CORESTA Congress, Online, 2020, Agronomy/Phytopathology Groups, AP 16

Nitrogen application programs for fine-textured soils of the North Carolina Piedmont

(1) North Carolina State University, Department of Crop & Soil Sciences, Raleigh, NC, U.S.A.; (2) Forsyth County Cooperative Extension, Winston-Salem, NC, U.S.A.; (3) Rockingham County Cooperative Extension, Reidsville, NC, U.S.A.; (4) Alamance County Cooperative Extension, Burlington, NC, U.S.A.

Late-season nitrogen (N) assimilation can greatly impact the yield and quality of flue-cured tobacco, particularly in the fine-textured Piedmont soils of North Carolina. Research was conducted in three environments to evaluate the effects of N application rate and number of N applications to the yield, quality, value, and leaf chemistry of flue-cured tobacco. Liquid N (28 % urea-ammonium nitrate) was applied at 56, 78, and 101 kg N/ha. Each rate was either applied in two (50 % of the target rate 7–10 days after transplanting and 50 % of the target rate five weeks after transplanting) or three splits (50 % of the target rate 7–10 days after transplanting, 25 % of the target rate five weeks after transplanting, and 25 % of the target rate seven weeks after transplanting). Cured leaf N concentration was similar at 56 and 78 kg N/ha (2.58 and 2.61 %, respectively) but was increased in treatments receiving 101 kg N/ha (2.77 %). Additionally, three N applications (2.73 %) increased cured leaf N relative to two N applications (2.58 %). The same treatment parameters did not impact yield or value but reduced cured leaf quality in one growing environment due to prolonged N assimilation resulting from dry conditions. Within this environment, quality was greatest when 56 kg N/ha was applied in two applications. Results indicate that current recommendations for N application rates (56 kg/ha) and timings (split-applied twice in equal portions) are adequate to obtain maximum yield, quality, and value in fine-textured soils similar to those evaluated in this study.