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Relationships among Soil Nitrate, Leaf Nitrate, and Leaf Yield of Burley Tobacco
Author(s) -
MacKown Charles T.,
CraftsBrandner Steven J.,
Sutton Tommy G.
Publication year - 1999
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1999.914613x
Subject(s) - loam , fertilizer , transplanting , soil water , agronomy , yield (engineering) , silt , curing of tobacco , chemistry , environmental science , biology , seedling , soil science , paleontology , materials science , metallurgy
Burley tobacco ( Nicotiana tabacum L.) requires large amounts of fertilizer N to produce high yields of cured leaf with the quality traits demanded by buyers. However, excessive N use produces air‐cured leaves with undesirable levels of NO − 3 , is uneconomical, and is environmentally unsound if substantial levels of residual soil NO − 3 remain following harvest. Effects of N fertilizer on relationships among leaf yield, NO − 3 concentrations of air‐cured leaves, and soil NO − 3 levels were investigated in 1991 and 1992 at two locations near Lexington, KY. Fertilizer N was broadcast at 0 to 448 kg ha −1 (56‐kg increments) before transplanting or banded at 168 kg ha −1 about 5 wk after transplanting. Soils were a well‐drained Maury silt loam (fine, mixed, mesic Typic Paleudalf) and a moderately well‐drained Captina silt loam (fine, silty, siliceous, mesic Typic Fragiudult). Cured leaf yield and lamina NO − 3 increased with increasing amounts of broadcast fertilizer N. Yield increased 3.7% with banded N, compared with an equivalent amount of broadcast N. Banding N also increased the NO − 3 level of cured leaf lamina by 37% for bottom leaves and 17% for middle leaves; top leaves were unaffected. Soil mineral N (NH + 4 + NO − 3 ) was proportional to the amount of broadcast N applied, and NO − 3 levels in the upper 30 cm of soil declined during the growing season. For predicted maximum leaf yields of 90%, critical soil mineral N values of 46 and 88 mg kg −1 (for Captina and Maury soils, respectively) were estimated from average mineral N concentrations in the upper 30 cm at 3 and 5 wk after transplanting. Early‐season soil NO − 3 testing to predict the NO − 3 level of cured leaf lamina was not useful; a nearly twofold difference in lamina NO − 3 was observed among years when soil NO − 3 levels were equivalent. At 280 kg N ha −1 , a rate commonly recommended for burley tobacco, as much as 37 mg NO − 3 –N kg −1 soil was found in the upper 30 cm of soil following harvest. Decreasing the amount of fertilizer N broadcast just before transplanting to 168 kg N ha −1 caused a 10% reduction in yield, a 37 to 65% decrease in lamina NO − 3 , and about a 60% decrease in residual soil NO − 3 at harvest. Better N management can reduce both the NO − 3 level of cured leaves and the amount of residual NO − 3 following harvest.