Salinity
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Hi Colin,
It depends on the area, as a landscaper I have seen flat areas of suburbia salted, parts of Geelong. But I think it could be to do with there being at least some trees in most gardens and nature strips. I am sure Peter talks about salt in surburban areas.
Melbourne's east in parts has deep top soil, where as in parts of the west there is minimal and these areas are more prone to salting. And also when I create a garden you often bring in fresh top soil and from my experience people use seaweed/fish emulsion liquid fertilizers and organic fertilizer, especially if they have children or are growing vegetables.
Where as I think on farmland there can be kilometers of expanses, without trees, being pumped with chemical fertilizers. I think there is also more organic matter in suburban gardens, leaves and weeds then on cleared farmland and this organic mulch somehow combats or neutralizes salinity
What are your theories?
It depends on the area, as a landscaper I have seen flat areas of suburbia salted, parts of Geelong. But I think it could be to do with there being at least some trees in most gardens and nature strips. I am sure Peter talks about salt in surburban areas.
Melbourne's east in parts has deep top soil, where as in parts of the west there is minimal and these areas are more prone to salting. And also when I create a garden you often bring in fresh top soil and from my experience people use seaweed/fish emulsion liquid fertilizers and organic fertilizer, especially if they have children or are growing vegetables.
Where as I think on farmland there can be kilometers of expanses, without trees, being pumped with chemical fertilizers. I think there is also more organic matter in suburban gardens, leaves and weeds then on cleared farmland and this organic mulch somehow combats or neutralizes salinity
What are your theories?
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Shirley Henderson
- Posts: 356
- Joined: Sun May 06, 2007 4:03 pm
- Location: Thirlmere
You know what Brett and Colin. That is a very interesting question about salinity. Suburban gardens are probably holding a lot of salt underneath them and once floods occur, as it will- including on farmlands, the salinity may appear if the soil is saturated enough. Suburban gardens are spoilt rotten. People put mulch on their gardens to prevent evaporation, retain moisture and protect plant roots. This is advertised on all the gardening shows, at all the nurseries and through any useful advise. Mulch is very key in keeping soil stable and healthy and as suburban people usually only have a small patch to worry about the cost is not to high. Suburbanites either love their gardens or neglect them totaly. The neglected gardens may be overgrown or full of weeds therefore I would say a good healthy groundcover is protecting the soil and maintaining that underlayer of fresh water that Peter talks about in his book. Also they love lawns, mow them, fertilise them and water them whenever they can. It all looks great on the surface but wait until they get a good soaking and that underwater salt will move through as Peter says and end up in drains, dams, waterways and out to sea eventually. So in my opinion I do not think that suburbia is free of salinity it is just hidden for the time being. Parks, gardens and reserves are the ones that worry me and this is where the signs will begin to show. I am involved in water quality monitoring through a bushcare group and after the rain is when the waterways are in their worst condition. Lucky for us the environment is always trying to rectify our poor management. I hope farmers in particular will heed this warning and cover their farms with mulch and plants so that when the rains saturate the soil they are not left with salty land and salty water in their rivers and dams. I know this is already happening but there is still time to turn it around if you heed Peters words. He really does know what he is talking about. IF governments ever decided to cease the watering of lawns as a water preservation measure I think you would see deserts and salt encrusted lands appearting soon after. Thats my opinion anyway. Does anyone else have a view on this? There are so many members now and it would be nice to hear some other comments.
Colin
Here are a few facts from the National Land and Water Resources Audit undertaken in 2000 about the extent of salinity in both urban and rural areas.....click on http://www.anra.gov.au/topics/salinity/ ... tents.html for more detailed information. The audit also reported that approximately 5.7 million hectares of Australia’s agricultural and pastoral zone are in regions at risk of developing dryland salinity.
It is predicted that this area could increase to 17 million hectares by 2050 unless effective solutions are implemented.
The largest affected areas are in the agricultural zone of south-west Western Australia, with areas within South Australia, Victoria, New South Wales and Queensland also affected or at risk.
In Western Australia, the area of salt-affected land has been estimated to have been increasing at the rate of one football field per hour, when averaged over the past 50 years.
Urban salinity has also been identified as a major problem in Western Australia and elsewhere, with a number of rural towns experiencing impacts on infrastructure, including roads, drainage networks and buildings with brickwork corrosion. The same problem is ocuring in NSW,Victoria and SA.
Overall, in the 2000 Audit, 1,600 kilometres of railways, 20,000 kilometres of road, 68 towns and 80 important wetlands were identified as being at risk of damage in Australia.
This country is of course not alone in facing these issues.
In the global scene as well as in Australia, the secondary salinisation of agricultural lands by irrigation is particularly widespread in arid and semi-arid environments with at least 20 percent of the area of all irrigated lands estimated to be salt-affected, especially affecting countries such as India, Pakistan and the United States.
Here are a few facts from the National Land and Water Resources Audit undertaken in 2000 about the extent of salinity in both urban and rural areas.....click on http://www.anra.gov.au/topics/salinity/ ... tents.html for more detailed information. The audit also reported that approximately 5.7 million hectares of Australia’s agricultural and pastoral zone are in regions at risk of developing dryland salinity.
It is predicted that this area could increase to 17 million hectares by 2050 unless effective solutions are implemented.
The largest affected areas are in the agricultural zone of south-west Western Australia, with areas within South Australia, Victoria, New South Wales and Queensland also affected or at risk.
In Western Australia, the area of salt-affected land has been estimated to have been increasing at the rate of one football field per hour, when averaged over the past 50 years.
