Editing Compost (section)

== Fundamentals ==
[[File:Composting in the Escuela Barreales.jpg|thumb|Home compost barrel]]
[[File:Compost bins at the Evergreen State College Organic Farm during mid June of 2019.jpg|thumb|Compost bins at the [[Evergreen State College]] organic farm in Washington]]
[[File:Compost pile.JPG|thumb|Materials in a compost pile]]
[[File:Food-scraps-compost.jpg|thumb|Food scraps compost heap]]

Composting is an [[wikt:aerobic|aerobic]] method of decomposing organic solid wastes,<ref>{{Cite book|url=https://books.google.com/books?id=3BhSAAAAMAAJ&q=Human+waste+can+also+be+added+as+an+input+to+the+composting+process+since+human+waste+is+a+nitrogen-rich+organic+material|title=Introduction to Environmental Engineering and Science|last=Masters|first=Gilbert M.|date=1997|publisher=Prentice Hall|isbn=9780131553842|language=en|access-date=28 June 2017|archive-date=26 January 2021|archive-url=https://web.archive.org/web/20210126005451/https://books.google.com/books?id=3BhSAAAAMAAJ&q=Human+waste+can+also+be+added+as+an+input+to+the+composting+process+since+human+waste+is+a+nitrogen-rich+organic+material|url-status=live}}</ref> so it can be used to recycle organic material. The process involves decomposing organic material into a humus-like material, known as compost, which is a good fertilizer for plants.

Composting organisms require four equally important ingredients to work effectively:<ref name=":5" />
* '''Carbon''' is needed for energy; the microbial [[oxidation]] of carbon produces the heat required for other parts of the composting process.<ref name=":5" /> High carbon materials tend to be brown and dry.<ref name=":4" /><ref name=":5" />
* '''Nitrogen''' is needed to grow and reproduce more organisms to oxidize the carbon.<ref name=":5" /> High nitrogen materials tend to be green<ref name=":4" /> and wet.<ref name=":5" /> They can also include colourful fruits and vegetables.<ref name=":4" />
* '''Oxygen''' is required for oxidizing the carbon, the decomposition process.<ref name=":5" /> Aerobic bacteria need oxygen levels above 5% to perform the processes needed for composting.<ref name=":5" />
* '''Water''' is necessary in the right amounts to maintain activity without causing locally [[wikt:anaerobic|anaerobic]] conditions.<ref name=":4" /><ref name=":5" />

Certain ratios of these materials allow microorganisms to work at a rate that will heat up the compost pile. Active management of the pile (e.g., turning over the compost heap) is needed to maintain sufficient oxygen and the right moisture level. The air/water balance is critical to maintaining high temperatures {{convert|130–160|F}} until the materials are broken down.<ref>{{Cite journal|last=Lal|first=Rattan|date=2003-11-30|title=Composting|url=http://link.galegroup.com/apps/doc/CX3408100055/GVRL?sid=GVRL&xid=54515a57|journal=Pollution a to Z|language=en|volume=1|access-date=17 August 2019|archive-date=13 July 2021|archive-url=https://web.archive.org/web/20210713211357/https://galeapps.gale.com/apps/auth?userGroupName=&sid=GVRL&origURL=https%3A%2F%2Fgo.gale.com%2Fps%2Fi.do%3Fp%3DGVRL%26u%3D%26id%3DGALE%7CCX3408100055%26v%3D2.1%26it%3Dr%26sid%3DGVRL%26asid%3D54515a57&prodId=GVRL|url-status=live}}</ref>

Composting is most efficient with a [[carbon-to-nitrogen ratio]] of about 25:1.<ref name="tilley2">{{cite book|url=http://www.eawag.ch/en/department/sandec/publications/compendium/|title=Compendium of Sanitation Systems and Technologies|last1=Tilley|first1=Elizabeth|last2=Ulrich|first2=Lukas|last3=Lüthi|first3=Christoph|last4=Reymond|first4=Philippe|last5=Zurbrügg|first5=Chris|publisher=Swiss Federal Institute of Aquatic Science and Technology (Eawag)|year=2014|isbn=978-3-906484-57-0|edition=2nd|location=Duebendorf, Switzerland|chapter=Septic tanks|chapter-url=http://ecompendium.sswm.info/sanitation-technologies/septic-tank?group_code=s|access-date=1 April 2018|archive-date=22 October 2019|archive-url=https://web.archive.org/web/20191022044558/https://www.eawag.ch/en/department/sandec/publications/compendium/|url-status=live}}</ref> [[Compost#Hot and cold composting – impact on timing|Hot composting]] focuses on retaining heat to increase the decomposition rate, thus producing compost more quickly. Rapid composting is favored by having a carbon-to-nitrogen ratio of about 30 carbon units or less. Above 30, the substrate is nitrogen starved. Below 15, it is likely to outgas a portion of nitrogen as ammonia.<ref>{{cite book|last1=Haug|first1=Roger|title=The Practical Handbook of Compost Engineering|url=https://books.google.com/books?id=MX_jbemODmAC&q=ammonium+phosphate+compost&pg=PA249|publisher=CRC Press|isbn=9780873713733|year=1993|access-date=16 October 2020|archive-date=13 July 2021|archive-url=https://web.archive.org/web/20210713211319/https://books.google.com/books?id=MX_jbemODmAC&q=ammonium+phosphate+compost&pg=PA249|url-status=live}}</ref>

