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Clemson Ag Service Lab - Soil Testing

This web app was developed as a calculator to help agricultural, horticultural, silvicultural, turfgrass, and even home lawn/garden producers evaluate different fertilizer blends for meeting their NPK application requirements in a cost effective and accurate manner.

Calculator outputs depend on user-indicated nutrient application rate and (user-indicated) fertilizers available. Nutrient requirements are input as nitrogen, phosphorus (P₂O₅), and potash (K₂O). Clemson University Extension recommends using a standard soil test to support agronomic recommendation of application rates. Fertilizers available are input percent composition of N, P₂O₅, and K₂O. To determine recommendations for a specific crop and S.C. soil code, visit our NPK Recommendations Calculator, which can pass recommendations back to this web app.

The web app determines blends or mixes from the (user-indicated) available fertilizers that can best meet the required application rates, maximizing ecological and economical benefits. Blend outputs are sorted, beginning with those that best meet the required application rates. Blends for which the application rate of any given nutrient fails to meet the target rate are flagged for under- and over-application to alert the user. Optionally, if the user provides fertilizer prices, blends that equally satisfy nutrient requirements are sorted by price, beginning with the least expensive on a per unit area basis.

The calculator supports two modes of entry. Direct NPK Entry allows the user to evaluate blends for a specific application rate. Guided Entry mode provides use of a worksheet to calculate rates required for a specific application, based on total (seasonal) NPK needs and after deducting other credits, such as litter/manure application, pre-plant application, etc.

Application rates and fertilizer prices can be specified in standard and metric units; output units are set to correspond with input units. Fertilizer price inputs can be entered in a wide range of units, supporting suppliers spanning from those supporting large ag to home lawn and garden.

Be sure to visit our other free fertility-related web apps and calculators from Clemson Precision Ag, including: NPK Recommendations Calculator, Lime Rate Calculator, Soil Acidification Calculator, Drip Fertigation Calculator, Pivot Fertigation Calculator, and Liquid Fertilizer Solution Calculator.

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This web app was developed as a calculator to help agricultural, horticultural, silvicultural, turfgrass, and even home lawn/garden producers evaluate different fertilizer blends for meeting their NPK application requirements in a cost effective manner.
(...click for more)

References:

• Bandel, Allan. Using manure to cut fertilizer costs. University of Maryland Cooperative Extension Fact Sheet 512.
• Camberato, J., Lippert, B., Chastain, J., and Plank, O. (1996). Land application of animal manure. Clemson Cooperative Extension Service. Retrieved from https://www.clemson.edu/public/regulatory/ag-srvc-lab/animal-waste/manure.pdf.
• Chastain, J. P., Camberato, J. J., and Skewes, P. (2004). Poultry Manure Production and Nutrient Content. In CAMM Poultry Training Manual. Clemson Cooperative Extension Service. Retrieved from https://www.clemson.edu/extension/camm/manuals/poultry/pch3b_00.pdf.
• Clemson Ag Service Lab. Fertility recommendations and nutrient management: Agronomy. Clemson University. Retrieved from https://www.clemson.edu/public/regulatory/ag-srvc-lab/soil-testing/pdf/agronomic_crops.pdf.
• Clemson Ag Service Lab. Fertility recommendations and nutrient management: Major nutrients. Clemson University. Retrieved from https://www.clemson.edu/public/regulatory/ag-srvc-lab/soil-testing/pdf/plant-nutrient-levels.pdf.
• Zublena, J. P., Barker, J. C., and Parker, J. W. Swine Manure as a fertilizer source. Publication AG-439-4. North Carolina Cooperative Extension Service.
• Zublena, J. P., Barker, J. C., and Carter, T. A. (1993). Poultry manure as a fertilizer source. Publication AG-439-5. North Carolina Cooperative Extension Service.

APA Citation:
Kirk, Kendall R., Alford, Shannon R., Croft, Jonathan, Davis, Charles, and Smith, W. Bryan. (2022). Clemson Fertilizer Blend Calculator. Clemson University Cooperative Extension. Retrieved from https://www.clemson.edu/extension/agronomy/PrecisionAgriculture/calculators/

(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, 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 additional nominal fertilizers, manure products, fertilizer deductions, or other improvements, please contact us by email.