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{{about|the organic matter in soil|the band|Humus (band)|the food|Hummus|}}
'''Humus''', the end product of the [[compost]]ing process when organic matter has fully broken down, can be summed up as the 'life-force' of the [[soil]]. Yet is difficult to define humus in precise terms; it is a highly complex substance, the full nature of which is still not fully understood. Physically humus can be differentiated from organic matter in that the latter is rough looking material, with coarse plant remains still visible, whilst once fully humified it become more uniform in appearance (a dark, spongy, jelly-like
substance) and amorphous in structure. That is, it has no determinate shape, structure or character.


[[Image:Soil profile.jpg|thumb|Humus has a characteristic black or dark brown color, due to an accumulation of organic [[carbon]]]]
Plant remains (including those that have passed through an animal and are excreted as manure) contain organic compounds, sugars, starches, proteins, [[carbohydrate]]s, [[lignins]], waxes, resins and [[organic acid]]s. The process of organic matter decay in the soil begins with the decomposition of sugars and starches from carbohydrates which break down easily as [[saprophyte]]s initially invade the dead plant, whilst the remaining [[cellulose]]
'''Humus''' (origin: 1790–1800; < ''[[Latin]]'': earth, ground)<ref>"humus". Dictionary.com Unabridged (v 1.1). Random House, Inc. 23 Sep. 2008. <Dictionary.com http://dictionary.reference.com/browse/humus>.</ref> is degraded organic material in [[soil]], which causes some soil layers to be dark brown or black.
breaks down more slowly. Proteins decompose into [[amino acid]]s at a rate depending on [[Carbon:Nitrogen ratio]]s. Organic acids break down rapidly, whilst fats, waxes, resins and lignins remain relatively unchanged for longer periods of time. The humus that is the end product of this process is thus a synthesis of compounds and complex life chemicals of plant, animal or microbial origin which has many functions and benefits in the soil as outlined below;


In [[soil science]], humus refers to any organic matter that has reached a point of stability, where it will break down no further and might, if conditions do not change, remain essentially as it is for centuries, if not millennia.<ref>Whitehead, D.C., Tinsley, J., 2006. The biochemistry of humus formation. Journal of the Science of Food and Agriculture 14:849–857.<small>{{doi|10.1002/jsfa.2740141201}}</small></ref>
*The mineralisation process that converts raw organic matter to the relatively stable substance that is humus feeds the soil population of micro-organisms and other creatures thus maintaining high and healthy levels of [[soil life]].
*Effective and stable humus (see below) are further sources of nutrients to microbes, the former providing a readily available supply whilst the latter acts as a more long term storage reservoir.
*Humification of dead plant material causes complex organic compounds to break down into simpler forms which are then made available to growing plants for uptake through their root systems.
*Humus is a [[colloid]]al substance, and increases the soil's [[Cation Exchange Capacity]], hence it's ability to store nutrients on [[clay]] particles, thus whilst these nutrient [[anion]]s are accessible to plants they are held in the soil safe from leaching away by [[rain]] or [[irrigation]].
*Humus can hold the equivalent of 80-90% of it's weight in moisture, thus increases the soil's capacity to withstand drought conditions.
*Humus has a light, fluffy texture, allowing greater [[aeration]] of the soil.
*The biochemical structure of humus enables it to moderate- or buffer- excessive [[acid]] or [[alkaline]] soil conditions.
*During the Humification process microbes secrete sticky gums- these contribute to the desirable crumb structure of the soil by holding particles together. Toxic substances such as [[heavy metal]]s, as well as excess nutrients, can be chelated (that is, bound as a compound within a complex [[organic molecule]]) and prevented from entering the wider [[ecosystem]].
*The dark colour of humus (usually black or dark brown) helps to warm up cold soils in the [[spring]].


