humic acid

American  

noun

1. a brown, melanin-tinted mixture of polymers, found in lignite, peat, and soils, where it acts as a cation exchange agent: used in drilling fluids and inks.

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Etymology

Origin of humic acid

First recorded in 1835–45

Example Sentences

The decaying mosses release humic acids and sphagnan, a complex sugar, that make life difficult for the microorganisms that would normally cause rotting and decay.

From New York Times

All of it has darkened somewhat because of the development of humic acids.

From Science Magazine

Organic-rich soils seem particularly problematic; they are ripe with molecules like humic acid, which behaves like DNA and can foul later sequencing.

From Science Magazine

When a plant dies, decay brings organic material, a component of which is large carbon-based molecules called humic acids, into the soil and binds them to the soil’s molecules.

From Washington Post

This is made by aerating sugars, compost and humic acids in non-chlorinated water and then spraying the brew on plants and soil.

From Washington Post