What is the pH of my subsoil?
Generally a laboratory recommends lime when the soil pH drops two to three units below the desired value. The desired value depends upon the crop and the pH of the subsoil. 3. Do I need magnesium (Mg)? Several parts of the state are historically low in soil magnesium (eastern and extreme southern Ohio). Adequate soil magnesium is important to reduce the risk of such problems as grass tetany for grazing animals. Soil test magnesium levels need to be greater than 50 ppm (100 lb) for optimal corn, soybean, wheat, and alfalfa production. Often areas low in magnesium also need lime, which has made the application of dolomitic lime an economic solution for both concerns. Unfortunately, some producers have been led to believe that magnesium levels in dolomitic lime may be undesirable. The Ohio State University has shown that crops yield the same over a wide range of calcium to magnesium ratios and is not critical as long as a lime source contains more calcium than magnesium. Thus the level of
