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1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Curing Burley Tobacco Curing Burley Tobacco ––Analyzing the Curing Environment Analyzing the Curing Environment
A brief A brief review review
of of whatwhat’’s s good,good,
more on more on a way to a way to evaluate evaluate
the the environenviron--
mentment
ByByGeorge Duncan, Linus WaltonGeorge Duncan, Linus WaltonB.A.E. Dept ., Coll. Of Agric., U.Ky.B.A.E. Dept ., Coll. Of Agric., U.Ky.
presented atpresented at42nd Tobacco Workers Conference42nd Tobacco Workers Conference
Charleston, SC Jan. 2006Charleston, SC Jan. 2006with recent additionswith recent additions
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Early studies by Jeffrey, 19401, 19462…
Best for burley:Temp. 60-90 ºF (daily mean) Relative Humidity 65-70% (daily mean)Air Flow 15 ft/min (minimum)
Note: Then 1288-2698 lbs/ac,thin, buff color leaf
and 15 ft/min ~ 1/6 mph
1References cited are listed at the end of this presentation.
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
O’Bannon, 19433…
Extensive study of wind effects on barn ventilation;vent doors open, closed;
graphics of temp., rel. hum. within barn:
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Walton & Henson4, 1971…
Study of effects of exposure to periods of low relative humidity on quality…
Temperature: 50 º, 65 º, 80 º FRel. Humidity: 30%, 45%, 60% Air Flow: 15 ft/minTimes of Exposure: 0, 12, 24, 48, 72, 96 hrsStages of cure: Initial (green), Yellow
Bur. 21, cured at 70 F and 70% R.H. except for exposure times
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Walton & Henson4, 1971…
Results: Minimum periods of exposure required for 6 ¢/lb to 10 ¢/lb decline in support price…
Rel. Humidity . 30% 45% 60%
Temperature Exposure time in hours
50ºF 12 48 7265ºF 72 96 *80ºF ** * **
* 5 ¢/lb decline after 96 hrs** No damage for exposure up to 96 hrs
(additional comments made in paper)
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Walton & Henson5, 1973…
Study of effects of exposure to periods of high relative humidity on quality…
Temperature: 50º, 65º, 80º FRel. Humidity: 80%, 90% Air Flow: 15 ft/minTimes of Exposure: 0, 48, 96, 144, 192, 240 hrsStages of cure: Initial (green), Yellow
Bur. 21, cured at 70 F and 70% R.H. except for exposure times
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Walton & Henson5, 1973…
Results: Decline in support price after 240 hrsexposure by prediction equation…
Initial Stage Yellow Stage
Temperature 80% 90% 80% 90%50ºF 0 9¢ 1¢ 1¢65ºF 0 3¢ 1¢ 8¢80ºF 2¢ 1¢ 4¢ 4¢
(additional comments made in paper)
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Many other burley studies since the 1970’s ..
J. Bunn, W. Henson, L. Walton, L. Bush, H. Burton, L. Davis, G. Duncan, others...
onbulked stalkshand, machine primed leaves,
heated air & natural air w/fanleaves cured on & off the stalkconcurrently field cured on frames, in ‘structures’,
plastic covered, and in barns…
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Early to mid 1980’s and continuing,a major cured burley concern…
N i t r o s a m i n e s !!!!
Affected by- -Genetics,Cultural practices,Curing,Storage & Handling
A Finding: TSNAs develop from browning phase on throughout curing with ‘high’ moisture…
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Now, continue with curing emphasis & means of evaluating ‘good’ curing…
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Outside Ambient Temperature & Relative Humidity, C. Ky. Barn, 2005
20.025.030.035.040.045.050.055.060.065.070.075.080.085.090.095.0
100.0
08/2
7/05
08/2
9/05
08/3
1/05
09/0
2/05
09/0
4/05
09/0
6/05
09/0
8/05
09/1
0/05
09/1
2/05
09/1
4/05
09/1
6/05
09/1
8/05
09/2
0/05
09/2
2/05
09/2
4/05
09/2
6/05
09/2
8/05
09/3
0/05
10/0
2/05
10/0
4/05
10/0
6/05
10/0
8/05
10/1
0/05
10/1
2/05
10/1
4/05
10/1
6/05
10/1
8/05
10/2
0/05
10/2
2/05
10/2
4/05
10/2
6/05
10/2
8/05
10/3
0/05
11/0
1/05
11/0
3/05
11/0
5/05
11/0
7/05
11/0
9/05
11/1
1/05
11/1
3/05
11/1
5/05
11/1
7/05
Date
Tem
p., R
H
RH Temp
Method to evaluate environment,e.g. How to ‘visualize’ good curing…
A lot of ‘overlapping’ lines here!! Let’s improve the analysis > >
4 day high
Humidity 6 day h.h.5 day h.h.
