Sustainable Salinity Management on Your Vineyard Tapas Biswas, John - - PowerPoint PPT Presentation

Sustainable Salinity Management

• n 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

S il li it i t t d t t t (dS/ )

2 4 6 8 10 20 40 60 80 100 120

Average grape rootzone salinity (ECe) dS/m

Threshold ECe represent data collected from Australian trials

Graph shows a threshold ECe for own rooted vines. Value changes with tolerant rootstocks or when a low target yield for high quality is required.

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,

• r ppm total dissolved salts.

How to diagnose soil salinity?

Wetting front detector Field collection

• f soil water

Needs wet conditions

EC Time

Saturated paste extract (ECe) Paste from soil sample Standard lab method Suction cup (ECsw) Field collection of soil water Real time measure

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

ECsw dSm

• 1

2 4 6 8 10 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Toxic or Excessive leaf petiole Cl

Effect of salinity on juice chloride

ECsw dSm

• 1

2 4 6 8 10 100 200 300 400 600

EU Maximum Cl limit for wine

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

200 400 600 800 1000 1200 1995-961996-971997-981998-991999-002000-01 2001-022002-032003-042004-052005-062006-07 Irrigation and Rainfall (mm)

Irrigation, mm Rainfall, mm

An example of water management in highly efficient Riverland/Murray Valley vineyards

Often due to: Very high WUE High salt content of irrigation water Drought

Highly efficient modern irrigation means less deep drainage

20% Sprinkler + Management 5-10% Drip + Management High Water Use Low Water Use 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

Year Irri Rain ETo Irri EC Deep Drainage 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 Soil Water EC (dS/m) …….mm……..

Modelling of salinity under drip

River Salinity = 0.8 dS/m Drought (Rainfall 200 mm)

3-6 dS/m soil salinity = 2-4 times higher than grape’s tolerance

Change in soil ECe (dS/m) at a Loxton vineyard - model simulation Days after irrigation

50 100 150 200 250

D th

• 800
• 600
• 400
• 200

1 2 3 4 5 6

Need >300 mm to leach salt

ECe dS/m

2000 kg salt will accumulate in 1 m root zone/ha/yr

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

soil salt water

Bypass flow through macro-pores

‘Piston

flow

• All water that flows through

rootzone doesnt mix completely with the salt.

• May be further reduced under

high WUE.

• Inefficiency of leaching process

will further increase salt build up.

Soil salinity survey results for 2002-03 and 2003-04

No of farms surveye d Years under irrigatio n ECirr

water

dS/m ECsw dS/m Predicted ECsw dS/m 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

10 20 30 40 50 60 Jan-06 Apr-06 Jul-06 Oct-06 Jan-07 Apr-07 Jul-07 Oct-07 Jan-08 Irrigation, rainfall & evapotranspiration (mm) 1 2 3 4 5 6 7 8 9 10 ECsw (dS/m) Irrig Rain ETo 30cm Soln 60cm Soln 90 cm Soln

Irrigation water salinity 1.2 to 1.6 dS/m

Impact of fertiliser on salinity readings

Almonds Conventional Drip

10 20 30 40 50 60 01-Apr-06 01-May-06 01-Jun-06 01-Jul-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-Jul-07 01-Aug-07 Irrigation / Rain (mm) and Fertilizer Application (kg/ha) 5 10 15 20 25 30 35 EC (dS/m) and ETo (mm) Irrig Rain ETo Fertiliser 30cm Soln 60cm Soln 90 cm Soln

NH4NO 3 applied weekly between October and December

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. Depth Conventional drip ECsw (dS/m) Sub-surface drip ECsw (dS/m) 0.3m 6.4 72 3 52 0.6m 9.8 21 4.9 32 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.

Wine grape sensitivity Varieties EC of soil water at which yield decline starts (dS/m) Sensitive to moderately sensitive Own roots (Vitis vinifera): eg- Sultana, Shiraz, Chardonnay. Rootstocks: 1202C, Kober 5BB, Teleki 5C, S04. 3.6 Moderately tolerant to tolerant Rootstocks: eg- Ramsey, 1103 Paulsen, Ruggeri 140, Schwarzmann, 101-14, Rupestris St George. 6.6

Modified from Zhang et al. 2002

If ECsw exceeds threshold, supplement with winter rainfall

• Overall aim is to reduce ECsw so that average annual

value is below threshold.

