Humic acid is a mixture of natural organic macromolecular compounds. Widely present in nature, the proportion of humic acid in the soil is the largest, soil humic acid is physicochemical heterogeneous complex mixture of molecular weight is polydisperse, the mixture is natural, high molecular weight, yellow to black, Amorphous, colloidal, fatty and aromatic organic polyelectrolyte composition, can not use a single chemical structure that.
Where does humic acid come from?
1, soil humic acid born, mainly plant under the action of microorganisms in the formation of a class of special macromolecule organic compounds mixture.
2, coal humic acid is a microbial decomposition and transformation of plants, but also after long-term geological and chemical effects, and the formation of a class of macromolecular organic compounds mixture.
Humic Acid Structure Function and Function
Humic acid is a class of natural organic weak acid, composed of fulvic acid, black fulvic acid and brown acid three parts.
2, the composition of elements
Coal humic acid and soil organic matter in humic acid has a similar structure and nature of the main elements of humic acid carbon, hydrogen, oxygen, there are a small amount of nitrogen and sulfur, in addition to a variety of functional groups.
3, the role of humic acid
Soil organic matter is generally above the humic acid, humic acid in the corrosive acid is the main body and its combination with metal ions, humic acid is the most active and most effective part of organic matter.
(1) the direct effect of humic acid
Promote plant growth and increase crop yields.
(2) indirect effect
A. Improve soil structure. B. Prevention of soil cracking and erosion. C. increase soil water holding capacity, improve cold resistance. D. make the soil color darker, is conducive to solar energy absorption.
② chemical effect. A. Adjust soil pH. B. Improve and optimize plant absorption of nutrients and water. C. increase soil buffer capacity. D. In alkaline conditions, is a natural chelating agent (chelated with metal ions, promote the absorption of plants). E. Rich in organic matter and minerals necessary for plant growth. F. Improve the solubility of organic fertilizers and reduce the loss of fertilizer. G. The nutrient element is converted into a state easily absorbed by the plant. H. can strengthen the plant nitrogen absorption, reduce phosphorus immobilization, can penetrate the soil in the nitrogen, phosphorus and potassium and other elements, the protection box stored in the soil, and can accelerate the process of nutrient into the plant body, improve the application of inorganic fertilizer Therefore, humic acid is a "reserve" for plant nutrient elements and physiologically active substances.
③ biological effects
A. stimulate the growth and reproduction of beneficial microbes in the soil. B. to improve the natural plant disease resistance, pest resistance.
Fourth, the commonly used humic acid species and characteristics
At present, humic acid commonly used as fertilizer is divided into lignite humic acid, weathered coal humic acid, peat (grassland humic acid).
1, lignite humic acid is the second stage of the process of coal (diagenetic) products, to the bitter coal phase has no humic acid, lignite humic acid in the general content of 1-85%, brown brown brown appearance, Black, according to the depth can be divided into
(1) soil lignite: the degree of coalification is shallow, low carbon content, humic acid content is higher, generally more than 40%.
(2) bright brown coal: a deeper degree of coal, carbon content is higher, humic acid content is low, generally 1-10%.
(3) dense lignite: between (1) and (2) between the general humic acid content of up to about 30%.
2, weathered coal humic acid that outcrop coal, commonly known as Johnson. Generally close to or exposed to the surface of the lignite, bituminous coal, anthracite, through the air, sunshine, rain and snow, sand, frozen and other infiltration of weathering, and the formation of the product. The humic acid produced by this process is weathering coal humic acid, also called natural regenerated humic acid, humic acid content in weathered coal fluctuates greatly, ranging from 5-80%.
3, peat (peat, peat, etc.) humic acid
Peat is the initial stage of coal formation, also known as peat, Chinese peat humic acid content in 20-40%. Peat in the organic matter, is not decomposed by the plant waste and humic acid composition, the Chinese peat humic acid content of 20-40%.