Humic and fulvic acids are some of the best biostimulant products in nature, improving the uptake of nutrients in both soil and hydroponics. Once you understand the difference between the two, you will soon discover many applications for your crops.

In this article we take a closer look at on how humic and fulvic’s enable the microbes in the soil beds to thrive.

Defining Humic and Fulvic and Their Purposes

Humic acid can be classified as humin, humic acid, and fulvic acid depending on its solubility at different pH. Humic acid precipitates at low pH, but fulvic acid is soluble. There are many complex compounds in the fulvic acid fraction; thus, the exact chemical structure is not well known. A plant biostimulant is any substance or microorganism applied to plants with the aim to enhance nutrition efficiency, abiotic stress tolerance and/or crop quality traits, regardless of its nutrients content. Humic and fulvic acids are not fertilizers. Any fertilizer must provide nutrient as its main function. This is clearly not the case of the biostimulants humic and fulvic, which by definition promote plant growth by other means than by providing nutrients. They provide the foundation for the nutrients. Humic and fulvic acid go hand in hand together eventhough they have different but complementing functions. They improve the uptake of nutrients and act as chelators. Chela means claw, so chelates are organic molecules that attach to mineral ions. These chelates are holding the ions in suspension so they don’t get held by the soil, and at the same time easily handing them off to the plant on demand. Green CHO and Purple CHO are good chleators. Humic acid molecules are larger than fulvic acid molecules which make them great soil conditioners. Fulvic acids are smaller, more biologically active molecules that are faster-acting and make excellent foliar sprays. Both improve the uptake of minerals, stimulate plant growth, and improve the plant’s natural resistance to environmental stresses. Both compounds have been shown to stimulate plant growth in terms of increasing plant height and dry or fresh weight as well as enhancing nutrient uptake. These effects seem to depend on the concentration (2,3,5) and source of the substance along with the plant species.

Humic substances or humus are the product of decomposing plants that have large molecular weights and complex structures. These substances are commonly found in peat or partly carbonized plant materials deposited underground in cool regions. Due to the nature of their chemical structures, humic substances can take up large quantities of water and cations and affect the physical properties of the soil, as well as increase the cation exchange capacity.

Why add humic:

– Enhance nutrient absorbsion by 50% – Increase plant’s resistance to stressors – Helps stimulate plant growth and vigor – Helps plants take up cations and water – Beneficial effects to living soil – Increase cation exchange properties

Humic and fulvic acids are the most characteristic compounds of soil humic substances. Humic substances are formed through the microbial degradation of plant material and the brown to black substances are the primary constituents of soil organic matter. Humic substances have the ability to hold seven times their volume in water, a greater water holding capacity than clay soils. Water stored within the topsoil enables plant roots to quickly access available nutrients required for plant growth and yield.

Fulvic acid has a much smaller molecular weight, and is more biologically active. Fulvic acid not only surrounds mineral ions, it can also help transport them through the cell membrane and release them inside the cell. Fulvic acid has many beneficial effects in soil amendments, such as increasing drought resistance to plants, improving uptake of nutrients, stabilizing soil pH, and reducing leaching of fertilizer. This means fulvic acid makes a great foliar spray, allowing trace elements such as copper, iron, manganese and zinc to be better absorbed through the leaves. Fulvic acid also stimulates the metabolisms of plants, which makes fulvic acid treatments a great way to quickly correct trace metal deficiencies while stimulating plant growth.

Why add fulvic:

– More bioligically active – Helps transport minerals through the cell membrane – Beneficial as a soil amendment – Increases drought resistance – Improves uptake of nutrients – Stabilizes soil pH – Reduces leaching of fertilizer – Makes a great foliar spray – Allows trace elements copper, iron, manganese and zinc so better absorbed through the leaves – Stimulates the metabolisms of plants

Helps To Improve Iron Uptake

Iron is one of the limiting factors in soil since it is easily oxidized and turned into rust. Once oxidized, iron becomes unavailable to plants, but humic and fulvic acids not only keep iron soluble, they also stimulate cell membranes to take up iron more efficiently. Iron is a catalyst for chlorophyll production. As plants take up more iron, they make more of the green chlorophyll that absorbs light energy to make sugars. Some of the sugars are used for energy to grow and reproduce, some are stored in the flowers and fruit, and some are used by the roots to feed plant growth-promoting microbes in the root area. Humic acid in the roots also stimulates the uptake of nitrates and other essential elements.

Promotes Root Structure

Root proliferation is a benefit from applications of humic and fulvic acids at low concentrations. These stimulatory effects also have been directly correlated with enhanced uptake of nitrogen, phosphorus, sulfur, zinc, and iron. However, use of these compounds at high concentrations also has been shown to decrease root and shoot growth. Stimulation of root growth may improve plant resistance to disease, and plant response to feeding by herbivores and nematodes, and water stress caused by drought. The use of soilborne compounds to protect seeds and enhance seedling growth is being investigated globally. Humic and fulvic acids are commonly used in organic crop production, greenhouse cropping of vegetables, and in horticultural programs. They also may have uses in Iowa’s large-scale production systems to improve seedling health and plant response to stress.

Another form of Humic

Humates, which are composed of various forms of carbon, are naturally occurring material that is very rich in humified organic matter and humic substances. Humates are now recognized as the single most productive input in sustainable agriculture.

In conclusion, agricultural producers worldwide are seeking to reduce dependency on synthetic fertilizers and chemicals. Humic products provide an efficient and economical means to return carbon to the soil. Without the replenishment of carbon, the addition of man-made synthetic nutrients is pointless. The use of humic products is thus the best path to coveted agricultural sustainability.

References: Korean Society for Horticultural Science and Springer-Verlag GmbH 2014