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

2

*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

4

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

5

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

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

8

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

11

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

12

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.

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