All you need to know about chelate fertilizer
Each summer resident has at least once heard something about chelate fertilizers, or chelates. But what is it really? How do chelate fertilizers differ from the usual mineral fertilizers? Why are chelates much more effective? Indeed, in some cases, conventional fertilizers, in general, do not work, and chelated ones successfully solve the problem. All this will be discussed today under the heading “Question and Answer” from the company “Buyskie Fertilizers”.
Question: What is a chelated form of trace elements or chelates? What is their advantage relative to sulfate trace elements? This question will be answered by the head of the agrochemical service of OAO Buisky Chemical Plant Belozerov Dmitry Alexandrovich
Answer: the chelated form of trace elements is a compound of metals (Fe, Zn, Cu, Mn, etc.) with an acid of organic origin, for example, ethylenediaminetetraacetic acid (EDTA) or diethylene triamine pentaacetic acid (DTPA). There is a list of such acids. They can be either artificially synthesized (EDTA, DTPA, EDDHA, etc.), or of natural origin (amino acids) obtained by extraction from organic raw materials.
Common trace elements that are widely used in agriculture are mineral salts formed by nitric, often sulfuric acid. For example, iron sulfate (iron sulfate), copper sulfate (copper sulfate) - salts of sulfuric acid.
The main question - why invent new drugs that are more complex in production and more expensive?
Let us consider one of the soil characteristics that plays a crucial role in the metabolism and affects the course of chemical reactions in the soil - this is acidity (pH).
Soils are different for everyone. Someone is acidic, somewhere alkaline. The effectiveness of fertilizers is directly dependent on acidity.
As we see in Fig. 1, the best range of assimilation of batteries is from 6.5 to 7.5 (maximum bandwidth). This applies to both soil (soil solution) and water (irrigation solution). Further, on both sides of the increase or decrease in pH, the action of macro- and microelements weakens or completely disappears.
For example, on carbonate soils with a pH from 7.5 to 8.5, phosphorus and boron are not absorbed by plants, as they form new compounds insoluble in the soil and become inaccessible. And despite the fact that phosphorus-containing fertilizers (superphosphate, ammophos, azofoska) can be applied to such soil every year and chemical analysis of the soil can show multiple excesses of permissible phosphorus norms, plants experience a deficiency in this element (data confirmed by soil and functional plant diagnostics) .
Acidic soils should be deoxidized with liming, and carbonate (alkaline) acidified with gypsum and try to bring the pH to 6.5-7.5.
In practice, in a garden, this is not always possible to implement. But you can pick up fertilizers that "work" in more severe conditions.
For macronutrients, the problem is solved through the use of granular organic mineral fertilizers (WMD). The organic shell of the granule does not actively interact with the soil environment and the elements inside the granule, while maintaining nutrition for plants in any conditions.
By micronutrients, a solution was found in the use of chelating compounds that are stable in a wide pH range and provide plants with the necessary metals. So, DTPA iron chelate is absorbed by plants in the pH range 2.0–9.0, EDTA zinc chelate - pH 2.0-11.0, EDTA copper chelate - pH 4.0-11.5, EDTA manganese chelate - pH 3 , 0-11.0 (data from the research laboratory of BHZ OJSC according to Helatem).
Consider the mechanism of the behavior of trace elements in the soil solution (in the irrigation solution similarly):
A) Iron sulfate (iron sulfate) has the chemical formula FeSO47N2A. When dissolved in water, this compound decomposes (dissociates) into positively and negatively charged Fe ions2+ and (SO4)2- .
At this point, it is important to know and understand that plants do not fully absorb chemicals from water or soil solution (FeSO47N2O), but only in the form of cations and ions (Fe2+ and (SO4)2-) Between the plant and the environment, an ion-cation exchange is constantly taking place - this is how plants feed.
Therefore, if you are preparing an irrigation solution in water from a well where carbonates are always present, or you have carbonate soils, an iron cation (Fe2+), as a very active element, easily forms a new compound FeCO3 - iron carbonate.
But it is insoluble in water (does not dissociate), therefore iron becomes inaccessible to plants. Iron from sulphate we lost!
B) Iron chelate DTPA has a more complex formula - C14N19FeN3NaO10. Iron is combined with organic acid by a strong tricovalent bond (chelate is a claw). When it enters a soil solution or water, the molecule also decomposes (dissociates) into an ion and a cation, but in this case the cation is not iron, but hydrogen (H+), and with the ion with a negative charge, the rest of the molecule C14N18FeN3NaO10—. In this form, iron does not interact with the environment, its bonds are closed, and is completely delivered to the plant.
A similar mechanism of assimilation in other chelated trace elements.
Chelated microelements are modern technological fertilizers. Widely used in professional greenhouses and fields, on all technologies of watering and spraying plants. Universal, efficient and convenient to work on all agricultural and ornamental crops.