Humic acid is a mixture of natural organic macromolecular compounds, which exists in all soils, plants, and animals. It ranges in molecular size from 10,000 to 100,000 and contains combinations of carbon chains and carbon rings. (In addition to carbon, they also contain oxygen, nitrogen, hydrogen, and phosphorus.)
Sources
The one source of humic acids is the sedimentation layers referred to as Leonardite.
Leonardite is an organic matter. It has not reached the state of coal and differs from soft brown coal by its high oxidation degree, a result of the process of coal formation (bog > peat > coal), and high humic acid content as well as higher carboxyl groups.
Humic Acid Products in the Market
There are many kinds of humic acid products for sale in the market, including granules, powder, liquid, and formula(Mix with npk, amino acid, seaweed)
From the data in amazon, we can find that many lawn fertilizers contain humic acid.
How Does Humic Acid Work
The application usually divided into Foliar Spray and Soil Amendment.
For soil amendments: Humic acids work best in the soil, where they readily unlock nutrients and bind to them, making them available for uptake into plants. And they chelate toxic metals, preventing harmful material from entering the plant.
For foliar applications, humic acid increases the cell wall permeability of plants, which in turn increases the uptake of nutrients. Besides, it also can enhance plant respiration, photosynthesis, and cell elongation.
Humic acid Beneifts for Plants
- Improve the structure of the soil, prevent high water and nutrient losses in light or sandy soils.
- Regulates the pH-value of soils.
- Promote the conversion of nutrient elements into available forms to plants.
- Stimulates root growth, enhance better uptake of nutrients.
- Increases crop quality & yields.
What’s more, In addition to these above benefits, its role in plant stress resistance has also received increasing attention. So what is humic acid used for?
1. Plant Drought Stress
Under drought conditions, the application of humic acid fertilizer can promote the increase of proline content in plant leaves to improve the drought resistance of crops.
2. Plant Salt And Alkali Stress
Humic acid can enhance the salt resistance by regulating the change of fructose concentration and alleviating the damage of material membrane under salt stress.
3. Plant Temperature Stress
Under low-temperature stress, it can increase crops’ proline and abscisic acid content, reduce the spread of transpiration rate, stomatal conductance, and net photosynthetic rate of plants.
Under high-temperature stress, It increases the activities of crop superoxide dismutase and peroxidase to enhances the heat resistance of crops.
3. Plant Diseases Resistance
Humic acid can promote growth by increasing the sugar content and chlorophyll content of leaves, which indirectly improves the disease resistance of crops.
Humic Acid Vs Fulvic Acid
1. Molecular Weight
The molecular weight of Fulvic acid (100-10,000) is much smaller than humic acid (50,000-500,000)
2. Solubility
Humic acids are slightly soluble in water, but can easily soluble in acetone and benzene-alcohol. Fulvic acids are soluble in water under all pH conditions.
3. Functions
Compared to Humic acid, the most significant advantages of Fulvic acid are:
1. Fulvic acid has a higher biological activity.
2. Fulvic acid is a high-efficiency chelating agent. It combines with nutrients in the soil to be absorbed by plants together.