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Recent chamber studies6, 7 indicate 75% ‘average’ R.H. is best for current burley. Then consider 10% above & below as ‘good’ range…
75%
85%
65%
A Concept… consider daily cycle of RH…
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Now, let’s analyze hourly RH data per the following sample data in a spreadsheet…
192
155
164
343Sum
173
186
177
160
30.0%40.0%30.0%%
189
182
169
>85%65%-85%<65%RH
Use logic to put a ‘1’ in one of 3 columns according to RH values, then sum the ‘1’s & calc. %:
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
which represents the cumulative ‘Low Humidity’, ‘Good Humidity’ & ‘High Humidity’ hours:
30.0%
40.0%
30.0%
00.5
11.5
22.5
33.5
4C
umul
ativ
e H
ours
<65% 65%-85%
>85%
Relative Humidity
And plot the sums as a bar graph,
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Now consider data from a Central Ky. Burley Barn8 in 2005..
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Hours x Outside Relative Humidity, 2 week periods, C. Ky. Farm, 2005
118 119
91 92
115
171
77
91
112102 100
111
142
127133
142
121
55
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
9/10/2005 9/24/2005 10/8/2005 10/22/2005 11/5/2005 11/19/2005
Date (ending of 2 week period)
Cum
ulat
ive
Hou
rs
<65% 65%-85% >85%
Ambient RH Outside the barn
Data is grouped in two week periods, representing typical ‘yellowing’, ‘browning’ and ‘leaf drying’ & ‘midrib drying’ stages:
Note rather good ‘balance’ of low & high RH around the daily average except for more ‘humid’ Aug., Oct. & ‘dry’ Nov. periods.
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
p y, y ,
20.025.030.035.040.045.050.055.060.065.070.075.080.085.090.095.0
100.0
5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
Tem
p., R
H
RH Temp
Hours x Outside Relative Humidity, 2 week periods, C. Ky. Farm, 2005
0102030405060708090
100110120130140150160170
9/10/2005 9/24/2005 10/8/2005 10/22/2005 11/5/2005 11/19/2005Date (ending of 2 week period)
Cum
ulat
ive
Hou
rs
<65% 65%-85% >85%
Now compare ‘overlapping’ lines of RH plot with bar graph, note ‘humid’ period in Aug. & Oct..(RH>85-95%), ‘dry’ period in Nov.(mostly 25-80%)
35%118
23%77
42%142
35%119
27%91
38%127
27%91
33%112
40%132
27%92
30%102
42%142
34%115 30%
100
36%121
51%171
33%111
16%55
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Hours x Inside Relative Humidity, 2 week periods, C. Ky. Barn, 2005
0102030405060708090
100110120130140150160170180190200210220230
9/10/2005 9/24/2005 10/8/2005 10/22/2005 11/5/2005 11/13/2005
Date (ending of 2 week period)
Cum
ulat
ive
Hou
rs
<65% 65%-85% >85%
RH Inside the barn, middle of 5 tiers.
Now look at data inside same barn (middle of 5 tiers), with vents managed for ‘good’ curing…Aug. & Oct. periods of high outside RH had similar ‘higher humidity’ in the barn,
(vents could have been opened more), however prevailing levels of good 65%-85% RH occurred during Oct. yellowing to browning and Nov. drying!
Note: Only 8 days of datafor 11/13/05
41%138
2%7
57%191
11%37
50%168
39%131
14%47
61%205
25%85 22%
72
34%113
45%151
29%97
50%167
22%73
57%109
38%74
5%10
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Hours x Outside Relative Humidity, 2 week periods, C. Ky. Farm, 2005
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
9/10/2005 9/24/2005 10/8/2005 10/22/2005 11/5/2005 11/19/2005
Date (ending of 2 week period)
Cum
ulat
ive Hou
rs
<65% 65%-85% >85%
Hours x Inside Relative Humidity, 2 week periods, C. Ky. Barn, 2005
0102030405060708090
100110120130140150160170180190200210220230
9/10/2005 9/24/2005 10/8/2005 10/22/2005 11/5/2005 11/13/2005
Date (ending of 2 week period)
Cum
ulative Hou
rs
<65% 65%-85% >85%
Comparison of ‘Outside’ & ‘Inside’ RH graphs for C. Ky. Barn, note dominance of ‘good’ curing conditions inside barn.
