Growth and Nutrient Uptake of
Burley Tobacco Fertilized with
Alternative Sources of Potassium
Bob Pearce
University of Kentucky
Presented at
49th Tobacco Workers’ Conference
Louisville, KY
January 20-23, 2020
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Typical Potassium Deficiency
Symptoms on Burley Tobacco 2020
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Potassium Impacts Both
Quality and Yield 2020
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Common Sources of Potassium Fertilizer
Sulfate of potash: 0-0-50– Intermediate cost
– Preferred source for tobacco
Muriate of potash: 0-0-60– Lower cost
– Quality issues for tobacco
Sul-po-mag: 0-0-22– High cost
Soda-potash: 15-0-14
Potassium nitrate: 13-0-44– High cost
– Limited availability
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Excess Chloride in Cured Tobacco Leaves
Poor cured leaf color
Imparts unpleasant flavor and aroma to smoke
Reduces burn rate
Cause cured leaf to hold moisture
Nitrosamines – recent evidence suggest using muriate of potash may reduce TSNAs
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Potential Alternative K source
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Poly-4 Analysis
K2O – 14% Typically required*
CaO – 17% Typically not required*
MgO – 6% Rarely required*
S – 19% Historically not required*
– Recent reductions emissions may
change S status.
* Refers to requirements in common soil types
where burley tobacco is grown in Kentucky
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Objectives
Evaluate Poly-4 as a potential alternative source of
fertilizer K for burley tobacco production.
– Is there value to secondary nutrients (Ca, Mg, and S)
Evaluate the impact of K source on leaf chemistry
(Alkaloids and TSNA)
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Materials and Methods
Spindletop Research Farm Lexington, KY
Maury Silt Loam Soil (Mollic Hapludalfs)– 2017
Soil test K2O: 200 (low)
Recommended K for this soil: 300 lb/ac
– 2018Soil test K2O: 116 (low)
Recommended K for this soil: 380 lb/ac
Conventional tillage
Burley Tobacco Variety KT 210
All other practices as recommended
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K fertilizer treatments 2017
TRT
#
Name Field applied rate of each material
(lb/ac)
MOP POLY-4 SOP SOPM
1 Check (No K) 0 0 0 0
2 MOP (100%) 500 0 0 0
3 MOP (20%) + POLY 4 (80%) 100 1920 0 0
4 POLY (100%) 0 2142 0 0
5 MOP (40%) + SOP (60%) 200 0 360 0
6 MOP (40%) + SOPM (60%) 200 0 0 840
7 SOP (100%) 0 0 600 0
8 SOPM (100%) 0 0 0 1394
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K fertilizer treatments 2018
TRT
#
Name Field applied rate of each material
(lb/ac)
MOP POLY-4 SOP SOPM
1 Check (No K) 0 0 0 02 MOP (100%) 633 0 0 03 MOP (20%) + POLY 4 (80%) 100 2286 0 04 POLY (100%) 0 2714 0 05 MOP (40%) + SOP (60%) 200 0 520 06 MOP (40%) + SOPM (60%) 200 0 0 12097 SOP (100%) 0 0 760 08 SOPM (100%) 0 0 0 1767
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K fertilizer treatments 2017
TRT
#
Name Nutrients applied (lb/ac)
K2O MgO Cl S
1 Check (No K) 0 0 0 0
2 MOP (100%) 300 0 235 0
3 MOP (20%) + POLY 4 (80%) 300 103 98 326
4 POLY 4 (100%) 300 129 64 407
5 MOP (40%) + SOP (60%) 300 0 95 64
6 MOP (40%) + SOPM (60%) 300 125 95 184
7 SOP (100%) 300 0 0 108
8 SOPM (100%) 300 209 0 307
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Field Operations and Sampling Dates
Task 2017 2018
Fertilizer App June 12 June 15
Planting June 13 June 18
Early Sample July 28 August 2
Topping August 25 August 28
Harvest Sept 19 September 25
Season Rainfall 27.15 in 29.96 in
Sept Rainfall 3.94 in 13.68 in
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Leaf N at Harvest (%)
3.00
3.50
4.00
4.50
5.00
5.50
Check MOP MOP +POLY -4
POLY - 4 MOP +SOP
MOP +SOPM
SOP SOPM
2017 2018
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Leaf P at Harvest (%)
0.00
0.10
0.20
0.30
0.40
0.50
Check MOP MOP +POLY -4
POLY - 4 MOP +SOP
MOP +SOPM
SOP SOPM
2017 2018
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Leaf K at Harvest (%)
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
Check MOP MOP +POLY -4
POLY - 4 MOP +SOP
MOP +SOPM
SOP SOPM
2017 2018
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Leaf Mg at Harvest (%)
0.00
0.20
0.40
0.60
0.80
1.00
1.20
Check MOP MOP +POLY -4
POLY - 4 MOP +SOP
MOP +SOPM
SOP SOPM
2017 2018
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Leaf Ca at Harvest (%)
2.00
2.50
3.00
3.50
4.00
4.50
Check MOP MOP +POLY -4
POLY - 4 MOP +SOP
MOP +SOPM
SOP SOPM
2017 2018
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Leaf S at Harvest (%)
0.00
0.10
0.20
0.30
0.40
0.50
0.60
Check MOP MOP +POLY -4
POLY - 4 MOP +SOP
MOP +SOPM
SOP SOPM
2017 2018
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Leaf Cl at Harvest (%)
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
Check MOP MOP +POLY -4
POLY - 4 MOP +SOP
MOP +SOPM
SOP SOPM
2017 2018
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Cured Leaf Yield (lbs./A)
0
500
1000
1500
2000
2500
3000
3500
Check MOP MOP +POLY-4
POLY-4 MOP +SOP
MOP +SOPM
SOP SOPM
2017 2018
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2018 Check Plot
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Alkaloids in Cured Leaf 2017 (%)
3.77 3.72 3.563.92
3.724.04
3.744.03
0
1
2
3
4
5
Check MOP MOP +POLY-4
POLY-4 MOP +SOP
MOP +SOPM
SOP SOPM
Nicotine Nornicotine Anabasine Anatabine
No significant difference in total Alkaloids
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Alkaloids in Cured Leaf 2018 (%)
1.15
2.913.02
3.08 3.03 2.942.51
2.74
0.00
1.00
2.00
3.00
4.00
5.00
Check MOP MOP +POLY-4
POLY-4 MOP +SOP
MOP +SOPM
SOP SOPM
Nicotine Nornicotine Anabasine Anatabine
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TSNAs in Cured Leaf 2017 (ug/g)
0.957
0.747
0.983
1.293
1.1371.226
1.107 1.132
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Check MOP MOP +POLY-4
POLY-4 MOP +SOP
MOP +SOPM
SOP SOPM
NNN NAT NAB NNK
cd d bcd a abc ab abc abc
* Letters reflect significant differences in the total TSNA
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TSNAs in Cured Leaf 2018 (ug/g)
10.049
1.237 1.084 1.174 1.3021.855
2.878
4.143
0
2
4
6
8
10
12
Check MOP MOP +POLY-4
POLY-4 MOP +SOP
MOP +SOPM
SOP SOPM
NNN NAT NAB NNK
d a a a a ab bc c
* Letters reflect significant differences in the total TSNA
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Summary
Poly-4 appears to be agronomically suitable as a potassium source for burley tobacco
Secondary nutrients supplied by alternative sources of potassium did not contribute to increased yield
Additional studies on the economic feasibility of POLY-4 will need to be conducted, assuming nutrient response is primarily to potassium only
Additional research is needed to assess the impact of MOP on cured leaf TSNA levels
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Acknowledgments
Jack Zeleznik
Will Barlow
Grace Ragain
Mitchell Richmond
Nolan Stephenson
SarahJo Diamond
Kiran Pavuluri
Brad Farber
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