Will my nitrogen source affect the PH?

  Added by: MedMan  Last edited by: MedMan  Viewed: 101 times  Rated by 3 users: 7.50/10
Contributed by: diels alder

The source of nitrogen in your fertilizer affects the pH of the medium you are growing in. The standard of measure of how acidic/basic a source is, is calcium carbonate, a common water mineral. Calcium carbonate is the major contributor of water alkalinity, the capacity for water to 'soak up', or buffer, acidity in water and lead to a high pH.

Note that it is much easier to lower the pH of water through the acidity of a given nitrogen source than it is to raise it, as nitrates are less basic than ammonium is acidic.

N Source Potential acidity Potential Basicity
Ammonium sulfate 2,200 0
Urea 1,680 0
Diammonium phosphate 1,400 0
Ammonium nitrate 1,220 0
Monoammonium phosphate 1,120 0
Calcium nitrate 0 400
Potassium nitrate 0 520
Sodium nitrate 0 580

Potential acidity = # of lbs of calcium carbonate needed to neutralize acidity of one ton of source.

Potential basicity = one ton of source has same effect as this many lbs of calcium carbonate.
  Last modified: 19:56 - Jan 16, 2002 

faq:1208 "Will my nitrogen source affect the PH?"