Active Carbon

What is Active Carbon?

Photo Credit: Jeff Vanuga, USDA-NRCS

A small portion of the total organic matter pool with a rapid turnover rate, indicating that it’s available to microbial decomposers. This portion of organic matter often responds more quickly and significantly to changes in agronomic management and is more closely correlated to crop productivity, than total soil organic matter. It can be measured in a variety of ways, including permanganate oxidizable C, mineralizable C, and water-extractable C. See soil organic matter and total organic carbon for more information.

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Regional Educator ResourcesOther Educator ResourcesTechnical Resources
Title Source Resource type and Date Short Summary / Preview
Active Carbon Soil Health Nexus How-to Video

May 2019

Amanda Wolfgeher of the University of Missouri provides an overview of how to conduct an active carbon demonstration.

How to use Haney Tests University of Minnesota Archived Webinar

Oct 2019


A 1-hour webinar from UMN Extension describing active C and active N pools measured in the Haney test, as well as comparisons of fertilizer recommendations from Haney and standard soil tests.

How to Understand and Interpret Soil Health Tests Purdue University Extension Fact Sheet

Jun 2018


Description of commercially available soil health tests covering a range of active C tests, with tips for sampling and interpretation.

Soil Quality Indicators: Chemical Indicators and Soil Functions USDA NRCS Fact Sheet

Feb 2015


Different chemical indicators widely used are related to the respective basic functions they measure.

Soil Quality Indicators: Reactive Carbon USDA NRCS Fact Sheet

Jan 2014


Fact Sheet. Soil organic matter (SOM) contains C compounds with different levels of degradability, from very easily decomposable to extremely resistant (recalcitrant) to decomposition.

Title Source Resource type and date Short Summary
Active Carbon Cornell University Extension Fact Sheet

Not Dated


Active carbon is an indicator of the small portion of soil organic matter that can serve as a readily available food and energy source for the soil microbial community, thus helping to maintain a healthy soil food web.

Title Source Resource type and Date Short Summary
The Sanborn Field Experiment: Implications for Long-Term Soil Organic Carbon Levels American Society of Agronomy Peer-Reviewed Publication

Jan 2011


It appears that an equilibrium level of SOC for some cropping systems takes about 30 to 40 yr to develop. Initial active carbon (AC) content assessment as a proxy for soil quality shows greater AC with manure and higher input management systems. The AC had a wide seasonal flux within a growing season as a function of temperature and moisture fluxes on microbial activity.

Comparison of Permanganate-Oxidizable Carbon and Mineralizable Carbon for Assessment of Organic Matter Stabilization and Mineralization Soil Science Society of America Journal Peer-Reviewed Publication

Sep 2016


Analyzes Pox-C and Mineralizable C on a range of long-term sites and compares them.

Conceptualizing soil organic matter into particulate and mineralā€associated forms to address global change in the 21st century Global Change Biology Peer-Reviewed Publication

Oct 2019


This paper suggests conceptualizing soil organic matter as particulate, or large and relatively un-decomposed, versus mineral-associated, or sorbed to silt and clay surfaces. It provides good background on current understandings of soil organic matter turnover and protection.

Persistence of soil organic matter as an ecosystem property Nature: International Journal of Science Peer-Reviewed Publication

Oct 2011

This paper describes the difference between concepts of humification and more modern concepts of soil organic matter storage, describing physical, biological and chemical means of protection.
This page reviewed by Liz Schultheis, Joe Rorick, andĀ  Anna Cates.

Last reviewed October 22, 2019