological [[biodegradation|degradation]]. More recalcitrant [[organic material|organic]] [[Biopolymer|carbon polymers]] such as [[cellulose]], [[hemi-cellulose]], [[lignin]], aliphatic compounds, waxes and [[terpenoid]]s are collectively retained as [[humus]].<ref>{{cite journal |author1=Klaus Lorenza |author2=Rattan Lala |author3=Caroline M. Prestonb |author4=Klaas G.J. Nieropc |title=Strengthening the soil organic carbon pool by increasing contributions from recalcitrant aliphatic bio(macro)molecules |journal=Geoderma |volume=142 |issue=1–2 |pages=1–10 |date=15 November 2007 |doi=10.1016/j.geoderma.2007.07.013 |url=https://zenodo.org/record/896885 |bibcode=2007Geode.142....1L }}</ref>

Organic matter tends to accumulate in litter and soils of colder regions such as the [[boreal forest]]s of North America and the [[Taiga]] of [[Russia]]. [[Leaf litter]] and humus are rapidly oxidized and poorly retained in [[sub-tropical]] and tropical [[climate]] conditions due to high temperatures and extensive leaching by rainfall. Areas, where [[shifting cultivation]] or [[slash and burn]] agriculture are practiced, are generally only fertile for two to three years before they are abandoned.  These tropical jungles are similar to coral reefs in that they are highly efficient at conserving and circulating necessary nutrients, which explains their lushness in a nutrient desert.<ref>{{cite web | access-date=19 September 2021 | title=Coral Reefs Biome "Underwater Rainforests" | url=https://untamedscience.com/biology/biomes/coral-reefs-biome/}}</ref>

[[Grassland]]s contribute to [[soil organic matter]], stored mainly in their extensive fibrous root mats. Due in part to the climatic conditions of these regions (e.g., cooler temperatures and semi-arid to arid conditions), these soils can accumulate significant quantities of organic matter. This can vary based on rainfall, the length of the winter season, and the frequency of naturally occurring lightning-induced [[Wildfire|grass-fires]]. While these fires release carbon dioxide, they improve the quality of the grasslands overall, in turn increasing the amount of carbon retained in the humic material. They also deposit carbon directly into the soil in the form of [[biochar]] that does not significantly degrade back to carbon dioxide.<ref>{{Cite journal|last1=Woolf|first1=Dominic|last2=Amonette|first2=James E.|last3=Street-Perrott|first3=F. Alayne|last4=Lehmann|first4=Johannes|last5=Joseph|first5=Stephen|date=2010-08-10|title=Sustainable biochar to mitigate global climate change|journal=Nature Communications|volume=1|issue=5|pages=56|doi=10.1038/ncomms1053|issn=2041-1723|pmc=2964457|pmid=20975722|bibcode=2010NatCo...1...56W}}</ref>

Much [[soil carbon|organic carbon]] retained in many agricultural areas worldwide has been severely depleted due to [[intensive farming]] practices.<ref name="cool">{{cite web |date=17 October 2009 |title=Organic Farming Can Cool the World that Chemical Farming Overheated |url=https://www.cornucopia.org/2009/10/organic-farming-can-cool-the-world-that-chemical-farming-overheated/ |access-date=18 September 2021}}</ref> Since the 1850s, a large proportion of the world's grasslands have been tilled and converted to croplands, allowing the rapid oxidation of large quantities of soil organic carbon. Methods that significantly enhance carbon sequestration in soil are called [[carbon farming]]. They include for example [[no-till farming]], residue mulching, [[cover crop]]ping, and [[crop rotation]].