Urban salinity has also been identified as a major problem in Western Australia and elsewhere, with a number of rural towns experiencing impacts on infrastructure, including roads, drainage networks and buildings with brickwork corrosion. The same problem is ocuring in NSW,Victoria and SA.
Overall, in the 2000 Audit, 1,600 kilometres of railways, 20,000 kilometres of road, 68 towns and 80 important wetlands were identified as being at risk of damage in Australia.
This country is of course not alone in facing these issues.
In the global scene as well as in Australia, the secondary salinisation of agricultural lands by irrigation is particularly widespread in arid and semi-arid environments with at least 20 percent of the area of all irrigated lands estimated to be salt-affected, especially affecting countries such as India, Pakistan and the United States.
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Shirley Henderson
- Posts: 356
- Joined: Sun May 06, 2007 4:03 pm
- Location: Thirlmere
Learning about salinity
I am learning more about salinity a I go. I do have a question about NSF. In Peters book where he speaks of salt outbreaks due to salt moving sideways.
Can these outbreak areas be covered with fill or soil and planted to recommence the fresh water lense higher than the salt outbreak?
Shirley
Can these outbreak areas be covered with fill or soil and planted to recommence the fresh water lense higher than the salt outbreak?
Shirley
Hi Shirley,
The answer to that question is a definite yes.
It is an intriguing aspect of salinity that I have seen many times that where earth is layered in a raised manner from the surrounding sterile saline landscape healthy plants grow strongly.
This can be seen where a road or causeway has been constructed through a saline area on a large scale or even on a smaller scale where a mound has developed through dust gathering and being deposited by the wind as it passes through small areas of trash.
I have always considered the possibility of using earth moving equipment on areas of my farm which are salt affected to raise the surface level above the breakout level of the salt to cure a local area of salinity.
Of course apart from the cost of the exercise being inhibitive one must also consider the high likelihood that in raising the surface of the entire effected area the result over time would be a slightly raised saline surface which is something that I have also observed.
It is possible to create an area unaffected by surrounding salinity by burying the salt and raising the topsoil above the saline area but only on an isolated scale by making islands of raised seed beds well above the salinity or by making a raised strip or bank as seen by road works or rail works but this effect cannot be replicated effectively on a large scale over an entire saline locality.
As for fertilisers being responsible for salinity, from my observations I would have thought that YES fertilisers do contribute in a very minor way to salinity but NO fertiliser use does not cause an area to become saline.
To qualify that statement I would say that by isolating and removing the addition of fertiliser as a treatment to an agricultural landscape such as that which we have here in WA would have very close to zero bearing on the likelihood of that area either becoming or not becoming saline effected.
Of the factors contributing to a healthy landscape becoming sterile through human management resulting in salinity the addition or non addition of fertiliser as a treatment would have to be seen as playing a very minor role.
To further strengthen this statement I would list those factors which if excluded or included as a treatment of an area would play an exponentially more consequential role.
Clearing of native vegetation.
Clearing of native vegetation.
Clearing of native vegetation.
The answer to that question is a definite yes.
It is an intriguing aspect of salinity that I have seen many times that where earth is layered in a raised manner from the surrounding sterile saline landscape healthy plants grow strongly.
This can be seen where a road or causeway has been constructed through a saline area on a large scale or even on a smaller scale where a mound has developed through dust gathering and being deposited by the wind as it passes through small areas of trash.
I have always considered the possibility of using earth moving equipment on areas of my farm which are salt affected to raise the surface level above the breakout level of the salt to cure a local area of salinity.
Of course apart from the cost of the exercise being inhibitive one must also consider the high likelihood that in raising the surface of the entire effected area the result over time would be a slightly raised saline surface which is something that I have also observed.
It is possible to create an area unaffected by surrounding salinity by burying the salt and raising the topsoil above the saline area but only on an isolated scale by making islands of raised seed beds well above the salinity or by making a raised strip or bank as seen by road works or rail works but this effect cannot be replicated effectively on a large scale over an entire saline locality.
As for fertilisers being responsible for salinity, from my observations I would have thought that YES fertilisers do contribute in a very minor way to salinity but NO fertiliser use does not cause an area to become saline.
To qualify that statement I would say that by isolating and removing the addition of fertiliser as a treatment to an agricultural landscape such as that which we have here in WA would have very close to zero bearing on the likelihood of that area either becoming or not becoming saline effected.
Of the factors contributing to a healthy landscape becoming sterile through human management resulting in salinity the addition or non addition of fertiliser as a treatment would have to be seen as playing a very minor role.
To further strengthen this statement I would list those factors which if excluded or included as a treatment of an area would play an exponentially more consequential role.
Clearing of native vegetation.
Clearing of native vegetation.
Clearing of native vegetation.
Salinity time line
Just out of interest, I found this graph at the site Duane suggested above.
It displays the growth of salinity affected areas over time at different rates of water recharge.
Now we can stop blaming the pioneers and take responsibility ourselves.
It is clear that the destruction to date is miniscule compared to that which about to engulf us if we fail to implement change.
In future times the finger will be pointed squarely at us when blame is attributed for the destruction because we had the knowledge and the ability to make changes.
It displays the growth of salinity affected areas over time at different rates of water recharge.
Now we can stop blaming the pioneers and take responsibility ourselves.
It is clear that the destruction to date is miniscule compared to that which about to engulf us if we fail to implement change.
In future times the finger will be pointed squarely at us when blame is attributed for the destruction because we had the knowledge and the ability to make changes.