Sustainable Salinity Management on Your Vineyard Tapas Biswas, John Bourne, Mike McCarthy, Pichu Rengasamy
What is Salinity? � Salinity is the concentration of salts in soil or water; when it exceeds certain level it affects plant growth. � It is commonly measured as electrical conductivity of water or soil water. � In Australia salinity is dominated by sodium chloride. � Other major ions can be calcium, magnesium, potassium, carbonate, bicarbonate, sulphate, borate and nitrate.
Irrigation and dry-land salinity � Irrigation salinity can result from poor quality water and improper irrigation management. � Dryland salinity can occur by salt accumulation in clay soils, or salts being brought into the rootzone by rising water tables. � In certain cases, both the above processes can occur together.
Impact of salinity � Salinity increases osmotic pressure of soil water and decreases its availability to plants. � Toxic concentrations of some ions (e.g. sodium, chloride and boron) affect plant metabolism and lead to reduced growth. � May lead to high levels of sodium and chloride in wine. � High levels of sodium in soils may cause sodicity and lead to soil structure decline.
Salt toxicity in grape vines
Grape vine tolerance to salt 120 represent Graph shows a threshold data 100 ECe for own rooted collected from vines. 80 Australian trials Threshold ECe Value changes with 60 tolerant rootstocks or 40 when a low target yield for high quality is 20 required. 0 0 2 4 6 8 10 S il li it i t t d t t t (dS/ ) Average grape rootzone salinity (ECe) dS/m
Unit for salinity measurement Standard unit for electrical conductivity (EC) is decisiemens/metre (dS/m) 1 dS/m = 100 millisiemens/metre = 1000 microsiemens/centimetre = 1000 micromhos/centimetre = 1000 EC units = approx 640 milligrams/litre, or ppm total dissolved salts.
How to diagnose soil salinity? Saturated paste extract (ECe) Paste from soil sample Standard lab method Wetting front Suction cup (ECsw) detector Field collection of soil water Field collection Real time measure of soil water Needs wet EC conditions Time
More expensive diagnostic techniques Electrical capacitance Field probe Requires more development Electromagnetic induction (EM) Rapid above ground survey Identifies hotspots
Plant tests for salinity Petiole test at flowering Sodium toxic if > 0.50 % Chloride toxic if > 1.0-1.5 % Berry juice test at harvest Export limit: 394 mg/L Sodium and 606 mg/L Chloride
Is a plant test good enough? Effect of soil water salinity on vine petiole chloride at flowering 1.4 1.2 Toxic or Excessive leaf petiole Cl 1.0 0.8 0.6 0.4 0.2 0.0 0 2 4 6 8 10 -1 EC sw dSm
Effect of salinity on juice chloride EU Maximum Cl limit for wine 600 400 300 200 100 0 0 2 4 6 8 10 -1 EC sw dSm
Why is salinity a problem now ? Early Irrigation Management Across the MDB � Pre 1960s primarily furrow irrigation. � 1960s permanent overhead sprinkler irrigation for horticulture. � Applications of 10-15ML/ha regardless of variety/soil type. � Resulted in perched water tables and rising regional groundwater. � Grapes for maximum production to produce wine for the � bulk market � .
Irrigation Management -1980s � New layout design introduced to match irrigation to soil type/varieties. � Increased adoption of micro-irrigation and drip systems. � Soil water monitoring widely adopted in viticulture to improve quality. � Irrigation volumes reduced to 6-7ML/ha and less.
Irrigation Management -1990s � Rapid increase in viticulture export sales. � Widespread adoption of RDI in red wine grapes across MDB. � Increasing use of root stocks for nematodes and salt tolerance. � On-farm reporting of irrigation efficiency by most irrigators.
Irrigation Management -2000s � Start of the � Millennium drought � . � Cuts in allocation across MDB. � Cuts in underground allocation. � On-site dams empty. � Increasing salinity issues. � Problems emerge from high WUE. � Increasing use of reclaimed water. � Climate change impact considered.
