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Common Fertilizers Used in Virginia: Secondary and Micronutrients



Authors as Published

Mark Reiter, Associate Professor and Extension Soils and Nutrient Management Specialist, Eastern Shore Agricultural Research and Extension Center, Virginia Tech


Secondary macronutrients are used in relatively large quantities by plants for optimal growth and are sulfur (S), calcium (Ca), and magnesium (Mg). Micronutrients on the other hand are needed in much smaller quantities than both primary and secondary macronutrients; however, micronutrients are still essential for plant growth. Often, soils in Virginia contain enough micronutrients and fertilizer amendments are not warranted. Micronutrients include iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), boron (B), chloride (Cl), molybdenum (Mo), cobalt (Co), sodium (Na), silicon (Si), selenium (Se), nickel (Ni), and Vanadium (V) (Havlin et al, 1996). Soil pH plays a large role in soil availability of secondary and micronutrients; therefore, proper soil testing and lime amendments are necessary to ensure adequate nutrient solubility within the soil system. Visit the Virginia Tech Soil Testing Lab website for additional publications and resources regarding proper soil sampling techniques and recommendations at: This publication will outline some possible secondary macronutrient and micronutrient fertilizer sources. However, numerous formulations and blends are available from many different companies and dealers. Regardless of product or source used, read the product’s label carefully and follow all recommendations for foliar and/or soil application.

Table 1. Common fertilizer sources used in Virginia for secondary macronutrient and micronutrient applications.

Fertilizer Material Chemical Formula Nutrient Percent Other Nutrients (%)
Calcium sources   % Ca  
Calcitic lime CaCO3 31.7  
Calcium nitrate Ca(NO3)2 21.0 15% N
Dolomitic lime CaCO3·MgCO3 21.5 11.4% Mg
Gypsum CaSO4·2H2O 22.5 16.8% S
Hydrated lime Ca(OH)2 46.1  
Marl CaCO3 24.0  
Polyhalite K2SO4·MgSO4·2CaSO4· 2H2O 12.0 14% K2O, 19% S, 4% Mg
Superphosphate, normal Ca(H2PO4)2 18-21 16-20% P2O5
Superphosphate, triple Ca(H2PO4)2 13-15 44-48% P2O5
Sulfur sources   % S  
Ammonium sulfate (NH4)2SO4 24 21% N
Ammonium thiosulfate (NH4)2S2O3 26 12% N
Fertilizer Material Chemical Formula Nutrient Percent Other Nutrients (%)
Gypsum CaSO4·2H2O 16.8 22.5% Ca
Polyhalite K2SO4·MgSO4·2CaSO4· 2H2O 19 14% K2O, 19% S, 4% Mg, 12% Ca
Potassium magnesium sulfate K2SO4·2MgSO4 22.0 22% K2O, 11% Mg
Potassium sulfate K2SO4 17-20 48-54% K2O
Potassium thiosulfate K2S2O3 17 25% K2O
Sulfur, elemental S 90-100  
Urea-sulfur CO(NH2)2+S 10-20 36-40% N
Urea-ammonium nitrate, sulfur blend Various 3-5 24-28% N
Zinc sulfate ZnSO4·H2O 17.8 36.4% Zn
Magnesium sources   % Mg  
Dolomitic lime MgCO3·CaCO3 11.4 21.5% Ca
Epsom salt MgSO4·7H2O 9.6 13% S
Magnesia MgO 55.0  
Polyhalite K2SO4·MgSO4·2CaSO4· 2H2O 4 14% K2O, 19% S, 12% Ca
Potassium magnesium sulfate K2SO4·2MgSO4 11.2 22% K2O, 22% S
Boron Sources   % B  
Borax Na2B4O7·10H2O 11.3  
Sodium octaborate, Borate 65 Na2B8O13·4H2O 20-21  
Sodium pentaborate Na2B10O16·10H2O 18  
Sodium tetraborate, Borate 46 Na2B4O7·5H2O 14-15  
Boric acid H3BO3 17.0  
Boron frits Frit 2-11  
Solubor Na2B4O7·5H2O + Na2B10O16·10H2O 20-21  
Molybdenum sources   % Mo  
Ammonium molybdate (NH4)6Mo7O24·2H2O 54 7% N
Molybdenum frits Frit 1-30  
Molybdenum trioxide MoO3 66  
Sodium molybdate Na2MoO4·2H2O 39  
Copper ammonium phosphate Cu(NH4)PO4·H2O 32 7.2% N, 36.5% P2O5
Copper chelates NaCuHEDTA 9  
Copper sources   % Cu  
Copper chelates Na2CuEDTA 13  
Copper frits Frit 40-50  
Copper sulfate CuSO4·5H2O 25.5 12.8% S
Manganese sources   % Mn  
Manganese chelate MnEDTA 12  
Manganese frits Frit 10-35  
Manganese oxide MnO 41-68  
Manganese sulfate MnSO4·4H2O 26-28 14.4% S
Zinc sources   % Zn  
Zinc carbonate ZnCO3 52  
Zinc chelates NaZnHEDTA 9  
Zinc chelates Na2ZnEDTA 14  
Zinc oxide ZnO 78  
Zinc phosphate Zn3(PO4)2 51 18.4% P2O5
Zinc sulfate ZnSO4·H2O 35 17.9% S
Iron Sources   % Fe  
Iron ammonium phosphate Fe(NH4)PO4·H2O 29 7.5% N, 38% P2O5
Iron ammonium polyphosphate Fe(NH4)HP2O7 22 5.6% N, 57% P2O5
Iron chelates NaFeEDTA 5-14  
Iron chelates NaFeEDDHA 6  
Iron chelates NaFeDTPA 10  
Iron frits Frit 30-40  
Iron sulfate, Ferrous sulfate FeSO4·7H2O 19 11.5% S


Alley, M.M. 2000. “Part VIII: Fertilizers.” Agronomy Handbook. Publication 424-100. Virginia Cooperative Extension, Blacksburg.

Gowariker, V. 2009. “The Fertilizer Encyclopedia.” John Wiley & Son, Inc., Hoboken, New Jersey. Havlin, J.L.,

J.D. Beaton, S.L. Tisdale, and W.L. Nelson. 1999. “Soil Fertility and Fertilizers, 6th Edition.” Prentice Hall, Upper Saddle River, New Jersey.

International Plant Nutrition Institute. 2015. “Boron.” Last Accessed April 8, 2020.

International Plant Nutrition Institute. 2019. “Nutrient Source Specifics.” Last Accessed April 3, 2020.

Sirius Minerals, LTD. 2019. “POLY4 Granular Product Specification Sheet.” Last Accessed April 2, 2020.

Binford, G.D. 2006. “Chapter 8: Commercial Fertilizers.” The Mid-Atlantic Nutrient Management Handbook. Publication MAWP-0602. Last Accessed April 3, 2020.


Funding for this work was provided in part by the Virginia Agricultural Experiment Station and the Hatch program of the National Institute of Food and Agriculture, US Department of Agriculture.

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Publication Date

April 10, 2020