The interest in production of vegetables without the use of synthetic fertilizers or pesticides has grown in both the general populace and those who are charged with conducting research to determine the efficacy of production systems.  This section of the web-site will be devoted to information developed from controlled experiments dealing with organic vegetable production.

In 2002 a long-term field experiment that compares organic and conventional production of vegetables was initiated.  Three years of data have been compiled.  The results are found later in this section.

During the production of bell pepper transplants for the 2002 season it was found that those in organic products appeared to be less vigorous than those in a conventional potting soil.  In 2003 this again occurred and it was decided to not use the transplants and establish the crop by seed.  This inconsistency in vigor led to the examination of ways to improve transplant production using organic materials.  Presented first is the results of the initial experiment.

Experiments with transplant production:

The experiment studied bell pepper, onion and watermelon.  Bell pepper is accepted as being established in the field as transplants, onion  is receiving attention for establishment as transplants, and watermelon is gaining acceptance for establishment as transplants.

The seed of each vegetable was placed in to the potting mixes.  Reddi-Earth is a conventional potting mix from Scott's.  The others are brand names from Garden-Ville.  The plants in the Reddi-Earth were fertilized with a half-strength Peter's water soluble, synthetic, fertilizer.  Those in the organic media were fertilized with SeaTea, an organically certified fertilizer from Garden-Ville, at full recommended strength.

Medium Height (mm) Dry weight (g) Height (mm) Dry weight (g) Height (mm) Dry weight (g)
  Bell pepper   Onion   Watermelon  
Reddi-Earth    111.2 0.37   198.2 0.48 48.3 0.16
Container Mix      41.3 0.09   105.3 0.21 43.8 0.09
Potting Soil      39.9 0.06     93.6 0.19 48.9 0.09
Lawn and Garden      27.5 0.04     82.2 0.11 34.6 0.10

The results indicated that bell pepper and onion seedlings did better in the Reddi-Earth than in any of the organic mixes.  Watermelon transplants, which are ready to be moved to the field in about three weeks following seeding, were generally similar.

Experiments to explain the lack of vigor of organically produced transplants

It was not clear if the organic media, or the SeaTea was the contributor to the reduced vigor of the organically produced transplants bell pepper and onion transplants.  Experiments were designed to see if this could be determined.

Extended maintenance of seedlings in organic media:

The first experiment maintained plants in the transplant trays to determine if they needed more time to develop a vigor similar to those produced in conventional potting soil.  Individual plants from from the trays were also transferred to 12.7 cm dia pots filled with Reddi-Earth potting soil.  These plants were fertilized with the half-strength water soluble, synthetic, fertilizer, or with full-strength SeaTea.

 

Container

 mix

Potting

 soil

Lawn and

 Garden
Condition of growth Height (cm) Dry weight (g) Height (cm) Dry weight (g) Height (cm) Dry weight (g)
     

Bell pepper

      
Maintained in transplant tray    65.3 0.22     79.9 0.28    51.2 0.14
Transferred to Reddi-Earth, fertilized with SeaTea 118.7 1.45 136.0 1.91 142.7 2.47
Transferred to Reddi-Earth, fertilized with Peter's 192.7 3.37 178.7 2.76 186.0 3.58
     

Onion

      
Maintained in transplant tray 149.3 0.14 147.4 0.15 138.7 0.10
Transferred to Reddi-Earth, fertilized with SeaTea 251.3 0.46 236.7 0.37 384.0 0.89
Transferred to Reddi-Earth, fertilized with Peter's 246.7 0.62 251.0 0.31 344.0 0.54

These data indicate that the SeaTea likely was not toxic.  However, there existed a question about whether the recommended concentration was sufficient.  An additional experiment was designed to determine the best rate of SeaTea to apply to developing seedlings.

Rate of SeaTea on seedling development:

Seed of bell pepper were placed in to Reddi-Earth and fertilized with SeaTea at 0.5-, 1-, 2- or 4-fold rates.  Plant heights and dry weights were determined at six weeks after emergence.

SeaTea Rate Height (cm) Dry weight (g)
0.5-fold   42 0.07
1.0-fold   45 0.08
2.0-fold   61 0.12
4.0-fold 112 0.16

The data indicate that SeaTea should be applied at the 4-fold rate to produce bell pepper transplants that are similar in size to those produced in Reddi-Earth and fertilized with 0.5-fold the recommended rate of Peter's.

Following is a picture of typical transplants produced after treatment with SeaTea, Rocket Fuel or the conventional fertilizer.