RH Inside the barn
RH Outside the barn35%118
23%77
42%142
35%119
27%91
38%127
27%91
33%112
40%132
27%92
30%102
42%142
34%115 30%
100
36%121
51%171
33%111
16%55
41%138
2%7
57%191
11%37
50%168 39%
131
14%47
61%205
25%85 22%
72
34%113
45%151
29%97
50%167
22%73
57%109 38%
74
5%10
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
TSNA data9 for five locations in the C. Ky. Barn:(Variety: TN90)
Samples from C. Ky. Barn, 2005
Location NNN NAT NAB NNK TSNAug g-1 ug g-1 ug g-1 ug g-1 ug g-1
BC01 0.73 0.85 ND 0.14 1.72BC03 0.83 1.44 ND 0.16 2.43BC04 0.93 1.74 ND 0.19 2.86BC05 0.89 1.44 ND 0.17 2.50BC06 1.06 1.39 ND 0.19 2.65
AVG: 2.43
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
RH Lexington Airport
Now go to another location: RH at Lexington Airport10 showing rather ‘dry’ curing weather for 2005
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
RH inside UK Spindletop Farm 10 miles away from Airport for a selected curing period,generally ‘good’ curing except for a two week Oct. ‘humid’ period.
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Samples from U. Ky. Barn & Lab Chamber Curing, 2005
Location NNN NAT NAB NNK TSNAug g-1 ug g-1 ug g-1 ug g-1 ug g-1
UK Barn 1.36 1.63 0.055 0.15 3.20BAE Lab #1 0.78 1.30 ND 0.18 2.26BAE Lab #2 1.12 1.70 ND 0.23 3.05Note: BAE Lab #1 cured at constant 70 F, 75% BAE Lab #2 cured at daily cycle of 60-80 F, 50%-90%
TSNA data9 for U.Ky. Barn and Chamber Curing, 2005:(Variety: KT204) 11
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
RH at Lexington Airport10 for 2004 showing more ‘humid’ periods.
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
RH at Lex. Airport10 for 2003 showing generally good curing with 3 ‘humid’ periods.
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
RH at Lexington Airport10 for 2002 showing generally 2 ‘dry’ periods, 1 ‘humid’ period, otherwise good curing periods.
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
RH at Lexington Airport10 for 2001 showing generally good early curing with 3 ‘dry’ periods in latter part of season.
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Summary of RH at Lexington Airport10 for 5 curing seasons.Note 2004 9% hours more ‘humid’, 2005 11% hours more ‘dry’.
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
11 days
14days
Missing
14days
Now analyze RH at Raleigh-Durham Airport12 for 2005, showing early ‘humid’ period, later ‘dry’ period, otherwise rather ‘good’ curing conditions.
Weather data missing in several periods
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
RH at Raleigh-Durham Airport12 for 2004, showing predominant ‘humid’ periods!
Hours x Relative Humidity, 2 week periods, Raleigh-Durham , 2004
8090
62
73 70
54
90
10698 99
8085 85
96 98108
158
147
194
178 181186
148
122
0102030405060708090
100110120130140150160170180190200
8/14/2004 8/29/2004 9/12/2004 9/27/2004 10/11/2004 10/25/2004 11/8/2004 11/22/2004
Dates (ending of 2 week period)
Cum
ulat
ive
Hou
rs
<65% 65%-85% >85%
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
RH at Raleigh-Durham Airport12 for 2003, showing predominant ‘humid’ periods except for mid Nov.
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
RH at Raleigh-Durham Airport12 for 2002, showing mostly ‘humid’ periods except for early ‘dry’ period & mid ‘good’ period!
Hours x Relative Humidity, 2 week periods, Raleigh-Durham, 2002
196
86 86
69 71
35
50
71
89 91 91
138
113
7065
72
51
159 159
129
152
231221
193
0102030405060708090
100110120130140150160170180190200210220230
8/14/2002 8/28/2002 9/11/2002 9/25/2002 10/9/2002 10/23/2002 11/6/2002 11/20/2002
Date (ending of 2 week period)
Cum
ulat
ive
Hou
rs
<65% 65%-85% >85%
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
RH at Raleigh-Durham Airport12 for 2001, showing mixture of ‘humid,’ ‘good’ & ‘dry’ periods!
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Summary of RH at Raleigh-Durham Airport12 for 5 curing seasons.Note 2005 rather ‘good’ curing season, 2001 ‘maybe’, other 3 very ‘humid!’
