The effect of potassium application rate, application method and timing on the yield and quality of flue-cured tobacco
With rising input costs, growing environmental concerns, and new higher yielding cultivars, potassium fertilizer recommendations for tobacco must be accurate. Research was conducted in North Carolina to evaluate the effect of potassium rate and application method on the yield and quality of flue-cured tobacco.
Research was conducted at the Upper Coastal Plain Research Station and the Oxford Tobacco Research Station in 2009 and 2010. One study evaluated the effect of nine rates of K2O from 0 to 252 kg ha-1, all applied at transplanting, on flue-cured tobacco. The second study evaluated the effects of four rates of K2O; 84, 140, 196, 252 kg ha-1, applied in four different methods; broadcast one month before transplanting, broadcast one week before transplanting, banded at transplanting, and one-half rate banded at transplant followed by one-half rated banded at layby, on flue-cured tobacco. Sulfate of potash magnesia (0-0-22) was used to supply potassium in both studies. Soil and tissue samples were collected throughout the season. Data was collected to evaluate leaf yield, crop quality, crop value, and certain chemical characteristics.
Increasing rates of K2O above 84 kg ha-1 did not significantly improve yield, quality, value, or any chemical constituents. Research indicates that current potassium recommendations are accurate and may even be higher than necessary on finer-textured soils with medium to high residual potassium. Alternatively, recommendations appear to be correct for coarse-textured soils with lower residual potassium. Application method and timing had no effect on the measured parameters under the conditions present in this study, thus demonstrating that alternative application methods are acceptable.