Salt accumulation in the root zone Salt deposit around dripper Often due to: � Very high WUE � High salt content of irrigation water � Drought An example of water management in highly efficient Riverland/Murray Valley vineyards 1200 Irrigation, mm (mm) 1000 Rainfall 800 and 600 Irrigation 400 Rainfall, mm 200 0 1995-961996-971997-981998-991999-002000-01 2001-022002-032003-042004-052005-062006-07
Highly efficient modern irrigation means less deep drainage Sprinkler + Drip + Management Management High Water Low Water Use Use 20% 5-10% Deep drainage
Salt build-up is associated with less deep drainage A drip irrigated Sunraysia vineyard: an example of reduced drainage and salinity build-up in the rootzone Deep Year Irri Rain ETo Irri EC Drainage Soil Water EC (dS/m) …….mm…….. dS/m (%) 30cm 60cm 90cm 2004-05 566 203 1491 0.15 1 2005-06 512 269 1577 0.145 3 0.7 0.8 7.4
Modelling of salinity under drip River Salinity = 0.8 dS/m Drought (Rainfall � 200 mm) Need >300 Change in soil ECe (dS/m) at a Loxton vineyard - model simulation mm to leach salt -200 ECe dS/m -400 3-6 dS/m soil 1 2 salinity = 2-4 times 3 4 D th -600 5 higher than grape’s 6 2000 kg salt tolerance -800 will accumulate in 1 m root zone/ha/yr 50 100 150 200 250 Days after irrigation
Rootzone salinity adjacent to in-line drippers McLaren Vale Shiraz. ECiw 1.0 -1.2 dS/m. Soil cores taken after winter rainfall 2006
Leaching does not mean a complete mixing of drainage water and salts � All water that flows through water rootzone doesn � t mix completely with the salt. salt � May be further reduced under high WUE. soil � Bypass � flow � Inefficiency of leaching process ‘ Piston � through will further increase salt build up. flow macro-pores
Soil salinity survey results for 2002-03 and 2003-04 No of Years EC irr EC sw Predicted farms under dS/m EC sw water dS/m surveye irrigatio dS/m d n 14 >45 0.12 1.2 0.5** Modified from LWA final project report DEP15:“Salinity Impact on Lower Murray Horticulture” SARDI 2007
Factors affecting leaching efficiency Top soil (30 cm) 70% LE Subsurface soil (60 -90 cm) >90% LE Leaching Window This coincides with Lowest ET, Dormant plant and Wet soil
Salinity variation during the year Cab-Sav, Langhorne Creek – Conventional Drip Irrig Rain ETo 30cm Soln 60cm Soln 90 cm Soln 60 10 Irrigation water salinity 1.2 to 1.6 dS/m 9 50 8 Irrigation, rainfall & evapotranspiration (mm) 7 40 6 ECsw (dS/m) 30 5 4 20 3 2 10 1 0 0 Jan-06 Apr-06 Jul-06 Oct-06 Jan-07 Apr-07 Jul-07 Oct-07 Jan-08
Impact of fertiliser on salinity readings 60 35 Irrig Almonds Conventional Drip Rain ETo 30 Irrigation / Rain (mm) and Fertilizer Application (kg/ha) Fertiliser 50 30cm Soln 60cm Soln 90 cm Soln 25 40 EC (dS/m) and ETo (mm) NH 4 NO 3 applied weekly between October and December 20 30 15 20 10 10 5 0 0 01-Jul-06 01-Jul-07 01-Apr-06 01-May-06 01-Jun-06 01-Aug-06 01-Sep-06 01-Oct-06 01-Nov-06 01-Dec-06 01-Jan-07 01-Feb-07 01-Mar-07 01-Apr-07 01-May-07 01-Jun-07 01-Aug-07
Impact of irrigation system on salinity Av Soil Water Salinity (dS/m) from suction cup, from Nov 05 – Sept 07. EC iw 1.2 dS/m. Conventional Sub-surface drip drip Depth ECsw (dS/m) ECsw (dS/m) 6.4 72 3 52 0.3m 9.8 21 4.9 32 0.6m 0.9m 8.3 14 6.6 19 Superscript refers to the number of samples collected
Best management practice for salinity in your vineyard � Need to measure before you can manage. � Compare measurements to critical values or indicative thresholds. � Use winter leaching if required. � Use tolerant rootstocks.
Soil sampling for salinity � Follow standard soil sampling procedure. � Sample at beginning and end of season, ie late Spring and Autumn. � Sample from different soil types or specific problem areas. � Sample at different depths in the root-zone eg 25, 50,75 and 100 cm. � Test for saturated paste ECe.
On-going measurement with suction cups � Locate cups 15 cms from dripper in drip-line to represent the root-zone, eg 30, 60 and 90 cm. � Collect sample a day after irrigation or rainfall. � Have at least 2 sets in each major soil type. � Take measurements every 2 weeks in summer and monthly in winter to watch trend over time.
Develop a strategy No leaching needed if average ECsw is below the appropriate threshold. EC of soil water at which Wine grape yield decline starts Varieties sensitivity (dS/m) Own roots (Vitis vinifera): eg- Sensitive to Sultana, Shiraz, Chardonnay. moderately 3.6 Rootstocks: 1202C, Kober 5BB, sensitive Teleki 5C, S04. Rootstocks: eg- Ramsey, 1103 Moderately Paulsen, Ruggeri 140, tolerant to 6.6 Schwarzmann, 101-14, Rupestris St tolerant George. Modified from Zhang et al. 2002
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