Presented by University of Minnesota Extension professor, Terry Nennich at the 2009 Minnesota Statewide High Tunnel Conference in Alexandria, MN on Dec. 2-3, 2009.

1. Organic High Tunnel
Fertility Research
Terrance T. Nennich
Extension Professor
Vegetable and Small Fruit Production
University of Minnesota Extension
nenni001@umn.edu
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2. High Tunnel Research Sites in
Minnesota
Experiment Stations
Grower Cooperators
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3. © 2009 Regents of the University of Minnesota

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5. Why Organic Fertility
Research in High
Tunnels?
The Concept
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6. Organic soil fertility studies
The purpose of this study is to measure
the amount of soil nutrients, used buy
tomatoes and cucumbers in a very high
production system in high tunnels.
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7. The Organic System
in High Tunnels
As in any organic production system,
chemicals and other commercial crop
inputs are traded for excellent
management.
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8. © 2009 Regents of the University of Minnesota

9. Crookston Organic Tunnel
What we did?
What Happened
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10. Water Testing
Consider testing the water for at least
nitrates .
The Crookston high tunnel was being
watered by the city water supply.
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11. Soil Texture Amending
The soil texture at the Crookston site was
a very heavy clay. ( Red River Mud)
We desired to change to a sandy clay
loam.
To do this we added about one cubic yard
of sand for every 100 square foot.
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12. Concerns from Previous High
Tunnel Experiences 1999-2006
Enough soil fertility between residual and
applied application to meet plant growth
and yield.
What is left at the end of the growing
season for future production
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15. Soil texture
The goal was to have a soil organic matter
of at least 5% and ideally 6-7%.
In order to accomplish this we added
about ½ yard of composted horse manure
per 100 Square ft.
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16. Soil Fertility
Soil fertility must start out very high with enough
organic matter to prevent leaching of nutrients.
In this case horse manure was used
It is very difficult to add enough soil nutrients
organically after plants are established
However there are some products that can help.
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17. Test the Sand
Test for Basics
- pH
- Other nutrients are ok but not as
important
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18. Compost/Manure
Use only very well rotted manure
Don’t assume that compost is high in nutrients.
Do regular soil test plus micros
May need to do a dilution test if the nutrients are
extremely high (off the chart)
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19. Test the compost
Horse Beef Plant
N 2418 1410 321
P 407 310 106
K 2321 1830 482
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20. Test Soil Before Planting
After all incorporation and soil amending is
done test the soil before planting.
– In high tunnels test 9-10 inches deep.
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21. Planting Beds
Planting beds were raised 1 inch (from 4
to 5 inches)
Width of the beds were increased 4 inches
(from 16 to 20 inches)
– This increased the soil volume of the beds by
approximately 55%, increasing available
nutrients and soil moisture to the plants.
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23. © 2009 Regents of the University of Minnesota

24. Additional Fertilization
A organic fish solution of a 4-1-1 was used
that was compatible with the drip tape.
The fish solution would be used on a
continuous flow basis
The rate would start at about 2 oz/100
running ft. of tape and increased to 6 oz as
the nutrient needs of the plants increased.
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27. Plant Spacing
Spacing between rows would remain the same at 48
inches.
Plant spacing in the row would be increased to allow for
more air flow and hopefully more natural disease control.
Alternate plant spacing would be used to maximize
nutrient availability and increase air flow around the
plants.
Hopefully the individual plants would compensate with
increased yield.
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28. Plant Spacing
In row plant spacing would be increased
to :
– 24 inches for indeterminate tomatoes such as
Coba and Ultra Sweet.
– 18 inches for determinant tomatoes such as
Sunstart, Sunshine, and Mountain Spring.
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29. Plant Spacing
– Cucumber varieties would be increased to 18
inches.
– Peppers would remain the same 2 rows on a
bed planted 18 inches in a staggered
configuration
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30. Alternate Spacing
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31. Plant Pruning
Reasonable plant pruning practices would be
done to increase earliness, size and allow more
airflow for disease control.
