Dark air-cured and dark fire-cured tobacco TSNA levels in response to potassium source and rate
Field experiments were conducted to evaluate the effect of potassium fertilizer source and application rate on yield, quality, and tobacco leaf chemistry constituents in dark air-cured (DAC) and dark fire-cured (DFC) tobacco. Field trials were located at the University of Kentucky Research and Education Center in Princeton, KY in 2016. Dark tobacco varieties used in both trials was KT D14LC. Potassium chloride (KCl) and potassium sulfate (K2SO4) were the potassium sources of interest. Treatments were applied utilizing a randomized complete block design with four replications. Each potassium source was broadcast-applied the day prior to transplanting at 100, 200, and 300 lbs K2O acre-1. An untreated control that received no potassium was also included. All plots received the same nitrogen and phosphorus according to soil test recommendations for the site. Numerical differences were observed in DFC and DAC treatments for N-nitrosonornicotine (NNN) levels, with KCl-treated tobacco having numerically higher NNN levels than K2SO4-treated tobacco. There was a main effect of potassium source as KCl treatments yielded higher than K2SO4 treatments in the DAC trial. However, this yield difference could be associated with significant differences in leaf moisture content when comparing potassium source. There were no differences in the quality grade index between KCl treatments and K2SO4 treatments. Preliminary observations and results from 2017 experiments will also be discussed.