1. Terrance T. Nennich
Extension Professor
Fruit and Vegetable Production
University of Minnesota Extension
TOMATO NUTRITION FROM
GERMINATION TO HARVEST IN HIGH
TUNNELS

2. Tomato Nutrient Problems

3. Defining Terms
• Soil pH
– pH = potential of hydrogen
– Greatly affects the availability of nutrients
– Relative acidity / alkalinity
– pH of 7 is considered neutral
– Tomatoes grow best at 6.2-6.5
– Logarithmic scale
– Test both soil and irrigation water
• We often add acid(s) to irrigation water

4. Plant Nutrient Terminology
• Sufficiency: Moving target that varies from
carrying a crop to carrying a profitable crop.
Usually expressed as a percentage.
• Deficiency: Not enough nutrient present to
satisfy even the most minimal plant needs.
• Toxicity: Overabundance to the point of
damaging a plant or causing other nutrients to
be out of balance.

5. Analyzing Your Water
• Test water 1st use for:
– pH
– Alkalinity
– N, P & K
– Clogging particulates
– Fe
• Regularly test for pH and Alkalinity
• Well vs. Spring vs. Stream vs. Pond

6. Understanding The Life of a Tomato
Plant
• Planting - Rapid increase in vegetative mass
• 1st flowering
• Development of fruit
• Ripening of fruit
• Continued development of flowers and fruit
(indeterminate plants only***)
• Determinate types 2nd fruiting potential

7. Tomato Fertility Demands in high
Tunnels
• Not hard to get 5-7 pounds per plant
• Usually enough fertility in soil with a little
extra compost
• 20 pounds per plant excellent fertility
• 25- 50 pounds per plant requires extremely
high fertility, supplied at the proper stages of
growth in proper amounts.

8. Putting a High Tunnel In Perspective
• 1 acre = 43560 sq ft.
• A 26 X 96 High Tunnel = 2496 sq/ft
• 26 X 96 High tunnel = .057 acres
• A little over 1/20th of a acre.
• So when a soil tests requires 300 pounds of
Nitrogen for Example
• 300 X .057 = 17 pounds of N applied in the
high tunnel

9. Fertilizer Placement
• It is important to keep the high tunnel fertility
to a high level through out the high tunnel
• But—
• In high tunnels the fertilizer extraction zone is
very narrow as compared to field production
• 12 inches as compared to 36 inches + in the
field

12. Fertilizer Uptake Zone
• Plants will take up fertilizer from this zone 12”
• Fertilizer you apply much be into this zone.
• Any soil testing you do during the season must be
taken from this zone to be accurate.
• Which leaves little room for error

13. Tomato Fertilizer Use 5lb Plant
N P K
Plant Part -------- lb per ton F.W. ------------
Fruit 3.4 0.4 6.0
Vines 2.6 0.4 3.4
Total 6.0 0.8 9.4
Field Production 13.5 ton: ( 5 Lbs Plant)
81 lbs N/A
11 lbs P/A (25.3 lbs P2O5)
127 lbs K/A (152 lbs K2O)

14. Tomato Fertilizer Use 20lb Plant
N P K
Plant Part -------- lb per ton F.W. ------------
Fruit 3.4 0.4 6.0
Vines 2.6 0.4 3.4
Total 6.0 0.8 9.4
A 50 ton yield/A would require: ( 20 Lbs Plant)
300 lbs N/A
40 lbs P/A (92 lbs P2O5)
470 lbs K/A (564 lbs K2O)

15. Tomato Fertilizer Use 40lb Plant
N P K
Plant Part -------- lb per ton F.W. ------------
Fruit 3.4 0.4 6.0
Vines 2.6 0.4 3.4
Total 6.0 0.8 9.4
A 100 ton yield/A would require: ( 40 Lbs Plant)
600 lbs N/A
80 lbs P/A (184 lbs P2O5)
940 lbs K/A (1128 lbs K2O)

16. High Tunnel Perspective
50 T/A or 20# Plant
• 26 X 96 High Tunnel = .057 acres
• 300 N = 17.1 # in high tunnel
• 92 P2O5 = 5.24 # in high tunnel
• 564 K2O = 32.15 # in high tunnel
• This is a combination of soil and added supply
in the root zone

17. High Tunnel Perspective
100 T/A or 40# Plant
• 26 X 96 High Tunnel = .057 acres
• 600 N = 34.2 # in high tunnel
• 184 P2O5 = 10.48 # in high tunnel
• 1128 K2O = 64.29 # in high tunnel
• This is a combination of soil and added supply
needed in the root zone.

18. Soil Nutrient Research 2008
Fertilized Plots
Cobra Tomatoes
0- 6 inch soil depth in row
N P K
Before Season 263 252 1349
After Harvest 26 235 173

19. Considerations
• Some varieties do not have the capability to
make high yields, especially early cultivars
• Heirlooms are often not high yielding a will
self destruct under high fertility management
• Cultivars will very tremendously
• High Productive cultivars will show stress.

20. Tomato Flowering
• Important part of tomato plants life
• Analyzes its production capacity
• Analyzes is maturity
• Can reset its biological clock buy pruning

21. Nutrition at flowering and first small
tomatoes
• Plant tissue analysis
• Soil test in row
• Adjust fertility program
• Bring Ca to 100% sufficiency
• K+ needs to be above 3% by dry matter
• Nutrients: Potassium Nitrate, Calcium
Nitrate, Calcium Chelate, Potassium
Carbonate, & Magnesium Oxide, fish
emulsions , organic fertilizers.

22. Tissue Testing
• Plant tissue analysis at first flower.
• Tissue analysis:
– 10-15 whole leaves
– Collect from average plants
– Collect 4-5th leaf from top
• Most recent mature leaf
– Paper bags only!
– Overnight or pickup

24. Continual Testing
Every Two Weeks
• Monitor N, K+, Ca & Mg levels
• Monitor irrigation water pH weekly
• Weather considerations
– Day length
– Relative sun / cloud cover
– Day / night temperature variations
• Creating high quality fruit requires careful
irrigating.

25. Fertilizer
• Needs to be added at least weekly
• Up to Flowering 1-1-1 ratio
• After flowering 2 -1- 2 ratio
• Possible 1-1-4 after harvest.
• Added fertilizer should have Micro Nutrients.

26. Tools
• pH meter in good order
• pH calibration solutions (fresh)
– pH 4.00 & pH 7.00
• Plant tissue test kits (mail or drop)
• N & K meters (optional)

27. Questions