Organic Matter

Also found in: Acronyms, Wikipedia.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Organic Matter


a necessary minor component of soils, surface and subterranean waters, most rocks (particularly sedimentary rocks), and also the atmosphere (see Figure 1). Plants are the primary source for organic matter; animals account for a significantly smaller proportion.

Figure 1. Content of organic matter in (1) soils, (2) marine sediment, (3) rock, (4) subterranean water, (5) soil solutions, (6) interstitial solutions, (7) sediment solutions, (8) surface water, (9) seawater, (10) atmospheric precipitation

Three types of organic matter are distinguished according to original composition. Humic organic matter is formed primarily from higher plants and soil organisms, mainly microorganisms; it makes up a varying proportion of soils and is a major component of brown and hard coals. The hydrogen/carbon ratio for humus is usually less than 0.9. Sapropelic organic matter is a product of transformation of lower plants, mainly planktonic algae. It is characteristic of sapropelites, combustible shale, and dispersed organic matter, and its hydrogen/carbon ratio is usually greater than 1.2. Liptobiolitic organic matter forms because of concentration of the most chemically stable components of plant matter.

Other types of organic matter are also known that were formed because of the existence of several groups of animal organisms in the past—for example, chitinous remains of graptolites and a number of crustaceans. Both organic matter dispersed in sedimentary rock and concentrated organic matter (coals) undergo catagenesis in a number of stages, from brown coal, in a zone with temperatures up to 60°-70°C, to anthracite, in a zone with temperatures higher than 250°C. Organic matter is finally transformed into graphite in the zone of metagenesis (metamorphism).

The average content of organic matter in sedimentary rocks is about 15–20 kg/m3; the total mass in the continental sector of the sedimentary crust (continents and shelves) is as high as 1016 tons. Organic matter is the source of petroleum and fuel gases.

In magmatic rocks, organic matter is most often allochthonous, carried to the place of deposition by water. Sometimes such organic matter is related to the intrusion of petroleum or other naphthides. In some cases, organic matter reaches magmatic rock by assimilation of sedimentary matter by the rocks.


Vassoevich, N. B. “Osnovnye zakonomernosti, kharakterizuiushchie organicheskoe veshchestvo sovremennykh i iskopaemykh osadkov.” In Priroda organicheskogo veshchestva sovremennykh i iskopaemykh osadkov. Moscow, 1973.
Shvets, V. M. Organicheskie veshchestva podzemnykh vod. Moscow, 1973.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Aim of this research was to determine the possibility of increasing organic matter content in humusless deposol topsoil and to form a more favourable adsorptive complex by introducing siderates, or green manure and growing siderates whose roots have beneficial effect on soil structure besides general increase of soil organic matter.
The new study submitted by Westall and her team could provide new evidence in the link between the evolution of life and the introduction of alien organic matter from space.
These mixes are made only from mineral aggregate and organic matter.
In this third stage, all remaining organic matter is broken into humus.
Different methods are currently applied to study carbon distribution in various organic matter pools (Blanco-Canqui and Lal, 2004).
He suspected that mycorrhizal fungi fed on decaying organic matter and served as root extensions that provided essential nutrients to plants.
We found significant differences (mound soil and undisturbed soil) in % water saturation, electrical conductivity (E/C), pH, organic matter, phosphorus, potassium and biomass in all types of soil.
The soil is rich in nutrients, however, and can be a very good fertile soil with the addition of organic matter to bind the fine particles.
"A number of studies have shown that practices commonly used in organic farming increase soil organic matter and soil health," notes Tracy Misiewicz, associate director of Science Programs for The Organic Center.
The treatments were distributed in randomized blocks, in a 2 x 5 x 2 factorial scheme, which corresponding to the following treatments: two irrigation depths, 50 and 100% of crop evapotranspiration (ETc); five doses of cattle manure to increase soil organic matter (SOM), from 1.8% to 2.8; 3.8; 4.8 and 5.8% (Table 1); and uncovered and covered soil (mulching) with a layer of 5 cm-thick of parsley triturated waste (Ipomoeaas arifolia) with four replicates, totalling 80 plots.
One of the leading roles belongs to the labile organic matter (LOM) including plant residues with varying degrees of decomposition and humification, as well as humus substances that are weakly bound to the mineral part of the soil.
Soil organic matter is plant and animal residues either decomposed or in the process of decomposition and can be black or dark in colour.

Full browser ?