The need for adding molybdenum to tobacco arises because contents in Kentucky soils generally are on the "borderline" of sufficiency and because amounts of available molybdenum in soil are low when soil pH is low. Soil pH in tobacco fields at midseason often is 0.5 to 1.0 pH unit lower than prior to fertilization. primarily because of the high rates of commercial fertilizers commonly applied to tobacco. This acidity greatly lowers the availability of molybdenum to tobacco plants. That is why we recommend the use of molybdenum when soil pH before fertilization is 6.4 or below.
Sims, J. L.; Smiley, Jones H.; Suchy, M. E.; and Wallace, A. M., "Use of Molybdenum in the Transplant Water for Burley Tobacco" (1981). Agronomy Notes. 88.