# Calculating Fertilizer Rates

## Steps to Calculating Fertilizer Application Rate

Example is for a 40 foot by 100 foot lawn area, using a 20-2-2- fertilizer.

## Fertilizer Application Rate Table

Because soil test recommendations for any given soil do not exactly match a fertilizer, select a fertilizer that gives comparative amounts of nitrogen, phosphorus and potassium as recommended by the soil test. In fertilizer application, it is most important to match the nitrogen requirement and compromise some for the phosphorus and potassium. The amount of fertilizer to apply that will give the recommended amount of nitrogen can be obtained from the following table:

 Table 1. Amount of fertilizer to apply based on actual nitrogen recommendations Nitrogen Rage: 0.1 pound N per 100 square feet 0.2 pound N per 100 square feet 1 pound N per 1,000 square feet Fertilizer Grade pounds fertilizer to apply per 100 square feet pounds fertilizer to apply per 100 square feet pounds fertilizer to apply per 1000 square feet 45-0-0 (urea) 0.2 0.4 2.2 37-3-3 0.3 0.5 2.7 36-6-6 0.3 0.6 2.8 33-0-0 0.3 0.6 3.0 32-4-4. 32-3-10 0.3 0.6 3.1 30-4-4, 30-0-10 0.3 0.7 3.3 28-3-3, 28-4-6 0.4 0.7 3.6 27-7-7, 27-3-3 0.4 0.7 3.7 25-5-5, 25-3-12 0.4 0.8 4.0 24-8-16, 24-0-15 0.4 0.8 4.2 22-4-4, 22-6-3 0.5 0.9 4.5 21-0-0, 21-3-12 0.5 1.0 4.8 20-20-20, 20-4-8 0.5 1.0 5.0 19-19-19,19-11-12 0.5 1.0 5.3 18-6-12, 18-3-6 0.6 1.1 5.6 16-8-8, 16-4-8 0.6 1.3 6.3 15-15-15, 15-5-5 0.7 1.3 6.7 13-3-9, 13-25-12 0.8 1.5 7.7 12-12-12, 12-4-4 0.8 1.7 8.3 10-10-10, 10-20-10 1.0 2.0 10.0 10-5-5, 10-10-20 1.0 2.0 10.0 6-12-12, 6-2-0 1.7 3.3 16.7 5-10-10, 5-10-5 2.0 4.0 20.0 Example:If the N (nitrogen) recommendation is for 0.1 lb. N/100 sq. ft. and the fertilizer grade selected has a ratio of 18-6-12 (column 1), apply 0.6 lb. of this fertilizer per 100 sq. ft.

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