46th TWC, Tob. Work. Conf., 2014, abstr. 29

Variable rate irrigation in South Carolina flue-cured tobacco

Clemson University, Pee Dee Research and Education Center, 2200 Pocket Road, Florence, SC 29506-9706, USA

Extended periods of drought are not uncommon in the flue-cured tobacco production area of South Carolina during the growing season. Timely application of sufficient volumes of water during critical phases of crop development can have a dramatic impact on tobacco leaf chemistry, quality, and yield. Given the available ground water supply of this area and the appealing rate of return on the cost of investing in center pivot irrigation equipment, many producers have increased their acreage under irrigation. While this irrigated land is most commonly used to produce more drought sensitive crops, tobacco still remains a viable crop to consider in a rotation on irrigated land. We conducted a study at the Pee Dee Research and Education Center in Florence, SC to assess flue-cure tobacco production under center pivot irrigation at various irrigation regimes and nitrogen fertility rates. Measurements were taken for soil volumetric water content and soil temperature at depths of 0.5, 1, 1.5, and 2’ and for leaf chlorophyll content, leaf light reflectance, leaf chemistry, yield, relative value, and quality index. Irrigated zones were set to have 0.5” or 1” of water applied upon soil volumetric water content falling below 10 percent at a depth of 12” in the zones set for 1” of irrigation. Excessive rain in the 2013 growing season prohibited us from applying any irrigation. Various nitrogen rates were applied in the form of calcium nitrate 18 days after transplanting at 65, 75, 85, and 95 lbs of nitrogen per acre. Yields were 2,377, 2,335, 2,503, and 2,474 lbs of cured leaf per acre for the aforementioned nitrogen rates respectively but were not statistical different. Quality index was 75, 81, 79, and 79 for the 65, 75, 85, and 95 lbs nitrogen rates respectively with significant statistical difference (p = 0.05) observed between the 65 and 75 lbs rates. The longstanding recommended nitrogen fertility rate for the region of 75 lbs of nitrogen resulted in the highest average for quality index among those tested in this study. (Reprinted with permission)