• During July-August soil evaporation rates low and soil

cracks minimal so less by-pass flow.

• 2-3 days after rain check salinity (and soil water to see that

profile is at least half full).

• Delay if further rain predicted.
• Apply several small leaching irrigations and recheck

salinity.

When to leach?

Jul-06 Sep-06 Nov-06 Jan-07 Mar-07 May-07 Jul-07 Sep-07 10 20 30 40 50 Rootzone Soil Water Salinity 2 4 6 8 10 12 14 Rain Irrigation Average Rootzone Salinity Evapotranspiration

Big winter rainfall event Big summer rainfall event Winter leaching irrigation window Summer leaching irrigation Grape salinity threshold (tolerant) Grape salinity threshold (sensitive)

Drip irrigated Cabernet Sauvignon Irrigation water salinity 3.3 to 6.0 dS/m

How much leaching is needed ?

• The amount of leaching

needed depends on:

• Existing salinity level, target

threshold, soil type, evaporation rates and rainfall.

• Require a leaching

calculator.

Example of a leaching calculation

• ECiw = 1.0 dS/m or 1000 EC units
• ECsw = 3.6 dS/m
• LR = 0.12 or 12%
• ET crop = 1200 mm
• LR = 171 mm or 1.71 ML/ha
• Assuming leaching fully efficient
• Need less if lots of rain above crop needs
• TAPAS to work further incl Leaching In-effic

Sodicity: an impact of salinity

• Sodicity refers to excess sodium in the soil and water
• Sodium occurring naturally or applied in saline irrigation

water can attach to clays in soil, and cause dispersion of fine particles that block soil pores.

• Sodic layers at the surface or at depth are impermeable

and can reduce soil water or root penetration.

• Poor structure may be due to other things, eg excess

mechanical tillage or compaction.

Development of sodic soil

Development of sodic soil

Toxic ion effect Sodicity (SARsw) Salinity (EC)

Development of sodic soil

Sodium Absorption Ratio (SAR) is one way of diagnosing whether the soil is sodic

Critical SAR levels in soil

Sodicity Hazard SARe SARsw Soil microstructure stability Non-sodic 0-6 0-9 Generally stable. Moderately- sodic 6-15 9-21 Damage when wet. Highly-sodic >15 >21 Spontaneous damage from irrigation or rain.

Example of SARsw in a Riverland Chardonnay vineyard

Sandy loam 04/05 05/06 06/07 Mean 30 cm 6.49 5.12 1.93 Mean 60 cm 6.27 4.15 1.64 Mean 90 cm 2.61 3.56 1.76 Low values; ECi = 0.25 to 0.30 dS/m. ECsw approx = 0.7 – 1.3 dS/m. Reduction of SAR in the 3rd year.

SARsw in a Langhorne Creek Cab Sav vineyard

High values; ECi = 1.2 – 1.4 dS/m ECsw approx = 3-6 dS/m. Loamy sand over loamy medium clay 05/06 06/07 07/08 Mean 30 cm 11.05 10.44 9.91 Mean 60 cm 12.93 11.41 6.35 Mean 90 cm

• 10.27

8.22

Reclamation of sodic soils

Prior to vineyard establishment

If chemical and physical soil tests suggest poor structure and presence of sodic layers, deep rip with gypsum.

Additional management for soil structure

• Avoid activities that damage structure, eg adding

Na to clay soils through irrigation water.

• Offset by adding gypsum to replace Na with Ca.
• Improve structure by building soil pores through deep tillage, or

perennial cover crops with fibrous root systems.

• Organic matter, eg as retained stubble, improves structure of all

degraded soils over the longer term.

After vineyard establishment

• If tests above critical values for soil and water SAR and

physical measurements, band gypsum on surface every 2-3 years, and establish a cover crop such as perennial rye grass.

• An annual dessicant spray to a perennial cover crop in

winter, will still allow effective winter leaching if needed.

