Abstract
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.
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Claims 15
Claim · model-written summary
Cured leaf yield rose with increasing broadcast nitrogen.
Not reportedComparator
Verbatim
e0“Cured leaf yield and lamina NO − 3 increased with increasing amounts of broadcast fertilizer N.”
Claim · model-written summary
Lamina nitrate rose with increasing broadcast nitrogen.
Not reportedComparator
Verbatim
e0“Cured leaf yield and lamina NO − 3 increased with increasing amounts of broadcast fertilizer N.”
t0“Burley Tobacco”
Claim · model-written summary
Banded nitrogen increased yield 3.7% over equivalent broadcast nitrogen.
Verbatim
e0“Yield increased 3.7% with banded N, compared with an equivalent amount of broadcast N.”
t0“Burley Tobacco”
Claim · model-written summary
Banding nitrogen increased nitrate in bottom cured leaves by 37%.
- Taxon
- Burley Tobaccot0
- Organ / stage
- bottom leavese0
- Treatment
- Banding Ne0
- Outcome
- NO − 3 level of cured leaf laminae0
- Direction
- increasede0
- Value
- 37%e0
Not reportedComparator
Verbatim
e0“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.”
t0“Burley Tobacco”
Claim · model-written summary
Banding nitrogen increased nitrate in middle leaves by 17%.
- Taxon
- Burley Tobaccot0
- Organ / stage
- middle leavese0
- Treatment
- Banding Ne0
- Outcome
- NO − 3 level of cured leaf laminae0
- Direction
- increasede0
- Value
- 17%e0
Not reportedComparator
Verbatim
e0“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.”
t0“Burley Tobacco”
Claim · model-written summary
Banding nitrogen did not affect nitrate in top leaves.
Not reportedComparatorDirection
Verbatim
e0“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.”
t0“Burley Tobacco”
Claim · model-written summary
Soil mineral nitrogen was proportional to broadcast nitrogen amount.
Not reportedDirection
Verbatim
e0“Soil mineral N (NH + 4 + NO − 3 ) was proportional to the amount of broadcast N applied”
t0“Burley Tobacco”
Claim · model-written summary
Upper-soil nitrate declined during the growing season.
Verbatim
e0“NO − 3 levels in the upper 30 cm of soil declined during the growing season.”
t0“Burley Tobacco”
Claim · model-written summary
Critical soil mineral nitrogen for 90% predicted maximum yield was 46 mg kg−1 for Captina soil.
Verbatim
e0“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”
t0“Burley Tobacco”
Claim · model-written summary
Critical soil mineral nitrogen for 90% predicted maximum yield was 88 mg kg−1 for Maury soil.
Verbatim
e0“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”
t0“Burley Tobacco”
Claim · model-written summary
Early season soil nitrate testing was not useful for predicting cured leaf nitrate.
Verbatim
e0“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.”
t0“Burley Tobacco”
Claim · model-written summary
At 280 kg N ha−1, postharvest upper-soil nitrate reached 37 mg nitrate-N kg−1.
Verbatim
e0“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.”
Claim · model-written summary
Reducing broadcast nitrogen to 168 kg N ha−1 reduced yield 10%.
Not reportedComparator
Verbatim
e0“Decreasing the amount of fertilizer N broadcast just before transplanting to 168 kg N ha −1 caused a 10% reduction in yield”
t0“Burley Tobacco”
Claim · model-written summary
Reducing broadcast nitrogen to 168 kg N ha−1 decreased lamina nitrate 37 to 65%.
- Taxon
- Burley Tobaccot0
- Treatment
- 168 kg N ha −1e0
- Outcome
- lamina NO − 3e0
- Direction
- decreasee0
- Value
- 37 to 65%e0
Not reportedComparator
Verbatim
e0“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”
t0“Burley Tobacco”
Claim · model-written summary
Reducing broadcast nitrogen to 168 kg N ha−1 decreased residual soil nitrate about 60%.
- Taxon
- Burley Tobaccot0
- Treatment
- 168 kg N ha −1e0
- Outcome
- residual soil NO − 3e0
- Direction
- decreasee0
- Value
- 60%e0
Not reportedComparator
Verbatim
e0“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.”
t0“Burley Tobacco”
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