Principle of Organic Fertilizer Fermentation

Transformation of Organic Matter During Composting

The organic matter in compost undergoes complex transformation under the action of microorganisms, and this transformation can be summarized into two processes: one is the mineralization process of organic matter, that is, the decomposition of complex organic matter into simple substances, finally generating carbon dioxide, water and mineral nutrients, etc.; the other is the humification process of organic matter, that is, organic matter is decomposed and then synthesized to generate more complex and special organic matter - humus. The two processes are carried out simultaneously, but in opposite directions, and the intensity of each is significantly different under different conditions.

Mineralization of Organic Matter

(1) Decomposition of nitrogen-free organic matter Polysaccharide compounds (starch, cellulose, hemicellulose) are first hydrolyzed into monosaccharides by the action of hydrolytic enzymes secreted by microorganisms. Glucose decomposes rapidly under well-aerated conditions, and intermediate products such as alcohol, acetic acid and oxalic acid do not accumulate easily, eventually forming CO2 and H2O while releasing large amounts of heat. If aeration is poor, under the action of gas-susceptible microorganisms, monosaccharides decompose slowly, produce less heat, and accumulate some intermediate products-organic acids. Under the condition of extremely gas-susceptible microorganisms, reduced substances such as CH4 and H2 are also produced.

(2) Decomposition of nitrogenous organic matter The nitrogenous organic matter in compost includes proteins, amino acids, alkaloids, humic substances and so on. Except for humus, most of them are easily decomposed. For example, proteins, under the action of protease secreted by microorganisms, are degraded step by step to produce various amino acids, and then formed into ammonium salts and nitrates respectively by ammonification and nitrification, which can be absorbed and used by plants.

(3) Transformation of phosphorus-containing organic matter The phosphorus-containing organic compounds in compost, under the action of a variety of saprophytic microorganisms, form phosphoric acid, which becomes a nutrient that can be absorbed and used by plants.

(4) Transformation of sulfur-containing organic compounds Sulfur-containing organic compounds in compost, by the action of microorganisms, generate hydrogen sulfide. Hydrogen sulfide tends to accumulate in a smelly environment and can be toxic to plants and microorganisms. However, under well-aerated conditions, hydrogen sulfide oxidizes to sulfuric acid under the action of sulfur bacteria and forms sulfate with the action of salt groups in the compost, which not only eliminates the toxicity of hydrogen sulfide but also becomes a sulfur nutrient that plants can absorb. In case of poor aeration, antisulfuration occurs, which transforms sulfuric acid into H2S for dissipation and toxicity to plants. Compost fermentation process, you can improve the aeration of compost through regular turning measures, you can eliminate the anti-sulfurization effect.

(5) Transformation of lipids and aromatic organic compounds Tannins and resins have complex structures and decompose slowly, and their end products are also CO2 and water; lignin is a particularly stable organic compound in compost containing plant materials (such as bark, wood chips, etc.), which has a complex structure, contains aromatic nuclei, and exists in plant tissues in a multimeric form, and is extremely difficult to decompose. Under well-aerated conditions, mainly through the role of fungi, actinomycetes, slowly decomposition, its aromatic nuclei can be changed into quinone-type compounds, which is one of the raw materials for the resynthesis of humus. Of course, these substances will continue to be decomposed under certain conditions.

To sum up, the mineralization of compost organic matter can provide quick-acting nutrients for crops and microorganisms, provide energy for microbial activities, and prepare basic raw materials for the humification of compost organic matter. When compost is mainly aerobic microbial activity, organic matter is rapidly mineralized to generate more carbon dioxide, water and other nutrients, decomposition is fast and complete, and releases a lot of heat; when the activity of aerobic microorganisms is mainly, the decomposition of organic matter is slow, and often incomplete, releasing less heat, and its decomposition products in addition to plant nutrients, but also easy to accumulate organic acids and CH4, H2S, PH3, H2, etc. Reduction substances, when it reaches a certain level, it is unfavorable or even harmful to crop growth. Therefore, the compost fermentation period is also turned over in order to convert the type of microbial activity, in order to eliminate harmful substances.

Humification Process of Organic Matter

There are many kinds of statements about the process of humus formation, which can be broadly divided into two stages: in the first stage, organic residues decompose to form the original materials that make up humus molecules, such as polyphenols, nitrogenous organic substances (amino acids, peptides, etc.); in the second stage, polyphenols are first oxidized to quinones by polyphenol oxidase secreted by microorganisms, and then quinones are condensed with amino acids or peptides to form humus monomers. Since there are many kinds of phenols, quinones and amino acids, the way of mutual condensation is also different, thus the humic monomers formed are also various. Under different conditions, these monomers are further condensed to form molecules of different sizes.