Soil is alive, and this life is soil microorganisms. As we all know, soil is the base camp of microorganisms and the natural culture medium for the growth and reproduction of microorganisms. Humic acid runs through the life of soil and is the "life core" of soil. Without asam humat, the soil will lose its activity. Based on this, clarifying the relationship between "soil-humic acid-microorganisms" has important practical significance for protecting land resources and promoting sustainable soil production.

Soil humic acid

 The basis of soil life

Biological organic fertilizer is the most profound "dark matter" in the soil, and every cycle of its life is related to living organisms.

① Born from living organisms: mainly animal and plant residues (mainly plant residues) as material sources;

② Transformed by living organisms: mainly through the participation and action of microorganisms, continuous decomposition, transformation, and synthesis;

③ Return to living organisms: mainly through the return of soil humic acid to living organisms, promoting the growth of green plants (producers), enhancing the immunity of livestock, poultry, aquatic products, humans, etc. (consumers), and providing nutrients and energy sources for microorganisms (decomposers).

According to this, humic acid accompanies the rhythm of life, realizes the cycle of "survival → transformation → extinction → rebirth", and becomes the original intention of revitalizing soil life by its existence.

The core of soil structure

The structural characteristics of soil include three meanings:

①During the soil formation process, organic matter and minerals form organic-inorganic complexes, micro-aggregates, macro-aggregates, etc.;

② Micro-aggregates are the core of soil structure and are the smallest structural units that can exist independently (equivalent to cells in soil) for the soil to perform its functions;

③ The structural properties of soil during soil utilization have a great impact on the function of soil. Micro-aggregates are the key to the stability of the "soil house" structure, and humic acid is the key component of building the soil "micro-house". During the soil formation process, humic acid combines with organic macromolecules such as polysaccharide uronic acid glycosides secreted by various microorganisms, clay minerals, and hydroxides of iron and aluminum, etc., through different forms and various forces to form various types of organic-inorganic complexes. At the same time, under various surface charges and forces, micro-aggregates of different particle sizes are formed through aggregation. Based on this, the formation process of humic acid micro-aggregates gives the soil organic-inorganic complex a fresh vitality and is the core and key to stabilizing the soil structure.

Key soil functions

The functions of soil ecosystems mainly include: the ability and level of material transformation and energy circulation in the soil, the activity of soil organisms, the balance of nutrients and water in the soil and its impact on the environment. Humic acid fertilizer(https://www.hhfertilizer.com/products/organic-fertilizer) is the most active part of soil organic matter and plays a vital role in the material cycle and energy conversion of the soil ecosystem.

① Active participant and promoter of soil formation and soil fertility;

② Promote and restrict the migration, fixation and leaching of soil metal ions and trace elements;

③ Stabilizer of soil structure;

④ Affects the base exchange capacity of the soil;

⑤ Affects the water holding capacity of the soil;

⑥ A warehouse for plant materials. Based on this, humic acid can regulate the material cycle, energy conversion and information transmission between biological systems, soil systems and environmental systems, and is an important substance for maintaining the stability of soil functions.

 Soil microorganisms

Composition of soil microorganisms

Soil is the base camp of microorganisms and the natural "culture medium" for their growth and reproduction. Soil microorganisms are a general term for bacteria, fungi, actinomycetes, algae, etc. that live in the soil and are important components of the soil. Their individual size is tiny, generally measured in micrometers or millimeter, and their types and numbers vary with the soil-forming environment and soil depth. Among them, bacteria are the most numerous, followed by actinomycetes and fungi, and algae are relatively rare. It is estimated that there are thousands or even tens of thousands of species, about hundreds of millions to billions of microbial individuals per gram of soil, and their types and numbers vary with the soil-forming environment and soil depth. Generally speaking, in each gram of cultivated layer soil, the number of bacteria is about 10^8~10^9, the number of actinomycetes is about 10^7~10^8, the number of fungi is about 10^5~10^6, and the number of algae is about 10^4~10^5. They all live in the soil.

 Soil microbial effects Soil microorganisms’ impact on soil formation and development, material circulation, fertility evolution, and plant growth

① Bacteria: Suitable for neutral and slightly alkaline living conditions. Among them, autotrophic bacteria have the ability to assimilate carbon dioxide, which directly affects the physical and chemical properties of the soil and balances the pH of the soil; heterotrophic bacteria exist in a symbiotic state with crops and have a direct promoting effect on crop growth, such as rhizobia of leguminous plants, which have a strong nitrogen fixation effect and produce a significant yield increase effect under the condition of less nitrogen fertilizer.

② Actinomycetes: Suitable for neutral and slightly alkaline living conditions. In the soil, actinomycetes live in an aerobic heterotrophic state. Their main activity is to decompose cellulose, lignin, and pectin substances in the soil. Through these actions, they improve the nutrient status of the soil and facilitate crops to directly absorb and utilize soil nutrients.