Five seedlings from the left: Equally aged seedlings grown in Sunshine potting mix and fertilized with Rocket Fuel at 1-, 2- or 4-times, or SeaTea at 2- or 4-times, the label rate.  Five seedlings from the right: Equally aged seedlings grown in a Gardenville product potting mix and fertilized with Rocket Fuel at 1-, 2- or 4-times, or SeaTea at 2- or 4-times the label rate.  The plant in the middle was grown using a conventional potting mix and fertilized with a soluble synthetic fertilizer.
 

 

A long-term program comparing effects of organic and conventional methods on vegetable production was begun in 2002.  The conventional method employs synthetic fertilizers and pest control methods.  The organic method employs organically certified fertilizers and pest control methods.  Bell pepper, cucumber and sweet corn are the crops being examined.  In the organic plots, in addition to the fertilizer applied to all plots, levels of humates (Hum) and corn gluten meal (CGM) were also applied.  The humates were applied and incorporated prior to planting.  The CGM, which is an organic herbicide and also supplies additional nutrition, was applied after the vegetable crops had established root systems.  The rates for humate were: 0 = none applied, 1 = 100 lbs/acre; 2 = 200 lbs/acre; and for CGM were: 0 = none applied; 1 = 400 lbs/acre; 2 = 800 lbs/acre.

                                                                                   Yields in Tons/acre

Bell pepper cv. Jupiter

 

Growing Season

 

System

2002

2003

2004

Conventional

8.55

3.97

  2.78

Organic

0.62

5.37

  4.00

Rate

 

 

 

Hum - CGM

 

 

 

0          0

0.46

7.33

 4.84

0          1

0.93

5.53

  3.75

0          2

0.68

5.20

  4.00

1          0

0.59

8.30

  3.60

1          1

0.41

5.81

  3.89

1          2

0.53

5.92

  3.85

2          0

0.35

4.98

  4.00

2          1

0.89

3.27

  3.87

2          2

0.78

1.96

  4.30

Rates for Hum (humate): 0 = none applied, 1 = 100 lbs/acre; 2 = 200 lbs/acre; and for

CGM (corn gluten meal): 0 = none applied; 1 = 400 lbs/acre; 2 = 800 lbs/acre.

 

Total yields for the first two years favor the conventional methods.  However, yields for organic production improved in 2003 and appeared to be higher than those for the conventional production.  The two organic treatments with the highest yields are expressed in bold italic. There did not appear to be a pattern in yield associated with the organic treatments between years.

 

                                                                                    Yields in Tons/acre

Cucumber cv. Earlipik

 

Growing Season

 

System

2002

2003

2004

Conventional

6.69  

10.8

3.41 

Organic

1.55

 

4.61

2.99

Rate

 

 

 

Hum - CGM

 

 

 

0          0

1.30

 

2.83

3.15

0          1

2.10  

3.41

3.70

0          2

1.30

 

3.73

3.84

1          0

1.40

 

3.52

2.30

1          1

1.16

 

4.58

2.94

1          2

1.53

 

6.45

2.67

2          0

1.88  

6.85

2.94

2          1

1.69

 

5.08

2.93

2          2

1.56

5.02

2.48

Rates for Hum (humate): 0 = none applied, 1 = 100 lbs/acre; 2 = 200 lbs/acre; and

CGM (corn gluten meal): 0 = none applied; 1 = 400 lbs/acre; 2 = 800 lbs/acre.

Total yields for the first two years favor the conventional methods.  However, yields for organic production improved in 2003.  The two organic treatments with the highest yields are expressed in bold italic. Only for Hum:CGM treatment 2:0 did there appear to be a pattern in yield associated with treatment between years.

 

                                                                                         Yields in Tons/acre

Sweet corn cv. Incredible

 

Growing Season

 

System

2002

2003

2004

Conventional

 4.37

6.93

2.83

Organic

1.32

1.48

1.98

Rate

 

 

 

Hum - CGM

 

 

 

0          0

1.57

1.02

2.56

0          1

1.82

1.58

2.83

0          2

1.48

1.40

2.26

1          0

1.23

1.96

2.65

1          1

0.93

1.34

2.90

1          2

0.77

2.03

3.30

2          0

1.31

1.55

3.09

2          1

1.20

1.46

2.77

2          2

1.53

0.95

3.15

Rates for Hum (humate): 0 = none applied, 1 = 100 lbs/acre; 2 = 200 lbs/acre; and

CGM (corn gluten meal): 0 = none applied; 1 = 400 lbs/acre; 2 = 800 lbs/acre.

Total yields for the first two years favor the conventional methods.  Yields for organic production in 2002 appeared to be similar to those for 2003.  The two organic treatments with the highest yields are expressed in bold italic.