The Benefits of Humic Acid at the Root Zone

Gardeners have observed the benefits of adding organic matter to soil for thousands of years. Organic matter not only improves the structure of the soil, it feeds the microorganisms in the soil, which in turn feed the plants. As microorganisms in the soil degrade organic matter, small organic molecules are produced that influence plant growth much more than the fertilizer value of the organic matter alone. Humic acid is one such compound.

plant growth soil humic acid benefits

Humic acid is a middle-weight organic substance extracted from ancient compost piles. Millions of years ago, during the Carboniferous Period, massive amounts of vegetation covered the earth. Over the millennia, layer upon layer of decomposing vegetative matter was covered and compressed into what we now know as fossil fuels. In the process, a mineral was formed called “leonardite”, a soft organic material with highly-active carbon compounds locked in its crystalline matrix. Through a process called alkaline hydrolysis, the organic compounds are unlocked and extracted from the leonardite as humic acid.

Soluble humic acid makes an excellent addition to soil or soilless media. Its unique characteristics help improve plant development at nearly every stage of growth from seed to harvest. Application of humic acid improves seed germination and seedling growth, stimulating root initiation and root growth. The humic acid doesn’t contain rooting hormones; instead, it helps prevent the oxidation and breakdown of rooting hormones, allowing IAA to remain active longer. With the addition of humic acid, root mass is increased, and the plant is better able to take up water and nutrients.

humic acid raw nutrients plant growth roots farming fruit roots water

Humic acid also stimulates vegetative growth, and it has been shown to enhance photosynthesis and chlorophyll content. Although it is still not fully understood, humic acid also enhances protein production, especially the synthesis of certain enzymes. These enzymes contribute to better shoot growth, and help protect the plant under times of environmental stress. Whether applied to the nutrient solution or used as a foliar spray, humic acids improve the health and vigor of the plant.

The greatest benefit of humic acid is its affect on mineral availability. Humic acid improves the solubilization of many essential elements such as phosphorus, calcium and potassium. It also improves the availability of important microelements such as iron, manganese and zinc. The microelements activate important enzymes in the plant. For example, zinc activates the enzymes that produce the rooting hormone, IAA. Other important plant-protection enzymes are activated by either an iron/manganese or a copper/zinc complex.

Humic acids are intermediate chelators. In other words, electrical charges on the surface of the molecules hold onto mineral ions like a claw and release them to the plant on demand. So at the root zone, humic acid forms a bridge between negatively-charged clay particles and positively-charged minerals nutrients. Whether the plant is grown in heavy clays, sandy soils or even hydroponics, the electrical charges of humic acid will help keep minerals from becoming locked up and unavailable to the plant.

Copyright© 2013
Harley Smith

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