Re: pH of soils occurring in major cereal production areas in the US

Originally the surface layers of many Corn Belt soils were moderately acid to neutral (pH 5.6 to 7.3) and most wheat belt soils were neutral to slightly alkaline (pH 6.6 to 7.8).

The additions of acidifying fertilizers, mostly in the Corn Belt, have lowered the pH of the surface layers of many of these soils, commonly to 5.0 or less. Lime (CaCO3) is being added to many of these soils to keep the pH near 6 or more.