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Calculate fertilizer application rates based on N-P-K ratio and desired nitrogen application.
N-P-K stands for Nitrogen-Phosphorus-Potassium, the three primary nutrients plants need. The numbers on a fertilizer bag (like 20-10-10) represent the percentage by weight of each nutrient.
Lbs Fertilizer = (Area ÷ 1000) × (Desired N lbs ÷ (N% ÷ 100))
Example: For 1 lb of nitrogen per 1000 sq ft using 20-10-10 fertilizer on a 1500 sq ft lawn:
Lbs = (1500 ÷ 1000) × (1 ÷ 0.20) = 1.5 × 5 = 7.5 lbs of fertilizer
To apply 1 lb of nitrogen using 20-10-10 fertilizer, you need 5 lbs of product per 1000 sq ft (1 ÷ 0.20 = 5).
Cool-season grasses: early spring and fall. Warm-season grasses: late spring through summer. Avoid fertilizing during extreme heat or drought.
A 50 lb bag contains 10 lbs nitrogen (20%), 5 lbs phosphorus (10%), and 5 lbs potassium (10%). The remaining 30 lbs is filler material.
Yes. Over-fertilizing causes "fertilizer burn" (brown patches), excessive growth, and can pollute waterways. Always follow recommended rates.