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Chelated Fertilizers

 

First of all, it should be mentioned that generally, the use of fertilizers increases the fertility of the soil, so as an important factor, it provides the elements and food resources needed for the plants. Now, there are obstacles in the way of receiving food resources by plants, which makes the fertilizer and nutrients not fully absorbed by the plant and out of its reach. Even in some cases, non-observance of nutritional principles and fertilization leads to damage to the soil and plants. Therefore, factors such as high soil pH, high bicarbonate content, imbalance between elements and excessive use of chemical fertilizers are effective in reducing the absorption of nutrients. One of the solutions used to facilitate the absorption of nutrients in plants is the chelation of nutrients and chelated fertilizers, which we will describe below.

Generally, most food elements can be complexed with chelating agents, and based on the type of chelating agent and specific formulations, they can create different effectiveness. But since micronutrients are one of the essential factors for the growth and development of plants, usually chelated fertilizers are used more for micronutrients (iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), boron (B) and It has molybdenum (Mo). On the other hand, elements such as iron, manganese, zinc and copper are easily oxidized or precipitated in the soil, so the use of their normal forms is not efficient and it is necessary to use the chelated forms of these elements to increase their efficiency and absorption. Micronutrient elements help to improve product quality and increase yield and fruit harvest, and micronutrient chelate fertilizers improve the availability of these elements in foliar and root applications in fields, gardens, and greenhouses. Chelated micronutrient fertilizers are soluble in water and are compatible with different types of chemical fertilizers. Some are also suitable for use in soilless cultivation and do not cause sediment in the active pH range.

What is Chelating ?

It should be noted that the word chelate is derived from the Greek word which means to hold or hold something. In the process of chelating fertilizers, food elements are covered with chelating agents and so called kept. So that the chelating agent, as a rake and protector, keeps the food element in it so that it can be more easily absorbed by the plant. Therefore, the chelate form of an element is absorbed faster by the plant compared to its normal form and increases the efficiency of the fertilizer and more and better absorption of elements.

In chemistry, chelation is a process in which a chemical compound (ligand or chelating agent) is combined with a metal ion and holds it tightly. A substance that forms a more stable structure by binding to metal ions and food elements is called a chelating agent. This chelating agent forms a complex that includes metal ions and atoms and molecules attached to it.

Chelating Agents

Finally, the purpose of chelating elements is for the plant to obtain the desired element. Chelated fertilizers should facilitate and provide the absorption of nutrients through the roots or leaves of plants. Because chelated fertilizers have different effects and efficiency according to the type of chelating agent and production process. The chelated fertilizer is more effective, which shows good performance in improving the nutrient absorption conditions in plants. As a result, chelating agents have different categories in terms of application and mode of operation.
Among the chelating agents that are more widely used in fertilizers today, synthetic or artificial chelating agents can be mentioned, which include EDTA, DTPA, EDDHA, HEDTA, and NTA chelating agents. For example, the chelating agent EDTA, which includes most of the chelating fertilizers available in the market, is mostly used for foliar spraying, and the chelating agent EDDHA is used for soil application and should not be used as foliar spraying.
Other chelating agents include lignosulfonates, humic and fulvic acids, which have the property of chelating elements and are mainly used in soil applications due to their molecular size and high weight.
The chelating agent of organic acids and amino acids are also other chelating agents that have high absorption capability and are also used as foliar and soil applications.
Any of the listed ligands or chelating agents, when combined with a micronutrient, can form a chelated fertilizer. Chelated micronutrients are protected from oxidation, precipitation and immobilization under certain conditions, because the ligand molecule can form a ring that surrounds the micronutrient element. The rake-like method in which the micronutrient binds to the ligand changes the surface properties of the micronutrient and improves the absorption efficiency of the micronutrient in foliar or soil applications. It is important to pay attention to the type of consumption of these chelates in agriculture. Because if you don't follow the way of consumption, you won't get the right result.

Stability of Chelates


The strength of chemical bond between ligand and metal ion in chelated fertilizers depends on the type of ligand, type of ion and pH of fertilizer and soil. The stronger the bond, the more stable the metal ion, and each chelating agent has a different stability during operation. First of all, at certain pH levels, chelate complexes are not permanently stable, that is, the ligand tends to dissociate from the metal ion. Therefore, it is important to choose the type of chelated fertilizer according to the plant and soil conditions. For example, in some areas with high alkaline pH, it is necessary to select the type of chelating agent specifically. And the chelate fertilizer can be absorbed by the plant simultaneously through foliar spraying and rooting to solve the lack of elements.

 

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