A nitrogen figure, a P2O5 figure or a chelated zinc percentage is only useful if you know exactly what it measures and can check it. Here is how to do both before money changes hands.
The short answer. First confirm what the figure measures: an element, an oxide such as P2O5 or K2O, or the purity of the whole compound. Then ask for the certificate of analysis format, test a sample independently using a method that matches your specification, and write the figure into the purchase order as a minimum.
Three kinds of figure appear on fertilizer and micronutrient grades, and they are not interchangeable.
| Written as | What it measures | Example from Taskon’s published grades |
|---|---|---|
| Element content | How much of one element is in the product | Zinc Sulphate Monohydrate: 33% Zn |
| Oxide content | A nutrient expressed as its oxide, the usual convention for phosphorus and potassium | Di Ammonium Phosphate: 18% N, 46% P2O5 |
| Chelated content | How much of the element is held in chelated form | EDTA Zn (Zinc): 12-14% Chelated Zn |
| Purity of the compound | How much of the product is the named compound | Zinc Oxide: 99% min |
Comparing a purity figure with an element figure, or an oxide figure with an element figure, gives a wrong answer even when every number is true. Ask the supplier which kind each figure is if the grade does not say.
Where a grade is written as a range, such as 19-20% Fe, plan against the lower figure. That is the minimum the supplier is standing behind.
Send a sample to an independent laboratory before a large order. Ask for the same basis as the claim, element, oxide or chelated content, and a method that matches your specification, so the figures can be compared. For chelated micronutrients, make sure the laboratory reports chelated content and not only total content, because the two can differ.
Write the figure into the purchase order as a minimum, on the same basis as the claim. Then check the batch certificate of analysis for the consignment against it, and test on arrival for a first order.
Every Taskon product page shows its published grade, and the guaranteed analysis where one is published. Send your specification with the enquiry and we will confirm, parameter by parameter, whether we can supply against it. A batch certificate of analysis travels with every consignment. To compare two grades on the cost of the element they carry, use the nutrient cost comparison calculator.
Not sure which grade suits your process? Describe the application and we will tell you what we would supply, and why.
Send us the product, the quantity and where it is going.