7 functions of soil organic matter:
The substances in the soil other than soil minerals are called soil organic matter. It is the most active part of the soil and the basis of soil fertility. It can be said that there is no soil fertility without soil organic matter.
7 functions of soil organic matter:
- The main source of plant nutrients. Organic matter contains various nutrients needed for plant growth and development, especially nitrogen in the soil. More than 95% of nitrogen exists in the soil in an organic state.
- Promote the growth and development of crops. Humic acid in organic matter can enhance plant respiration, improve cell membrane permeability, and enhance nutrient absorption. At the same time, vitamins and some hormones in organic matter can promote plant growth and development.
- Improve soil structure. Humus in organic matter is the main binder of soil aggregates and can promote the formation of a good structure. Organic matter can also increase heat absorption capacity, improve soil fertility, and create suitable soil tightness.
- Improve the water and fertilizer retention capacity of the soil. Soil organic matter belongs to organic colloids, which have a strong adsorption capacity and can absorb many nutrients and water.
- Promote the activity of soil microorganisms. Soil organic matter supplies the energy and nutrients required by soil microorganisms, which is conducive to the activity of microorganisms.
- Increase soil temperature. Organic matter is darker in color, generally brown to dark brown, with strong heat absorption capacity, which can increase ground temperature. It can improve soil thermal conditions.
- Improve soil nutrient content. Humus in organic matter has a chelating effect, which helps to eliminate soil pollution. For low-yield fields, increasing the content of organic matter can fertilize the soil and improve the soil fertility level. For high-yield fields, due to the continuous decomposition of organic matter, organic matter also needs to be continuously supplemented. Humus can form complexes or chelates with phosphorus, iron, and aluminum ions to avoid the precipitation of insoluble phosphates and increase the number of effective nutrients.
6 types of soil organic matter
- In addition, soil organic matter can be divided into 6 major types according to its type of function!
- Provide various nutrients needed by crops (basic function)
In the gradual mineralization of soil organic matter, nutrients are converted into simple inorganic forms and absorbed and utilized by crops and microorganisms. The organic acids and humic acids produced during the conversion process have a certain solubility for soil minerals, promote mineral weathering, and release nutrients. - Enhance the water and fertilizer retention and buffering capacity of the soil (chemical effect)
Humic acid is loose and porous, a hydrophilic colloid with a strong water absorption capacity. Humic substances have a strong adsorption capacity for cations. Humic acid is a weak acid and can form a buffer system with its salts. - Promote the formation of aggregate structure and improve soil physical properties (physical effect)
Soil humus is a colloid, whose cohesiveness and adhesion are greater than sand and less than clay, suitable for the formation of aggregate structure so that the permeability, water storage, and aeration of the soil can be improved.
Humic acid is dark in color, which makes the soil warm up quickly; it has a large heat capacity and a higher soil temperature. - Promote the physiological activity of microorganisms and plants (biological effect)
Soil organic matter is the main source of nutrients and energy required for the life activities of soil microorganisms. Humic acid is a type of plant physiologically active substance that can improve the drought resistance of crops and the activity of peroxidase. - Reduce the pollution of pesticides and heavy metals (environmental effects)
Fixation of organic pollutants such as pesticides; complexation, adsorption, and reduction of heavy metal ions. - Impact on global carbon balance (ecological effects)
Soil organic matter is an important carbon reservoir in the global carbon balance process.