Due to soil and ecological concerns, more and more people are paying attention to humic acid, and various types of humic acid are available on the market. Shandong WINNERS has compiled a comprehensive list of 28 frequently asked questions about humic acid for farmers!
1. What is humic acid?
With so many types of humic acid on the market, what exactly is it? Humic acid is actually an organic substance formed from the remains of plants and animals, primarily plants, through microbial decomposition and transformation, as well as a series of chemical processes and accumulation.
Humic acid is acidic (pH 3-5) and can be used to improve alkaline soils in saline-alkali areas, while also increasing crop yields.
2. Classification of humic acid:
Classified by molecular weight, humic acid can be divided into three types:
(1) Brown humic acid: The portion of humic acid that is soluble in alkali but insoluble in acid is called brown humic acid.
(2) Black humic acid: The portion of humic acid that is insoluble in both alkali and acid is called black humic acid.
(3) Fulvic acid: The portion of humic acid that is soluble in both alkali and acid is called fulvic acid.
Among these, fulvic acid is the most active and has the most significant effect on increasing crop yield.
3. What are the main functions of humic acid in agriculture?
The main functions of humic acid in agriculture can be categorized into five types:
(1) Soil improvement: Primarily manifested in improving soil structure and increasing crop yield.
(2) Fertilizer enhancement: This involves reducing nitrogen volatilization and promoting nitrogen absorption.
(3) Crop stimulation: Promotes root growth and enhances photosynthesis.
(4) Enhances crop resistance: Under adverse conditions such as water, temperature, salinity, and heavy metals, the application of humic acid can help plants maintain a faster growth rate.
(5) Improves agricultural product quality: Makes crop stems stronger, more resistant to lodging, and produces more lush leaves, increasing chlorophyll content, etc. 4. What’s the difference between humic acid, alginic acid, and amino acids?
Pure humic acid and alginic acid, through their effects on crops, promote growth by regulating the environment or a specific aspect of crop metabolism. Amino acids, on the other hand, are directly absorbed by crops and become part of their metabolic processes.
In other words, after absorption, amino acids become an integral part of the metabolic process, transforming into what crops need most. Humic acid, however, promotes the synthesis of essential nutrients after absorption.
5. What’s the difference between sodium humate, humic acid-based compound fertilizers, potassium humate, etc.?
Sodium humate: The sodium salt of humic acid, formed by the reaction of humic acid with caustic soda (sodium hydroxide). It is alkaline (pH 8-11) and can be used in acidified soils to improve soil acidity.
Humic acid compound fertilizer: A type of fertilizer that combines humic acid with macronutrients, possessing the functions of both humic acid and ordinary compound fertilizers, thus greatly improving fertilizer utilization.
Potassium humate is a highly efficient organic potassium fertilizer because its humic acid content is a bioactive agent that can increase the content of available potassium in the soil, reduce potassium loss and fixation, and increase the absorption and utilization rate of potassium by crops.
6. Why is there such a large price difference in humic acid on the market, ranging from a little over 1000 to tens of thousands?
This is because humic acid on the market is divided into biochemical humic acid and mineral-derived humic acid.
Mineral-derived humic acid is extracted from peat, lignite, and weathered coal. It is composed of fulvic acid, palmitic acid, and black humic acid. A small amount, such as 1-2 kg/acre, can be very effective throughout the growing season.
Biochemical humic acid is much cheaper than mineral-derived humic acid. It is mostly made from byproducts or molasses produced during yeast production. Because it contains fewer nutrients, it requires large-scale application to be effective.
7. What is the difference between soil humic acid and coal humic acid? The main difference is the origin of the raw materials. Soil humic acid is primarily composed of lower organisms, animal remains, and herbaceous plants, with significant mineral involvement. Coal humic acid, on the other hand, is mainly composed of higher plants, with less animal and mineral involvement. Therefore, we primarily use soil humic acid, as the minerals required by the soil are guaranteed.
8. In recent years, some companies have been heavily promoting enzymatically hydrolyzed humic acid. What exactly is it?
Enzymatic hydrolyzed humic acid is actually a production process using biological enzymes and bacteria to decompose humic acid. It’s not significantly different from ordinary humic acid.
Usage Effects Potassium Humate Issues
1. Is good potassium humate usually in shiny tablet form? What’s the difference between it and sodium humate?
Good mineral-sourced potassium humate will definitely be shiny, but it’s not necessarily in tablet form. The production process is different from sodium humate.
2. How to judge the quality of potassium humate? We can check the potassium fulvate content in potassium humate. A higher content naturally indicates better quality. We can also check the water solubility of potassium humate; the more it dissolves in water, the higher the potassium fulvate content, meaning better fertilizer effectiveness and quality. More sediment indicates poorer effectiveness.
3. Does using potassium humate mean we don’t need to apply potassium fertilizer later?
Actually, no. The potassium content in potassium humate isn’t that high. For example, potassium fulvate of 50% or higher doesn’t necessarily mean a K2O content of 50% or higher. Generally, 50% potassium fulvate has a K2O content of around 5%.
