"Korleone" wrote in message
...

Hello.

I have some simple questions about fertilizers.

For the last few days I've spent a lot of time figuring out ideal
profiles for fertilizers for indoor tomatoes.

I wrote a program that figures out how to mix seperate fertilizers
together to better match your custom fertilizer profile. Which is
great (and bloody genius), but..


Why? What is the need for this?

.figuring out an ideal fertilizer profile for tomatoes is difficult.
Lots of info online is contradictory.

Typically, tomato fertilizers on the shelf are 3-2-5.

For instance, Phostrogen Plant Food and Chempak Tomato Food are close
to a 3-2-5, have trace elements and seem like great plant foods for
tomatoes.

But the fortnightly dose is 516ppm-328ppm-829ppm. So all at once, that
concentration is added to the soil. Why isn't that a problem?


Why would it be?

(That was the first simple question. Here comes the second.)


Why is it better to feed a plant with emphasis on a particular
nutrient?


It isn't necessarily. Sometimes it is.

Isn't the plant going to take what it needs? In other words, if you
use a balance fertilizer, say, 6-6-6 at 100ppm, and the plant needs
more Potassium, couldn't you just increase the concentration of 6-6-6
to, say, 150ppm instead of changing to a fertilizer that's, say, 6-6-8?


Simply what I'm asking is: does a plant take only what it needs from
the soil, or does a plant eat everything it's given?

Different plants require different proportions of nutrients. For example
things with lots of green leaves (eg grass) need more nitrogen. Also overdose
can be harmfull and not just at the level that is toxic, for example carrots
grow strange, twisty and bifurcated if over fertilised. The shotgun approach
(hit 'er with some more of everything) is at best wasteful and can be
disasterous.


If the first is true, then we need only use a balanced fertilizer and
increase the ppm to suit. If the second is true, then altering the
ratio and the ppm would be necessary.

Btw, I know most of you are organic growers. This is just an exercise
for me, to figure this out. So please, you don't need to tell me of
the evils of non-organic fertilizers.


One key thing you have left out is the existing nutrients available in the
soil. Plants don't get only what is added as fertilser, nutrients come from
many sources, some plants even have little mates that make nutrients for them.
Also different soils bind nutrients to various degrees. This means there is
no such thing as "ideal" tomato fertiliser or anything else fertilser. And
texture and drainage make a huge difference. And lots more, this matter is
much deeper than it first looks.

Writing your own software is admirable. May I suggest that whatever you write
will be far more useful and you will learn far more from doing it if you
understand the subject matter that you are modelling or work from a
specification written by someone who does. There is much more to good
software than kool kode and a fAnCy iNTerFAce.

David