A 10,000 sq ft lawn requires 4 lb N per 1,000 sq ft per year. If you apply 34-0-0 urea fertilizer containing 46% N, how many pounds of product are needed to reach the annual N rate?

• A. 87 lb
• B. 40 lb
• C. 60 lb
• D. 100 lb

Answer: (A)

Start with the annual nitrogen needs: 4 lb N per 1,000 sq ft for 10,000 sq ft is 4 × (10,000/1,000) = 40 lb of N per year.

The fertilizer provides 46% N, so each pound of product delivers 0.46 lb of N. To supply 40 lb of N, you need 40 ÷ 0.46 ≈ 86.96 lb of product, which rounds to about 87 lb.

So 87 lb is just enough to meet the annual N rate. The other amounts would supply too little (e.g., 40 lb gives ~18.4 lb N) or too much (e.g., 100 lb gives 46 lb N).