Growth and Nutrient Uptake of Burley Tobacco Fertilized ... · Burley Tobacco Fertilized with...

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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

Typical Potassium Deficiency

Symptoms on Burley Tobacco 2020

Potassium Impacts Both

Quality and Yield 2020

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

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

Potential Alternative K source

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

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)

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

K fertilizer treatments 2017

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

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

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

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

Leaf N at Harvest (%)

Check MOP MOP +POLY -4

POLY - 4 MOP +SOP

MOP +SOPM

SOP SOPM

2017 2018

Leaf P at Harvest (%)

POLY - 4 MOP +SOP

MOP +SOPM

SOP SOPM

2017 2018

Leaf K at Harvest (%)

POLY - 4 MOP +SOP

MOP +SOPM

SOP SOPM

2017 2018

Leaf Mg at Harvest (%)

POLY - 4 MOP +SOP

MOP +SOPM

SOP SOPM

2017 2018

Leaf Ca at Harvest (%)

POLY - 4 MOP +SOP

MOP +SOPM

SOP SOPM

2017 2018

Leaf S at Harvest (%)

POLY - 4 MOP +SOP

MOP +SOPM

SOP SOPM

2017 2018

Leaf Cl at Harvest (%)

POLY - 4 MOP +SOP

MOP +SOPM

SOP SOPM

2017 2018

Cured Leaf Yield (lbs./A)

Check MOP MOP +POLY-4

POLY-4 MOP +SOP

MOP +SOPM

SOP SOPM

2017 2018

2018 Check Plot

Alkaloids in Cured Leaf 2017 (%)

3.77 3.72 3.563.92

3.724.04

3.744.03

POLY-4 MOP +SOP

MOP +SOPM

SOP SOPM

Nicotine Nornicotine Anabasine Anatabine

No significant difference in total Alkaloids

Alkaloids in Cured Leaf 2018 (%)

2.913.02

3.08 3.03 2.942.51

POLY-4 MOP +SOP

MOP +SOPM

SOP SOPM

Nicotine Nornicotine Anabasine Anatabine

TSNAs in Cured Leaf 2017 (ug/g)

1.1371.226

1.107 1.132

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

TSNAs in Cured Leaf 2018 (ug/g)

10.049

1.237 1.084 1.174 1.3021.855

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

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

Acknowledgments

Jack Zeleznik

Will Barlow

Grace Ragain

Mitchell Richmond

Nolan Stephenson

SarahJo Diamond

Kiran Pavuluri

Brad Farber

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