Fertilizers

Fertilizers• What are the numbers?

– N, P2O5, K2O– “primary” macronutrients

• Nutrients derived from…

Fertilizers

• Secondary macronutrients• Micronutrients

• Nitrogen breakdown

• Organic fertilizers– Kelp meal 0.6-0-1.5

• Organic fertilizers– Feather Meal 12-0-0 to

14-0-0 (different suppliers)

– Slow release!

• Organic fertilizers– Green sand 0-0-3

• lbs/acre ÷ 2.7225 = oz/1,000 ft2

Application Strategy• Soil Test Response

– Preplant Adjustments• pH (liming) 100%

– Dolomitic limestone (CaMg)(CO3)2

– Calcitic limestone CaCO3

• Calcium (Ca) / Magnesium (Mg) 100%– If pH is ok & Ca needed: gypsum CaSO4•2H2O– If pH is ok & Mg needed: Epsom salt MgSO4•7H2O

• Phosphorus (P2O5) 100%• Potassium (K2O) 30 to 50% (unless slow-release)• Nitrogen (N) 30 to 50% (unless slow-release)• Sulfur (S) – Epsom salt or other sulfate fertilizer 100%

– Micronutrients (B, Cl, Cu, Fe, Mn, Mo, Zn)?• Usually not in soil test unless requested (UGA does Zn and

Mn in routine tests); usually not deficient

Application Strategy• Soil Test Response

– Postplant Adjustments• Potassium (K2O) 50 to 70% as sidedress (as-needed for SRF)• Nitrogen (N) 50 to 70% as sidedress (as-needed for SRF)