Managing pH in a Douglas fir Soilless
Substrate for Containerized Nursery Crops
B. Moore, J. Klick, J. Kowalski and J.S. Owen Jr.
Study Objectives
•!Evaluate effectiveness of commonly used
Pre-Mix Liming Agents
•!Determine best rates for desired pH
•!Longevity of products
Douglas Fir Bark
•!Widely used by most
growers
•!Consistency can vary
•!Ideal pH range
for most container
crops, 5.2 - 6.3 range
(BMP)
pH Influences in Container Crops
•!Addition of other media
components
•!Peat & Compost
•!Water Alkalinity
•!110 ppm-NWREC
•!Fertilizers Types
•!Pre-Mix
Liming Agents
Materials & Methods
•!Euonymus fortunei
‘Emerald Gaiety’
•!1 Gallon Containers
•!5 individual plant
replications
•!CRD-Completely
randomized design
Materials & Methods
•!Douglas fir bark
(<3/8 in)
•!CRF 19-6-12 (8-9 month)
23 g/pot.
•!Irrigated as needed
•!Cravo Greenhouse
Materials & Methods
•!Imperial Lime
•!Ag Dolo 65
•!0, 2, 4, 6 lbs/yd3
•!Ag Dolo 10
•!0, 2, 4, 8 lbs/yd3
•!Flowable Lime•!(3.5g/7000ml)
•!Sunshade (14 mL)
•!Limestone F (7 mL)
Materials & Methods
•!Pour-thru done weekly or monthly on 3 reps
pH of fresh and aged Douglas fir bark over time
5.5
Fresh
5.0
pH
4.5
4.0
3.5
3.0
Aged
Imperial Lime
6.5
6.0
Range
pH
5.5
5.0
4.5
4.0
!"
#"
$"
%"
&"
Flour lime rate (lb/yd3)
'"
("
6.5
Imperial Lime
0
6.0
2
5.5
4
pH
5.0
4.5
4.0
3.5
3.0
6
Dolomite 10
6.5
6.0
pH
5.5
Range
5.0
4.5
4.0
!"
#"
$"
%"
&"
'"
Coarse dolomite (lb/yd3)
("
)"
*"
Dolomite 10
7.0
Rate (lb/yd3)
6.5
6.0
pH
5.5
5.0
4.5
4.0
3.5
3.0
0
2
4
8
Dolomite 65
6.5
Range
6.0
pH
5.5
5.0
4.5
4.0
!"
#"
$"
%"
&"
Fine dolomite (lb/yd3)
'"
("
7.0
Rate (lb/yd3)
0
2
4
6
6.5
6.0
pH
5.5
5.0
4.5
4.0
3.5
3.0
Dolomite 65
7.5
7.0
Flowable Lime Drench
Limestone F
Sun Shade
Untreated
pH
6.5
6.0
5.5
5.0
4.5
4.0
Application
Date
Conclusions
•!Dolomitic Lime, at higher rates, adjusts pH
to desired levels
•!For quick results, both Limestone F and
Sunshade raise pH when drenched.
•! Short term duration only
•!Guidelines only~
•! Remember other factors influence pH.
•! Alkalinity, Specific Crop, Media
Components.
2010 Lime Research
Assessment of Earth Mix and Microna
Agricultural Gardening Lime
•!Earth Mix 14M
•!Microna Lime
•!Garden Pearls Pelletized lime
North Willamette
Research and
Extension Center
Thank You!
North Willamette
Research and
Extension Center