In [[agriculture]], humus is sometimes also used to describe mature [[compost]], or natural compost extracted from a forest or other spontaneous source for use to amend soil. It is also used to describe a [[topsoil]] [[horizon]] that contains [[organic matter]] (humus type,<ref> Chertov, O.G., Kornarov, A.S., Crocker, G., Grace, P., Klir, J., Körschens, M., Poulton, P.R., Richter, D., 1997. Simulating trends of soil organic carbon in seven long-term experiments using the SOMM model of the humus types. Geoderma 81:121–135.<small>{{doi|10.1016/S0016-7061(97)00085-2}}</small></ref> humus form).<ref>Baritz, R., 2003. Humus forms in forests of the northern German lowlands. Schweizerbart, Stuttgart, Germany, 145 pp.[http://www.schweizerbart.de/pubs/isbn/bgr/sonderheft-3510959086-desc.html]</ref>, humus profile<ref>Bunting, B.T., Lundberg, J., 1995. The humus profile-concept, class and reality. Geoderma 40:17–36.<small>{{doi|10.1016/0016-7061(87)90011-5}}</small></ref>
[[Image:humus2.png]]


==Humification==
''Humification of leaf litter and formation of clay-humus complexes''
===Transformation of organic matter into humus===
The process of “humification” can occur naturally in [[soil]], or in the production of [[compost]]. The importance of chemically stable humus is thought by some to be the [[fertility]] it provides to soils in both a physical and chemical sense,<ref>Hargitai, L., 1993. The role of organic matter content and humus quality in the maintenance of soil fertility and in environmental protection. Landscape and Urban Planning 27:161–167.<small>{{doi|10.1016/0169-2046(93)90044-E}}</small></ref> though some agricultural experts put a greater focus on other features of it, such as disease suppressiveness.<ref>Hoitink, H.A., Fahy, P.C., 1986. Basis for the control of soilborne plant pathogens with composts. Annual Review of Phytopathology 24:93–114<small>{{doi|10.1146/annurev.py.24.090186.000521}}</small></ref> Physically, it helps the soil retain [[moisture]] by increasing micro[[porosity]],<ref>De Macedo, J.R., Do Amaral Meneguelli, N., Ottoni, T.B., Araujo de Sousa Lima, J., 2002. Estimation of field capacity and moisture retention based on regression analysis involving chemical and physical properties in Alfisols and Ultisols of the state of Rio de Janeiro. Communications in Soil Science and Plant Analysis, 33: 2037 - 2055.<small>{{doi|10.1081/CSS-120005747}}</small></ref> and encourages the formation of good [[soil structure]].<ref>Hempfling, R., Schulten, H.R., Horn, R., 1990. Relevance of humus composition to the physical/mechanical stability of agricultural soils: a study by direct pyrolysis-mass spectrometry. Journal of Analytical and Applied Pyrolysis 17:275–281.<small>{{doi|10.1016/0165-2370(90)85016-G}}</small></ref><ref>http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/soil_systems/soil_development_soil_properties.html</ref> Chemically, the incorporation of oxygen into large organic molecular assemblages generates many active, negatively charged sites that bind to positively charged [[ions]] ([[cations]]) of plant [[nutrients]], making them more available by [[ion exchange]].<ref>Szalay, A., 1964. Cation exchange properties of humic acids and their importance in the geochemical enrichment of UO2++ and other cations. Geochimica et Cosmochimica Acta 28:1605-1614.<small>{{doi|10.1016/0016-7037(64)90009-2}}</small></ref> Biologically, it allows soil organisms (microbes and animals) to feed and reproduce.<ref>Elo, S., Maunuksela, L., Salkinoja-Salonen, M., Smolander,A., Haahtela, K., 2006. Humus bacteria of Norway spruce stands: plant growth promoting properties and birch, red fescue and alder colonizing capacity. FEMS Microbiology Ecology 31:143 - 152<small>{{doi|10.1111/j.1574-6941.2000.tb00679.x}}</small></ref><ref>Vreeken-Buijs, M.J., Hassink, J., Brussaard, L., 1998. Relationships of soil microarthropod biomass with organic matter and pore size distribution in soils under different land use. Soil Biology and Biochemistry 30:97–106<small>{{doi|10.1016/S0038-0717(97)00064-3}}</small></ref> Humus is often described as the “life-force” of the soil. Yet, it is difficult to define humus in precise terms; it is a highly complex substance, the full nature of which is still not fully understood. Physically, humus can be differentiated from organic matter in that the latter is rough looking material, with coarse plant remains still visible, while once fully humified organic matter becomes more uniform in appearance (a dark, spongy, jelly-like substance) and amorphous in structure, and may remain such for millennia or more.<ref>di Giovanni1, C., Disnar, J.R., Bichet, V., Campy, M., 1998. Sur la présence de matières organiques mésocénozoïques dans des humus actuels (bassin de Chaillexon, Doubs, France). Comptes Rendus de l'Académie des Sciences de Paris, Series IIA, Earth and Planetary Science 326:553–559<small>{{doi|10.1016/S1251-8050(98)80206-1}}</small></ref> That is, it has no determinate shape, structure or character. However, humified organic matter, when examined under the microscope without any chemical treatment, may reveal tiny but clearly identifiable plant, animal or microbial remains which have been mechanically, but not chemically degraded<ref>Bernier, N., Ponge, J.F., 1994. Humus form dynamics during the sylvogenetic cycle in a mountain spruce forest. Soil Biology and Biochemistry 26:183-220<small>{{doi|10.1016/0038-0717(94)90161-9}}</small></ref>. This points to a fuzzy limit between humus and organic matter. In most recent literature, humus is clearly considered as an integral part of [[soil organic matter]] (SOM).<ref>http://www.humintech.com/001/articles/article_definition_of_soil_organic_matter.html</ref>


