CORESTA Congress, Edinburgh, 2010, AP 31

Evaluation of potassium application methods and rates on the yield and quality of flue-cured tobacco

VANN M.C.; FISHER L.R.; STEWART A.M.; PRIEST J.A.; WHITLEY D.S.; JOHNSON V.A.
North Carolina State University, Raleigh, NC, USA

With rising input costs, growing environmental concerns, and new higher yielding cultivars, potassium fertilizer recommendations must be accurate. Research is being conducted to evaluate the effects various potassium rates and application methods have on the yield and quality of flue-cured tobacco. Research was conducted at the Upper Coastal Plain Research Station in Rocky Mount, NC and the Oxford Tobacco Research Station in Oxford, NC in 2009. One trial evaluated the effects of nine potassium (K-Mag) rates from 0 to 225 lbs/A, all applied at transplanting, on flue-cured tobacco. Potassium-magnesium sulfate was used to supply fertilizer potassium. Nitrogen fertilizer was sidedressed after transplant in the form of 30% UAN at Rocky Mount and 15.5-0-0 at Oxford. Control plots received a base fertilizer and a sidedressed application of nitrogen. Soil samples were collected at transplant from control plots, and tissue samples were collected throughout the season. Cured leaf yield as well as chemical and physical quality data was also collected. The second trial evaluated the effects of four potassium rates; 75, 125, 175, 222 lbs/A, and four application timings; broadcast one month before planting, broadcast one week before planting, at planting, and at planting and layby, on flue-cured tobacco. Potassium-magnesium sulfate was used to supply fertilizer potassium. Nitrogen fertilizer was sidedressed after transplant in the form of 30% UAN at Rocky Mount and 15.5-0-0 at Oxford. Control plots were sidedressed with nitrogen, and did not receive any potassium amendments. Soil and tissue samples were collected throughout the season. Cured leaf yield as well as chemical and physical quality data was also collected. There was no significant difference between any fertilizer treatments and control plots receiving no additional potassium. Lower rates of K-Mag were acceptable under these conditions, along with broadcast application.