RE: PPM Calculations


I posted a ppm formula last year but I think it only tells you the resulting
ppm of the diluted fertilizer & water mix. You may be able to work backward
from the lb/A = ppm x 2 formula, then divide by 435? So would that be 

40ppm x 2 =80 lbs/A
80 lbs/A divided by 435 = 0.184 lb/100sq ft?
Then round & say that equals 1 fifth lb. of 100% N. Wouldn't that mean 1 lb of
20-0-0 = 1/5 lb of 100-0-0?

The mixed fertilizer solution formula was:

Oz of fertilizer divided by gallons of water, x grade of fertilizer x 75 = PPM

Example:

1 oz
----------- x 20 x 75 = 15ppm
100 gallons


(15ppm divided by 1500) x 100 gal = 1 oz


40ppm
---------------- x 100 gallons = 2.666 oz
(20 grade x 75)

Don't know how 40ppm of a solution would relate to increasing your soil ppm
though.

Hope this helps.

Mark



-----Original Message-----
From: owner-pumpkins@hort.net [o*@hort.net] On Behalf Of
vince
Sent: Thursday, April 28, 2005 1:18 PM
To: pumpkins@hort.net
Subject: PPM Calculations


Ok, I've seen the posts on how to do this but I need a
simplified version.  Here's my question. My soil test says that
I have 20 ppm nitrogen.  I want to bump it to 60 ppm.  How many
pounds of 21% nitrogen fertilizer do I put per 100 square feet
to add 40 ppm of n to my soil???

This is a test of your math agility.

Now can you give me a single equation to solve this generally
in the form of

(Number of ppm of amendment you want to add)
Times
(Strength of Ferilizer in Percent}
Times
(Conversion Factor)

Equals
 = Number of pounds fertilizer/100Sq ft.

This is really testing those brain cells.....

vince
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