1) Several key factors are important for good composting, including oxygen, moisture, food sources, and maintaining heat levels during the active composting stage. Proper production methods such as pile size, turning frequency, and moisture levels are also important. 2) A good compost is evaluated based on its pH, EC, C:N ratio, smell, appearance, and temperature stability. The compost should have a soil-like smell and structure and not contain recognizable substrates. 3) Trials of different greenhouse mixes found that maintaining pH between 5.5-6.5, EC between 1.9-3.9, and potassium levels of 200-250 ppm led to

1. Presented at:
ACORN 2013
1

2. 
Greenhouse mixes
◦ Important variables
◦ Mix components

Greenhouse trials
◦ Observations
◦ Lessons learned

Compost
◦
◦
◦
◦
Important variables
Production methods
Materials used
How to evaluate a good compost
2

3. Aaron Randall, Owner, Sweet Valley Herbs
3

4. Tim & Kirsten Livingstone, Owners, Strawberry Hill Farm
with Pat Toner, DAAF
4

5. 
Germinating mix
◦ Starter mix, Plug mix

Transplanting mix
◦ Growing mix, Grow On mix
5

6. 
Important Factors
pH: 5.5 to 5.8
EC: <1.0 mmhos/cm
Must be low to prevent damage to young seedlings

Structure
Good porosity, excellent drainage
Fine particle sized material
6

7. 
Typical materials
◦ Peat
◦ Perlite
◦ Vermiculite

Other possible materials
◦ Worm Castings: <3%
◦ Compost: <5% -> Must have low EC
7

8. 
Important Factors
pH: 5.5 to 6.5
EC: Recommended ranges
NB Soil Lab
U of Mass
MOFGA
NBDAAF trials

.75
1.5
1.0
1.9
–
–
–
–
3.0
3.0
2.0
3.9
Structure
Courser material
Porosity & moisture holding capacity balanced
8

9. 
Typical materials used
◦
◦
◦
◦

Sphagnum peat, AND/ OR
Coir (the coconut husk)
Perlite
Vermiculite
Other common materials
◦
◦
◦
◦
Compost
Peat Humus (black peat, muck peat)
Aged bark
Worm Casting
9

10. Pro’s



Excellent drainage
Good moisture
holding capacity
(MHC)
Plentiful in NB
Con’s




Considered by some to
be a Non-renewable
resource
Low pH – needs lime
Low EC – needs fertilizer
Hard to wet
Caution
Certified Organic Growers: Make sure no
commercial wetting agent added
10

11. Pro’s
Con’s







Renewable resource
Peat substitute
Good MHC
pH is higher than peat
Less lime needed
Easier to re-wet

Carbon foot print
Costs
Caution
Make sure Coir has low salt (EC) content
11

12. Pro’s


Helps increase porosity
Good drainage capacity
Con’s


Does not provide any
nutrients
Cannot hold nutrients
12

13. Pro’s




Provides good porosity
Good MHC
Holds nutrients
Good source of
Calcium & Magnesium
Con’s


Costs
Easy to crumble
Caution
Know your source
Some US sources contain 2-3% asbestos
13

14. Pro’s







Con’s
 Can rob nutrients from
Renewable resource
plant if C:N is high
Can replace some peat
 Attracts fungus gnats
Reduces lime
& shore flies if wood
Source of nutrients
based
Holds nutrients
 Reduces porosity
Good MHC
Disease suppression
Caution
qualities
1. Watch % used
2. Keep EC in range
14

15. Pro’s


Renewable resource
Replaces some peat
Con’s



Difficult to re-wet
Can rob nutrients due
to high C:N ratio
Attracts fungus gnats,
shore flies
Caution
1. Keep to <10% of mix
2. Don’t confuse with compost – different product
15

16. Pro’s

Good MHC
Con’s


Reduces porosity
Not a nutrient source
Caution
1. Stay away from muck peat
2. Keep between 10 to 20% of mix
16

17. Pro’s
Con’s





Renewable resource
Natural slow release
fertilizer
Good nutrient holding
capacity
Good MHC

Reduces porosity
Cost
Caution
1. Keep around 5% of mix
2. Nutrient levels can vary from source to source
17

18. 
Lime
◦
◦
◦
◦
Fine grade needed, not agriculture grade
Calcitic lime for Ca (>30 % Ca)
Dolomitic lime for Mg (22% Ca, 13% Mg)
Choose type based on needs
18

19. 
Nitrogen sources
◦ Plant based
◦ Seafood based
◦ Animal based
 Caution Notes: Can restart composting process, or
release of ammonia at first watering (seek
professional advice)

Phosphorus (P) sources
◦
◦
◦
◦
Bone meal
Fish meal
Calphos
Bat and Seabird guano
19

20. 
Potassium (K) sources
◦
◦
◦
◦
◦
Kelp meal
Greensand
Wood ash
Sul-Po-Mag
Potassium sulfate (OMRI)
◦ “Compost “

Calcium (Ca)

Magnesium (Mg)
◦ Calcitic lime
◦ Gypsum
◦ Dolomitic lime
◦ Epsom salts
sources
sources
20

21. Four Trials Conducted
1. Basil – No supplemental fertilizer
2. Tomatoes, Lettuce, Broccoli – No supplemental
fertilizer
3. Broccoli -With supplemental feed starting 14 days after
transplanting
4. Lettuce – With supplemental liquid fertilizer – starting day
of transplanting
21

22. April 3 – 23
756 (3”) pots, 42 trays – 13 mixes used
22

23. Apr 18 - May 9
Trial 2 - 270 (4”) pots used
Trial 3 – 90 (4”) pots used
8 mixes used
23

24. May 22 – June 7
90 (4”) pots used
Picture taken day 7
8 mixes used
24

25. 
8 greenhouse mixes used in all trials

1 control used in all trials

Weekly observations

Grower’s assessment

Computer randomizing utilized
25

26. Laying out treatments according to computer selection
26

27. 
Types
1.
2.
3.
4.
5.

Seafood & wood based products (WBP)
Seafood & peat
Animal manures & WBP
Animal manures & peat
Hay, straw, silage
Inclusion rates
◦ 5 to 20% in most trials
◦ 30% in one and 60% in another
27

28. There were a total of 15 different mixes trialed
Component
Sphagnum peat
Used in how many mixes
14
Peat Humus
5
Coir
2
Aged bark
2
Castings
3 - @ 4.5 to 5%
Perlite
Vermiculite
11
5
28

29. Note differences in color and texture
29

30. 
No significant impact on performance from:
◦ Type of compost (with supplemental fertilizer)
◦ Compost inclusion rate
◦ Use of worm castings
◦ Coir vs peat
◦ Interchange of peat humus, compost & castings
◦ pH range (5.2 to 7.0)
◦ Levels - P, Ca, Mg
30

31. 1) Even with a wide range of mix
configurations used and compost inclusion
rates, (5 to 20%), the two items that
consistently made positive impacts were
when:
a. EC levels: 1.9 to 3.9 mmhos/cm
b. K levels: 200 to 250 ppm
2)
All mixes (other than controls) required
liquid supplemental fertilizer. Best results
when started on day of transplanting
31

32. 32

33. 33

34. 34

35. 35

36. 36

37. 
Used at Strawberry Hill Farm – trial #4
◦ Day 1 & 8 – Rain Grow (4-2-3) chicken compost
based fertilizer @ 1 oz/ gallon
◦ Day 15 – Neptunes Harvest liquid fish with seaweed
blend (2-3-1) @ 2 oz/ gallon

Many other options available – check ACORN
Inputs and Supplier Directories on-line
37

