N:P ratio or NO3:PO4 ratio? - Fertilizing

Laith · 09-10-2004, 07:56 AM

I've read that an estimated ratio of 10:1 seems to work pretty well for N:P, at least as a starting point...

But now I have a doubt: are we talking about N & P or NO3 & PO4?

Robert B · 09-10-2004, 08:21 AM

The ratio refers to N and P.

Robert.

gpodio · 09-10-2004, 09:40 AM

I think it can be used for both probably. I mean NO3 is what we dose to provide N for the plants, we don't really look at other nitrogen sources such as ammonia, and PO4 is what we use as a source of P, so it should be valid for both if that's what you are dosing to provide these two elements, at least in this context.

Giancarlo Podio

Edward · 09-10-2004, 09:54 AM

Quote:

Originally Posted by Laith

are we talking about N & P or NO3 & PO4? :?

Yes, this is confusing. Some research been done with N:P and some with NO3:PO4.

N:P of 10:1 = NO3:PO4 of 10:0.69

Usually, in this hobby, we use NO3:PO4 because our test kits measure NO3 and PO4. In practice, ratio NO3:PO4 of 10:0.69 works great for plants. Keeping it that way is another matter. To maintain this ratio in the water column, dosing NO3:PO4 of 10:1 to 10:3 is needed.

Edward

Laith · 09-11-2004, 02:42 AM

ok, thanks!

Rolo · 09-11-2004, 02:10 PM

Actually I've read that the 10:1 is for NO3:PO4 only. Then somewhere else that 16:1 is the N: P ratio.

dennis · 09-11-2004, 02:14 PM

well, if you adjust Edward's 10:.69 ratio you get 15:1 N:P. Maybe that has nothing to do with it

Rolo · 09-11-2004, 06:24 PM

Yeah Dennis, it was acutally 15 not 16.

But isn't the 10:1 for NO3:PO4 and 15:1 for N: P? Edward had it the other way around.

plantbrain · 09-12-2004, 03:53 AM

MOST of the submersed aquatic macrophytes(SAM) have a ratio of 10:1 N:P.

We dose NO3/NH4 and PO4.

16:1 comes from algae, the redfield ratio , we are not growing marine phytoplankton last time I checked here which is what Refield was looking at.

Issue number #2.

Plants might have this ratio for many reason's out in nature, they might have far more or less depending on if they are limited and in terms of luxury uptake, perhaps even 100X more/less.

I still feel ratios are fine but have a very wide range in most cases.

Regards,
Tom Barr

dennis · 09-12-2004, 06:18 AM

My htinking about ratios is that they are only important to you. I feel, at lesat so far inlmy limited experience, that a tank seems to have a raatio that it likes. That ratio may or may not work for another tank and if it works, it is mearly chance. I agree that there is probably a range of ratios that will cover most tanks but yuo will still need to tailor you specific one, that may change over time.