Nearly all dead plant and animal materials have both carbon and nitrogen in different amounts.<ref>{{Cite web|url=http://www.klickitatcounty.org/SolidWaste/fileshtml/organics/compostCalc.htm|archiveurl=https://web.archive.org/web/20111117112037/http://www.klickitatcounty.org/solidwaste/fileshtml/organics/compostCalc.htm|url-status=dead|title=Klickitat County WA, USA Compost Mix Calculator|archivedate=17 November 2011}}</ref> Fresh grass clippings have an average ratio of about 15:1 and dry autumn leaves about 50:1 depending upon species.<ref name=":5" /> Composting is an ongoing and dynamic process; adding new sources of carbon and nitrogen consistently, as well as active management, is important.

=== Organisms ===
Organisms can break down organic matter in compost if provided with the correct mixture of water, oxygen, carbon, and nitrogen.<ref name=":5" /> They fall into two broad categories: chemical decomposers, which perform chemical processes on the organic waste, and physical decomposers, which process the waste into smaller pieces through methods such as grinding, tearing, chewing, and digesting.<ref name=":5" />

==== Chemical decomposers ====
* [[Bacteria]] are the most abundant and important of all the [[microorganism]]s found in compost.<ref name=":5" /> Bacteria process carbon and nitrogen and excrete plant-available nutrients such as nitrogen, phosphorus, and magnesium.<ref name=":5" /> Depending on the phase of composting, [[Mesophile|mesophilic]] or [[Thermophile|thermophilic]] bacteria may be the most prominent.
** Mesophilic bacteria get compost to the thermophilic stage through oxidation of organic material.<ref name=":5" /> Afterwards they cure it, which makes the fresh compost more bioavailable for plants.<ref name=":5" /><ref name=":1">{{Cite web|title=Compost Physics - Cornell Composting|url=http://compost.css.cornell.edu/physics.html#:~:text=Compost%20heat%20is%20produced%20as,microbial%20breakdown%20of%20organic%20material.&text=Compost%20managers%20strive%20to%20keep,help%20to%20dissipate%20the%20heat.|access-date=2021-04-11|website=compost.css.cornell.edu|archive-date=9 November 2020|archive-url=https://web.archive.org/web/20201109215044/http://compost.css.cornell.edu/physics.html#:~:text=Compost%20heat%20is%20produced%20as,microbial%20breakdown%20of%20organic%20material.&text=Compost%20managers%20strive%20to%20keep,help%20to%20dissipate%20the%20heat.|url-status=live}}</ref>
** Thermophilic bacteria do not reproduce and are not active between {{cvt|-5|and|25|C}},<ref>{{Cite journal|last1=Marchant|first1=Roger|last2=Franzetti|first2=Andrea|last3=Pavlostathis|first3=Spyros G.|last4=Tas|first4=Didem Okutman|last5=Erdbrűgger|first5=Isabel|last6=Űnyayar|first6=Ali|last7=Mazmanci|first7=Mehmet A.|last8=Banat|first8=Ibrahim M.|date=2008-04-01|title=Thermophilic bacteria in cool temperate soils: are they metabolically active or continually added by global atmospheric transport?|url=https://doi.org/10.1007/s00253-008-1372-y|journal=Applied Microbiology and Biotechnology|language=en|volume=78|issue=5|pages=841–852|doi=10.1007/s00253-008-1372-y|pmid=18256821|s2cid=24884198|issn=1432-0614|access-date=29 April 2021|archive-date=13 July 2021|archive-url=https://web.archive.org/web/20210713211321/https://link.springer.com/article/10.1007/s00253-008-1372-y|url-status=live}}</ref> yet are found throughout soil. They activate once the mesophilic bacteria have begun to break down organic matter and increase the temperature to their optimal range.<ref name=":1" /> They have been shown to enter soils via rainwater.<ref name=":1" /> They are present so broadly because of many factors, including their spores being resilient.<ref>{{Cite journal|last=Zeigler|first=Daniel R.|date=January 2014|title=The Geobacillus paradox: why is a thermophilic bacterial genus so prevalent on a mesophilic planet?|journal=Microbiology|volume=160|issue=Pt 1|pages=1–11|doi=10.1099/mic.0.071696-0|doi-access=free |issn=1465-2080|pmid=24085838}}</ref> Thermophilic bacteria thrive at higher temperatures, reaching {{cvt|40|–|60|C}} in typical mixes. Large-scale composting operations, such as [[windrow composting]], may exceed this temperature, potentially killing beneficial soil microorganisms but also [[pasteurizing]] the waste.<ref name=":1" />
** [[Actinomycetota]] are needed to break down paper products such as newspaper, [[Bark (botany)|bark]], etc., and other large molecules such as lignin and cellulose that are more difficult to decompose.<ref name=":5" /> The "pleasant, earthy smell of compost" is attributed to Actinomycetota.<ref name=":5" /> They make carbon, ammonia, and nitrogen nutrients available to plants.<ref name=":5" />
* [[Fungi]] such as [[Mold (fungus)|mold]]s and [[yeast]]s help break down materials that bacteria cannot, especially cellulose and [[lignin]] in woody material.<ref name=":5" />
* [[Protozoa]] contribute to biodegradation of organic matter and consume inactive bacteria, fungi, and micro-organic particulates.<ref name=":0">{{Cite web|last1=Trautmann|first1=Nancy|last2=Olynciw|first2=Elaina|title=Compost Microorganisms|url=http://compost.css.cornell.edu/microorg.html|url-status=live|access-date=2021-07-12|website=CORNELL Composting|publisher=Cornell Waste Management Institute|archive-date=15 November 2019|archive-url=https://web.archive.org/web/20191115202006/http://compost.css.cornell.edu/microorg.html}}</ref>

