Hoo-boy... Understanding Fertilizer Numbers: N-P-K ...NOT!

love_the_yard(z9A Jax FL)March 21, 2012

"Understanding Fertilizer Numbers: N-P-K" - NOT!

Here is a link that might be useful: Understanding Fertilizer Numbers: N-P-K

Thank you for reporting this comment. Undo
fortyonenorth(6b)

These numbers represent the percentage (by weight) of the three major nutrients required for healthy plant growth, always in the same order: nitrogen-phosphorus-potassium (N-P-K)

Shouldn't that be "Nitrogen, Phosphate and Potash?"

    Bookmark   March 21, 2012 at 11:14AM
Thank you for reporting this comment. Undo
rina_

Nitrogen = N
Phosphorus = Phosphate = P (Technically, phosphorus is an element (P), and phosphate is a molecular anion (PO4_3-), part of phosphoric acid (H3PO4). In (medical) diagnostic testing, they're often used interchangeably, sometimes called "inorganic phosphorus." It's also an essential plant nutrient, so on fertilizers you'll see the phosphorus content expressed as a percentage (by weight) measured as P2O5, the anhydride of phosphoric acid.
Potassium = Potash = K ( from latin kalium)

    Bookmark   March 21, 2012 at 7:48PM
Thank you for reporting this comment. Undo
tapla (mid-MI z5b-6a)

In order to determine the actual weight of P & K in fertilizers, an extra step is required. A fertilizer formula reports phosphorus as P2O5, not actual phosphorus (P), and potassium is reported as K2O, not actual potassium (K). To convert P2O5 to P, multiply the listed P2O5 % by .43, and to convert K2O to actual K, multiply the K2O value by .83.

3:1:2 ratio fertilizers actually supply nutrients in a 3:.43:1.7 ratio, which squares rather nicely with the average actual NPK usage.

Your fertilizer's NPK RATIO is a much more important consideration than its NPK %s.

Al

    Bookmark   March 21, 2012 at 9:45PM
Sign Up to comment
More Discussions
Trying Petunias indoors
I thought that I would try to grow some Petunias indoors,...
nopets
CONTAINER SOILS - WATER MOVEMENT and RETENTION XXII
Hello! Houzz's new format has presented some challenges,...
tapla (mid-MI z5b-6a)
Meyer Exploding in 5-1-1
My meyer lemon in 5-1-1 is just going nuts right now....
Jay Part Shade (Zone 10B, S21, Los Angeles)
Help with 1:1:1 - weight and sourcing in the UK
I've just clicked that weight is going to be an issue...
containergardenerbeginner
Zuchinni/Courgette, lots of leaf growth, but not many fruit
Hi, My courgette plant is doing great in terms of leaf...
bopwinter
© 2015 Houzz Inc. Houzz® The new way to design your home™