T HE EFFECT OF SALINITY ON FARM PRODUCTION AND PROFITABILITY

Growth response to salinity

Halophytes grow better on mildly saline than non-saline sites. They are therefore key components of saltland pastures.

Non-halophytesvary in their tolerance to salt. The more tolerant species may be components of saltland pastures while the less tolerant species will almost certainly not be.

Waterlogging and salinity interactions

Worksheet 3

Write down 2 to 3 effects of waterlogging on plant growth and crop production

List the effects of waterlogging on crop and pasture

production?

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Three broad groups of plants

Growth

River saltbush

Barley

Beans

Salt/waterlogging interactions Salt/waterlogging interactions

Slide produced by: T Lacey

Produced by: EG Barrett-Lennard

Slide 45.

Salt/waterlogging interactions Salt/waterlogging interactions

Slide produced by: EG Barrett-Lennard

Slide 46.

Waterlogging is a problem because ...

Produced by: EG Barrett-Lennard

xDecreases diffusion of oxygen into soil.

xCauses energy deficiency in roots.

xBreaks down salt exclusion.

xAdversely affects growth and survival.

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Waterlogging saturates the pores in the soil that are normally filled with gas, making them oxygen deficient. This affects the ability of roots to get energy for their

metabolism and makes roots leaky to salt. If salt accumulates to a substantial degree in the shoots, plant growth and survival are affected. The following series of photos shows the effect of salinity and waterlogging on plants.

The four pots pictured in each photo are growing wheat. The two pots on the left are waterlogged while the two pots on the right are freely drained. The photos show the effects of waterlogging on wheat grown with (a) no salt, (b) salt equivalent to 4% sea water and (c) salt equivalent to 20% sea-water. The effect of salinity and waterlogging combined has a much harsher effect on plant growth than salinity on its own. This indicates the potential for removing the waterlogging from the system with surface water drainage. Raised beds are one option that can be used to remove the waterlogging (Barrett-Lennard 2003).

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‘low’ salinity

‘low’ salinity (2 dS/m)

(2 dS/m) = 4 x = 4 x

Salt in the leaves Salt in the leaves

‘moderate’ salinity

(12 dS/m) = 20% x

Seawater Seawater Salt concentrations

Slide produced by: EG Barrett-Lennard

Slide 48.

Sodium in leaves Sodium in leaves

(‘moderate’ salinity - 12 dS/m) (‘moderate’ salinity - 12 dS/m)

P e r c e n t s o d iu m ( o r g a n ic d r y w t b a s is )

0 3 6 9 1 2

= waterlogged

= waterlogged = drained

= drained

Slide produced by: EG Barrett-Lennard

Slide 49.

Waterlogging and Salinity Waterlogging and Salinity

Effects on Growth

Slide produced by: EGBarrett-Lennard

zero salt zero salt

(Photographs: Simon Eyres) _________________________

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Impact of loss of productivity to profitability of the farm

Options include:

Do nothing (live with salinity) and continue farming with current system and accept that a percentage of land will be lost to salinity in the future. The risk associated with this depends on the area of the farm that is likely to be affected or lost. If you are nearing the new equilibrium where the discharge sites are adequate to deal with the recharge then the best option may be to do nothing, get more land etc. If however you have large areas of valley floors that are likely to go saline before the new equilibrium is reached then the cost to your farm will be greater. The land that goes saline will often be some of the most productive on the farm.

Contain the spread of salt-affected land. This will mean adopting a change in farming systems and mindset. There will be no “Silver Bullet“ for managing salinity and a suite of profitable farming practices including perennial pastures, trees, saltland grazing systems and water management practices will need to be adopted. There will be a lag period in seeing results even if moving to 100% perennials, as there is already an excess of water in the groundwater system. Containment may not stop salinisation altogether but it may buy time. Recent modelling work is indicating that areas with broad valley floors (largely in the ancient drainage zones) will get the greatest response

(buying time) from managing recharge in the valley floors themselves.

Recovery of salt-affected land. This is the most difficult and costly option to achieve. It will usually involve the continued use of engineering options.

Adaptation to saline areas. This involves the inclusion of alternative productive options on land that has gone saline. Grazing management of saline pastures utilising salt and waterlogging-tolerant species.

There are many ways to move into new farming systems. The transitional period is critical to the profitability of the farm. STEP is one option that allows farmers to examine the implications of a range of transitional strategies.

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Broad options

Do nothing - Cost of lost productive land and land value Containment - Costs in moving to new profitable system, reduced loss of productive land, land value, feel good etc.

Recovery - Expensive with ongoing cost, disposal of saline water issues

Adaptation - Costs in moving to new profitable system, increased profitability of land

Slide produced by: T Lacey

Costs and benefits Costs and benefits

Slide 51.

Decisions on management options Decisions on management options

Need to be kept in context with overall farm objectives and goals

xReasons for managing salt x$ spent elsewhere etc.

Slide produced by: T Lacey

Slide 52.

