Skip to main content
ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #361064

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: Using humic fractions to understand natural organic matter processes in soil and water: Selected studies and applications

item Olk, Daniel - Dan
item BLOOM, PAUL - University Of Minnesota
item DENOBILI, MARIA - University Of Udine
item CHEN, YONA - Hebrew University Of Jerusalem
item MCKNIGHT, DIANE - University Of Colorado
item WELLS, MARTHA - Envirochem Services Inc
item WEBER, JERZY - Wroclaw Medical University

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2019
Publication Date: 8/21/2019
Citation: Olk, D.C., Bloom, P.R., De Nobili, M., Chen, Y., McKnight, D.M., Wells, M.J.M., Weber, J. 2019. Using humic fractions to understand natural organic matter processes in soil and water: Selected studies and applications. Journal of Environmental Quality. 48(6):1633-1643.

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 describe selected examples of a chemical separation method whose results were used to solve practical problems in agriculture and the environment. These successful applications justify further use of the chemical separation method. The findings are important to researchers of agricultural and environmental issues that involve natural organic matter.

Technical Abstract: To study the structure and function of natural organic matter (NOM), soil scientists have performed alkali extractions for humic acid (HA) and fulvic acid (FA) fractions. Critics have claimed that alkali-extractable fractions are laboratory artifacts, hence unsuitable for studying NOM structure and function in field conditions. To expand on our recent review of evidence for the accuracy of humic fractions in representing NOM, here we present several detailed case studies in which chemical characterization of humic fractions identified environmental processes affecting NOM in soil and natural water bodies and in cases led to practical resolutions of scientific or management issues. Humic fractions were analyzed to elucidate NOM contributions to As poisoning of drinking water supplies in Bangladesh and to modeling of Hg binding in soil. Their analyses in laboratory conditions explained compost maturation and quality, NOM binding of prions, benefits of animal manure to improving K availability in vermiculitic soils and its potential benefit to mitigating a long-term cotton lint yield decline in California. Similarly, these fractions were used to explain crop residue management effects on inhibited nitrogen cycling and potentially long-term grain yield declines in tropical monoculture paddy rice. Their study facilitated new strategies for cleansing urban drinking water supplies of unwanted organic compounds and for cleansing soils of organic pollutants. Humic fraction extraction has proven to enable valid insights into NOM cycling.