Potassium Rate and Application Effect on Flue-Cured Tobacco

Research was conducted at two locations in 2009 and 2010 to evaluate the effect of various K rates and application methods on the yield and quality of flue-cured tobacco (Nicotiana tabacum L.). Treatments included five rates of K from sulfate of potash magnesia (0-0-22): 0, 84, 140, 196, and 252 kg K2O ha(-1) that were applied: broadcast 1 mo before transplanting, broadcast 1 wk before transplanting, banded at transplanting, and a split application with one-half rate banded at transplanting followed by one-half rate banded at layby. Tissue samples were collected throughout the season at three separate growth stages: layby, topping, and aft er curing. Tissue samples were analyzed for total alkaloid and reducing sugars, N,P,K, and Mg content. Soil samples were collected the same day as K fertilizer application from plots not receiving supplemental K. Data were subjected to ANOVA using the PROC GLM procedure in SAS. Treatment means were separated using Fisher's Protected LSD test at p <= 0.05. Application method and timing had no effect on any measured parameters; furthermore, crop yield and quality was not affected by K rates > 0 kg K2O ha(-1) at three of four locations. It is likely that early broadcast applications of K2O with current rate recommendations would only be of concern with combinations of conditions that included coarse soil textures, low K indices, and/or excessive leaching rainfall.