③ Fungi: Suitable for slightly acidic living conditions. Participating in the decomposition of animal and plant residues, they become an indispensable driving force for nitrogen and carbon cycles in the soil. Especially in the early stages of plant organism decomposition, fungi are more active than bacteria and actinomycetes.

④Algae: a type of single-celled organism that mainly exists in aquatic environments. Cyanobacteria in algae also have the function of fixing nitrogen in the air. It is more suitable for working in an alkaline environment.

 Soil microbial activity

Soil microorganisms are not only an important component of the soil, but also the source of vitality of the soil ecosystem.

① The gases and organic acids produced by the metabolism of various microorganisms contribute to the formation of soil aggregate structure;

② Decompose organic matter, synthesize soil humus-humic acid, and fertilize the soil;

③ Decompose minerals and promote the dissolution of insoluble substances in the soil (such as phosphorus bacteria, potassium bacteria, etc.);

④ Fix atmospheric nitrogen and increase soil nitrogen nutrients;

⑤ Regulate plant growth, such as rhizobia, mycorrhizae, fungi, etc. that coexist with plants;

⑥ Secrete antibiotics (such as actinomycetes) to prevent soil-borne diseases;

⑦ Secrete a large amount of enzymes to promote the transformation of soil nutrients;

⑧ Degrade residual organic pesticides, urban pollutants and factory waste in the soil.

The above 8 items reflect the important relationship between soil microorganisms and soil fertility, soil health, and plant growth, and are the main force of material circulation and energy flow in soil ecosystems.

Soil humic acid and microorganisms

 Microbiological mechanism of soil humic acid formation

There are seven main hypotheses about the microbiological mechanism of humic acid formation:

① Waksman theory believes that in the process of plant humus formation, nitrogen-containing organic matter and nitrogen-free organic matter are decomposed by aerobic microorganisms to produce microorganisms (soil protein) and lignin, which are then combined with alkali to form humus.

② Williams theory believes that humic acid is the secretion of soil microorganisms;

③ The microbial synthesis hypothesis believes that microorganisms use plants as carbon sources and energy sources, and can synthesize high-molecular humus substances in cells. After the death of microorganisms, they are released into the soil and degraded into humic acid and fulvic acid outside the cells;

④ The cell autolysis hypothesis believes that humus is the product of cell autolysis after the death of plants and microorganisms;

⑤ The coal chemical theory believes that there are two main conditions that affect the accumulation of plant residues in swamps and the formation of peat. One is the physical condition that isolates plant residues from the air, and the other is the chemical condition that maintains the good activity of microorganisms;

⑥ Kononova theory believes that the formation of humus includes two stages of "decomposition-condensation", both of which involve soil microorganisms;

⑦ The anaerobic fermentation theory believes that the formation of humic acid includes three stages of "hydrolysis-acid production-synthesis", and the role of microorganisms is mentioned to varying degrees. Regardless of which hypothesis, the important role of microorganisms in the formation of humic acid is fully affirmed.

 Humic acid effects on soil microbial reproduction

The formation of humic acid is inseparable from soil microorganisms, and the reproduction of soil microorganisms is also inseparable from humic acid.

① Humic acid provides a source of material and energy for soil microorganisms. Soil microbial nutrition mainly includes carbon, hydrogen, oxygen, nitrogen and some mineral elements. Humic acid contains carbon, oxygen, hydrogen, nitrogen and other elements, which can provide soil microorganisms with carbon and nitrogen sources for their survival and reproduction.

② Humic acid creates a suitable living environment for soil microorganisms. Soil microorganisms need suitable temperature, humidity, pH, etc. to survive. Humic acid can directly or indirectly improve soil temperature, moisture and air permeability, regulate soil pH, promote the growth and reproduction of soil microorganisms, and increase their number and types.

③ Humic acid provides a living home for soil microorganisms. The total number of microorganisms in soils with deep soil layers, loose soil, good physical properties and rich effective nutrients is also high. Humic acid is the core of soil fertility. When humic acid is prosperous, soil fertility is prosperous; when soil fertility is prosperous, microorganisms are prosperous.

Humic acid and microorganisms are both part of the soil life community

Humic acid is the carrier of soil life, providing carbon and nitrogen sources for microorganisms and accompanying them throughout their lives, promoting the number, types and diversity of microorganisms; microorganisms are the embodiment of soil life, playing the role of decomposers, and playing an indelible role in the formation and decomposition of humic acid. The formation of humic acid is inseparable from soil microorganisms, and the survival and reproduction of soil microorganisms are inseparable from humic acid. The two are interdependent and jointly promote the formation and development of soil, the evolution of fertility, the circulation of materials and the conversion of energy. It can be seen that "soil-humic acid-microorganisms" are inseparable and belong to a life community.