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Clemson Pivot Fertigation Calculator

This resource was developed to help producers easily calculate the flow rate of liquid fertilizer and injection pump settings needed to fertigate through a center pivot irrigation system. ( for more)

Fertilizer Formulation

Pivot Size

Pivot Name:
Why? Pivot name is optional, but included for your ID purposes if links are emailed.

Help? Generally, radius equals machine length plus endgun throw (if present)

Help? Pivot rotation entered should represent total area intended to be fertigated. Example: If only 1/4 of a full circle pivot will be fertigated, 90° should be entered here.

Pivot Travel Time

* For determining travel times, be sure to use pivot timer settings planned to be used during fertigation.

Speed Setting:
Why? Speed setting is included for your documentation purposes if outputs are emailed.


Fertilizer Rate

Injection Pump

* If you have a pump model not listed that you would like added, please contact us using the link at the bottom of the page and we will try to add it.

Schedule Builder




Fertilizer Density:
N %:
P2O5 %:
K2O %:
4th Nutrient %:
4th Nutrient Abbv:

N lb/gal:
P2O5 lb/gal:
K2O lb/gal:
4th nutrient lb/gal:

Wet Radius:
Wet Acres:
Wet Circumference:
Travel Angle:

Field Capacity:
Time Between Stops, hr:

Fertilizer gpm:
Fertilizer gal/ac:
Fertilizer gal:

Pump Make/Model:

Start DateTime:
End DateTime:

This URL:

Onload fertilizer_select:
Onload component_for_rate_select:
Onload input_lb_per_ac_selected_component:
Onload select_pump_manufacturer:
Onload select_pump_model:
Onload start_dt_final:

Create/Email Links

* Hyperlinks can be created and emailed in this section for direct links to the settings specified above.

Pivot Fertigation Calculator
(c) 2020 Clemson University Cooperative Extension
Author: Kendall R. Kirk, Precision Ag Engineer

Disclaimer: The Pivot Fertigation calculator is brought to you as a free service by Clemson University Cooperative Extension. The accuracy of the calculator is not guaranteed. User assumes all risks and liabilities from its use.

Acknowledgments: This work greatly benefited from the recommendations by and discussions with several individuals. Thank you for your assistance to all of the following: Rob Bates, Alex Coleman, Ben Fogle, Brent Gandy, Daniel Hunter, Spencer McLeod, Walker Nix, Jacob Oswald, Joe Oswald, Alex Samenko, David Segars, and James Thomas.

We are dedicated to making this a valuable tool for you. If you have suggestions for bug fixes, additional nominal fertilizer products, or any other improvements, please contact us by email.