1、土壤有机质（soil organic matter）：土壤中形成的和外部加入的所有动、植物残体不同分解阶段的各种产物和合成产物的总称（土壤学名词，1998）。土壤中形成的和外部加入的所有动、植物残体不同分解阶段的各种产物和合成产物和土壤微生物的总称（林学名词，1998）。The organic fraction of the soil exclusive of undecayed plant and animal residues. See also humus（Glossary of Soil Science Terms）. The organic fraction of the soil that includes plant, animal and microbial residues in various stages of decomposition, biomass of soil microorganisms, and substances produced by plant roots and other soil organisms. It is commonly determined as the total organic (non-carbonate) carbon in a soil sample passed through a 2-mm sieve ( The Nature and Properties of Soils, 2016).
2、土壤有机残体（soil organic residue ）：Animal and vegetative materials added to the soil of recognizable origin（Glossary of Soil Science Terms）.
3、土壤腐殖质（soil humus）：除未分解的动、植物组织和土壤生命体等以外的土壤中有机化合物的总称（土壤学名词，1998）。土壤中由动植物残体形成的、完全分解的、无定形的且有一定稳定性的高分子有机化合物（林学名词，1998）。The well decomposed, more or less stable part of the organic matter in mineral soils. Humus is an organic soil material which is also one of the USDA textures of muck (sapric soil material), mucky peat (hemic soil material), or peat (fibric soil material.) Most likely it is muck（Glossary of Soil Science Terms）. The portion of soil organic matter that is not alive or recognizable plant tissue, and is protected from rapid decomposition to some degree by the soil environment. It is generally colloidal in particle size and black in color. Previuously thought to be composed mainly of very large polymer molecules operationally defined as humic acids, folic acids and humin, which see( The Nature and Properties of Soils, 2016).
4、腐殖物质（humic substances）与非腐殖物质（nonhumic substances）：腐殖物质（humic substances） ——土壤和沉积物等中，除有机体中已知的各类有机化合物(非腐殖物质)以外的各种淡棕色至暗褐色的天然高分子化合物的总称。它由胡敏酸、富啡酸和胡敏素等三类物质组成（土壤学名词，1998）。A series of relatively high-molecular-weight, yellow to black colored organic substances formed by secondary synthesis reactions in soils. The term is used in a generic sense to describe the colored material or its fractions obtained on the basis of solubility characteristics. These materials are distinctive to soil environments in that they are dissimilar to the biopolymers of microorganisms and higher plants (including lignin). See also humic acid, fulvic acid, and humin（Glossary of Soil Science Terms）. A series of complex, high molecular weight, brown- to black-colored organic substances that occur in natural waters, sediments, and to a small extent in aerobic soils( The Nature and Properties of Soils, 2016).非腐殖物质（nonhumic substances）——The portion of soil organic matter comprised of relatively low molecular weight organic substances; mostly identifiable biomolecules( The Nature and Properties of Soils, 2016).
5、腐殖化作用（humification）：动物、植物、微生物残体在微生物作用下，通过生化和化学作用而形成腐殖质的过程（土壤学名词，1998）。土壤有机质在微生物作用下，一些分解的中间产物重新合成复杂高分子聚合物的过程（生态学名词，2006）。The process whereby the carbon of organic residues is transformed and converted to humic substances through biochemical and abiotic processes（Glossary of Soil Science Terms）. The processes involved in the decomposition and partial stabilization of organic matter and leading to the formation of humus( The Nature and Properties of Soils, 2016).
5、有机土壤物质（organic soil materials ）：经常被水饱和，具高有机碳的泥炭、腐泥或被水饱和时间很短，具极高有机碳的枯枝落叶（土壤学名词，1998）。Soil materials that are saturated with water and have 174 g kg-1 or more organic carbon if the mineral fraction has 500 g kg-1 or more clay, or 116 g kg-1 organic carbon if the mineral fraction has no clay, or has proportional intermediate contents, or if never saturated with water, have 203 g kg-1 or more organic carbon（Glossary of Soil Science Terms）. (As used in Soil Taxonomy): (1) Saturated with water for prolonged periods unless artificially drained and having 18% or more organic carbon (by weight) if the mineral fraction is more than 60% clay, more than 12% organic carbon if the mineral fraction has no clay, or between 12 and 18% carbon if the clay content of the mineral fraction is between 0 and 60%. (2) Never saturated with water for more than a few days and having more than 20% organic carbon. Histosols develop on these organic soil materials( The Nature and Properties of Soils, 2016). There are three kinds of organic materials:
纤维有机土壤物质（ fibric soil materials）——含有大量纤维的未分解植物残体（土壤学名词，1998）。Organic soil material that contains 3/4 or more recognizable fibers (after rubbing between fingers) of undecomposed plant remains. Bulk density is usually very low and water holding capacity very high（Glossary of Soil Science Terms）.The least decomposed of all the organic soil materials, containing very high amounts of fiber that are well preserved and readily identifiable as to botanical origin; with very low bulk density( The Nature and Properties of Soils, 2016).
半腐有机土壤物质（hemic soil materials）——中度分解的有机土壤物质（土壤学名词，1998）。Organic soil material at an intermediate degree of decomposition that contains 1/6 to 3/4 recognizable fibers (after rubbing) of undecomposed plant remains. Bulk density is usually very low, and water holding capacity very high（Glossary of Soil Science Terms）.Intermediate in degree of decomposition of organic materials between the less decomposed fibric and the more decomposed sapric materials( The Nature and Properties of Soils, 2016).
高腐有机土壤物质（sapric soil materials）——高度分解的有机土壤物质（土壤学名词，1998）。Organic soil material that contains less than 1/6 recognizable fibers (after rubbing) of undecomposed plant remains. Bulk density is usually very low, and water holding capacity very high（Glossary of Soil Science Terms）.The most highly decomposed of the organic materials, having the highest bulk density, least amount of plant fiber, and lowest water content at saturation( The Nature and Properties of Soils, 2016).
