Water Use of Southern
Highbush Blueberry
Jeff Williamson
Horticultural Sciences Department
IFAS, University of Florida
Pine Bark Culture
Pine Bark Culture
• Bark beds are
currently one of the
common methods for
growing SHB.
• Pine bark increases
organic matter,
decreases soil pH,
maintains N in NH4
form.
Before planting
Newly planted blueberry field on
pine bark beds in Florida
Newer system – bark incorporated into
soil with ground cloth and drip irrigation
Examples of SHB production systems
Bark incorporated into soil
Bark beds
Incorporated bark with ground cloth
Pine bark increases organic matter, decreases soil pH, maintains N in NH 4 form,
While overhead irrigation is still needed for freeze
protection, most new plantings are low-volume, usually drip
or drip with ground cover.
Excavated Blueberry Plant
Root system was only a few inches deep
The bark bed and root system was easily separated from
soil with very few roots located in the underlying soil
Blueberry roots at three soil depths for two soil treatments
Soil depth
(inches)
0 to 3.5
4 to 7.0
7.5 to 10.5
Soil treatment
Percent of
total roots
Bark bed
44
Bark incorporated
46
Bark bed
37
Bark incorporated
45
Bark bed
19
Bark incorporated
8
Plant water potential during the fruit
ripening period - 2010
OBJECTIVES
• The objective of this
study was to evaluate
plant drought stress
during the final stages of
fruit development of
blueberry grown in
several soil management
systems without irrigation.
MATERIALS AND
METHODS
• Predawn and solar noon
plant water potential of
‘Emerald’ SHB was
measured with a pressure
chamber during a dry
period of fruit
development and no
irrigation was applied.
Drought - Predawn 2010
0
Irrigation was shut off
kilopascals (kPa)
-200
b
b
b
a
-400
Incor.+Mulch.
-600
b
b
b
a
Bed
b
ab
ab
Incorpor.
-800
Soil
5/10
a
5/11
5/12
5/13
Date
5/14
5/15
5/16
Drought - Solar Noon + 2 hours 2010
-1000
kilopascals (kPa)
-1200
-1400
b
b
b
a
Irrigation was shut off
b
b
b
b
b
b
a
-1600
b
b
b
a
Incor.+Mulch.
-1800
a
Bed
b
ab
ab
a
b
ab
ab
Incorpor.
-2000
Soil
5/10
5/11
a
5/12
5/13
Date
5/14
5/15
5/16
Preparing holes for lysimeters
Bark or soil/bark mixture added
Transplanting blueberry plant
Plant positioned above lysimeter
December, 2009
June, 2011
December, 2011
Plant canopy volume (yd3)
June
2010
Aug
2010
June
2011
After
pruning
Dec.
2011
Dec
2012
B
2.36
1.64
3.73
2.03
2.45
3.52
B+S
2.03
1.85
3.08
2.05
2.35
3.57
1x/day
2.11
1.64
3.26
2.05
2.32
3.32
2x/day
2.27
1.86
3.55
2.03
2.48
3.77
Treatme
nt
Soil
Irr. freq.
Berry yield (lbs./plant) in 2011 and 2012
Treatment
2011
2012
Bark
17.7
11.3
B+S
15.3
10.2
Once/day
16.6
8.9
Twice/day
16.6
12.5
Soil
Irrigation
Daily plant water use of mature ‘Emerald’ blueberry
plants by month averaged across treatments and years.
Gallons.plant-1.day-1
2.5
2
1.5
1
0.5
0
Jan*
Feb*
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Monthly means + SE of daily water use of mature ‘Emerald’ southern highbush blueberry plants
averaged across treatments and years from April, 2010 to Sept. 2012.
*Means for one year due to complications from overhead irrigation for freeze protection.
2.5
Gallons/plant/day
Harvest
2
Pruned
1.5
1
0.5
Mean
0
16-Apr 1-May 16-May 31-May 15-Jun 30-Jun 15-Jul 30-Jul
Monthly crop coefficients (Kc) for mature ‘Emerald’ blueberry plants
Averaged across treatments and years from April, 2010 to Sept. 2012
1
Overall means
0.9
Crop coefficient (Kc)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Jan*
Feb*
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Monthly Kc means + SE for mature ‘Emerald’ southern highbush blueberry plants averaged across treatments and years from
April, 2010 through September, 2012. Kc values are based on 3 ft. in-row by 10 ft. between row plant spacing (1452 plants/a.).
*Mean for one year due to complications from overhead irrigation for freeze protection. Mean annual Kc = 0.65.
Estimated per acre water use of mature ‘Emerald’ blueberry
plants at 3’ by 10’ spacing (1452 plants/a)
Jan
Feb
Mar
Apr
May
Jun
July
Aug
Sep
Oct
Nov
Dec
gal/day
625
1452
2091
2265
2875
2643
2846
3151
2686
1888
1496
842
gal/month
19,375
40,656
64,821
67,950
89,125
79,290
88,226
97,681
80,580
58,528
44,880
26,102
Yearly water use = 757,214 gal. per acre or 27.88 acre-inches in
the planted field. Assuming 4 ft. wide beds with 10 ft. row spacing
≈ 69.71 inches in the row bed (area with root system).
Conclusions
• Southern highbush blueberry plants are shallow-rooted
and drought susceptible. 80+% of roots were in the top 7
inches of soil.
• Frequent, light, irrigations are needed during the growing
season.
• Bark, applied as either a bed or incorporated into the soil
reduced drought stress.
• Regardless of soil treatment, plant water stress
increased significantly after 3 days without irrigation.
Conclusions
•
Monthly averages for daily plant water use of mature ‘Emerald’ blueberry plants
ranged from about 0.6 gal/day (winter) to over 2 gallons/day (mid to late
summer).
•
Water demands increased rapidly in the spring (March) and peak water
demands occurred during the late stages of fruit development (late April and
May) and in mid to late summer (July – Sept.). Maximum monthly averages
≈ 2.0 – 2.25 gal./plant/day.
•
Monthly averages do not reflect the day to day variation in water demand which
is heavily influenced by weather and can be considerably greater or less than
the monthly averages.
•
Summer pruning significantly reduced plant water use for 3 to 4 weeks until
plant canopies were re-established.
•
Kc values can be used with reference ET to determine general water
requirements. Soil moisture monitoring devices along with a knowledge of
rooting depth, distribution, and soil water holding characteristics are useful when
developing irrigation schedules.
Acknowledgements
Southwest Florida Water Management District
Florida Blueberry Growers Association
Luis Mejia, graduate student, Horticultural Sciences Department, IFAS, UF
Bradley Ferguson, graduate student, Horticultural Sciences Department, IFAS, UF
Paul Miller, former biologist, Horticultural Sciences Department, IFAS, UF
Eric Ostmark, biologist, Horticultural Sciences Department, IFAS, UF
Thank You!
Questions?