The Purpose of a Fertilizer is
to Supply Nutrients.
Tobacco Fertilization
• Not only important for optimum yield, but
extremely important for quality
• Ripenning of tobacco is caused by N starvation
• Begins with the bottom leaves (same as N
deficiency) and moves up the stalk
• Proper fertilization is key to ripenning
Fertilization Principles
• Understand the nutrient needs of the plant.
• Know the level of nutrients supplied by the
soil.
• Use fertilizers to supply the difference.
• Lime to the optimum pH.
Soil Testing
•
•
•
•
Before any fertilizer is applied
P index
K index
pH
Effect of pH on Nutrient Availability
Troug, 1948
The pH of Tobacco Soils in the
Coastal Plain and Piedmont
45
40
35
30
25
Coastal Plain
Piedmont
20
15
10
5
0
0-4.9
5-5.4
5.5-5.9
6.0-6.4
6.5+
2002
Recommended pH
• For Tobacco Soils
– 5.8 to 6.2
Essential Elements
• Carbon, Hydrogen, Oxygen
• Nitrogen, Phosphorus, Potassium, Calcium,
Magnesium, Sulfur, Chloride
• Boron, Manganese, Iron, Zinc, Copper, and
Molybdenum
Nutrient Removal by a 2000
Pound Tobacco Crop
Nutrient
Pounds/Acre
Nitrogen
70
Phosphorus
12
Potassium
80
Calcium
55
Magnesium
22
Sulfur
18
McCants and Woltz
Nutrient Removal by a 2000
Pound Tobacco Crop
Nutrient
Pounds/Acre
Boron
0.07
Manganese
0.7
Iron
Trace
Zinc
Trace
Copper
0.04
Molybdenum
Trace
McCants and Woltz
Fertilization Principles
(The Five R’s)
•
•
•
•
•
Apply the right nutrient,
at the right rate,
at the right time,
in the right place,
at the right cost.
Effect of Base Fertilizer
Application Methods on Yield
2360
2340
2320
2300
Lb/A 2280
Yield
2260
2240
2220
2200
Brdcast
1 Bd Deep 2 Bd/Trans 2 Bd/7-10D
Application Method
64 OFT, 1972-79
WKC and SNH
Proper Timing, Rate, and
Placement of Nutrients
• Increases uptake efficiency by:
– Minimizing leaching of mobile nutrients such
as nitrogen.
– Minimizing fixation of nutrients such as
potassium and phosphorus in certain soils.
• Reduces pollution of ground and surface
waters through increased uptake by plants.
Weeks After Transplanting
Soil Nitrate Levels With 150 lbs
N Applied in 1 Application
4 Weeks
0-15 cm
16-30 cm
31-45 cm
46-60 cm
61-75 cm
8 weeks
12 Weeks
0
5
10
15
20
25
Soil Nitrate (PPM)
Smith, 1980
Time After Transplanting
Soil Nitrate Levels With 150 lbs
N Split Over 3 Applications
4 Weeks
0-15 cm
16-30 cm
31-45 cm
46-60 cm
61-75 cm
8 weeks
12 Weeks
0
5
10
15
20
25
Soil Nitrate (PPM)
Smith, 1980
$/Ha
Effect of Application Number on
Tobacco Value
8800
8600
8400
8200
8000
7800
7600
7400
7200
7000
6800
6600
Value
1
2
3
4
5
Number of Nitrogen Sidedressings
Smith, 1980
Nitrogen
The Most Important Nutrient
Affecting Yield and Quality
As Nitrogen Rate Increases
• Yield increases to a point then decreases.
• Leaf size increases, but leaf thickness
(body) decreases.
• Total alkaloids increase and sugars decrease
in cured leaf.
• Maturity and ripening are delayed.
• Cured-leaf color darkens.
As Nitrogen Rate Increases
• Sucker growth increases and control
decreases.
• Leaf drop and leaf break increase.
• Hornworm and aphid populations increase.
• Blue Mold losses are more severe.
Effect of Nitrogen Rate on
Quality
Quality Factor
N Rate
1
2
3
-------------Percent--------------Low
30
70
0
Rec.
25
73
2
Excess
19
64
17
Suggested Base Nitrogen Rates
Based on Topsoil Depth
Topsoil Depth
Inches (cm)
5 (13)
Nitrogen Rate
lb/a (kg/ha)
50 (56)
10 (25)
60 (67)
15 (38)
70 (78)
20+ (51)
80 (90)
Maturity vs. Ripeness
• Maturity
– When a leaf reaches maximum size and weight.
– A function of leaf age (time in the field).
• Ripeness
– A function of nitrogen metabolism (uptake).
– A leaf will not ripen until nitrogen uptake is
nearly zero.
– A nitrogen starvation process.
Nitrate Reduction and Starch
Accumulation- Ideal Conditions
Nitrate Reduction and Starch
Accumulation- Delayed N Uptake
Nitrate Reduction and Starch
Accumulation- Restricted N Uptake
Ammonium vs. Nitrate N
Sources
• Lower yields when N absorbed primarily
in ammonium form.
• Response to ammonium in the fertilizer is
related to nitrification rate.
• Nitrification rate is slower when:
– Soil pH is low.
– Soil moisture is low.
– Low soil temperature.
Ammonium vs. Nitrate N
Sources
• Recommendations for North Carolina
conditions.
– As long as pH is correct, N source will not
affect yield and quality
• Calcium nitrate, Potassium Nitrate,
Ammonium Nitrate, Urea, 30% UAN,
24%S etc.
Fertilization
• Greater than 90% of tobacco soils in North
Carolina have a high or very high
phosphorus index
• No phosphorus needed to produce tobacco
• NC average is about 65 lbs P per acre
• Agronomically and Environmentally sound
practice to eliminate or reduce P use
• GAP
Fertilization
• If no or low P is needed then it could
possibly reduce fertilizer costs
• Definitely opens the door for additional
sources and application methods of N and K
Effect of Fertilizer Treatment on
Tobacco Value 2004-05
7000
6000
5000
3000
2000
1000
0
Du
p
Ro 04
ck
CC 04
R
UC S 0
PR 4
S
0
O 4
UC ns 0
PR 5
S
CC 05
RS
05
Av
g
Value ($/A)
4000
6-6-18/15.5-0-0
0-0-22/15.5-0-0
Effect of Fertilizer Treatment on
Tobacco Value 2005
4500
4000
3500
3000
2500
Value ($/A)
2000
1500
1000
500
0
G
AV
RS
CC
S
PR
UC
O
ns
lo
w
6-6-18/15.5-0-0
6-3-18/15.5-0-0
0-0-22 Band/CN-9
0-0-22 Bdcst/CN-9
Fertilization
• Even though there is no yield response to P
application on high P soils there may an
early growth response
• Especially under cool, wet conditions
immediately following transplanting
• Ability of a small root system to “find”
phosphorus if none is applied in fertilizer
Effect of Fertilizer Treatment on
Flowering 2005
40
35
6-6-18/15.5-0-0
Flowers/Plot
30
6-3-18/15.5-0-0
25
20
0-0-22/15.5-0-0
15
0-0-30/30%
UAN/TPW
10
5
0
62
66
70
Days After Transplanting
76
UCPRS
Fertilization
• Same early growth response from 20 lbs of P from
6-3-18 or 5 lbs of P in the transplant water
• Allows for a significant reduction in P application
without affecting early season growth
• Allows for alternative K sources
• Allows for 100% of N to be supplied from a N
only product
Nitrogen Study
• Two Locations
Kinston and Oxford
• Three Sources
Ammonium Nitrate
Calcium Nitrate
30% UAN
• Rates
0, 20, 40, 60, 80 (lb/A) - 2004
100, 120 (lb/A) – added in 2005
Effect of N Rate on Tobacco
Yield and Value at LCPRS
*
lbs. or $/A
5000
4000
Yield
Value
*
3000
2000
0
20
40
60
Nitrogen Rate (lb/A)
80
2004
Effect of N Rate on Tobacco
Yield and Value at LCPRS
5000
lbs. or $/A
4500
*
4000
Yield
Value
3500
*
3000
2500
2000
0
20
40
60
80
Nitrogen Rate (lb/A)
100
120
2005
Fertilization
• Avoid K and N sources that contain more
than 20-30 lbs of Cl per acre
• State Law limits Cl levels in “tobacco
grade” fertilizers
• Only small amounts of KCl are acceptable
• K Mag
• Sulfate of Potash
Fertilizer Selection
• Choose ratio based on soil test P.
–
–
–
–
0 Lb/A: 1-0-3 (8-0-24), 0-0-1 (0-0-30, 0-0-22)
1-40 Lb/A: 1-1-3 (6-6-18, 8-8-24)
41-80 Lb/A: 1-2-3 (4-8-12, 6-12-18)
81+ Lb/A: 1-3-3 (3-9-9, 6-18-18)
• Apply at the rate to supply all of the P
recommended and no more than 40 Lb N/A.
Fertilizer Selection
• Additional N from a sidedresser
• Use N/K sidedresser if additional K is
needed. 15-0-14, 13.5-0-14
Nitrogen Applications to
Partially Drowned Tobacco
3500
3400
3300
3200
3100
$/A 3000
2900
2800
2700
2600
2500
Value
0
15
30
Nitrogen Rate (Lb/A)
Peedin,
2 Loc., 1995
Effect of Fertilizer Addition to
Partially Drowned Tobacco
3500
3400
3300
3200
3100
$/A 3000
2900
2800
2700
2600
2500
Value
None
16-0-0 30%, 15-0-14 8-0-11
BC-OT WB-RM BC-OT BC-OT
Fertilizer Treatment
Peedin,
2 Loc., 1995
Organic Nitrogen
• Undesirable for tobacco
– Organic N not adsorbed by roots. Must undergo
mineralization prior to uptake.
– Mineralization rate is unpredictable.
• Makes rate determination difficult.
• Usually too slow, and contributes to late-season N
uptake. Delays ripening.