Blueberry Fertilization
Demonstration Trials
November 20, 2014
BC Blueberry Council Field Day
David Poon1, Eric Gerbrandt2, Mark Sweeney1
1.
2.
BC Ministry of Agriculture
University of the Fraser Valley
Introduction
*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
2
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
Methods - Duke trial
(8-yr old planting)
• 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
Treatment
May 4 May 12 May 19 May 26 Total N (lbs/ac)
0 Drips
171
1 Drip
●
3 Drips
4 Drips
●
184.3
●
●
●
210.9
●
●
●
224.2
4
Methods - Reka trial
(12-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
Treatment
May 12
May 19
0 Drips
50
1 Drip
2 Drips
Total N (lbs/ac)
●
●
63.3
●
76.6
5
Bud Set and Flower Counts
• 4 rows for each treatment
• Baseline data in 2014
6
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?
7
Methods
Soil sampling
Leaf tissue
8
Preliminary results for soil nitrogen: ammonium (NH4) and nitrate (NO3) at 0-30 cm depth
50
50
45
45
40
40
50
35
35
35
171 lb N/ac
30
30
30
15
Aug 25-27,
2014
10
5
0
mg NH4-N per kg soil
Early
June
Blueberry
plants use
Late
Ammonium
(NH4)
June
40
35
Reka
a
b
b
30
25
20
15
10
+1 drip
drip
+1
+3 drips
+3 drips
drips
+3
+4 drips
15
+4 drips
drips
+4
15
10
10
55
0
0
50
45
Late
June
Blueberry plants do not
use Nitrate (NO3)
30
50 lb N/ac
25
+1 drip
20
+2 drips
15
10
0
0
Sep 8-11,
2014
Early
June
35
5
Late
June
August 25-27,
2014
40
5
Early
June
171 lb
lb N/ac
N/ac
N/ac
171
+1 drip
20
20
20
45
a
25
25
25
50
mg NO33-N per kg soil
40
mg NO3-N per kg soil
mg NH4-N per kg soil
Duke
45
Early
June
Late
June
Sep 8-11,
2014
9
Discussion
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.
11
Expected Outcomes
Avoid reduced bud set
Avoid excess N uptake
Ammonium NH4
Nitrate NO3
In the long term, optimizing N may save fertilizer $
and prevent losses in yield potential.
12
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.
13
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.
14