Redirecting rain to manage soil salinity: Lessons from groundwater and recycled wastewater irrigated vineyards Redirecting rain to manage soil salinity: Lessons from groundwater and recycled wastewater irrigated vineyards Tim Pitt, Rob Stevens, Jim Cox and Mike McCarthy SARDI – Water Resources, Viticulture & Irrigated Crops 4 June 2014 Tim Pitt, Rob Stevens, Jim Cox and Mike McCarthy SARDI – 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 Hypothesis Results Progress Outline Project Background

1000EC= 1000µS/cm = 1mS/cm = 1dS/m= 640mg/L = 640ppm 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)

SAR Salinity higher UV than in MR Sodicity higher UV than in MR Salt symptoms in vines, petiole Cl - = % (toxic) Mid-rowUnder-vine Salinity EC e (dS/m) Sodicity Salt and sodicity distribution across vineyard floor Infiltration >30 mm/hr at both points Pre-trial measures 2009 Proof of Concept

(mm) EC e (dS/m) Autumn Spring Average rootzone salinity under-vine Rain Irrigation Yield decline 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 Hypothesis Proof of Concept

SoilEC PlantNa + and Cl - Yield components Vigour 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? JuiceVintageNoYes Na + (mg/L) * ** Cl - (mg/L) * ** * < 0.05 ** < Re-directing rain from mid-row to under-vine soils: reduced juice Na + by 25 % and Cl - by 40 % Results Proof of Concept

Treatments are NOT commercially viable!! PROBLEM Will more commercial treatments be as effective? Will more commercial treatments be as effective? A C B DE 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 % Mid-rowUnder-vine EC e (dS/m) Soil salinity (Sept 2012) Petiole (Nov 2012) Pre-trial - Vintage 2013 Pilot Study

Control (no change) A Mid-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

ACBDE Treatments installed in December 2012 < 20 mm rain between treatment construction and vintage 2013 Yield = 2.2 kg/vine Sugar = 25.3°Brix pH = 3.5 TA = 6.0 g/L Na = 20 mg/L Cl = 30 mg/L UV soil = 3.3 dS/m MR soil = 0.9 dS/m Pruning wt = 1.7 kg/vine Vintage 2013 No significant difference in: post-harvest soils pruning weights harvest data Pilot Study

ABCDE 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 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 bunches113/vine Vintage 2014 Pilot Study No difference in: berry weight0.83 g juice pH3.6

ABCDE 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 2014 Pilot Study Leaf petiole at flowering: Trends emerge at P=0.1

ABCDE 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 2014 Pilot Study Leaf blade at harvest:

ABCDE 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 2014 Pilot 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: Agricultural Water Management Vol 129, Nov 2013, p

australianwaterrecycling.com.au goyder.sa.gov.au Tim Pitt SARDI – Water Resources, Viticulture & Irrigated Crops T M Further information from: