Control of soil acidity by liming is very important in successful tobacco culture. Adding lime to an acid soil increases the availability of nearly all plant nutrient elements, increases the efficiency of added fertilizers, and prevents the toxic effects of high concentrations of soluble aluminum, manganese, and iron. It is a natural tendency for most Kentucky soils to become acid with time due to losses of bases (calcium, magnesium, potassium, and sodium) from soil by rainfall, However, tobacco soils possess certain unique problems that warrant careful monitoring of soil pH every two to three years.
Sims, J. L., "Liming Tobacco Soils" (1982). Soil Science News and Views. 159.