Interpreting Soil Test Nitrogen Recommendations for Tall Fescue

Introduction

Soil test (Clemson) shows very low nitrogen, recommends 16-0-0 in Sept, Nov, Feb. User also aerates/seeds in fall with starter fertilizer.

Key Points

• Soil tests **cannot reliably measure nitrogen** (lost in drying/transport).
• Follow seasonal schedule: late spring (early April), early fall (Sept), late fall (Nov).
• Starter fertilizer = high phosphorus. Only use if soil test shows low P/K.
• If P/K adequate, use straight nitrogen (16-0-0, 29-3-4, 33-3-3).
• Rate: 1 lb actual N per 1000 sq ft. Calculate: (100 / N%) × (lawn sq ft / 1000).

Application

• Do not combine starter + straight N.
• Use either/or based on soil test P/K.
• Common lawn fertilizers (29-3-4, 33-3-3) are fine if P/K not excessive.

Conclusion

Ignore soil test N; follow calendar. Use starter only if P/K deficient. Apply 1 lb N/1000 sq ft per application.