Implications of chloride application rate and nitrogen fertilizer source to flue‐cured tobacco

Abstract

AbstractChloride assimilation by flue‐cured tobacco (Nicotiana tabacum L.) can negatively impact leaf development and quality when tissue concentration exceeds 1%. The influences of Cl− application rate and N fertilizer sources have not been fully described in field research utilizing reduced‐cost or custom‐blend fertility programs that are common in modern times. Research was conducted to test the interaction of four Cl− application rates (0, 34, 67, and 101 kg ha−1) and four N fertilizer sources {calcium nitrate, Ca(NO3)2; ammonium nitrate, NH4NO3; liquid urea‐ammonium nitrate [UAN], and ammonium sulfate, (NH4)2SO4} on the growth and development of flue‐cured tobacco. The impact of N source was minimal in green leaf tissue; however, (NH4)2SO4 reduced cured leaf quality relative to other N sources. Two weeks after fertilizer application, Cl− rates ≥34 kg ha−1 reduced foliar total N and NO3− measurements by 0.12−0.42% and 789−1348 mg kg−1, respectively. Leaf NO3− concentration was also reduced by Cl− application at the layby growth stage, while P, K, and Mg increased following Cl− application in late‐season measurements. After curing, total N and alkaloids were reduced by an average of 0.17 and 0.23%, respectively, while reducing sugars were increased by 1.67% where Cl− was applied. Chloride concentration exceeded 1% in application rates ≥34 kg ha−1 in early‐season and post‐curing measurements, although toxicity symptoms were not observed nor were yield, quality, or value affected. Farmers should adhere to the current recommendation of ≤34 kg Cl− ha−1 to ensure that cigarette manufacturers receive tobacco that is usable in products.