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Clemson Ag Service Lab - Soil Testing

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NPK Recommendation Calculator

This web app was developed to provide N, P, and K fertilizer recommendations for agricultural, turf, silvicultural, and home/garden producers based on Clemson Extension recommendations. ( for more)

Crop and Soil

Need help? Click here for more information on soil codes in South Carolina.

Soil Test Levels

lb P2O5 per acre

lb K2O per acre

Fertilizer Recommendations

Note: Recommendations here do not precisely match those currently in place on official Clemson Ag Service Lab results. The recommendations here are generated from equations fitted to the tabulated recommendations used by the Lab.


This URL:
Fert Recs Csv:
Fert Level Lookup Csv:
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APA Citation:
Kirk, Kendall R., Alford, Shannon R., Croft, Jonathan, and Davis, Charles (2022). NPK Recommendation Calculator. Clemson University Cooperative Extension. Retrieved from

(c) 2022 Clemson University Cooperative Extension

The authors are grateful for the many individuals that helped to review this tool during its development. Thank you to Dan Anco, Justin Ballew, Matt Burns, Brian Callahan, Jay Crouch, Matt Fischer, Ben Fogle, Rob Last, Fleming McMaster, Chris Ray, Scott Sell, Bryan Smith, Zack Snipes, and James Thomas.

Disclaimer: This 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.

We are dedicated to making this a valuable tool for you. If you have suggestions for improvements, please contact us by email.