To calculate the total gallons of chemical injection to achieve a concentration of one part per million (ppm) follow these steps:

1. Determine the chemical’s weight per gallon. If you do not know, consult your chemical suppliers.
   
   
2. Determine the pounds of active ingredients or nutrient per gallon. To do this, multiply the manufacturer’s stated percent of active ingredient by the chemical’s weight per gallon.
   
   
3. Divide 2.72 by the pounds of active ingredient per gallon. This equals the gallons of chemical injection required per acre foot to equal one ppm.
   
   
4. To determine the gallons of chemical injection per 100,000 gallons of water, multiply the result in Step 3 by 0.31.

CAUTION: The injection of chemicals into an irrigation system may be governed by local, state or federal ordinance. Please consult appropriate authorities before proceeding.