Recommendations for the major winegrowing areas of the MDB

• The following slides look at wine-

growing areas along the Murray River system from east to west.

• Management issues become more

critical down-stream.

• Management will depend upon;

climate, soils, quality of water source, and irrigation system.

Salinity monitoring protocol: based on water quality

• River or bore EC < 0.5 dS/m or 500 EC units

Monitor salinity 1-2 times yr with soil sampling

• River or bore EC > 0.5 dS/m or 500 EC units

On-going monitoring of salinity during the year and check trends Petiole and juice sampling for Na and Cl

• If on clay soils or subsoils, monitor sodicity once

a year

North-East Victoria

• High altitude, very high rainfall.
• Sandy loams and loams, mostly on lower slopes.
• Good quality local streams, ground-water

and Murray water.

• Minimal salinity issues at present.
• Annual rainfall sufficient for leaching.
• Annual salinity monitoring together with nutrient test by soil

sampling is recommended.

• Need to check for soil structure problems.

Riverina

• Good rainfall year round: approx 400 mm.
• Mostly red-brown earths, some heavy cracking flood-plain soils.
• Currently low salinity river water (<0.2 dS/m).
• Under current irrigation volumes, annual salinity monitoring by

soil sampling is recommended.

• Rising water table and adoption of drip irrigation require salinity

monitoring with suction cups.

• If groundwater is used, monitor and manage soil structural

problems.

Murray Valley

• Hot, dry climate,low rainfall ~300 mm.
• Red-brown loamy sand to sandy loam with a few local perched

water-tables.

• Low saline Murray water (0.3 dS/m) and high saline lower

Darling (1-5 dS/m) .

• Annual rainfall is not enough for leaching, especially with high

WUE drip systems in lower Darling.

• On-going soil salinity monitoring & management recommended.

For new areas/replanting use tolerant root-stocks.

• Soil structural problems less likely, except clay river flats.

Riverland

• Hot, dry climate with low rainfall < 300 mm.
• Sands to loamy sands over clay and limestone.
• Water quality varies between 0.4 and 0.8 dS/m.
• Piped infrastructure and high WUE drip systems.
• Ongoing salinity monitoring program is recommended tolerant

root-stocks.

• For new areas/replanting use tolerant root-stocks.
• Soil physical problems less likely, except clay river flats.

Clare Valley

• High rainfall approx 600 mm. Saline soils in some areas.
• In the past low quality ground-water. Now supplemented with

piped River Murray water.

• On-going soil salinity monitoring/management recommended,

and use of tolerant root-stocks.

• Optional monitoring of petiole Na and Cl.
• Monitoring and management of soil structural problems

recommended.

Barossa and Eden Valleys

• High rainfall approx 500 mm.
• Low fertility clay loams to more sandy soils.
• Poor quality ground-water (up to 3.5 dS/m) supplemented with

piped River Murray water.

• On-going salinity monitoring/management recommended, and

use of tolerant root-stocks.

• Optional monitoring of petiole Na and Cl.
• Monitoring and management of soil structural problems

recommended.

Adelaide Hills

• High to very high rainfall 500 - 1000 mm.
• Good quality dam and groundwater.
• Annual rainfall mostly OK for leaching.
• Annual salinity monitoring with soil samples suggested.

McLaren Vale

• High rainfall ~ 500 mm.
• Reclaimed water (~1.2 dS/m), groundwater (2-3 dS/m) and town

supply for irrigation.

• Annual rainfall mostly OK for leaching. Annual salinity

monitoring with soil samples suggested.

• Emerging salinity problems with high WUE drip systems using

groundwater and reclaimed water.

• On-going soil salinity monitoring recommended.
• Monitoring and management of soil structural problems

recommended.

Lower Lakes

(Langhorne, Finniss and Currency Creek)

• Annual rainfall ~ 400 mm.
• Sandy loams and loams over clays.
• Very high salinity water (up to 6 dS/m).
• Access to better quality water from local rivers in winter for

storage dams.

• On-going salinity monitoring/management recommended, and

use of tolerant root-stocks.

• Monitoring of juice Na and Cl.
• Monitoring and management of soil structural problems

recommended.