[[Plant]] remains (including those that passed through an animal gut and were excreted as faeces) contain organic compounds: [[sugar]]s, [[starch]]es, [[protein]]s, [[carbohydrate]]s, [[lignin]]s, [[wax]]es, [[resin]]s and [[organic acid]]s. The process of organic matter decay in the soil begins with the decomposition of sugars and starches from [[carbohydrates]], which break down easily as [[saprotrophs]] initially invade the dead plant organs, while the remaining [[cellulose]] and [[lignin]] break down more slowly.<ref>Berg, B., McClaugherty, C., 2007. Plant litter: decomposition, humus formation, carbon sequestration, 2nd ed. Springer, 338 pp., ISBN 3540749225</ref> Simple proteins, organic acids, starches and sugars break down rapidly, while crude proteins, [[fat]]s, waxes and resins remain relatively unchanged for longer periods of time. [[Lignin]], which is slowly transformed by white-rot [[fungi]],<ref>Levin, L., Forchiassin, F., Ramos, A.M., 2002. Copper induction of lignin-modifying enzymes in the white-rot fungus Trametes trogii. Mycologia 94:377-383 [http://www.mycologia.org/cgi/content/full/94/3/377]</ref> is one of the main precursors of humus,<ref>González-Pérez, M., Vidal Torrado, P., Colnago, L.A., Martin-Neto, L., Otero, X.L., Milori, D.M.B.P., Haenel Gomes, F., 2008. 13C NMR and FTIR spectroscopy characterization of humic acids in spodosols under tropical rain forest in southeastern Brazil. Geoderma 146:425-433<small>{{doi|10.1016/j.geoderma.2008.06.018}}</small></ref> together with by-products of microbial<ref>Knicker, H., Almendros,G., González-Vila, F.J., Lüdemann, H.D., Martin, F., 1995. 13C and 15N NMR analysis of some fungal melanins in comparison with soil organic matter. Organic Geochemistry 23:1023-1028<small>{{doi|10.1016/0146-6380(95)00094-1}}</small></ref> and animal<ref>Muscoloa, A., Bovalob, F., Gionfriddob, F., Nardi, S., 1999. Earthworm humic matter produces auxin-like effects on Daucus carota cell growth and nitrate metabolism. Soil Biology and Biochemistry 31:1303-1311<small>{{doi|10.1016/S0038-0717(99)00049-8}}</small></ref> activity. The humus, that is the end product of this manifold process, is thus a mixture of compounds and complex life chemicals of plant, animal, or microbial origin, which has many functions and benefits in the soil. Most humus in the soil is included in animal faeces of more or less dark color according to their content in organic matter.<ref>Ponge, J.F., 1991. Food resources and diets of soil animals in a small area of Scots pine litter. Geoderma, 49:33–62.<small>{{doi|10.1016/0016-7061(91)90090-G}}</small></ref> [[Earthworm]] humus ([[vermicompost]]) is considered by some to be the best organic manure there is.<ref>http://agri.and.nic.in/vermi_culture.htm</ref>


