A chelate carries far less of the element by weight than the equivalent sulphate, and costs more per kilogram. Here is what the published assays actually say, and how to compare the two honestly.
The short answer. On our own published figures, EDTA chelates carry roughly 6–15% of the element, while the equivalent sulphate salts carry roughly 19–33%. So a kilogram of chelate delivers between a third and a half as much of the nutrient as a kilogram of sulphate. Whether that is worth paying for is a question about your application, not about the chemistry alone — and it is a question we would rather answer against your process than in general.
| EDTA chelate | Element content | Sulphate salt | Element content |
|---|---|---|---|
| EDTA Zn (Zinc) | 12-14% Chelated Zn | Zinc Sulphate Monohydrate | 33% Zn |
| EDTA Fe (Iron) | 12-13% Chelated Fe | Ferrous Sulphate Heptahydrate | 19-20% Fe |
| EDTA Mn (Manganese) | 12-13% Chelated Mn | Manganese Sulphate Monohydrate | 31-32% Mn |
| EDTA Cu (Copper) | 14-15% Chelated Cu | Copper Sulphate Pentahydrate | 24-25% Cu |
Every figure in this table is the grade published on that product’s own page on this site. Nothing here is estimated.
In a sulphate the element is a straightforward part of a small molecule. In an EDTA chelate the element sits inside a much larger organic molecule that wraps around it. That surrounding molecule is most of the weight. You are not buying less product; you are buying a different kind of product, in which the element is held rather than simply dissolved.
Take the delivered price per kg and divide by the element fraction. A chelate at 12% and a sulphate at 33% are not comparable per kilogram of bag; they are comparable per kilogram of the element inside it. Our nutrient cost comparison calculator does that arithmetic on any two products in our range and shows the working, so the comparison can be checked rather than taken on trust.
That calculation tells you the cost side and nothing else. It does not tell you which product suits your process, and it should not be read as if it did.
The honest answer is that this is decided by the application, and by facts about your own situation that we cannot see from here: how the product is applied, what it is mixed with, the water or soil it has to work in, what your specification or your customer’s specification demands, and what the finished product has to cost. Any supplier who answers that question without asking about your process is guessing.
Tell us the application and we will tell you what we would supply and why. Where a sulphate does the job, we will say so — we manufacture both, so we have no reason to steer you to the dearer one.
Six EDTA chelates — EDTA Zn (Zinc), EDTA Fe (Iron), EDTA Mn (Manganese), EDTA Cu (Copper), EDTA Ca (Calcium) and EDTA Mg (Magnesium) — and the full range of sulphate salts, all manufactured at our works at Changodar, Ahmedabad. The complete lists are on the EDTA chelated micronutrients and sulphates category pages.
Working to a specification? Send it and we will tell you plainly whether we can meet it before you commit to anything.
Tell us the application and the quantity. We manufacture both, so the recommendation is not a sales pitch.