The general potassium humate content is around 20%. For example, 60% potassium humate should have around 12% K2O. From a pure potassium fertilizer perspective, this content is very low. Regardless of the amount applied, supplemental potassium fertilizer will be necessary later.
Fulvic Acid and Potassium Fulvicate Issues
1. What are the common reasons for fulvic acid’s resistance to flocculation and its lack of flocculation resistance?
It’s mainly due to differences in their content.
2. What is the optimal content of high-quality agricultural-grade mineral-derived potassium fulvicate?
For high-quality agricultural-grade mineral-derived potassium fulvicate, the humic acid content is around 60%, the fulvic acid content is around 30%, and the potassium oxide content is around 10%.
3. What are the characteristics and advantages of potassium fulvicate compared to potassium sulfate?
Potassium fulvicate is an organic potassium, while potassium sulfate is an inorganic potassium. Potassium fulvicate has higher absorption and utilization rates and is also safer than potassium sulfate.
Application Scope and Methods
1. What crops is humic acid generally suitable for?
It is generally believed that humic acid has better fertilizer effects on vegetable crops such as cabbage, radish, and tomato, followed by root and tuber crops, and lastly on crops such as rapeseed, soybeans, and peanuts. However, its fertilizer effect on cereal crops is relatively low.
2. When is the best time to apply humic acid fertilizers to the same crop?
The best time is during the early growth stage (seedling stage) and the vigorous reproductive growth stage.
This is because in the early growth stage, the root system is relatively weak. Foliar application of humic acid allows for rapid absorption by the leaves, promoting strong seedling growth. During the vigorous growth stage, the demand for nutrients is higher, and the application of humic acid results in a more significant yield increase.
3. Which is better for the fruit expansion stage: potassium humate or potassium sulfate?
It’s best to use them in combination for better results.
4. After using humic acid on crops, are other fertilizers unimportant?
Definitely not. Although humic acid has excellent effects in agriculture, its effectiveness is not ideal if applied alone without combining it with other mineral elements.
Humic acid should be applied in combination with other fertilizers because it contains relatively low levels of readily available nutrients and cannot replace chemical fertilizers. It should be used in conjunction with chemical fertilizers and farmyard manure.
5. Can humic acid be applied directly to the soil?
Yes, it can. Humic acid is a high-organic-matter fertilizer; direct application not only replenishes soil organic matter but also improves soil structure, enhancing its water and fertilizer retention capacity.
6. What is the recommended concentration of humic acid?
We need to control the temperature. In the early stages of crop growth, a concentration of 100 mg/L is recommended. In the middle and later stages of growth, a concentration of 100-500 mg/L is recommended.
7. How does humic acid exhibit its inhibitory effect? In other words, at what concentration will applying humic acid be detrimental to crop growth?
Generally, excessively high fertilizer concentrations are detrimental to crop growth. However, to date, no limit has been found for the concentration of humic acid used in irrigation, so its inhibitory effect is likely relatively weak.
8. At what temperature should we generally apply humic acid? Pay attention to the temperature during application. Generally, the temperature should be above 18 degrees Celsius, but not higher than 38 degrees Celsius. Humic acid fertilizers are slower to take effect in cold weather, while excessively high temperatures will reduce the accumulation of dry matter, leading to reduced yield.
9. Can humic acid be sprayed on the leaves of citrus trees bearing fruit?
It can be sprayed on the leaves of citrus trees bearing fruit, but avoid using it within one month before harvest to prevent black residue from contaminating the fruit surface.
10. How often should humic acid be used via drip irrigation?
It is better to apply it in an intermittent manner, such as alternating humic acid with macronutrients.
11. What are the effects of long-term drip irrigation application of mineral-derived humic acid? Does humic acid have antagonistic effects with other elements?
Higher quality mineral-derived humic acid contains higher levels and stronger activity of fulvic acid. If pipe blockage is observed, it can be relieved by rinsing with clean water for half an hour to an hour. Humic acid does not have antagonistic effects with other elements.
12. Why do spots appear on leaves after applying mineral-derived humic acid to plants later in the growing process?
This is because normal mineral-derived humic acid has relatively high activity. It will leave water droplets on the plant, but these will be absorbed. If spots remain on the finished product, it indicates insufficient activity or a high concentration.
How to distinguish the quality of humic acid?
1. How can we distinguish genuine from fake humic acid on the market by its color?
When buying humic acid, you can pour a small amount of water-soluble fertilizer or powder into clean water. If the water is very dark, it may be dyed. The normal color should be brownish-black.
If it is granular humic acid, rub it vigorously with your hands. If the color comes off and cannot be washed off with water, it is likely dyed. You can also crush the granules; if the color inside is not the same dark brown as the outside, it may also be dyed.
Additionally, there is a type of fertilizer on the market that is white granules and claims to contain white humic acid. This is definitely fake because there is no such substance as white humic acid!
2. How can we distinguish between genuine and fake humic acid based on its solubility?
Put the humic acid fertilizer in water and observe the speed of dissolution, whether it dissolves completely, and whether there is any sediment. Generally, high-quality humic acid fertilizer dissolves completely and quickly without leaving any sediment.
