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This article in AJ

  1. Vol. 70 No. 2, p. 345-348
    Received: May 20, 1977



Effect of Slow Release Fertilizer on Fertilizer Residues and on Yield and Composition of Flue-cured Tobacco1

  1. G. O. San Valentin,
  2. W. K. Robertson,
  3. J. T. Johnson and
  4. W. W. Weeks2



Many of the fine soils on which tobacco (Nicotiana tobacum L.) is grown do not retain applied K following irrigation or rainfall long enough to satisfy plant requirements. Losses should be reduced by the use of materials that restrict K solubility or by split application.

Tobacco was grown for 5 years on Lakeland fine sandy soil (Typic Quartzipsamment), a soil which retains very little K. Split applications of K~SO4 were compared to single applications of K2SO4 and resin- polyvinyl-, and S-coated K materials. Yields and chemical composition of tobacco leaves and soil were used to measure the relative effectiveness of K treatments.

Yields and K contents of tobacco leaves were increased by K fertilization. Split applications of K2SO4 were more effective than single applications at planting. In years with heavy rainfall, applying slowly-soluble sources all at planting was better than applying K2SO4 in split application. Potassium from slowly soluble materials was less readily leached than from K2SO4, resulting in higher concentration of K within 60 cm of the surface at the time of tobacco flowering. When various thickness of S were applied to give a range of K release, the thicker coatings gave higher yields. Treatments that provided higher K contents increased total alkaloids and decreased reducing sugars in the first of the two years that they were measured. Application of K fertilizers with reduced solubility should assure good yields, quality, and a high level of K in tobacco.

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