Nutrient content of water soluble hydroponic fertilizers
The nutrient content of water soluble hydroponic fertilizers is not always clearly indicated on packaging. It is fine that fertilizer companies take control out of our hands by formulating nutrient solutions for us, but there are times that we want to take control ourselves. That usually happens when things are not working out and yields start to fail our expectations. Often growers feel fertilizer companies hold their cards very close to their chests.
I am amazed at how little information is available of the nutrient content of fertilizers there is.
Some companies list their fertilizers as a recipe with two mixes which must be added to a certain amount of water. That is ok for DIY growers, but for commercial hydroponic farmers I think we need a little more information. Professional growers need to know that what they are buying is the right thing and since farming is a dynamic process, things change daily and we need to react to these changes with insight.
There are often times that we have to add an element (nutrient) to the plant due to some biochemical reaction that causes a deficiency or toxicity (via an interaction with another element). For instance, iron (Fe) is an element that is mobile and we can see the deficiency symptoms quickly. With complex water soluble hydroponic fertilizers or recipes, you cannot just add them since you will be added all the other elements as well. You have to know the precise concentration of Fe in the fertilizer to know how much you must add without causing additional problems. It does not help adding too little since it will not correct the problem, that is also money down the drain.
In any case, the exact composition of fertilizers is only important to commercial hydroponic farmers, scientists testing nutrient variations and hobbyists experimenting. I just wish more information is available and clear. For instance, the concentration of P and K is very confusing. Sometimes it is listed as %K or %P, or as % and %. It is not always clear which of the two and in terms of the value it makes quite a difference for the dollar you spend for the content. There is only 36.52% K in and 35.71% P in . Big commercial hydroponic farms using tonnes of fertilizers will see the difference not only in their pockets but also in the reactions of the plant. Thinking you increased the K content with 10 ppm but it only went up with 6.4 ppm will have an effect on yields. Especially if there was a deficiency.
This table is not complete, that is obvious. But I think it is a good start. As I receive more data on water soluble hydroponic fertilizer combinations I will add them. Just a note of warning. This is just water soluble fertilizers and not fertilizers that are used in open field conditions. They are mostly standard and the ranges are limited.
The table can be downloaded for free >> here <<. This is an Open Office spreadsheet, .odt extension so you can open it in Microsoft Excel as well. Just save it again with the .xlxx extension. As usual please let me know if there are mistakes so I can correct them.