– Determinate tomatoes would have 2 punning
– Indeterminate tomatoes would have moderate
continuous pruning
– Christmas tree method pruning would be used to
control side growth.
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33. Soil Nutrient Research
2007
Before planting soil was tested at
0-6 inches
6-12 inches
12-24 inches
Soil was retested for each crop after season
production.
All plots were fertilized equally
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34. Tomato Results 2007
Variety Cobra
First harvest June 21
Total Yield 37 Pound/plant
Culls 4 Pound/Plant
Marketable 3.89 Pound sq/ft
Total Yield 4.63 Pound sq/ft
Acre Yield 101 ton acre
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35. Soil Nutrient Research
2007
Cobra Tomatoes
0-6 inch soil depth
N P K
Before Season 335 330 1050
After Harvest 11 215 235
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36. Soil Nutrient Research
2007
Cobra Tomatoes
6-12 inch soil depth
N P K
Before Season 100 150 580
After Harvest 8 80 320
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37. Soil Nutrient Research
2007
Cobra Tomatoes
12-24 inch soil depth
N P K
Before Season 18 60 275
After Harvest 8 55 260
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38. Cucumber Results
2007
Cucumbers
All the fruit from all 26 cucumber plants were weighed
and evaluated for quality. All data is in pounds per plant.
Sweet Success
First Harvest June 21
Total Yield/Plant 65.12
Culls 8.0
MKT/sq/ft 9,52
Total sq/ft 10.85
Total Yield Acre = 472,628 or 236 tons.
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39. Soil Nutrient Research
2007
Sweet Success Cucumbers
0-6 inch soil depth
N P K
Before Season 335 330 1050
After Harvest 12 175 256
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40. Soil Nutrient Research
2007
Sweet Success Cucumbers
6-12 inch soil depth
N P K
Before Season 100 150 580
After Harvest 7 69 320
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41. Soil Nutrient Research
2007
Sweet Success Cucumbers
12-24 inch soil depth
N P K
Before Season 18 60 275
After Harvest 6 60 235
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42. Soil Nutrient Research
2008
The 2008 research question was:
If the soil fertility is at high levels before
planting will additional yield be obtained by
adding a organic approved fertilizer to the
irrigation water at a continuous flow rate
through the season?
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43. Soil Nutrient Research
2008
The plots (rows) were divided in two, one
half fertilized through drip tape, the other
half received no supplemental fertilization
Tomatoes from both plots were weighed
and evaluated during the growing season.
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44. 2008 Soil Amending
Enough manure based compost was
added to raise the beginning soil nutrient
levels to very high.
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45. Fertilized Plot
Added 10 gallons of a 4-1-1 fish solution
evenly through drip tape
- per acre nutrients added were
- N 280
- P 70
- K 70
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46. Soil Nutrient Research
2008
Before planting soil was tested at
0-6 inches
6-12 inches
12-24 inches
Soil was retested for each crop after season
production.
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47. Tomato Results
2008
Variety Yield fertilized Yield Unfertilized
Cobra 49 Pounds/Plant 45Pounds/Plant
269,500 Pounds/Acre 247,500 Pounds/Acre
134 Tons Acre 123 Tons/Acre
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48. Soil Nutrient Research 2008
Fertilized Plots
Cobra Tomatoes
0-6 inch soil depth
N P K
Before Season 263 252 1349
After Harvest 26 235 173
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49. Soil Nutrient Research 2008
Unfertilized Plots
Cobra Tomatoes
0-6 inch soil depth
N P K
Before Season 263 252 1349
After Harvest 24 125 103
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50. Soil Nutrient Research 2008
Fertilized plots
Cobra Tomatoes
6-12 inch soil depth
N P K
Before Season 115 160 610
After Harvest 17 140 476
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51. Soil Nutrient Research 2008
Unfertilized plots
Cobra Tomatoes
6-12 inch soil depth
N P K
Before Season 115 160 610
After Harvest 13 111 269
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52. Soil Nutrient Research 2008
Fertilized Plots
Cobra Tomatoes
12-24 inch soil depth
N P K
Before Season 18 72 375
After Harvest 12 53 326
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53. Soil Nutrient Research 2008
Unfertilized Plots
Cobra Tomatoes
12-24 inch soil depth
N P K
Before Season 18 72 375
After Harvest 28 60 299
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54. Cucumber Results
2008
Cucumbers
Sweet Success
Fertilized Unfertilized
18 Pounds/Plant 13 Pounds/Plant
132,000 Pounds/Acre 95,329 Pounds/ Acre
66 Tons/Acre 48 Tons/Acre
There was considerably less yield in 2008, plants were removed early.
