Blueberry Fertilization Demonstration Trials
November 20, 2014 BC Blueberry Council Field Day
David Poon1, Eric Gerbrandt2, Mark Sweeney1
1. BC Ministry of Agriculture
2. University of the Fraser Valley
Introduction
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*FBI = Flower Bud Initiation
*
Source: Strik, B. Nutrient management in raspberry and blueberry. Presentation at 2013 Washington Small Fruit Conference http://whatcom.wsu.edu/ag/edu/sfc/2013presentations.html
Objectives
• Determine the effect of changing nitrogen (N) rates and number of applications on blueberry bud set and yield
• Observe leaf N and mineral N in soil, and determine whether they explain treatment effects on blueberry bud set and yield
3
• Base granular fertilizer on April 11, 2014
– 171 lb N/acre
• 4 treatments, each with a different number of drips @ 13.3 lb N/acre per drip
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Treatment May 4 May 12 May 19 May 26 Total N (lbs/ac) 0 Drips 171
1 Drip ● 184.3
3 Drips ● ● ● 210.9
4 Drips ● ● ● ● 224.2
Methods - Duke trial (8-yr old planting)
• Base granular fertilizer on April 11, 2014
– 50 lb N/acre
• 3 treatments with a different number of drips @ 13.3 lb N/acre per drip
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Treatment May 12 May 19 Total N (lbs/ac) 0 Drips 50
1 Drip ● 63.3
2 Drips ● ● 76.6
Methods - Reka trial (12-yr old planting)
Bud Set and Flower Counts
• 4 rows for each treatment
• Baseline data in 2014
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Yield and Fruit Size
• Yield from each row of the experiment
• Fruit weight sampled x 3 from each of 10 plants in each row
• In 2015 and beyond:
– Can we increase yield by improving bud-set?
– How does this relate to soil/tissue nitrogen?
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Methods
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Leaf tissue
Soil sampling
0
5
10
15
20
25
30
35
40
45
50
mg
NO
3-N
per
kg
soil
171 lb N/ac
+1 drip
+3 drips
+4 drips
9
0
5
10
15
20
25
30
35
40
45
50
mg
NH
4-N
per
kg
soil
171 lb N/ac
+1 drip
+3 drips
+4 drips
0
5
10
15
20
25
30
35
40
45
50
mg
NO
3-N
per
kg
soil
171 lb N/ac
+1 drip
+3 drips
+4 drips
Late June
Early June
Late June
Early June
Late June
Early June
Late June
Du
ke
Re
ka
0
5
10
15
20
25
30
35
40
45
50
mg
NO
3-N
per
kg
soil
171 lb N/ac
+1 drip
+3 drips
+4 drips
Sep 8-11, 2014
Sep 8-11, 2014
Preliminary results for soil nitrogen: ammonium (NH4) and nitrate (NO3) at 0-30 cm depth
Aug 25-27, 2014 August 25-27,
2014
Early June
0
5
10
15
20
25
30
35
40
45
50
mg
NH
4-N
per
kg
soil
0
5
10
15
20
25
30
35
40
45
50
mg
NO
3-N
per
kg
soil
50 lb N/ac
+1 drip
+2 drips
a
b
a
b
Blueberry plants use Ammonium (NH4)
Blueberry plants do not use Nitrate (NO3)
Discussion
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Ammonium NH4 Nitrate NO3
There’s potential, esp. in the Duke trial, to avoid excess N by decreasing N rates or adjusting timing
of N fertilization.
Expected Outcomes
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Ammonium NH4 Nitrate NO3
In the long term, optimizing N may save fertilizer $ and prevent losses in yield potential.
Avoid reduced bud set
Avoid excess N uptake
The project is funded in part through Growing Forward 2, a federal-provincial-territorial initiative.
We thank the blueberry growers for their cooperation and the BC Blueberry Council for their assistance with outreach.
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Corrections and Updates
• The original presentation indicated the Reka plants were 18 years old at the time of the presentation. They were 12.
• Slide 9 was updated after the presentation with comments that were provided verbally.
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