Chelate and sugar alcohol fertilizers are key factors in increasing crop yields and incomes. We often see terms like chelated iron, chelated calcium, and sugar alcohol calcium on fertilizer packaging. These fertilizers are often expensive, but their effectiveness is remarkable. Let’s explore the secrets of these fertilizer ingredients.
Basic Concepts of Chelates and Complexes
Chelation, a technical term in chemistry, refers to the process of tightly binding a metal ion to a molecule with a specific structure (a chelating agent) through coordination bonds. When there is only one coordination bond, it is called a standard complex; when there are two or more coordination bonds, it is called a chelate. This technology makes chelates not only highly thermally stable and structurally robust, but also highly soluble in water.
Characteristics and Advantages of Chelated and Complex Fertilizers
Both chelates and complexes exhibit excellent thermal stability, a stable structure, and good water solubility. However, compared to complexes, chelates offer superior thermal stability and structural robustness, making chelated products more common on the market. These characteristics enable more efficient absorption and utilization of nutrients by crops, significantly improving their utilization rate.
The Excellent Performance of EDTA and Its Chelation Technology
EDTA, as an important chelating agent, is primarily available in the domestic market as chelated trace element fertilizers, such as EDTA iron, EDTA copper, EDTA manganese, EDTA zinc, EDTA calcium, and EDTA magnesium. In addition, a range of products, including DTPA chelated fertilizers, HEDTA chelated fertilizers, NTA chelated fertilizers, and EDDHA chelated fertilizers, provide a wide range of options for the agricultural sector.
Among the many chelating agents, EDTA stands out for its exceptional chelating properties. It possesses six coordination bonds, tightly encapsulating metal ions in a hexahedral configuration, achieving highly efficient chelation of most metal ions. Consequently, EDTA products occupy a premium position in the market, offering superior efficacy and affordability compared to other chelated products.
Testing of Chelated Trace Element Products
△ a. Metal Content Determination
Chelated trace element products typically contain six key metal elements. Taking the EDTA chelated series as an example, the specific content is as follows: EDTA iron contains 13% iron, EDTA copper contains 15% copper, EDTA manganese contains 13% manganese, EDTA zinc contains 15% zinc, EDTA calcium contains 10% calcium, and EDTA magnesium contains 6% magnesium. These precise metal content levels are crucial for ensuring product authenticity. Excessively high or low content levels may indicate quality issues. Since general manufacturers may not be able to perform such precise measurements, it is recommended to send your product to a reputable testing center for professional testing using techniques such as atomic spectroscopy.
△ b. Complexation Degree Testing
The degree of complexation, also known as the degree of chelation, is a key indicator of whether the metal elements in a product are fully chelated. It is also an important method for detecting the addition of inorganic salts. To perform this test, we dissolve 2 grams of the product in 20 milliliters of water. Then, add 10 milliliters of a 10% sodium carbonate solution and 5 milliliters of a 5% sodium dihydrogen phosphate solution and mix thoroughly. If the solution remains clear and transparent, the complexation is acceptable; if turbidity or precipitation occurs, the complexation is unacceptable. Note that if sodium dihydrogen phosphate is unavailable, water-soluble monoammonium phosphate or potassium dihydrogen phosphate can be used as alternatives, but the amount of sodium carbonate added should be increased to 40 milliliters. Furthermore, if the product contains inorganic salts such as zinc sulfate or manganese, this method can quickly detect the formation of a precipitate.
△ c. Detecting the Presence of Sulfate Anions
Dissolve 5 grams of the product in an appropriate amount of water, then acidify with hydrochloric acid to a pH of approximately 1. Then, add 20% barium chloride solution. If a white precipitate forms, the product contains sulfate. Note that qualified chelated trace element products should not contain anions such as sulfate and chloride.
In summary, if a product meets the requirements of sufficient content, acceptable chelation, and the absence of sulfate, it can be preliminarily judged to be of good quality. Of course, the final judgment of the product also requires consideration of other indicators, such as appearance, pH, and water-insoluble matter content.
The Unique Advantages of Sugar Alcohol Fertilizers
Sugar alcohol fertilizers are commonly used as chelating agents in agriculture. Raw materials such as xylitol and sorbitol offer significant advantages.
Sugar alcohol chelated products combine the advantages of trace elements and surfactants, making them the only substances capable of rapidly transporting mineral nutrients through the phloem of crops.
As natural wetting agents, sugar alcohol fertilizers possess excellent moisturizing properties, effectively extending the time it takes for leaves to absorb nutrients and preventing pesticides from becoming ineffective due to drying.
As plant surfactants, they promote the uniform distribution of chelated nutrients across leaves, increasing the absorption area while preventing leaf burns caused by localized high concentrations of trace nutrients.
Sugar alcohol fertilizers can also enhance crop resistance, particularly drought tolerance, providing comprehensive protection.
Sugar alcohol calcium is the most common sugar alcohol fertilizer on the market. Compared to regular calcium, sugar alcohol calcium combines the high absorbability and mobility of sugar alcohols, more effectively promoting calcium absorption and utilization. However, different sugar alcohol raw materials vary in their calcium chelation capacity. Erythritol and mannitol have strong chelation abilities but are relatively expensive, while sorbitol has poor chelation and is more affordable. Therefore, when choosing a sugar alcohol calcium product, it is important to pay attention to the type and quality of the raw materials to ensure product effectiveness and crop absorption.
