1. Water Use of Southern Highbush Blueberry
Jeff Williamson
Horticultural Sciences Department
IFAS, University of Florida

2. Pine Bark Culture

3. 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.

4. Before planting

6. Newly planted blueberry field on pine bark beds in Florida

7. Newer system – bark incorporated into soil with ground cloth and drip irrigation

8. 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 NH4 form,

9. While overhead irrigation is still needed for freeze protection, most new plantings are low-volume, usually drip or drip with ground cover.

10. Excavated Blueberry Plant
Root system was only a few inches deep

11. The bark bed and root system was easily separated from soil with very few roots located in the underlying soil

13. Blueberry roots at three soil depths for two soil treatments
Soil depth (inches)
Soil treatment
Percent of total roots
0 to 3.5
Bark bed 44
Bark incorporated 46
4 to 7.0 37 45
7.5 to 10.5 19 8

14. Plant water potential during the fruit ripening period - 2010
OBJECTIVES
MATERIALS AND METHODS
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.

15. Irrigation was shut offb a b a ab b a

16. Irrigation was shut offb a b a b a b a ab b a ab b a

17. Blueberry irrigation
Root zone coverage is critical in pine bark culture where lateral water movement is limited.

18. Preparing holes for lysimeters

20. Bark or soil/bark mixture added

21. Transplanting blueberry plant

22. Plant positioned above lysimeter December, 2009

23. June, 2011

24. December, 2011

25. Plant canopy volume (yd3)
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
1.85
3.08
2.05
2.35
3.57
Irr. freq.
1x/day
2.11
3.26
2.32
3.32
2x/day
2.27
1.86
3.55
2.48
3.77

26. Berry yield (lbs./plant) in 2011 and 2012
Treatment
2011
2012
Soil
Bark
17.7
11.3
B+S
15.3
10.2
Irrigation
Once/day
16.6
8.9
Twice/day
12.5

27. Estimate of daily water use of microsprinkler-irrigated blueberries from April, 2010 to December 1202.

29. Daily plant water use of mature ‘Emerald’ blueberry
plants by month averaged across treatments and years.
Monthly means + SE of daily water use of mature ‘Emerald’ southern highbush blueberry plants
averaged across treatments and years from April, 2010 to Sept
*Means for one year due to complications from overhead irrigation for freeze protection.

31. Monthly crop coefficients (Kc) for mature ‘Emerald’ blueberry plants
Averaged across treatments and years from April, 2010 to Sept. 2012
Monthly Kc means + SE for mature ‘Emerald’ southern highbush blueberry plants averaged across treatments and years from
April, 2010 through September, 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.

32. 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 acre-inches in
the planted field. Assuming 4 ft. wide beds with 10 ft. row spacing
≈ inches in the row bed (area with root system).

33. 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.

34. 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.

35. 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

36. Thank You!
Questions?