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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #353911

Research Project: Managing Carbon and Nutrients in Midwestern U.S. Agroecosystems for Enhanced Soil Health and Environmental Quality

Location: Soil, Water & Air Resources Research

Title: Environmental and agricultural relevance of humic fractions extracted by alkali from soils and natural waters

item Olk, Daniel - Dan
item BLOOM, PAUL - University Of Minnesota
item PERDUE, E - Ball State University
item MCKNIGHT, DIANE - University Of Colorado
item CHEN, YONA - Hebrew University Of Jerusalem
item FARENHORST, ANNEMEIKE - University Of Manitoba
item SENESI, NICOLA - University Of Bari
item CHIN, YU - University Of Delaware
item SCHMITT-KOPPLIN, PHILIPPE - German Research Center For Environmental Health
item HERTKORN, NORBERT - German Research Center For Environmental Health
item HARIR, MOURAD - German Research Center For Environmental Health

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2019
Publication Date: 3/8/2019
Publication URL:
Citation: Olk, D.C., Bloom, P.R., Perdue, E.M., McKnight, D.M., Chen, Y., Farenhorst, A., Senesi, N., Chin, Y.P., Schmitt-Kopplin, P., Hertkorn, N., Harir, M. 2019. Environmental and agricultural relevance of humic fractions extracted by alkali from soils and natural waters. Journal of Environmental Quality. 48:217-232.

Interpretive Summary: The organic part of soil and natural waters, the natural organic matter, plays several important roles in soil performance and aquatic ecology. Portions of it cycle over shorter times, while other portions can be stable for centuries. To understand how recent land or water management practices affect the properties of natural organic matter and its altered roles in soil performance or aquatic ecology, it is often necessary to separate its younger portions. There are several methods for separation, and none is ideal. Here we report the uses of a chemical separation method for solving practical problems in agriculture and the environment. These results justify further use of the chemical separation method, despite criticisms from users of other methods. The findings are important to researchers of agricultural and environmental issues that involve natural organic matter.

Technical Abstract: Alkaline extractions of natural organic matter (NOM) have been used for two centuries to characterize the chemical composition of NOM in soils and natural waters. In recent years chemical extractions have been criticized as creating artificial fractions whose compositions are laboratory artifacts and hence irrelevant to the study of environmental and agricultural processes. To refute this criticism, we describe examples of laboratory-based chemical extractions that generated valid knowledge of NOM composition and cycling, which in turn was used to identify solutions to practical issues in agriculture and the environment. The examples are drawn from diverse research settings, including fertilizer and cropping system treatments in agriculture that caused nutrient cycling issues, land management practices for sequestering soil C, heavy metal adsorption, pesticide detoxification, compost maturation, binding of infectious prions, chemical characterization of aquatic NOM, and fouling of membranes used for water purification. This assenblage of information demonstrates that while chemical extraction of NOM is an imperfect approach, its generated fractions are reasonable indices for NOM and offer advantages for some research objectives that cannot be matched by other approaches for NOM extraction.