Editing Humus (section)

==Humification==
[[Microorganism]]s decompose a large portion of the soil organic matter into inorganic minerals that the roots of plants can absorb as [[nutrient]]s. This process is termed ''[[mineralization (soil science)|mineralization]]''. In this process, [[nitrogen]] ([[nitrogen cycle]]) and the other nutrients ([[nutrient cycle]]) in the decomposed organic matter are recycled. Depending on the conditions in which the decomposition occurs, a fraction of the organic matter does not mineralize and instead is transformed by a process called ''humification''. Prior to modern analytical methods, early evidence led scientists to believe that humification resulted in concatenations of organic [[polymer]]s resistant to the action of microorganisms,<ref>{{cite book |last=Brady |first=Nyle C. |title=The nature and properties of soils |url=https://www.academia.edu/23641831 |date=1984 |edition=9th |publisher=[[Macmillan Publishing Company]] |location=New York, New York |language=en |isbn=978-0029460306 |page=265 |access-date=1 September 2024 }}</ref> however recent research has demonstrated that microorganisms are capable of digesting humus.<ref>{{cite web |url=https://www.quantamagazine.org/a-soil-science-revolution-upends-plans-to-fight-climate-change-20210727/ |title=A soil-science revolution upends plans to fight climate change |quote=Soil researchers have concluded that even the largest, most complex molecules can be quickly devoured by soil’s abundant and voracious microbes |work=[[Quanta Magazine]] |last=Popkin |first=Gabriel |year=2021 |access-date=1 September 2024 }}</ref>

Humification can occur naturally in [[soil]] or artificially in the production of [[compost]]. Organic matter is humified by a combination of [[Saprotrophic nutrition|saprotrophic]] fungi, bacteria, microbes and animals such as earthworms, nematodes, protozoa, and arthropods (see [[Soil biology]]). Plant remains, including those that animals digested and excreted, contain organic compounds: sugars, starches, proteins, carbohydrates, lignins, waxes, resins, and organic acids. Decay in the soil begins with the decomposition of sugars and starches from carbohydrates, which decompose easily as [[detritivore]]s initially invade the dead plant organs, while the remaining [[cellulose]] and [[lignin]] decompose more slowly. Simple proteins, organic acids, starches, and sugars decompose rapidly, while crude proteins, fats, waxes, and resins remain relatively unchanged for longer periods of time.<ref>{{cite journal |last1=Krishna |first1=M. P. |last2=Mohan |first2=Mahesh |date=July 2017 |title=Litter decomposition in forest ecosystems: a review |journal=Energy, Ecology and Environment |volume=2 |issue=3 |pages=236–49 |doi=10.1007/s40974-017-0064-9 |url=https://www.academia.edu/119720860 |access-date=8 September 2024 }}</ref>

Lignin, which is quickly transformed by [[Wood-decay fungus#White rot|white-rot fungi]],<ref>{{cite journal |last1=Levin |first1=Laura |last2=Forchiassin |first2=Flavia |date=9 May 2001 |title=Ligninolytic enzymes of the white rot basidiomycete ''Trametes trogii'' |url=https://www.academia.edu/120239930 |journal=Acta Biotechnologica |volume=21 |issue=2 |pages=179–86 |doi=10.1002/1521-3846(200105)21:2<179::AID-ABIO179>3.0.CO;2-2 |access-date=15 September 2024 }}</ref> is one of the primary precursors of humus,<ref>{{cite journal |last1=González-Pérez |first1=Martha |last2=Vidal Torrado |first2=Pablo |last3=Colnago |first3=Luiz A. |last4=Martin-Neto |first4=Ladislau |last5=Otero |first5=Xosé L. |last6=Milori |first6=Débora M. B. P. |last7=Haenel Gomes |first7=Felipe |date=31 August 2008 |title=13C NMR and FTIR spectroscopy characterization of humic acids in spodosols under tropical rain forest in southeastern Brazil |journal=Geoderma |volume=146 |issue=3–4 |pages=425–33 |doi=10.1016/j.geoderma.2008.06.018 |bibcode=2008Geode.146..425G |url=https://www.academia.edu/14026276 |access-date=15 September 2024 }}</ref> together with by-products of microbial<ref>{{cite journal |last1=Knicker |first1=Heike |last2=Almendros |first2=Gonzalo |last3=González-Vila |first3=Francisco Javier |last4=Lüdemann |first4=Hans-Dietrich |last5=Martín |first5=Fracisco |date=November–December 1995 |title=13C and 15N NMR analysis of some fungal melanins in comparison with soil organic matter |journal=[[Organic Geochemistry]] |volume=23 |issue=11–12 |pages=1023–28 |doi=10.1016/0146-6380(95)00094-1 |bibcode=1995OrGeo..23.1023K |url=https://www.academia.edu/78009567 |access-date=15 September 2024 }}</ref> and animal<ref>{{cite journal |last1=Muscolo |first1=Adele |last2=Bovalo |first2=Francesco |last3=Gionfriddo |first3=Francesco |last4=Nardi |first4=Serenella |date=August 1999 |title=Earthworm humic matter produces auxin-like effects on ''Daucus carota'' cell growth and nitrate metabolism |journal=[[Soil Biology and Biochemistry]] |volume=31 |issue=9 |pages=1303–11 |doi=10.1016/S0038-0717(99)00049-8 |bibcode=1999SBiBi..31.1303M |url=https://www.academia.edu/78825632 |access-date=15 September 2024 }}</ref> activity. The humus produced by humification is thus a mixture of compounds and complex biological chemicals of plant, animal, and microbial origin that has many functions and benefits in soil.<ref name="Dou2020"/> Some judge earthworm humus ([[vermicompost]]) to be the optimal organic [[manure]].<ref>{{cite journal |last1=Oyege |first1=Ivan |last2=Sridhar |first2=B. B. Maruthi |date=10 November 2023 |title=Effects of vermicompost on soil and plant health and promoting sustainable agriculture |journal=[[Soil Systems]] |volume=7 |issue=4 |page=101 |doi=10.3390/soilsystems7040101 |doi-access=free }}</ref>