Soluble calcium fertilizer effects on early growth and nutrition of burley tobacco

During production of burley tobacco (Nicotiana tabacum L.), initial soil pH needs to be 6.6 in order to maintain pH at midseason in the range of 5.8 to 6.2 to control manganese (Mn) toxicity, molybdenum (Mo) deficiency, and to enhance overall nutrient availability in soil. A field experiment was conducted at Lexington, Kentucky, during 2 years to determine the effects of rate of soluble calcium (Ca) (as gypsum-CaS04) on early growth and chemical composition of burley tobacco. On Maury silt loam soil (Typic Paleudalf; pH 6.6), plant dry weight and concentrations of potassium (K), Ca, and magnesium (Mg) 40 days after transplanting increased with rate of Ca fertilization up to 380 kg Ca/ha. Further increases in Ca fertilization decreased dry weight and K but had no effect on plant Ca or Mg concentrations. Generally, the effect of Ca on growth and nutrient accumulation was greatest in the presence of supplemental irrigation, K fertilization, and use of a nitrate (N03) source of N. Plant Ca concentration was not affected markedly by any cultural treatment and Ca had no effect on plant growth in urea treatments without irrigation and where no K fertilizer was added; plants in these treatments showed K-deficiency symptoms. These results can best be explained as a Viet's effect of Ca on K nutrition, resulting in increased growth of plants.