Humic acids are an excellent natural and organic way to provide plants and soil with a concentrated dose of essential nutrients, vitamins and trace elements.Humic Acid Liquid is basic raw material for manufacturers in agriculture and industrial products.
Ⅰ. Liquid humic acid
HA liquid fertilizer (including foliar fertilizer, irrigation fertilizer, drip irrigation fertilizer, etc.) is prepared by using monovalent salt of FA or HA as water-soluble organic substrate, combined with N, P, K and trace elements. This kind of product can not only provide available nutrients, but also give full play to the biological activity of HA substances, low cost, high added value, convenient application, quick effect, and is very popular with users. In recent years, it has become the main HA variety in the international market. For example, K67 produced by lignite in the United States and KOMIX, Japan produced by lignite NHA are famous for their "foliar vitality dispersant".
The "leaf treasure", "spray treasure", "agricultural heirloom" and "Huimanfeng" developed at the end of the last century in China are also more influential brands.
In recent years, HA liquid fertilizer has developed rapidly, and has become an important supplementary product of leading fertilizer. it also plays an important role in the development of green ecological agriculture. I. basic principles and related requirements. In the preparation of HA liquid fertilizer, the problems of material thickening, coagulation and precipitation are encountered, which is an inevitable natural phenomenon. The solubilization, colloid dissolution, complexation and adsorption of various inorganic substances by HA determine their solubility and stability in colloidal system, specifically, The dispersed phases in the HA- water-inorganic salt system of fluid fertilizers can be divided into four cases, as shown in the table. Table 1 characteristics of colloidal system and range of liquid fertilizer. Name dispersed particle size fluid fertilizer roughly belongs to grain species in the system. True solution ions, molecular level HA-K, HA-NH4, UHA HA-COO-, CO (NH2) 2, K +, NH4+, NO3-, etc. The sol (colloid solution) 1~100nm foliar fertilizer is the same as above, and there are complex ions and microaggregates in addition. Suspension 0.1 ~ 10 μ m foliar fertilizer, fertilization as above, in addition to colloidal dispersed particles. Coarse dispersion system > 10 μ m fertilization is the same as above, and there are also large dispersed particles.
From the situation summarized in Table 1, there are three kinds of fluid fertilizers: 1) dilute solution, including HA monovalent salt, HA- urea compound, etc.; 2) foliar fertilizer, which can be colloidal solution, allowing a small amount of suspension, but must have a certain degree of stability,
Water insoluble matter is very few, dilution with hard water will not appear flocculation; 3) washing fertilization, allowed to be suspended and coarse dispersion system, but the stability is better.
Some countries call such fertilizers "suspended fertilizers", which stipulate that they do not precipitate or condense for several months at room temperature. when used, they can be uniformly dispersed with water and have a certain ability to resist hard water flocculation.
II. Technical elements.
At present, the key technical problems and difficulties of HA liquid fertilizer are as follows: one is the activity of HA, the other is the stability of colloid.
This section briefly provides a few reference measures and innovative ideas:
The main results are as follows: 1. the physical dispersion method was used to deal with the problem.
Irrigation and fertilization does not necessarily require complete "dissolution", but drip irrigation still has high requirements for particle fineness and dispersion.
The particle size can be reduced by strengthening grinding, rapid stirring, proper heating, ultrasonic treatment and other physical means, and the spatial repulsion between particles can be increased, and the dispersion can be improved.
Select suitable HA raw materials.
Use young lignite or high decomposition peat as much as possible.
There are a few special weathered lignite, such as Kozgro coal HA in the United States, lignite HA in Azerbaijan, HA of Wuchuan weathered coal in Inner Mongolia (E4/E6 ratio is about 6.7), and the hard water resistance is very good. this type of raw material should be selected.
the method of chemical activation modification is used to fully reduce the molecular weight of HA and increase the functional groups, which is the key measure to improve the chemical activity and biological activity, as well as to improve the protection and complexation properties of colloid.
