Application of humic acid in agriculture: The application of humic acid in agriculture has been widely recognized. The main functions include: to increase fertilizer efficiency, improve soil, improve quality, regulate crop growth and enhance crop resistance and so on. The main product types include: humic acid soil improvement type, humic acid fertilizers, humic acid pesticides and humic acid seedlings, etc.
I. For soil
(1) Humic acid contains the soil conditioners of water conservation and drought resistance,which is one of the main ways to solve the problems of agricultural drought and low yield, etc. in China. It can reduce the opening degree of crop stomata to reduce the transpiration of water, so as to make plants and soil maintain more moisture. It is an excellent anti-drought agent.
(2) Humic acid can interact with heavy metals in soil, such as ion exchange, adsorption andcomplexation (chelation), etc., to reduce the activity of heavy metals and reduce the content of effective heavy metals, so as to achieve the purpose of repairing the heavy metal pollutionin the soil.
(3) Humic acid can promote the formation of soil water-stable aggregate structure, regulate soil pH value and the conditions of soil water, fertilizer, air and heat, increase soil exchange capacity, achieve acid-base balance, so as to improve soil water and fertilizer conservation capacity, promote the activity of soil microorganisms, which can increase the number ofaerobic bacteria, actinomycetes and cellulose-degrading bacteria, accelerate the decomposition and transformation of organic matter, promote the release of nutrient elements and facilitates the absorption of nutrients by crops.
II. For crops:
(1) It can stimulate physiological metabolism, improve the activity of various enzymes and chlorophyll content, increase metabolism and photosynthesis, as well as increase sugar and dry matter, so as to improve crop’s ability of tolerating adversity to freezing and disease resistance, increase crop yield and improve crop quality, which is a new type of plant growth regulator.
(2) It can promote growth and development. Humic acid can promote early seed germination with high emergence rate, the effect of which is significant at low temperatures; It can stimulate division and growth of root apical meristem cell, then the seedlings root quickly with more secondary roots, the amount of roots is increased and the root system is elongated, so that crops’ ability of absorbing water and nutrient increases. Therefore, the nutrient supply is adequate, the crop stems grow fast and robust, the foliage is lush and the photosynthesis is enhanced, so as to accelerate the transfer of nutrients transferred to the fruit body, to promote the fruit colored and matured in advance.
(3) It can increase crops production and improve quality. Humic acid can form complexes or chelate compounds with trace elements to increase the amount of trace elements running from roots to leaves or other parts, and adjust the proportion and balance of macro elements and trace elements, then to strengthen the synthetic operation of enzymes on sugars, starches, proteins, fats and various vitamins. It can promote the activity of enzymes to convert polysaccharides into soluble monosaccharides and increase the synthesis accumulation of starches, proteins and fatty substances, then to accelerate the transfer of various primary products of metabolism from stems and leaves, or roots to fruits and seeds. All these can make the fruit plump and full of seeds, so as to increase the fruit yield.
III. In terms of plants:
(1) It can strengthen the stress resistance of plants. Humic acid can reduce the stomatal opening intensity of plants leaves and reduce the transpiration of the leaves surface, thereby reducing the water consumption of the plants, so that the water status is improved, the normal growth and development of the crop under drought conditions can be guaranteed, and the drought resistance is enhanced. Most of humic acids belong to amphoteric colloid and have large surface activity, which has inhibitory effect on fungi and can enhance the cold resistance of crops. It is easily adsorbed by cell membranes and can change cell membrane permeability, promote absorption of inorganic nutrients and prevent valsa mali and root rot, so as to improve the utilization rate of nutrients.
(2) Physiological activity of humic acid in plants is manifested as stimulating plant growth metabolism, improving seed quality and enhancing the tolerating adversity ability of plants, but which is related to the concentration and molecular weight of humic acid. It contains various functional groups, such as carboxyl groups and phenolic hydroxyls and so on, with high capacity of ion exchange and adsorption, which can reduce the loss of ammonium nitrogen and improve the utilization of nitrogen fertilizer.