Download - Water Use of Southern Highbush Blueberry
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
Bark beds Bark incorporated into soil
Incorporated bark with ground clothPine bark increases organic matter, decreases soil pH, maintains N in NH4 form,
Examples of SHB production systems
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
Soil depth (inches)
Soil treatment Percent of total roots
0 to 3.5 Bark bed 44
Bark incorporated 46
4 to 7.0 Bark bed 37
Bark incorporated 45
7.5 to 10.5 Bark bed 19
Bark incorporated 8
Blueberry roots at three soil depths for two soil treatments
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.
• 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.
MATERIALS AND METHODS
5/10 5/11 5/12 5/13 5/14 5/15 5/16-800
-600
-400
-200
0Drought - Predawn 2010
Incor.+Mulch.
Bed
Incorpor.
Soil
Date
kilo
pasc
als (
kPa) b
b
a
b bb
a
b
ab
b
a
ab
Irrigation was shut off
5/10 5/11 5/12 5/13 5/14 5/15 5/16-2000
-1800
-1600
-1400
-1200
-1000
Drought - Solar Noon + 2 hours 2010
Incor.+Mulch.
Bed
Incorpor.
Soil
Date
kilo
pasc
als (
kPa)
bb
a
b
ab
b
aab
bb
a
b bb
a
bbb
a
b
abb
a
ab
Irrigation was shut off
Preparing holes for lysimeters
Bark or soil/bark mixture added
Transplanting blueberry plant
Plant positioned above lysimeter December, 2009
June, 2011
December, 2011
Treatment
June 2010
Aug 2010
June 2011
After pruning
Dec. 2011
Dec 2012
Soil
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
Irr. freq.
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
Plant canopy volume (yd3)
Treatment 2011 2012
Soil
Bark 17.7 11.3
B+S 15.3 10.2
Irrigation
Once/day 16.6 8.9
Twice/day 16.6 12.5
Berry yield (lbs./plant) in 2011 and 2012
Jan* Feb* Mar Apr May Jun Jul Aug Sep Oct Nov Dec0
0.5
1
1.5
2
2.5
Gal
lons
.pla
nt-1
.day
-1
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.
Daily plant water use of mature ‘Emerald’ blueberry plants by month averaged across treatments and years.
16-Apr 1-May 16-May 31-May 15-Jun 30-Jun 15-Jul 30-Jul0
0.5
1
1.5
2
2.5
Mean
Gal
lons
/pla
nt/d
ay
Pruned
Harvest
Jan* Feb* Mar Apr May Jun Jul Aug Sep Oct Nov Dec0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9Overall means
Cro
p co
effic
ient
(Kc)
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.
Monthly crop coefficients (Kc) for mature ‘Emerald’ blueberry plants Averaged across treatments and years from April, 2010 to Sept. 2012
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
Estimated per acre water use of mature ‘Emerald’ blueberry plants at 3’ by 10’ spacing (1452 plants/a)
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, UFEric Ostmark, biologist, Horticultural Sciences Department, IFAS, UF
Thank You!
Questions?