==== Physical decomposers ====
* [[Ant]]s create nests, making the soil more porous and transporting nutrients to different areas of the compost.<ref name=":5" />
* Beetles as [[Grub (larva)|grubs]] feed on decaying vegetables.<ref name=":5" />
* [[Earthworm]]s ingest partly composted material and excrete worm castings,<ref name=":5" /> making nitrogen, calcium, phosphorus, and magnesium available to plants.<ref name=":5" /> The tunnels they create as they move through the compost also increase aeration and drainage.<ref name=":5" />
* [[Fly|Flies]] feed on almost all organic material and put bacteria into the compost.<ref name=":5" /> Their population is kept in check by [[mite]]s and the thermophilic temperatures that are unsuitable for fly larvae.<ref name=":5" />
* [[Millipede]]s break down plant material.<ref name=":5" />
* [[Rotifer]]s feed on plant particles.<ref name=":5" />
* [[Snail]]s and [[slug]]s feed on living or fresh plant material.<ref name=":5" /> They should be removed from compost before use, as they can damage plants and crops.<ref name=":5" />
* [[Sow bugs]] feed on rotting wood and decaying vegetation.<ref name=":5" />
* [[Springtail]]s feed on fungi, molds, and decomposing plants.<ref name=":5" />

=== Phases of composting ===
[[File:Komposztáló.JPG|thumb|Three year old household compost]]
Under ideal conditions, composting proceeds through three major phases:<ref name=":0" /><ref>{{Cite web |title=Phases of composting |url=https://compostsegria.com/ca/en/fases-del-compostaje/ |access-date=2025-02-14 |website=Compost Segrià |language=en-GB}}</ref> 
# '''Mesophilic phase:''' The initial, mesophilic phase is when the decomposition is carried out under moderate temperatures by [[Mesophile|mesophilic]] microorganisms. 2 to 8 days
# '''Thermophilic phase:''' As the temperature rises, a second, thermophilic phase starts, in which various [[thermophilic bacteria]] carry out the decomposition under higher temperatures ({{convert|50|to|60|C}}.)
# '''Cooling phase''' (also called Mesophilic II)
# '''Maturation phase:''' As the supply of high-energy compounds dwindles, the temperature starts to decrease.

Semicomposting is the degradation process that handles volumes of organic waste lower than that recommended for composting and therefore does not present a [[thermophilic]] stage, because [[mesophilic]] microorganisms are the only responsible ones, for the degradation of [[organic matter]].<ref>* [https://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392017000300287#B11 Comparison of three systems of decomposition of agricultural residues for the production of organic fertilizers. Chilean J. Agric. Res. vol.77 no.3 Chillán set. 2017.]</ref><ref>[https://www.redalyc.org/journal/339/33953499012/html/ SEMICOMPOST AND VERMICOMPOST MIXED WITH PEAT MOSS ENHANCE SEED GERMINATION AND DEVELOPMENT OF LETTUCE AND TOMATO SEEDLINGS, Interciencia, vol. 42, no. 11, pp. 774-779, 2017]</ref>

=== Hot and cold composting – impact on timing ===
The time required to compost material relates to the volume of material, the particle size of the inputs (e.g. [[wood chips]] break down faster than branches), and the amount of mixing and aeration.<ref name=":5" /> Generally, larger piles reach higher temperatures and remain in a thermophilic stage for days or weeks. This is hot composting and is the usual method for large-scale municipal facilities and agricultural operations.

The Berkeley method produces finished compost in 18 days. It requires assembly of at least {{convert|1|m3}} of material at the outset and needs turning every two days after an initial four-day phase.<ref>{{cite web|url=http://vric.ucdavis.edu/pdf/compost_rapidcompost.pdf|title=The Rapid Compost Method by Robert Raabe, Professor of Plant Pathology, Berkeley|access-date=21 December 2017|archive-date=15 December 2017|archive-url=https://web.archive.org/web/20171215190533/http://vric.ucdavis.edu/pdf/compost_rapidcompost.pdf|url-status=live}}</ref> Such short processes involve some changes to traditional methods, including smaller, more homogenized particle sizes in the input materials, controlling carbon-to-nitrogen ratio (C:N) at 30:1 or less, and careful monitoring of the moisture level.

Cold composting is a slower process that can take up to a year to complete.<ref>{{cite web |title=Composting |url=https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs144p2_014870.pdf |publisher=USDA Natural Resources Conservation Service |access-date=30 December 2020 |date=April 1998 |archive-date=6 May 2021 |archive-url=https://web.archive.org/web/20210506090827/https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs144p2_014870.pdf |url-status=live }}</ref> It results from smaller piles, including many residential compost piles that receive small amounts of kitchen and garden waste over extended periods. Piles smaller than {{convert|1|m3}} tend not to reach and maintain high temperatures.<ref>{{cite web |title=Home Composting |url=https://ecommons.cornell.edu/bitstream/handle/1813/44638/compostbrochure.pdf?sequence=2&isAllowed=y |publisher=Cornell Waste Management Institute |access-date=30 December 2020 |date=2005 |archive-date=16 October 2020 |archive-url=https://web.archive.org/web/20201016191518/https://ecommons.cornell.edu/bitstream/handle/1813/44638/compostbrochure.pdf?sequence=2&isAllowed=y |url-status=live }}</ref> Turning is not necessary with cold composting, although a risk exists that parts of the pile may go anaerobic as it becomes compacted or waterlogged.

=== Pathogen removal ===
Composting can destroy some [[pathogen]]s and [[seed]]s, by reaching temperatures above {{convert|50|C}}.<ref name="Graves">{{Cite web|last=Robert|first=Graves|date=February 2000|title=Composting|url=https://www.wcc.nrcs.usda.gov/ftpref/wntsc/AWM/neh637c2.pdf|website=Environmental Engineering National Engineering Handbook|pages=2–22|access-date=19 October 2020|archive-date=15 January 2021|archive-url=https://web.archive.org/web/20210115060905/https://www.wcc.nrcs.usda.gov/ftpref/wntsc/AWM/neh637c2.pdf|url-status=live}}</ref> 
Dealing with stabilized compost – i.e. composted material in which microorganisms have finished digesting the organic matter and the temperature has reached between {{cvt|50|and|70|C}} – poses very little risk, as these temperatures kill pathogens and even make [[oocysts]] unviable.<ref name="sciencedirect.com">{{Cite journal|date=1995-08-01|title=Occurrence of enteric pathogens in composted domestic solid waste containing disposable diapers|url=https://www.sciencedirect.com/science/article/abs/pii/S0734242X95900810|journal=Waste Management & Research|language=en|volume=13|issue=4|pages=315–324|doi=10.1016/S0734-242X(95)90081-0|issn=0734-242X|access-date=19 April 2021|archive-date=19 April 2021|archive-url=https://web.archive.org/web/20210419114736/https://www.sciencedirect.com/science/article/abs/pii/S0734242X95900810|url-status=live|last1=Gerba|first1=C.|bibcode=1995WMR....13..315G }}</ref> The temperature at which a pathogen dies depends on the pathogen, how long the temperature is maintained (seconds to weeks), and pH.<ref>{{Cite journal|last1=Mehl|first1=Jessica|last2=Kaiser|first2=Josephine|last3=Hurtado|first3=Daniel|last4=Gibson|first4=Daragh A.|last5=Izurieta|first5=Ricardo|last6=Mihelcic|first6=James R.|date=2011-02-03|title=Pathogen destruction and solids decomposition in composting latrines: study of fundamental mechanisms and user operation in rural Panama|journal=Journal of Water and Health|volume=9|issue=1|pages=187–199|doi=10.2166/wh.2010.138|pmid=21301126|issn=1477-8920|doi-access=free|bibcode=2011JWH.....9..187M }}</ref>

