What the heck is NPK in fertilizers?


Every package of fertilizer lists an NPK rating on the label. So what exactly does it mean? It is the percentage of Nitrogen (N), the percentage of Phosporus(P) and of Potassium(K) found in that particular mixture of fertilizer; the 'backbone' nutrients found in all fertilizer. garden fertilizer My hydroponics fertilizer shows "10-8-22" for an N-P-K rating meaning that by volume it contains 10% Nitrogen, 8% Phosphorus and 22% Potassium. Since this adds up to 40%, it means that the remaining 60% of the fertilizer is made of inert compounds. This extra inert matter helps dilute harsh chemical nutrients in the fertilizer protecting plant roots.

So don't take the rating too literally for it is really just a general guideline as to the potency of the fertilizer.

In fact the same fertilizer in liquid form will have a lower overall N-P-K rating than it's exact counterpart in powder form due to the fact that in liquid it is a little more diluted by volume and this rating is also misleading because it does not show any other nutrients at all such as the all-important trace elements.

For example, my favorite nutrient powder is 10-8-22 which seems rather low for a complete fertilizer when in fact it contains many other nutrients making it a complete fertilizer but you would never know this by the N-P-K rating alone. Another fertilizer with the same N-P-K may lack the other nutrients and would not be able to be used alone.

So, when checking the quality of a fertilizer, use N-P-K as a very rough guideline and always check the actual percentage of all nutrients listed on the back of the package.


If you like this website, consider downloading this free toolbar for your browser.

Previously I featured a conduit toolbar with radio for download but replaced it with the Alexa toolbar featuring website anaysis tools along with real-time related links to facilitate searching. Alexa is owned by Amazon and will not embed spyware into their toolbar. It's safe and it's free!


Site Search

Automatically Translate this Webpage

[?] Subscribe To
This Site

Add to Google
Add to My Yahoo!
Add to My MSN
Add to Newsgator
Subscribe with Bloglines

Bookmark and Share

| Top of NPK page | Worrm Castings |
| Homepage | Contact Us | Policies | About Us | Privacy Policy | Advertise |
Copyright© Hydroponics-At-Home.com 2006-2012 All Rights Reserved.