Organic carbon

Muhammad Rashid

Organic carbon is a better indicator since it is the one measured in a soil sample.

Soil organic carbon is a measurable component of soil organic matter and it is very good indicator for soil fertility. However, soil organic carbon is a component of soil organic matter, organic carbon makes up approximately 60% of the soil organic matter, and the remaining 40% of soil organic matter contains nitrogen, calcium, hydrogen and oxygen. Soil organic matter conserve moisture, absorb and store nutrients and act as a primary food source for soil microorganisms so that soil organic matter is best indicator for soil quality and soil health.

A little bit confusing aspects...whether organic carbon or organic matter governs the fertility status of soil. Actually both organic carbon as well as organic matter governs soil fertility..organic matter is broader term rather than organic carbon as organic carbon constitute some fraction (may be around 50-60 %) in the organic matter.. organic carbon as such can't governs soil fertility but this is the organic matter with definite fraction of organic carbon governs...no doubt if soil is rich in appreciable percent if organic carbon, this would add in soil fertility as they both correlate positively.. if complete organic matter is applied it will influence and improve all soil physical chemical and biological properties resulting in efficient release of all the essential nutrients for efficient uptake and translocation in the plant body resulting in maintaining soil fertility....so we can say organic carbon is the first aspect which results in organic matter and thus in soil fertility..

Second is quality..so quality of the soil is very different from fertility..as soil fertility only depicts inherent capacity to supply plant nutrients in adequate amount with suitable proportion while soil quality depicts about optimization of all physical chemical and biological properties of the soil

Both soil organic matter and soil organic carbon are measurement of a specific property or aspect of soil and as the previous comments note are related to each other. As a measurement by itself, neither makes a statement about a soils quality or fertility. Yes, a soil that is high in organic matter or organic carbon is likely to have higher fertility, productivity or quality than on that is low in SOM or SOC. However, a soils fertility or quality depends many other factors such as texture, depth, slope as well as whether the soil might have been contaminated by chemicals or heavy metals, etc. For example, I have worked with soils that have been contaminated with hydrocarbons, (oil spills, fuel spills, etc.). Measuring these soils for SOM or SOC would give high values but they wouldn't likely grow anything. So, it really depends on the context within which you are making the measurements.

Soil fertility is a part of soil quality , while soil quality is a bigger parameter and more talks of functional delivery of soil ...

Soil fertility, as well as soil health or soil quality, are determined in more than one way by soil organic matter or soil organic carbon content. To me, soil organic carbon is a measure of soil organic matter. Because soil organic matter is a very complex entity and there is no way we can quantitatively estimate it except by measuring soil organic carbon.

Both soil organic carbon and soil organic matter are a good indicator of soil fertility. The difference b/n them is organic carbon is one a major component of organic matter.

Organic Carbon

Organic matter or better to say organic material mainly consists of carbon based components, but these components may come from different sources like it maybe formed of the plant, animals or other organisms remnants.

Organic matter is commonly and incorrectly used to describe the same soil fraction as total organic carbon. Organic matter is different from total organic carbon in that it includes all the elements (hydrogen, oxygen, nitrogen, etc) that are components of organic compounds, not just carbon.

A conversion factor of 1.724 is commonly used to convert organic carbon to organic matter:

In terms of fertility, there is no difference between organic carbon and organic matter. the importance of organic carbon estimation lies in the fact that it gives an indication of the organic matter content of the soil which is an important index of soil fertility. The organic carbon content of soil, is reported directly as percentage of C or calculated as organic matter by multiplication with a factor of 1.724 assuming that soil organic matter contains on an average 58 percent carbon, so that 100/58 = 1.724

Sandip Kumar Gupta Navazollah Moradi Muhammad Rashid

You are right about the conversion factor of organic C to organic matter. Just to add some historical information on it: In the 1820s, Carl Sprengel of Goettingen Univ found that organic matter contains 58% carbon. In 1864, Emil Wolff of the University of Hohenheim introduced the value of 1.724 in his book "Entwurf zur Bodenanalyse" (Outline for soil analysis) based on the 58% carbon value by Sprengel. The 1.724 value is often wrongly credited to Jakob van Bemmelen who cited it in his publication of 1890 (Über die Bestimmung des Wassers, des Humus, des Schwefels, der in den colloidalen Silikaten gebundenen Kieselsäure, des Mangans u. s. w. im Ackerboden. Die Landwirthschaftlichen Versuchs-Stationen 37, 279-290). In fact, Van Bemmelen referred to it as the Wolff factor. Now, we know that a value of 2.0 is more correct but still the original Wolff factor of 1.724 is very popular around the world.

thank you Dr Victor B. Asio and I agree with you that " we know that a value of 2.0 is more correct but still the original Wolff factor of 1.724 is very popular around the world"

Factor is 1.724 for top soil and 2.5 for sub surface soil

thank you Dr Swaminathan Chitraputhira Pillai I did not know this ( Factor is 1.724 for top soil and 2.5 for sub surface soil ), I'm interested in this research - could you provide the full-text for it? or link it

Does not matter if you are measuring one or the other, what matter is that you have a full overview of soil characteristics including physical and chemical characteristics (much better if you have also some microbiological and biological information) and the soil history (e.g. previuos crops) so that you can have a clear picture of soil potential fertility.

Organic matter is commonly and incorrectly used to describe the same soil fraction as total organic carbon. Organic matter is different from total organic carbon in that it includes all the elements (hydrogen, oxygen, nitrogen, etc) that are components of organic compounds, not just carbon. The key difference between inorganic and organic carbon is that the inorganic carbon is the carbon extracted from ores and minerals whereas the organic carbon is found in plants and living things in nature. The organic carbon content of soil, is reported directly as percentage of C or calculated as organic matter by multiplication with a factor of 1.724 assuming that soil organic matter contains on an average 58 percent carbon, so that 100/58 = 1.724

We have worked on these aspects related to organic matter as an indicator of soil quality:

Article Relationship Between Soil Properties and Banana Productivity...

Thesis Determination of the potential influence of soil in the diff...

Article Correlation of banana productivity levels and soil morpholog...

Muhammad Rashid

Organic matter is commonly and incorrectly used to describe the same soil fraction as total organic carbon. Organic matter is different from total organic carbon in that it includes all the elements (hydrogen, oxygen, nitrogen, etc) that are components of organic compounds, not just carbon.