Summary
Joel Simmons interviews chemist Lawrence Mayhew about the science and history of humic substances. Mayhew describes how he was hired by Gary Zimmer at Midwest BioAg in 2000 to research humic materials, spending years in university archives studying the International Humic Substances Society literature. He explains that humic acids are operationally defined extracts from Leonardite (oxidized lignite coal), processed via potassium hydroxide extraction, and compares them to coffee as a complex extract that defies simple chemical characterization. The conversation covers how humic substances function in soil as a coral reef-like habitat for microbes, buffering pH, chelating minerals, and increasing fertilizer efficiency. Mayhew distinguishes genuine humic acids from lignosulfonates (paper industry byproducts) that are frequently mislabeled as humic acids. They also discuss the founding of the Humic Products Trade Association (HPTA) and the ISO 19822 analytical standard that finally gave regulators a validated method for measuring humic acid content.
Key Points
- Humic substances are derived from Leonardite (oxidized lignite coal) via potassium hydroxide extraction and are operationally defined, meaning their exact chemical structure remains unknown
- Humic acids act as a coral reef in soil, housing microbes, buffering pH, chelating minerals, and increasing fertilizer efficiency -- especially for micronutrients
- Lignosulfonates from the paper industry are frequently mislabeled as humic acids but lack the structural complexity and soil-building properties of genuine humic substances
- The California Department of Food and Agriculture analytical method is flawed, counting co-extracted minerals like iron and silicon alongside actual humic acid content
- Lawrence Mayhew and his wife founded the Humic Products Trade Association (HPTA) to establish quality standards and the ISO 19822 analytical method
- Liquid humic acid products can realistically contain only 6-12% humic acid by weight; claims of 85% indicate flawed testing methods
- Animals like hogs and calves instinctively eat Leonardite material when given free choice, possibly for detoxification purposes
