Mehlich III Soil P Calibration to Corn Fertilizer P Response in Northeast Louisiana.

The need for soil test P calibration to determine optimum fertilizer P rates is critical for maximizing yield and protecting the environment. The Mehlich III soil test is currently used for P fertilizer recommendations in Louisiana, but local calibrations of P fertilizer rates to crop responses at varying Mehlich III soil test P levels are currently limited in number. Relationships of corn yield, applied P rates, and preseason and postseason soil Mehlich III P test values were examined for Commerce silt loam in northeast Louisiana.