===Stability of humus===
Humus which is readily capable of further [[decomposition]] is referred to as effective or active humus. It is principally derived from sugars, starches and proteins and consists of simple organic (fulvic) acids. It is an excellent source of plant nutrients, but of little value regarding long term soil structure and tilth. Stable (or passive) humus consisting of [[humic acid]]s, or humins, on the other hand, are so highly [[insoluble]] (or tightly bound
Compost that is readily capable of further [[decomposition]] is sometimes referred to as effective or active humus, though again scientists would say that if it is not stable, it's not humus at all. This kind of compost, rich in plant remains and [[fulvic acid]]s, is an excellent source of plant nutrients, but of little value regarding long-term soil structure and tilth. Stable (or passive) humus consisting of [[humic acid]]s and humins, on the other hand, are so highly [[insoluble]] (or so tightly bound to [[clay]] particles and [[hydroxide]]s) that they cannot be penetrated by microbes and therefore are greatly resistant to further decomposition. Thus stable humus adds few readily available nutrients to the soil, but plays an essential part in providing its physical structure. Some very stable humus complexes have survived for thousands of years.<ref>di Giovanni1, C., Disnar, J.R., Bichet, V., Campy, M., 1998. Sur la présence de matières organiques mésocénozoïques dans des humus actuels (bassin de Chaillexon, Doubs, France). Comptes Rendus de l'Académie des Sciences de Paris, Series IIA, Earth and Planetary Science 326:553–559<small>{{doi|10.1016/S1251-8050(98)80206-1}}</small></ref> The most stable humus is that formed from the slow oxidation of black carbon, after the incorporation of finely powdered charcoal into the topsoil. This process is at the origin of the formation of the fertile [[Amazonian Dark Earth]]s or [[Terra preta]] de Indio.<ref>Lehmann, J., Kern, D.C., Glaser, B., Woods, W.I., 2004. Amazonian Dark Earths: origin, properties, management. Springer, 523 pp. ISBN 978-1402018398</ref>
to clay particles that they cannot be penetrated by microbes) that they are greatly resistant to further decomposition. Thus they add few readily available nutrients to the soil, but play an essential part in providing it's physical structure. Some very stable humus complexes have survived for thousands of years. Stable humus tends to originate from [[wood]]ier plant materials, eg, cellulose and lignins.


Humus is transformed by soil organisms, which may contribute to increase or decrease its stability according to their [[enzyme]] equipment.<ref>Wolters, V., 2000. Invertebrate control of soil organic matter stability. Biology and Fertility of Soils 31:1–19<small>{{doi|10.1007/s003740050618}}</small></ref> The disappearance of humus is hastened by warm and moist climate, which explains why most tropical soils are so poor in organic matter and suffer from both lack of good structure and available nutrients<ref>Tiessen, H., Cuevas†, E., Chacon, P., 2002. The role of soil organic matter in sustaining soil fertility. Nature 371:783-785<small>{{doi|10.1038/371783a0}}</small></ref>. In boreal countries and at high altitudes, the lack of active transformation of organic matter into humus, because of harsh climate conditions, leads to a similar decrease in soil [[fertility]], although for opposite reasons.<ref>Jerabkova, L., Prescott, C.E., Kishchuk, B.E., 2006. Nitrogen availability in soil and forest floor of contrasting types of boreal mixedwood forests. Canadian Journal of Forest Research 36:112–122<small>{{doi|10.1139/X05-220}}</small></ref> Among other factors, this explains why temperate climates were most favourable to the development of sedentary agriculture in the past millennia, before the advent of mineral [[fertilizers]].<ref>http://history-world.org/agriculture.htm</ref>
Humus should not be thought of as 'dead'- rather it is the 'raw matter' of life- the transition stage between one life form and another. It is a part of a constant process of change and organic cycling, thus must be constantly replenished- for when we are removing prunings and crops for the kitchen we are depriving nature's cycle of potential humus. This is why we need to substitute compost and other sources of organic matter to maintain the fertility of our productive land.
 
