Effect of Slow Release Fertilizer on Fertilizer Residues and on Yield and Composition of Flue-cured Tobacco1
- G. O. San Valentin,
- W. K. Robertson,
- J. T. Johnson and
- 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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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