Nitrogen fertilization, nitrogen and nicotine content of burley tobacco

Field experiments were conducted to study the effect of rates and time of nitrogen application on growth, nitrogen and nicotine contents of leaves and stalks of Burley 21. Rates of nitrogen used were 0, 75, 150 and 225 pounds per acre. Nitrogen was applied as preplant and/or as post plant applications.

The maximum rate of growth and nitrogen uptake occurred during the month prior to topping. During the period prior to topping 74 percent of the total dry matter, 80 percent of the total nitrogen and 34 percent of the total nicotine accumulated in the shoots.

Applying 2/3 of the 75 pounds of nitrogen per acre 21 days after transplanting increased the yield over treatments in which nitrogen was applied earlier or later. However, split application of 150 and 225 pounds of nitrogen per acre did not affect the yield. Split applications in general did not affect average price, nitrogen and nicotine contents of leaves and stalks. Increasing nitrogen rates up to 225 pounds per acre significantly increased the nitrogen and nicotine levels of cured leaves as well as the nitrogen levels in non-cured leaves and stalks. The increase in percent nicotine of non-cured stalks and leaves was not significant beyond applications of 75 and 150 pounds of nitrogen per acre, respectively. Increasing nitrogen rates lowered the ratio of nitrogen incorporated into nicotine in relation to total shoot nitrogen. The average increase in percent nicotine was 0.6 percent for each 1 percent increase in percent nitrogen of cured leaves. Yield and acre-value significantly increased with nitrogen rates up to 225 pounds per acre. Applying 225 pounds of nitrogen per acre significantly decreased the average price and delayed the flowering.