==Benefits of soil organic matter and humus==
*The mineralization process that converts raw organic matter to the relatively stable substance that is humus feeds the soil population of micro-organisms and other creatures, thus maintaining high and healthy levels of [[soil life]].<ref>Elo, S., Maunuksela, L., Salkinoja-Salonen, M., Smolander,A., Haahtela, K., 2006. Humus bacteria of Norway spruce stands: plant growth promoting properties and birch, red fescue and alder colonizing capacity. FEMS Microbiology Ecology 31:143 - 152<small>{{doi|10.1111/j.1574-6941.2000.tb00679.x}}</small></ref><ref>Vreeken-Buijs, M.J., Hassink, J., Brussaard, L., 1998. Relationships of soil microarthropod biomass with organic matter and pore size distribution in soils under different land use. Soil Biology and Biochemistry 30:97–106<small>{{doi|10.1016/S0038-0717(97)00064-3}}</small></ref>
*The rate at which raw organic matter is converted into humus promotes (when fast) or limits (when slow) the coexistence of [[plants]], [[animals]] and [[microbes]] in terrestrial [[ecosystems]].<ref>Ponge, J.F., 2003. Humus forms in terrestrial ecosystems: a framework to biodiversity. Soil Biology and Biochemistry 35:935–945<small>{{doi|10.1016/S0038-0717(03)00149-4}}</small></ref>
*Effective and stable humus (see below) are further sources of nutrients to [[microbe]]s, the former providing a readily available supply while the latter acts as a more long-term storage reservoir.
*Decomposition of dead plant material causes complex organic compounds to be slowly oxidized (lignin-like humus) or to break down into simpler forms ([[sugars]] and [[amino]]-sugars, [[aliphatic]] and [[phenolic]] [[organic acids]]) which are further transformed into microbial biomass (microbial humus) or are reorganized (and still oxidized) in humic assemblages (fulvic and [[humic acids]], humins) which bind to clay minerals and metal hydroxides. There has been a long debate about the ability of plants to uptake humic substances from their root systems and to [[metabolize]] them. There is now a consensus about humus as playing a [[hormonal]] role rather than a [[nutritional]] role in [[plant physiology]].<ref>Eyheraguibel, B., Silvestrea, J. Morard, P., 2008. Effects of humic substances derived from organic waste enhancement on the growth and mineral nutrition of maize. Bioresource Technology 99:4206-4212<small>{{doi|10.1016/j.biortech.2007.08.082}}</small></ref>
*Humus is a [[colloid]]al substance, and increases the soil's [[cation exchange capacity]], hence its ability to store nutrients by [[chelation]] as can [[clay]] particles; thus while these nutrient [[cation]]s are accessible to plants, they are held in the soil safe from leaching away by [[rain]] or [[irrigation]].<ref>Szalay, A., 1964. Cation exchange properties of humic acids and their importance in the geochemical enrichment of UO2++ and other cations. Geochimica et Cosmochimica Acta 28:1605-1614.<small>{{doi|10.1016/0016-7037(64)90009-2}}</small></ref>
*Humus can hold the equivalent of 80–90% of its weight in moisture, and therefore increases the soil's capacity to withstand drought conditions.<ref>Olness, A., Archer, D., 2005. Effect of organic carbon on available water in soil. Soil Science 170:90-101</ref><ref>http://journals.lww.com/soilsci/Abstract/2005/02000/Effect_of_Organic_Carbon_on_Available_Water_in.2.aspx</ref>
*The biochemical structure of humus enables it to moderate — or buffer — excessive [[acid]] or [[alkaline]] soil conditions.<ref>Kikuchi, R., 2004. Deacidification effect of the litter layer on forest soil during snowmelt runoff: laboratory experiment and its basic formularization for simulation modeling. Chemosphere 54:1163-1169<small>{{doi|10.1016/j.chemosphere.2003.10.025}}</small></ref>
*During the humification process, microbes ([[bacteria]] and [[fungi]]) secrete sticky [[gum]]s and [[mucilage]]s; these contribute to the crumb structure of the soil by holding particles together, allowing greater [[aeration]] of the soil.<ref>Caesar-Tonthat, T.C., 2002. Soil binding properties of mucilage produced by a basidiomycete fungus in a model system. Mycological Research 106:930-937<small>{{doi|10.1017/S0953756202006330}}</small></ref> Toxic substances such as [[heavy metals]], as well as excess nutrients, can be chelated (that is, bound to the complex organic molecules of humus) and prevented from entering the wider [[ecosystem]], thereby detoxifying it.<ref>Huang, D.L., Zeng, G.M., Feng, C.L., Hu, S., Jiang, X.Y., Tang, L., Su, F.F., Zhang, Y., Zeng, W., Liu, H.L., 2008. Degradation of lead-contaminated lignocellulosic waste by Phanerochaete chrysosporium and the reduction of lead toxicity. Environmental Science and Technology 42:4946-4951<small>{{doi|10.1021/es800072c}}</small></ref>
*The dark color of humus (usually black or dark brown) helps to warm up cold soils in the [[spring (season)|spring]].
 
