Redirecting rain to manage soil salinity:Lessons from groundwater and recycled wastewater irrigated vineyards

Tim Pitt, Rob Stevens, Jim Cox and Mike McCarthySARDI – Water Resources, Viticulture & Irrigated Crops

4 June 2014

Adelaide

Mt Gambier

Padthaway

McLaren Vale

Salinity and yield response

Proof of concept – Padthaway (Groundwater)Pre-trial investigations

Pilot study – McLaren Vale (Recycled Wastewater)

Summary

HypothesisResults

Progress

Outline

Project Background

1000EC = 1000µS/cm = 1mS/cm

= 1dS/m = 640mg/L = 640ppm

Salinity and Yield Response

0 2 4 6 8 100

20

40

60

80

100

120

ECe (dS/m)

Rela

tive

Yiel

d (%

)

Grape yield decline threshold~2.1 dS/m (1340 ppm)

Salinity and Yield Response

2007 – 2009 salinity project developed for South East SA

Increasing groundwater salinity

Downward trend in rainfall

Introduction of regulated allocations

Emerging salinity damage

2010 – 2012 ‘Proof of concept’ trial

AIM – to identify techniques to manage rootzone salinity in vineyards receiving supplementary saline ‘groundwater’ irrigation

Project Background

Adelaide

Mt Gambier

Padthaway

Padthaway:Wine grape (Chardonnay)

Sandy loam to clay over limestone

Groundwater irrigation ~1.9 ML/yr

Proof of Concept

Groundwater Irrigation ~2.2 dS/m (1400 ppm)

0

2

4

6

8

10

0

2

4

6

8

10

0

4

8

12

16

20

SAR

Salinity higher UV than in MR

Sodicity higher UV than in MR

Salt symptoms in vines, petiole Cl- = 1-1.5 % (toxic)

Mid-rowUnder-vine

Salinity

ECe

(dS/

m)

Sodicity

Salt and sodicity distribution across vineyard floor

Infiltration >30 mm/hr at both points

Pre-trial measures 2009Proof of Concept

Nov-08 May-09 Nov-09 May-10 Nov-10

(mm

)

0

20

40

60

Ave

rag

e r

oo

tzo

ne

EC

e (

dS

/m)

0

2

4

6

8

10

(mm

)EC

e (dS

/m)

Autumn AutumnSpring Spring

Average rootzonesalinity under-vine

RainIrrigation

Yielddecline

threshold

Winter rain flushing salt from rootzone

High SAR under-vine not impeding infiltration

Proof of Concept

Re-distributing rain falling on the mid-row to under the

vine will reduce rootzone salinity

HypothesisProof of Concept

Soil ECPlant Na+ and Cl-

Yield componentsVigour

Proof of Concept

Reduced under-vine soil salinity by 40%

Results

4.1 dS/m 2.5 dS/m

Proof of Concept

Rain re-directed from mid-row to under-vine?

Juice Vintage No Yes Na+ (mg/L)

2010 46 -

2011 33 28 *

2012 28 18 **

Cl- (mg/L)

2010 138 -

2011 72 49 *

2012 59 29 **

* < 0.05 ** < 0.001

Re-directing rain from mid-row to under-vine soils:

• reduced juice Na+ by 25 % and Cl- by 40 %

ResultsProof of Concept

Treatments are NOT commercially viable!!

PROBLEM Will more commercial treatmentsbe as effective?

A

C

B

D E

Proof of concept Pilot study

Adelaide

Mt Gambier

Padthaway

McLaren Vale:Wine grape (Cabernet Sauvignon)

Clay loam over medium clay

Recycled Wastewater irrigation ~1.4 ML/yr

Pilot Study

Recycled Wastewater irrigation ~1.2 dS/m (770 ppm)

McLaren Vale

Cl- < 0.5 % Na+ < 0.15 %

0

1

2

3

4

Mid-rowUnder-vineEC

e (d

S/m

)

Soil salinity (Sept 2012)

Petiole (Nov 2012)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Rai

n (m

m/m

onth

)

0

20

40

60

80

100

120

140

160

50yr AVG 2012

Pre-trial - Vintage 2013Pilot Study

Pilot Study

Control (no change)

AMid-row plastic covered mound

B

Mid-row mound

Pilot Study

C

Mid-row mound sprayed with surface sealing polymer

Pilot Study

D

Buried plastic covered mid-row mound

Pilot Study

E

A CB D E

Treatments installed in December 2012

< 20 mm rain between treatment construction and vintage 2013

Yield = 2.2 kg/vineSugar = 25.3°Brix pH = 3.5TA = 6.0 g/LNa = 20 mg/LCl = 30 mg/LUV soil = 3.3 dS/mMR soil = 0.9 dS/mPruning wt = 1.7 kg/vine

Vintage 2013

No significant difference in:

• post-harvest soils

• pruning weights

• harvest data

Pilot Study

A B C D E

Yield (kg/vine) 4.8 b 6.1 a 5.2 ab 5.1 ab 5.2 ab

Bunch Wt (g) 43.3 b 51.1 a 45.1 ab 46.8 ab 45.6 ab

Juice TSS (°Brix) 22.9 a 22.2 b 23.0 a 23.0 a 22.6 ab

Juice TA (g/L) 5.2 b 5.7 a 5.3 ab 5.4 ab 5.7 a

Values followed by same letter are not significantly different (P=0.05)

number of bunches 113/vine

Vintage 2014Pilot Study

No difference in:berry weight 0.83 gjuice pH 3.6

A B C D E

Na+(% dw) 0.33 a 0.22 b 0.28 ab 0.30 ab 0.29 ab

Cl-(% dw) 0.83 a 0.63 b 0.71 ab 0.72 ab 0.71 ab

Values followed by same letter are not significantly different (P=0.05)

Vintage 2014Pilot Study

Leaf petiole at flowering:

Trends emerge at P=0.1

A B C D E

Na+(% dw) 0.13 ab 0.12 b 0.14 ab 0.16 a 0.13 b

Cl-(% dw) 0.47 a 0.37 b 0.46 a 0.47 a 0.46 a

Values followed by same letter are not significantly different (P=0.05)

Vintage 2014Pilot Study

Leaf blade at harvest:

A B C D E

Na+(% dw) 28.6 ab 24.6 b 29.3 a 28.6 ab 27.9 ab

Cl-(% dw) 37.0 a 29.5 b 35.4 a 36.5 a 32.1 ab

Values followed by same letter are not significantly different (P=0.05)

Vintage 2014Pilot Study

Grape juice at harvest:

Trends emerge at P=0.1

Proof of concept – Groundwater, Padthaway SA

Pilot study – Recycled Wastewater, McLaren Vale SA

Summary

Early results consistent with ‘Proof of Concept’ trial(Same response with different climate, soil, management etc.)

reduced under-vine soil salinity by 40%

‘Proof of concept’ treatments commercially impractical

Rainfall redirection:reduced juice sodium by 25%

reduced juice chloride by 40%

Commercially applicable treatments differentiate at P=0.1

Further information from:

www.npsi.gov.au/products/npsi1212 Agricultural Water ManagementVol 129, Nov 2013, p130-137

australianwaterrecycling.com.au

goyder.sa.gov.au

Tim PittSARDI – Water Resources, Viticulture & Irrigated Crops

T. 08 8303 9690 M. 0434 600 504tim.pitt@sa.gov.au

Further information from: