A Detailed Explanation of the Effects and Methods of Use of Humic Acid Fertilizer
Humic acid fertilizer refers to products made from peat, lignite and weathered coal through different production methods, containing large amounts of humic acid as well as the nitrogen, phosphorus, potassium and certain trace elements needed for crop growth and development. Its role in agricultural production is mainly to stimulate crop growth, improve soil, increase nutrients and strengthen soil microbial activity. Let us take a look below at the effects and uses of humic acid fertilizer.
Types of Humic Acid Fertilizer
1. By source, humic acid fertilizer can be divided into two major categories: natural humic acid and artificial humic acid. Among natural humic acids, they are further divided by the field in which they exist into soil sodium humate (white) humic acid, coal humic acid, water-body humic acid and mold humic acid, etc.
2. By formation method, humic acid fertilizer can be divided into primary humic acid and regenerated humic acid (including humic acid in natural weathered coal and artificially oxidized coal).
3. By solubility in solvents and color, humic acid fertilizer can be divided into fulvic acid, brown humic acid and black humic acid. In earlier literature there were also names such as gray humic acid, brown humic acid and green humic acid, which are in fact all separated out by different solvents.
4. By natural combined state, humic acid fertilizer is further divided into free humic acid and (calcium, magnesium) bound humic acid.
5. By the degree of humification of the humic acid (light absorption coefficient and other indicators), humic acid fertilizer is divided into type A, type B (true humic acid), type RP and type P (immature humic acid), etc.
The Effects of Humic Acid Fertilizer
1. It can increase the utilization rate of nitrogen fertilizer: Nitrogen fertilizer is an indispensable fertilizer for plant growth, mainly urea and ammonium carbonate. When urea and ammonium carbonate are applied to the soil, they are soon lost with air and water, and only 30% of the nitrogen nutrient can actually be absorbed and used by crops. The aromatic nuclei, hydroxyl groups, carboxyl groups and other acidic functional groups in humic acid can react with nitrogen to form very stable new ionic groups. These complexes remain in the soil for a relatively long time, gradually decomposing and releasing nitrogen for plants to absorb slowly.
2. It has a synergistic effect on phosphate fertilizer: After quick-acting phosphate fertilizer is applied to the soil, phosphorus is fixed by metal ions in the soil, turning quick-acting phosphorus into slow-acting or ineffective phosphorus. The aromatic nuclei, hydroxyl groups, carboxyl groups and other acidic functional groups in humic acid can react with phosphorus, making it soluble phosphorus, increasing the activity of phosphorus and making it easy for plants to absorb. According to statistics, after additional application of humic acid fertilizer, the fertilizer efficiency of phosphate fertilizer can be relatively increased by 5-10%.
3. It has a synergistic effect on potassium fertilizer: The functional groups in humic acid can also absorb and store potassium ions, which can both prevent potassium ions from being lost with water in sandy soil and prevent potassium fixation in clay soil, and can increase the utilization rate of potassium fertilizer by about 5%.
4. It has a water-retaining and fertilizer-retaining effect: Humic acid interacts with calcium ions in the soil to form a flocculent precipitated gel, which can cement the soil together, turning soil particles into small reservoirs and fertilizer stores that retain water and fertilizer, increasing soil pores and thereby improving the soil's water-retaining and fertilizer-retaining capacity.
Methods of Use of Humic Acid Fertilizer
1. Seed soaking: Seed soaking can increase the seed germination rate, bring about earlier emergence and enhance the ability of seedlings to develop roots. The general soaking concentration is 0.005-0.05%, and the general soaking time is 5-10 hours; for hard-shelled seeds such as rice and cotton it is 24 hours.
2. Root soaking: Before transplanting, rice, sweet potato and the like can be soaked as seedlings using sodium humate or potassium humate solution at a concentration of 0.01-0.05%. After soaking, they show fast root development and a high survival rate.
3. Spraying: The general concentration is a 0.01-0.05% solution. Spray 2-3 times during the crop flowering period, with each spraying amount of 50 liters of aqueous solution per mu; the best effect is achieved when spraying is done between 2 and 4 p.m.
4. Base fertilizer: For solid humic acid fertilizer (such as ammonium humate, etc.), the general amount is 100-150 kg per 6 mu. When humic acid solution is used as a base fertilizer, the concentration is 0.05-0.1%, and the amount is 250-400 liters of aqueous solution per 6 mu; it can be applied mixed with farmyard manure, either by furrow application or hole application.
5. Topdressing: During the crop seedling stage and before the heading stage, use about 250 liters of aqueous solution at a concentration of 0.01-0.1% per 6 mu, pouring it near the crop root system. In paddy fields it can be applied along with irrigation water or splashed on the water surface, and it can play a role in promoting seedlings, strengthening seedlings and promoting growth and development.