Compost products such as compost tea and compost extracts have been found to have an inhibitory effect on ''[[Fusarium oxysporum]]'', [[Rhizoctonia solani|''Rhizoctonia'' species]], and ''[[Pythium debaryanum]],'' plant pathogens that can cause crop diseases.<ref name=":2">{{Cite journal|last1=Milinković|first1=Mira|last2=Lalević|first2=Blažo|last3=Jovičić-Petrović|first3=Jelena|last4=Golubović-Ćurguz|first4=Vesna|last5=Kljujev|first5=Igor|last6=Raičević|first6=Vera|date=January 2019|title=Biopotential of compost and compost products derived from horticultural waste—Effect on plant growth and plant pathogens' suppression|url=http://dx.doi.org/10.1016/j.psep.2018.09.024|journal=Process Safety and Environmental Protection|volume=121|pages=299–306|doi=10.1016/j.psep.2018.09.024|bibcode=2019PSEP..121..299M |s2cid=104755582|issn=0957-5820|access-date=27 April 2021|archive-date=13 July 2021|archive-url=https://web.archive.org/web/20210713211321/https://linkinghub.elsevier.com/retrieve/pii/S0957582018309704|url-status=live}}</ref> Aerated compost teas are more effective than compost extracts.<ref name=":2" /> The [[microbiota]] and enzymes present in compost extracts also have a suppressive effect on fungal plant pathogens.<ref>{{Cite journal|last1=El-Masry|first1=M.H.|last2=Khalil|first2=A.I.|last3=Hassouna|first3=M.S.|last4=Ibrahim|first4=H.A.H.|date=2002-08-01|title=In situ and in vitro suppressive effect of agricultural composts and their water extracts on some phytopathogenic fungi|url=https://doi.org/10.1023/A:1016302729218|journal=World Journal of Microbiology and Biotechnology|language=en|volume=18|issue=6|pages=551–558|doi=10.1023/A:1016302729218|s2cid=81831444|issn=1573-0972|access-date=27 April 2021|archive-date=13 July 2021|archive-url=https://web.archive.org/web/20210713211358/https://link.springer.com/article/10.1023/A:1016302729218|url-status=live}}</ref> Compost is a good source of [[Biocontrol|biocontrol agents]] like [[Bacillus subtilis|''B. subtilis'']], ''B. licheniformis,'' and P. ''chrysogenum'' that fight plant pathogens.<ref name=":2" /> Sterilizing the compost, compost tea, or compost extracts reduces the effect of pathogen suppression.<ref name=":2" />

=== Diseases that can be contracted from handling compost ===
When turning compost that has not gone through phases where temperatures above {{cvt|50|C}} are reached, a mouth mask and gloves must be worn to protect from diseases that can be contracted from handling compost, including:<ref name=":3">{{Cite web|title=Compost Pile Hazards|url=https://www.nachi.org/compost-pile-hazards.htm|access-date=2021-04-19|website=www.nachi.org|language=en|archive-date=19 April 2021|archive-url=https://web.archive.org/web/20210419120553/https://www.nachi.org/compost-pile-hazards.htm|url-status=live}}</ref>
* [[Aspergillosis]]
* [[Farmer's lung]]
* [[Histoplasmosis]] – a fungus that grows in guano and bird droppings
* [[Legionnaires' disease]]
* [[Paronychia]] – via infection around the fingernails and toenails
* [[Tetanus]] – a central nervous system disease

[[Oocyte]]s are rendered unviable by temperatures over {{cvt|50|C}}.<ref name="sciencedirect.com"/>