SOLUBLE CALCIUM FERTILIZER EFFECTS ON EARLY GROWTH AND NUTRITION OF BURLEY TOBACCO

During production of burley tobacco (Nicotiana tabacum L.), initial so il pH needs to be 6.6 in order to maintain pH at midseason in the rang e of 5.8 to 6.2 to control manganese (Mn) toxicity, molybdenum (Mo) de ficiency, and to enhance overall nutrient availability in soil. A fiel d experiment was conducted at Lexington, Kentucky, during 2 years to d etermine the effects of rate of soluble calcium (Ca) (as gypsum-CaSO4) on early growth and chemical composition of burley tobacco. On Maury silt loam soil (Typic Paleudalf; pH 6.6), plant dry weight and concent rations of potassium (K), Ca, and magnesium (Mg) 40 days after transpl anting increased with rate of Ca fertilization up to 380 kg Ca/ha. Fur ther increases in Ca fertilization decreased dry weight and K but had no effect on plant Ca or Mg concentrations. Generally, the effect of C a on growth and nutrient accumulation was greatest in the presence of supplemental irrigation, K fertilization, and use of a nitrate (NO3) s ource of N. Plant Ca concentration was not affected markedly by any cu ltural treatment and Ca had no effect on plant growth in urea treatmen ts without irrigation and where no K fertilizer was added; plants in t hese treatments showed K-deficiency symptoms. These results can best b e explained as a Viet's effect of Ca on K nutrition, resulting in incr eased growth of plants.