Generally speaking, the total acidic group of, HA (FA) ≥ 10mmol/g (of which COOH accounts for 2 ≤ 3), E _ 4 / E _ 6 ≥ 8, coagulation limit ≥ 12 mmol ≥ g, or hydrophilic groups such as-CH2SO3H and-SO3H can be introduced. It can obviously improve the stability and application effect of foliar fertilizer.
proper addition of auxiliaries to increase the stability of colloid.
All kinds of thickeners, dispersants and wetting (spreading) agents should be added to suspended fertilizers.
The commonly used thickeners and dispersants are bentonite, sepiolite, silicomagnesia, xanthan gum, modified cellulose and modified starch, polyvinylpyrrolidone and so on.
The common spreading agents are: silicone surfactants, dodecyl sulfonate, alginic acid, alkyl phosphate, β-naphthalenesulfonic acid-formaldehyde condensate, alkyl polyglycosides, polyglycerides and so on, which can be selected and used according after all, the complexing ability of HA substances is limited. if you want to dissolve more metal elements, you can add proper amount of high efficiency chelating agent.
It includes ammonia carboxylic complexing agents (EDTA, diethylenetriamine pentaacetic acid, etc.), succinic acid, citric acid, salicylic acid and some amino acids.
Cheap ammonium polyphosphate and potassium polyphosphate have strong ability to dissolve and complex high valence metal ions. developed countries have been used as components of fluid fertilizers for more than 30 years and can be used in HA liquid fertilizers. the development of special and functional HA fluid fertilizer is a good way to save labor and save time, complement and increase efficiency, and it is also an important direction for the development of liquid fertilizer in the future.
Recently, special fertilizers for a certain crop (such as peanut fertilizer, grape fertilizer, fruit fertilizer, etc.) emerge in endlessly, generally better than the effect of general fertilizer.
For example, a concentrated viscous liquid containing HA, amino acids, carbohydrates, a large amount of trace elements, and inorganic salts is prepared by compounding organic wastewater from the production of alcohol or monosodium glutamate, poultry fecal extract after rotten fermentation, and humic acid solution with inorganic salts,
As a plant cultivation, aquaculture, edible fungi cultivation of multi-component nutrient solution.
Functional liquid fertilizers containing HA, nutrient elements, growth regulators, pesticides and other components, in recent years, innovative technologies and innovative varieties are also refreshing.
The Heilongjiang Institute of Agricultural Modernization of the Chinese Academy of Sciences and other units are aimed at the problems of serious continuous cropping soybean Huolong seedlings in Northeast China, low yield per unit area, and poor quality.
A compound foliar fertilizer "Verticillium wilt leaf spray" composed of HA, trace elements, amino acids and growth agents (sodium nitrophenol, DA-6) was developed, which solved the historical problem of repeated cropping soybean in light alkali land.
The development of liquid HA selenium fertilizer is in the ascendant, but the source of raw material sodium selenite is limited and the price is expensive. some people use selenium powder (including SeO2) to make water-soluble selenate after high temperature treatment, and add it into other HA liquid nutrient solution to become selenium-containing liquid fertilizer.
The "HA biological liquid fertilizer" developed by Heilongjiang Biological Organic Fertilizer Research Center is a compound of coal HA+ trace element + double-effect bacterial agent + growth regulator.
Significant results were obtained in increasing crop yield, improving quality (increasing soluble sugar and VC, reducing nitrate).
The combination of HA (FA) with chemical fertilizer or micro-fertilizer and pesticide also showed obvious complementary advantages.
Experience has proved that the rational mixture of HA, fertilizer, medicine and growth agent has an indisputable and significant effect, but it must be based on theoretical guidance and scientific experiments, and should not be blindly mixed, so as not to lead to antagonism or even failure of the preparations.
III. Technological process.
There are many processes for producing HA liquid fertilizer, the most valuable of which should be high activity fulvic acid foliar fertilizer. the production process is as follows:
Oxidative degradation of lignite by solid-liquid Separation (fulvic Acid) complexation and dissolution of nutrient elements in liquid Fertilizer.