% Area Ha % AreaHa % Area Ha % Area Ha % A

Severe (unusable) 2% 32 4% 80 4% 80 5% 100 5%

Low yield 2% 40 4% 80 6% 120 8% 160 8%

2% 40 6% 120 6% 120 6% 120 6%

2% 32 2% 32 2% 32 1% 20 1%

7% 144 16% 312 18% 352 20% 400 20%

Salinity level LYSA MYSA HYSA (Barley) Total Area

2000

85%

2025 2050 2075

% of potential (Non Saline) profit

25%

40%

2115

% Area Ha % Area Ha % Area Ha % Area Ha

ere (unusable) 2% 32 4% 80 4% 80 5% 100

w yield 2% 40 4% 80 6% 120 8% 160

2% 40 6% 120 6% 120 6% 120

2% 32 2% 32 2% 32 1% 20

7% 144 16% 312 18% 352 20% 400

ey)

2000

85%

2025 2050 2075

% of potential (Non Saline) profit

25%

40%

% Area Ha % Area Ha % Area Ha % Area Ha

Severe (unusable) 2% 32 4% 80 4% 80 5% 100

Low yield 2% 40 4% 80 6% 120 8% 160

2% 40 6% 120 6% 120 6% 120

2% 32 2% 32 2% 32 1% 20

7% 144 16% 312 18% 352 20% 400 2

nity level A

A A (Barley) l Area

2000

85%

2025 2050 2075

% of potential (Non Saline) profit

25%

40%

% Area Ha % Area Ha % Area Ha % Area Ha

Severe (unusable) 2% 32 4% 80 4% 80 5% 100 5

Low yield 2% 40 4% 80 6% 120 8% 160 8

2% 40 6% 120 6% 120 6% 120 6

2% 32 2% 32 2% 32 1% 20 1

7% 144 16% 312 18% 352 20% 400 2

Salinity level LYSA MYSA HYSA (Barley) Total Area

2000

85%

2025 2050 2075

% of potential (Non Saline) profit

25%

40%

Cost of “Do nothing” scenario Cost of “Do nothing” scenario

Assumptions: Broad flat valley floor landscapes

• 2000 ha property

• 20% total future salinity (by year 2075)

• Watertables are saline and rising, leading to the areas of salinity indicated in the scenario above

Current level of salinity

Slide produced by: T Lacey _________________________

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Cost of “No Change Scenario”

This spreadsheet looks at the cost if no attempts are made to adopt management practices to reduce recharge to the system. The spreadsheet is based upon“Broad Flat Valley Floors” where planting 40 to 50% of the area at risk of becoming saline to perennials may increase the time to salinity developing by 40 years (buying 40 years).

The spreadsheet allows you to change farm area, future salinity area, current profit from non-saline land and how profitable the new management options are in comparison to current farm management.

Where management options putting 40% or area at risk into perennials is adopted the same final level of salinity is reached but instead of being reached in the year 2075 it is taking 40 years longer (final salinity levels reached in 2115). The average per year difference can be looked at over the periods of 2000 to 2025, 2000 to 2050, 2000 to 2075 or 2000 to 2115.

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Cost of “Do nothing” scenario Cost of “Do nothing” scenario

•Average profit from non-saline areas = $200/ha/yr

Slide produced by: T Lacey

No Change - Costs of Lost Production

-50000 -45000 -40000 -35000 -30000 -25000 -20000 -15000 -10000 -5000 0

1950 2000 2050 2100 2150

Year

$/Year

-50 -100 -150 Profit from non s aline land $/Ha

Slide 54.

% Area Ha % Area Ha % Area Ha % AreaHa % Area Ha

Severe (unusable) 2% 32 3% 60 3% 60 4% 80 5% 100

Low yield 2% 40 3% 60 3% 60 6% 120 8% 160

2% 40 3% 60 3% 60 6% 120 6% 120

2% 32 2% 32 2% 32 2% 32 1% 20

7% 144 11% 212 11% 212 18% 352 20% 400 LYSA

MYSA HYSA (Barley) Salinity level

2000

25%

Total Area

2025 2050 2115

40%

% of potential (Non Saline) profit

85%

2075 0%

Cost of “40% Management” scenario Cost of “40% Management” scenario

Total area Starting point and finishing point haven't

changed It has taken 40 years longer to reach

the new equilibrium point

Total area, starting and finishing salinity levels

haven't changed

•Recharge management scenario buying 40 years

Slide produced by: T Lacey

Slide 55.

-3550 -6075 -6537 -5101 Average $'s Difference/Yr Total from2000 to2020

Total from2000 to2050 Total from2000 to2075 Total from2000 to2115 No Change vs delay by 40

years. Cumulative $

Cost of loss of productive land to salinity.

-$586,650 -$88,750 -$303,750 -$490,250

Comparison

Comparison--Cumulative positionCumulative position

Comparison of "No Change" to "Buying 40 Years"

-35000 -30000 -25000 -20000 -15000 -10000 -5000 0

1950 2000 2050 2100 2150

Year

CostProfit Forgone $/Yr

Management Options No Change

The value of delaying salinity by 40 years

Slide produced by: T Lacey

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In document Introduction to salinity - workshop manual for participants (Page 45-53)