Influence of liming and nitrogen forms on boron uptake by tobacco

The purpose of this study was to investigate the influence of soil liming and fertilizer nitrogen forms on the availability of soil B and its uptake by tobacco plant. A field experiment was conducted on an acid Typic Haploxeralf soil, located in Pieria, Northern Greece. The experimental design was factorial 3 x 3 with four replications. The first factor included three rates of lime (0, 4000, and 8000 kg/ha limestone) and the second three combinations of nitrogen forms i.e. a) NO3-N 100%, b) NH4-N 100%, c) N03-N 50% plus NH4-N 50%. Tobacco harvesting was done in four cuttings. Composite leaf samples were selected and analysed for B, Ca, and K. At the end of the experiment composite soil samples were also collected from each experimental plot and were analysed for pH, exchangeable cations and available B using the hot 0.01M CaCl2 extraction procedure. The results showed that soil liming increased soil pH proportionally to the amount of limestone applied. Fertilizer N forms did not significantly affect soil pH. Soil liming significantly decreased available B, which was strongly correlated with soil pH negatively. Boron concentration in tobacco leaves was significantly decreased up to deficiency levels being strongly correlated with available B positively but negatively with soil pH. Ca/B ratio was significantly increased indicating B deficiency. This ratio was strongly correlated with soil pH and exchangeable Ca. Fertilizer N forms did not cause any significant influence on B uptake. The latter was also true for potassium