38. Item
Min
Max
Comments
pH
5.5
6.5
5.5 to 5.8 for starter mixes
EC (mmhos/cm)
1.9
3.9
<1.0 for starter mixes
Phosphorus (ppm)
1
20
ppm range in the trial mixes
Potassium (ppm)
200
250
Best performance range – Note: basil
Calcium (ppm)
60
380
ppm range in the trial mixes
Magnesium (ppm)
35
100
Hort grade peat
0%
100%
Coir fiber
did well even at 500 ppm
Ditto
Grower’s choice - Feed & water will
be needed more frequently
Sub for peat
38

39. Item
Min
Max
Comments
Compost
0%
20-25%
The better the compost, the higher
% can be used
Peat Humus
0%
20%
Aged Bark
0%
5-10%
Economics will dictate its use
Castings
0%
5- 7 %
Benefit: Long term crops
30–35%
Compost, humus, castings
Combinations 0%
Perlite
0%
15–20%
Vermiculite
0%
5 – 10%
NOTE:
1) Observations in this presentation are based on the 4
trials conducted between April and June of 2013.
39

40. Important Analysis
1.
2.
3.
pH:
EC:
K:
Fertilizing
1.
2.
- keep in range of 5.5 – 6.5
- 1.9 to 3.9 performed better
- 200 to 250 ppm for veggies,
higher seems OK for basil
Fertilizing
- BEST to start day 1
Mix Fertility - Important to have in the mix, but
don’t rely on it alone
40

41. Mix Components:
1.
2.
3.
4.
5.
6.
Compost
Castings
Peat Humus Combination –
Aged bark
Structure
beneficial to use, keep <20%
long term crops, <5 to 7%
keep <20%
combination of above 3 items
kept<35%, or porosity impacted
-caution, keep<10%, needs feed
- needs balance of porosity &
moisture holding capacity
41

42. 42

43. 
“All composts are not created equal.”
◦ From: Tim Livingstone presentation on Mixes and
Transplants

Remember, just because a little is good,
does not mean more is better.
43

44.  This
section will provide some basics on:
◦ Critical elements for good composting
◦ Production methods
◦ Evaluation of a good compost
44

45. 
Oxygen

Moisture

Food

Heat
45

46. 
Factors which influence availability of oxygen
Pile size
Turning frequency
Turning method
Porosity

Oxygen availability determines compost type
Aerobic, or
Anaerobic
46

47. 
Moisture Range
 Acceptable - 40 to 65%
 Optimum – 50 to 60%
• Squeeze/ feel test

Rules of Thumb
◦
◦
◦
◦
Higher during active stage
Lower during curing stage
Hot months - add water
Cold months – keep it out
47

48. 
Both Carbon (C) and Nitrogen (N) essential

Beginning C:N ratios: 20 & 40:1

Prevent N loss. Add soil (5 to 10%)
48

49. High carbon sources


Wood based products
Cardboard & newspaper
Medium carbon & low nitrogen sources


Hay and straw
Leaf waste
Nitrogen sources




Animal manures
Silage, fresh green materials
Yard waste
Food processing waste
49

50. Heating will occur naturally - IF there is a;
 Good C:N ratio, and
 Adequate moisture, and
 Sufficient porosity

Active heating range: 50 – 65˚C
Turn when temps in this range

CAUTION: Excessive heat destroys beneficial

microbes
50

51. 
Turning windrows
Front end loader
Excavator
Straddle windrow turner
Farm manure spreader
Pitchfork

Other methods include:
In-vessel systems
Static aeration with vents
Bins
51

52. Critical Parameter
Range/ Comment
pH
6.5 to 8.0
EC
3.0 to 6.0 mmhos/cm
C:N ratio
15 to 25:1 (when finished)
Smells
Like a good forest soil
Appearance
No original substrates recognizable
Temperature
Will not reheat if moisture is brought to 50 –
55%
NOTE: To be sold, must also meet CCME
Guidelines for Heavy Metals and pathogens
52

53. Need to Know:




Analysis: pH, EC, K levels
Compost type, % used
Percent of non peat ingredients
Structure
Remember: start fertilizing early
Advice on making your own:


Start small, trial, test
Don’t switch until proven
Enjoy!
53

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