1. Effect of Soil Water Tension Threshold for Irrigation on Cranberry Yield, Yield Components and Water Productivity A UGUST 27 TH 2013 NACREW Q UÉBEC Vincent Pelletier vincent.pelletier.8@ulaval.ca Jacques Gallichand Jean Caron

2. 1. I NTRODUCTION

3. Water Table 40 cm 10 cm 4 kPa h = 40 cm SWT = 4 kPa φ m = -4 kPa S OIL W ATER T ENSION ( O R S OIL WATER P OTENTIAL )

4. Y IELD VS S OIL W ATER T ENSION

5. 2. O BJECTIVE

6. This study was conducted to determine the optimum soil water tension for starting irrigation that would optimize water productivity without decreasing yield and yield components (Water productivity was calculated as the yield per unit depth of rainfall and irrigation) O BJECTIVE

7. 3. M ETHODOLOGY

8. 3 sites in Québec 1 site in Wisconsin E XPERIMENTAL S ETUP

9. W ET (5.5 kPa) D RY (7.0 – 10.0 kPa) C ONTROL (6.0 - 6.5 kPa) I RRIGATION T HRESHOLDS R ETENTION C URVE

10. M EASUREMENTS Soil water tension (Tensiometer) Rainfall (Weather Station) Irrigation water (Flow meter) Yield : 2474 samples (929 cm 2 ) Yield components : 132 samples (929 cm 2 ) Water Productivity (Yield / (Rainfall+Irrigation)) Statistical analysis to determine the best threshold

11. 4. R ESULTS

12. Y IELD In 2011  No difference between treatment In 2012  No difference between 5.5 to 8.5 kPa Significant reduction of 11 % in the driest treatment (10.0 kPa) Average yield: 33690 lbs/acre

13. Y IELD COMPONENTS In 2011 : No significant difference In 2012 - Significant differences :  - 21 % of marketable berries at 10.0 kPa  - 14 % of berries / upright at 8.5 kPa  - 9 % less fruit set at 8.5 kPa  - 7 % of berry weight at 8.0 kPa  No difference between 5.5 and <8.0 kPa

14. W ATER P RODUCTIVITY 2011-2012 : Significantly greater in Dry treatments Wet (5.5 kPa) : 54 – 186 % more irrigation water Dry (7.0–10.0 kPa) : 21 – 93 % less irrigation water

15. H YDRAULIC C ONDUCTIVITY VS S OIL W ATER T ENSION Water stress affected yields and yield components Good capillary rise Optimum yields Water savings Energy savings Maximum ET rate

16. 5. C ONCLUSION

17. C ONCLUSION In fine sand, Dry treatments, with irrigation thresholds ranging from 7.0 to 7.5 kPa, improved significantly the water productivity without decreasing yield and yield components C URRENT RESEARCH (2013-2015) The capillary rise is sufficient to meet the plant needs when the water table is controlled at an optimal level

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