RH x Percentages of Hours by Year, Raleigh-Durham, 2001-2005
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
2001 2002 2003 2004 2005
Year
Perc
enta
ge o
f Hou
rs
<65% 65%-85% >85%
35%
40%
25% 25%27%
48%
23%
28%
49%
23%
28%
49%
37%
33%31%
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
Comparison of Lexington & Raleigh-Durham for 2001-2005 curing seasonsLex. shows mostly ‘good’ curing seasons with one having 9% ‘humid’ & one 12% ‘dry’ hours.
Raleigh-Durham shows one ‘good’ curing season, one ‘maybe’, three with 21% more ‘humid’ hours.
Hours x RH Percentages by Year, Lexington, 2001-2005
40%
30%
24%25%
45%
37%36%
38%
33% 34%
23%
34%
39%42%
21%
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
2001 2002 2003 2004 2005Year
Percen
tage
of H
ours
<65% 65%-85% >85%
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
1. Principles and brief studies of air curing conditions for burleytobacco have been reviewed.
2. A method for analyzing relative humidity data to graphically andvisually portray ‘dry’, ‘good’ and ‘humid’ conditions has been presented.
3. An analysis of Central Kentucky, Lexington, KY, and Raleigh-Durham, NC, weather data shows the prevalence of ‘dry’, ‘good’& ‘humid’ curing seasons in traditional and non-traditional burley curing regions.
4. For the past 5 years, Lex. shows mostly ‘good’ curing seasons with one having 9% ‘humid’ & one 12% ‘dry’ cumulative hours.
5. For the past 5 years, Raleigh-Durham shows one ‘good’ curing season, one ‘maybe’, three with 21% more ‘humid’ cumulative hours.
6. Additional years of data & locations should be studied for more longer-term analyses of burley curing conditions.
Summary:
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
1 Jeffrey, R. N. The Effects of Temperature and Relative Humidity During and After Curing upon the Quality of White Burley Tobacco. Bull. No. 407, Ky. Agr. Exp. Sta., Univ. of Ky., Lexington, July, 1940
2 Jeffrey, R. N., The Relation of Curing Conditions to Quality in Burley Tobacco. Bull. No. 496, Ky. Agric. Exp. Sta., Univ. of Ky., Lexington, Dec., 1946
3 O’Bannon, Lester S., Distribution of Temperature and Relative Humidity Within a Burley Tobacco Barn. Bull. No. 444, Ky. Agric. Exp. Sta., Univ. of Ky., Lexington, May, 1943
4 Walton, L. R., and W. H. Henson, Jr. Effect of Environment During Curing on the Quality of Burley Tobacco: I. Effect of Low Humidity Curing on Support price. Tob. Sci. 15:54-57. May 14, 1971
5 Walton, L. R., and W. H. Henson, Jr. Effect of Environment During Curing on the Quality of Burley Tobacco: II. Effect of High Humidity Curing on Support price. Tob. Sci. 17:25-27. 1973
6 Duncan, G. A., M. Montross, J. Calvert, D. Smith, D. Mereand. Ongoing Studies of Barn, Field and Chamber Curing Environments on TSNA Formation in Burley Tobacco. Presented at the 2002 CORESTA Congress, New Orleans, LA, Sept. 22-27, 2002, Abstract in Proceedings.
References Cited:
1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton
7 Duncan, G. A., J. Calvert, D. T. Smith and D. C. Middleton. Further Studies of Fertility levels and Barn and Chamber Curing Environments on TSNA Formation in Burley Tobacco. Presented at the 2004 CORESTA Congress, Kyoto, Japan, 3-7 Oct., 2004, Abstract in Proceedings.
8 Thanks to Mr. Ben Crain and Family, Liberty Hall Farm, Woodford Co., and to Mr. David Talley, Grower, for cooperation, support and assistance with the 2005 curing study.
9 Thanks to Dr. Lowell Bush & Lab Technicians, Dept. of Plant and Soil Science, U. Ky., Coll. of Agr., for the TSNA analyses.
10 Data downloaded from archives of Ag. Weather Center, U. Ky., Coll. Of Agric., Mr. Tom Priddy, Dir., http://wwwagwx.ca.uky.edu/
11 Thanks to Dr. Bob Pearce and Mr. Jack Zeleznik, Dept. of Plant and Soil Science, U. Ky., Coll. of Agr., for the mature tobacco plants.
12 Thanks to Mr. Tom Priddy, Dir., Ag. Weather Center, Col. Of Agric. For obtaining the NOAA weather records for the Raleigh-Durham Airport location for Aug.-Nov., 2001-2005.
*** End ***
References Cited (Cont’d):