During the 1998/1999 tobacco campaign the following study was carried out at the Research institute for Tobacco in the Partido Zone of San Antonio de los Banos, Havana, Cuba. A random block design was used with five treatments and four replications. Treatments were distributed at random. The variety used was Habana 92 and the cultural practices used was the usual for the Partido Zone. Traditional fertilization (Treatment 1) was compared with four other alternatives including potassium nitrate (Treatments 2 to 5). Only Treatment 5 had a greater fertilization rate. All treatments presented greater yields, greater amount of usable leaves, greater economic income and greater percentage of exportable leaves, with respect to the traditional treatment. This result is due to the incorporation of nitric nitrogen and of soluble potassium, split in three fertilizer applications. The chemical properties of the leaves improved in the treatments using nitric nitrogen (2 to 5), and potassium, calcium and magnesium contents were greater than in the traditional treatment. This is explained by the ionic synergy existing when nitrate (anion) is applied promoting absorption of the soil cations (potassium, calcium and magnesium). These values give the plant a better leaf quality, greater resistance to climatic adversities (drought, rain, frost, etc.) and a greater tolerance to diseases.