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CORESTA Meeting, Agronomy/Phytopathology, Santa Cruz do Sul, 2005, A 18

Evaluating nitrogen sources and rates with current flue-cured tobacco varieties

PARKER R.G.; SMITH W.D.; FISHER L.R.
North Carolina State University, Dept. of Crop Science, Raleigh, NC, USA

The North Carolina Extension Flue-Cured Tobacco Information bulletin is used to convey information to flue-cured tobacco producers about production practices ranging from new varieties to disease management practices. The nitrogen recommendations for flue-cured tobacco in North Carolina range from 67 - 90 kg/ha, depending on soil texture and depth to the argilic horizon. However, government mandated nutrient management plans limit the amount of nitrogen that growers can use on a whole farm basis in certain river basins, thus causing growers to examine practices which will reduce nutrient inputs. Also, research has shown that modern flue-cured varieties are more efficient in nitrogen uptake and use than older varieties. Therefore, research was conducted to reevaluate nitrogen recommendations for flue-cured tobacco to determine if they are still valid for use with current varieties. Tests were conducted at two locations in 2004 to evaluate nitrogen rate and source effects on yield and quality with current flue-cured tobacco varieties. Nitrogen sources were ammonium nitrate, potassium nitrate, and 30% urea ammonium nitrate. All sources were applied at 0, 23, 45, 67, and 90 kg/ha. Applications were split with one-half of the nitrogen being applied 7 days after transplanting and the remainder applied 14 days later. Results from the studies in 2004 indicate that nitrogen source did not affect yield and quality. As the rate of nitrogen increased the total yield and net return per hectare increased. However, quality decreased with the highest nitrogen rate regardless of the nitrogen source. Tests will be repeated in 2005 using the same rates and sources of nitrogen as used in 2004. However, two higher rates of nitrogen will be added to better determine effects excessive nitrogen modern flue-cured varieties.