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Supplementary fertilization using standard commercial fertilizers is the routine practice on conventionally managed farms. Nitrogen is managed carefully to avoid excessive growth and accumulation of nitrogen compounds in the leaves. Phosphate also is managed carefully, as excessive amounts in the leaves alter burning characteristics of the leaf. High potash levels, on the other hand, are desirable. Adequate soil potash is also important in suppressing angular leaf spot (P. angulata) and bacterial leaf spot (P. tabaci). Chlorine-based fertilizers, however, such as potassium chloride, cannot be used, as they too reduce burning quality of the tobacco. Supplementary fertilization commonly includes a source of magnesium. Inadequate levels of soil magnesium encourage incidence of a nutritional disorder called “sand drown.” About 24–35 lbs/acre of soluble magnesium is considered adequate for most fields. Either dolomitic lime or sulfate of potashmagnesia is commonly used to supply magnesium in both conventional and organic cropping systems.

Soil pH should be maintained in the slightly acidic range (5.5–6.5) with an available calcium level five times that of magnesium.(6) At higher pH levels, the incidence of black root rot increases. Manures have historically been used in tobacco production, with rates of supplementary fertilizers reduced accordingly. Dark tobacco, especially, responds well to fertilization by manures, though it is advisable that they be applied and incorporated the previous fall. Application of animal manures to flue-cured and other lighter tobaccos is much more risky. Dr. W.D. Smith of North Carolina State Cooperative Extension has advised that manures be used on corn and other crops in rotation, to minimize any possible side effects on the tobacco crop.(7) ATTRA provides additional guidelines for manure use in Manures for Organic Crop Production.