How we calculate
Fertilizer rate = nutrient rate ÷ nutrient share in the grade. A 20-0-20 fertilizer has 20% N, 0% P₂O₅ and 20% K₂O.
Example
To apply 90 lb/acre of N with 20-0-20, use 450 lb/acre. On 10 acres that is 4,500 lb, or 90 bags of 50 lb, which also supplies 90 lb/acre of K₂O.
Tips
- Base the rate on a soil test and local extension advice.
- Split large nitrogen rates.
- Calibrate the spreader first.
Frequently asked questions
What do the three numbers mean?
The percentages of N (nitrogen), P₂O₅ (phosphate) and K₂O (potash), in that order.
Does it work for lawns and gardens?
Yes. One acre is 43,560 sq ft, or follow the per-1,000 sq ft rate on the bag.
See also
Results are estimates for information only and are not financial, legal or medical advice. Rates, taxes and fees vary — confirm with a professional or your lender.