.
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55. Soil Nutrient Research
2008
Fertilized Plots
Sweet Success Cucumbers
0-6 inch soil depth
N P K
Before Season 263 252 1349
After Harvest 110 320 814
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56. Soil Nutrient Research
2008
Unfertilized Plots
Sweet Success Cucumbers
0-6 inch soil depth
N P K
Before Season 263 252 1349
After Harvest 122 185 318
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57. Soil Nutrient Research
2008
Fertilized Plots
Sweet Success Cucumbers
6-12 inch soil depth
N P K
Before Season 115 160 610
After Harvest 42 140 505
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58. Soil Nutrient Research
2008 Unfertilized Plots
Sweet Success Cucumbers
6-12 inch soil depth
N P K
Before Season 115 160 610
After Harvest 58 120 261
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59. Soil Nutrient Research
2008
Fertilized plots
Sweet Success Cucumbers
12-24 inch soil depth
N P K
Before Season 18 72 375
After Harvest 40 45 367
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60. Soil Nutrient Research 2008
Unfertilized Plots
Sweet Success Cucumbers
12-24 inch soil depth
N P K
Before Season 18 60 275
After Harvest 6 60 235
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61. 2009 Soil Fertility Results
As in 2008 the high tunnel was divided into
two areas for fertigated and unfertigated
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62. Compost Fertility Composition
2009
N 2418
P 407
K 2321
S 120
B 7.0
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63. Cucumber Yields 2009
Variety : Sweet Success
Fertilized, Yield per plant = 42 pounds
Not Fertilized ,Yield per plant = 28 pounds
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64. Preplant Soil Test.
2009
N P K
0-6 630 198 847
6-12 285 160 250
12-24 60 100 150
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65. Cucumbers
after harvest fertilized/drip tape
N P K
0-6 inch 81 lb/ac 189 230
6-12 inch 44 lb/ac 150 140
12 – 24 inch 32 lb/ac 70 90
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66. Cucumbers
After harvest not fertilized/drip tape
N P K
0-6 36 lb/ac 106 89
6-12 26 lb/ac 64 100
12-24 24 lb /ac 51 81
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67. Tomato Yields 2009
Variety: Cobra
Fertilized/drip tape : 31 pounds/plant
Not fertilized 25 : pounds plant.
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68. Tomatoes after harvest
fertilized/drip tape
N P K
O-6 inch 47 lb/ac 134 91
6-12 inch 28 lb/ac 108 145
12-24 inch 34 lb/ac 52 217
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69. Tomatoes
after harvest not fertilized/drip tape
N P k
0-6 inch 28 lb/ac 97 72
6-12 inch 30 lb/ac 85 119
12-24 inch 54 lb/ac 95 128
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70. Is Organic Production Feasible?
The 2007, 2008, and 2009 research and
demonstration projects show that organic
production in high tunnels works well and
can be very profitable if certain production
practices are followed and high nutrient
levels are maintained and supplied.
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71. Organic Production Concerns
1. Adequate fertility to supply nutrient
needs of high yields in the high tunnel.
- Special precautions will be needed
the second and subsequent years.
2. Plant spacing may need to be increased
3. Air flow and keeping plants dry
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72. Organic
Concerns/Recommendations
4. Continual feeding of plants even if a small
amount of nutrients.
5. Special precaution to take out all old plant
debris.
6. Extreme water management.
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73. Organic
Concerns/Recommendations
7. Seed selection
8. Learn early disease identification
8. Have organic approved crop protectants
on hand
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74. Questions
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