What are the multifunctional effects of humic acid fertilizers?
Effects on plant growth Humic acid can promote plant root growth. It enhances root vigor and promotes an increase in the number of tillers and secondary roots and their elongation. It improves the seed germination rate. Applying humic acid can accelerate seed germination and increase the emergence rate, especially in early spring and at low temperatures (generally germination can be 1-3...
Effects on plant growth
Humic acid can promote plant root growth. It enhances root vigor and promotes an increase in the number of tillers and secondary roots and their elongation.
Improving the seed germination rate. Applying humic acid can accelerate seed germination and increase the emergence rate, especially in early spring and at low temperatures (generally germination can be 1-3 days earlier, and the emergence rate increases by 10%-30%).
Improving crop drought resistance. The application of humic acid can reduce the opening degree of plant leaf stomata, lower leaf transpiration, reduce water consumption, improve the water status inside the plant, and increase leaf water content. This thus lays the foundation for tillering and seed formation. The application of humic acid can also increase chlorophyll content and support normal photosynthesis, which is very important for matter accumulation and the increase of 1000-grain weight.
Improving crop cold resistance. Applying humic acid has obvious effects on early spring rice seedling raising in the south and on wheat cold resistance in the north. In various places in southern China, during early rice seedling raising, low-temperature and rainy weather is often encountered, and dead seedlings and rotted seedlings often occur. After applying humic acid, the ground temperature is raised and the quality of the seedlings is generally improved. In experiments, Southwest Agricultural University found that winter wheat in most areas of northern China is commonly damaged by winter conditions because late spring cold spells often occur, and the application of humic acid effectively improved the cold resistance of wheat and reduced freezing damage to varying degrees.
Effectively increasing the chlorophyll content in crops. Humic acid has a very obvious effect on increasing plant chlorophyll content. No matter what method is used to treat crops, it can significantly increase crop chlorophyll content. For example, when humic acid fertilizer is applied to wheat, its leaf senescence index is twice as good as that of the control group.
Stimulating crop physiological metabolism and increasing enzyme activity. After humic acid enters the plant, it has a stimulating effect on the plant, mainly manifested in increased respiration intensity, increased photosynthesis, and enhanced activity of various enzymes, thereby enabling fruits to color and mature earlier and achieving high yield and high value (market timeliness of cash crops).
Slow-release and synergistic effects on nutrients
Synergistic effect on nitrogen fertilizer. Humic acid is a natural urease inhibitor, can slow the enzymatic decomposition of urea, and reduce ammonia volatilization; groups such as carboxyl and phenolic hydroxyl in humic acid have complexation and adsorption slow-release effects on ammonium nitrogen, which can reduce nitrogen loss and improve nitrogen fertilizer use efficiency.
Synergistic effect on phosphate fertilizer. Humic acid can inhibit the fixation of phosphorus by soil, increase the migration distance of phosphorus in soil, and at the same time delay the conversion of available phosphorus into slowly available and unavailable phosphorus. It can also activate phosphorus fixed by soil, increase the available phosphorus content in soil, and improve phosphate fertilizer use efficiency and fertilizer effect.
Synergistic effect on potassium fertilizer. Humic acid has a relatively strong cation exchange capacity and adsorption capacity. Its functional groups can absorb and store potassium ions, causing potassium fertilizer to decompose slowly, increasing the amount of potassium released, and raising the content of available potassium; it activates soil potassium and improves the use efficiency of potassium fertilizer.
Synergistic effect on trace elements. Humic acid can undergo chelation reactions with poorly soluble trace elements to form humic acid trace element chelates with good solubility that can be absorbed by crops, thereby facilitating the absorption of trace elements by roots and leaves.
Soil environmental protection function
Improving soil environmental conditions. The use of humic acid can change the physical and chemical properties of soil with excessively high salt content, excessively strong alkalinity, highly dispersed soil particles, and poor soil structure, promote the formation of soil aggregates, and bring them into a good state, thereby creating good conditions for plant root growth and development.
Humic acid can promote the formation of soil aggregates. The hydroxyl and carboxyl functional groups in humic acid readily undergo coagulation reactions with calcium ions in soil, and then through the physiological action of plant roots, soil aggregate structure is formed, thereby relatively increasing soil porosity and improving permeability, which is beneficial for crops to absorb nutrients and grow normally.
Using the principle that the acidity of humic acid neutralizes the alkalinity in saline-alkali soil, soil pH can be adjusted, thereby achieving the effect of treating salinity and alkalinity. Humic acid is dark in color, which is beneficial for absorbing solar energy. When humic acid is decomposed by microorganisms, it releases heat. Sufficient humic acid in soil can raise ground temperature and fully play a role in resisting spring cold.
Preventing and controlling soil heavy metal pollution. Humic acid participates in ion exchange reactions in soil, adsorbs and fixes heavy metal ions in soil, and prevents them from entering the biological cycle; it can stabilize soil structure and provide substrate and energy for soil microbial activity, thereby indirectly affecting the mobility of heavy metal ions in soil.
Humic acid undergoes complexation reactions with heavy metal ions in soil, thereby passivating heavy metal ions and preventing large amounts of heavy metal ions from entering plant systems.