Grain Crop Phosphate and Potash Rate Recommendations: AGR-1 Updates

By John Grove and Edwin Ritchey
Published on Mar. 30, 2025

Grain crop fertilizer phosphate (P2O5) and potash (K2O) maintenance rate recommendations in AGR-1 (Ritchey and McGrath, 2020) have not been reexamined since their inception - 1992. Other UK extension faculty (G. Schwab, pers. comm.; B. Lee, pers.

Corn Nitrogen Rate Recommendations: AGR-1 Updates

By John Grove and Edwin Ritchey
Published on Mar. 30, 2025

Corn fertilizer nitrogen (N) rate recommendations had not been deeply reexamined in 20 years. Additionally, there have been no substantial change to AGR-1 (Ritchey and McGrath, 2020) corn N management recommendations since the 2004-2005 version of the document. Information on the use of urease inhibitors was added at that time.

Corn Yield Recovery with At-Tasseling/Early Silking N Application

By John Grove and Edwin Ritchey
Published on Feb. 21, 2025

In the past decade, over 50 % of the years have given corn growers some difficulty with wet early season conditions. These conditions can complicate corn nitrogen (N) management. Sustained wetness can delay/prevent N application, resulting in uncertainty in corn’s N status at-tasseling/early silking (VT/R1), when ear development commences.