Dear Maher,

Importance of humic acid in agriculture, particulary in soil fertility and plant nutrition, may be understood from the following facts:

(1) Humic acid is a principal component of humic substances, which are the major organic constituents of soil (humus), peat and coal. Humic acids can form complexes with ions that are commonly found in the environment creating humic colloids. Humic and fulvic acids (fulvic acids are humic acids of lower molecular weight and higher oxygen content than other humic acids) are commonly used as a soil supplement in agriculture.

(2) Humus influences soil fertility through its effect on the water-holding capacity of the soil. Also, since plants have been shown to absorb and translocate the complex organic molecules of systemic insecticides, they can no longer discredit the idea that plants may be able to absorb the soluble forms of humus.  This may in fact be an essential process for the uptake of otherwise insoluble iron oxides.

(3) The presence of carboxylate and phenolate groups gives the humic acids the ability to form complexes with ions such as Mg2+, Ca2+, Fe2+ and Fe3+. Many humic acids have two or more of these groups arranged so as to enable the formation of chelate complexes. The formation of (chelate) complexes is an important aspect of the biological role of humic acids in regulating bioavailability of metal ions.

I hope you find this input interesting and useful.

Humic acids can contribute to soil the following benefits:

• Stimulate root development.
• They help slowly release nitrogen sources, phosphorus, potassium and sulfur for plant nutrition and microbial growth.
• Involved in regulating soil pH.
• Contribute to energy absorption and heat the soil, because of its dark color.
• Increase Cation Exchange Capacity (CIC).
• They help soil structure by adding particles of clay and silt, and help prevent soil erosion.
• They help link micronutrients and thus avoid the possibility of hauling and loss.
• Chelating have effect on iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu).
• They can act as stimulants of plant growth through the organic constituents in the humic substances.
• Contribute to cost reduction potential by reducing the use of certain pesticides.

Humic acids in crop protection

• Increased resistance: Improve crop health by providing greater resistance to pathogen attack by action of phenols.
• Disease prevention: They favor the activity of the plant and thus their immunity against the invasion of parasites in the cells.
• Stimulation of microorganisms: By stimulating the activity of mycorrhiza and antagonists, biological balance occurs in the root zone.

 It is interesting to know that it improves crop health by providing greater resistance to pathogen attack by action of phenols.

Please have a look at this link also.

http://www.agriculture.com/crops/organic-farming/humic-acid-application-in-agriculture_169-ar33548

Dear Maher,

Importance of humic acid in agriculture, particulary in soil fertility and plant nutrition, may be understood from the following facts:

(1) Humic acid is a principal component of humic substances, which are the major organic constituents of soil (humus), peat and coal. Humic acids can form complexes with ions that are commonly found in the environment creating humic colloids. Humic and fulvic acids (fulvic acids are humic acids of lower molecular weight and higher oxygen content than other humic acids) are commonly used as a soil supplement in agriculture.

(2) Humus influences soil fertility through its effect on the water-holding capacity of the soil. Also, since plants have been shown to absorb and translocate the complex organic molecules of systemic insecticides, they can no longer discredit the idea that plants may be able to absorb the soluble forms of humus.  This may in fact be an essential process for the uptake of otherwise insoluble iron oxides.

(3) The presence of carboxylate and phenolate groups gives the humic acids the ability to form complexes with ions such as Mg2+, Ca2+, Fe2+ and Fe3+. Many humic acids have two or more of these groups arranged so as to enable the formation of chelate complexes. The formation of (chelate) complexes is an important aspect of the biological role of humic acids in regulating bioavailability of metal ions.

I hope you find this input interesting and useful.