==See also==
*[[Biomass]]
*[[Biotic matter]]
*[[Compost]]
*[[Detritivore]]
*[[Glomalin]]
*[[Humic acid]]
*[[Organic matter]]
*[[Plant litter]]
*[[Soil horizon]]
 
==References==
{{Reflist}}

Revision as of 06:56, 11 April 2010

Humus, the end product of the composting process when organic matter has fully broken down, can be summed up as the 'life-force' of the soil. Yet is difficult to define humus in precise terms; it is a highly complex substance, the full nature of which is still not fully understood. Physically humus can be differentiated from organic matter in that the latter is rough looking material, with coarse plant remains still visible, whilst once fully humified it become more uniform in appearance (a dark, spongy, jelly-like substance) and amorphous in structure. That is, it has no determinate shape, structure or character.

Plant remains (including those that have passed through an animal and are excreted as manure) contain organic compounds, sugars, starches, proteins, carbohydrates, lignins, waxes, resins and organic acids. The process of organic matter decay in the soil begins with the decomposition of sugars and starches from carbohydrates which break down easily as saprophytes initially invade the dead plant, whilst the remaining cellulose breaks down more slowly. Proteins decompose into amino acids at a rate depending on Carbon:Nitrogen ratios. Organic acids break down rapidly, whilst fats, waxes, resins and lignins remain relatively unchanged for longer periods of time. The humus that is the end product of this process is thus a synthesis of compounds and complex life chemicals of plant, animal or microbial origin which has many functions and benefits in the soil as outlined below;

  • The mineralisation process that converts raw organic matter to the relatively stable substance that is humus feeds the soil population of micro-organisms and other creatures thus maintaining high and healthy levels of soil life.
  • Effective and stable humus (see below) are further sources of nutrients to microbes, the former providing a readily available supply whilst the latter acts as a more long term storage reservoir.
  • Humification of dead plant material causes complex organic compounds to break down into simpler forms which are then made available to growing plants for uptake through their root systems.
  • Humus is a colloidal substance, and increases the soil's Cation Exchange Capacity, hence it's ability to store nutrients on clay particles, thus whilst these nutrient anions are accessible to plants they are held in the soil safe from leaching away by rain or irrigation.
  • Humus can hold the equivalent of 80-90% of it's weight in moisture, thus increases the soil's capacity to withstand drought conditions.
  • Humus has a light, fluffy texture, allowing greater aeration of the soil.
  • The biochemical structure of humus enables it to moderate- or buffer- excessive acid or alkaline soil conditions.
  • During the Humification process microbes secrete sticky gums- these contribute to the desirable crumb structure of the soil by holding particles together. Toxic substances such as heavy metals, as well as excess nutrients, can be chelated (that is, bound as a compound within a complex organic molecule) and prevented from entering the wider ecosystem.
  • The dark colour of humus (usually black or dark brown) helps to warm up cold soils in the spring.

File:Humus2.png

Humification of leaf litter and formation of clay-humus complexes


Humus which is readily capable of further decomposition is referred to as effective or active humus. It is principally derived from sugars, starches and proteins and consists of simple organic (fulvic) acids. It is an excellent source of plant nutrients, but of little value regarding long term soil structure and tilth. Stable (or passive) humus consisting of humic acids, or humins, on the other hand, are so highly insoluble (or tightly bound to clay particles that they cannot be penetrated by microbes) that they are greatly resistant to further decomposition. Thus they add few readily available nutrients to the soil, but play an essential part in providing it's physical structure. Some very stable humus complexes have survived for thousands of years. Stable humus tends to originate from woodier plant materials, eg, cellulose and lignins.

Humus should not be thought of as 'dead'- rather it is the 'raw matter' of life- the transition stage between one life form and another. It is a part of a constant process of change and organic cycling, thus must be constantly replenished- for when we are removing prunings and crops for the kitchen we are depriving nature's cycle of potential humus. This is why we need to substitute compost and other sources of organic matter to maintain the fertility of our productive land.

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