MALLEE seeps have become more prevalent on the Eyre Peninsula, especially since the wet season of 2016 and extensive rainfall this past year.
Consultant Chris McDonough, from Insight Extension for Agriculture, was on the west coast recently at a farmer forum at Rudall, where he outlined seep trials under way on five farms across eastern EP and successful management results so far.
He also showed attendees how to use the new 'Mallee Seeps Decision Tree' application on the Mallee Sustainable Farming website.
The online interactive tool was launched in May, using information gathered during the four-year MSF seeps project.
It helps users to identify seeps from other saline land degradation, such as creekline salinity, regional groundwater salinity or dry saline land; explains how seeps form in our modern farming systems; what farmers need to be able assess a seep; and provides strategies to farmers that suit their individual situations.
While early identification and strategic action is vital in reducing impacts, even well-established seep scalds have been brought back into production.- CHRIS McDONOUGH
There are also multiple video links from various SA and Vic sites that show practical on-farm management techniques and successful results of rehabilitation in recent years.
"The key to successfully managing Mallee seeps lie in understanding both the salinity level of the perched water tables, as well as the stage of seep development," Mr McDonough said.
"While early identification and strategic action is vital in reducing impacts, even well-established seep scalds have been brought back into production.
"But if left untreated, farmers will keep seeing hectares of productive cropping land grow into saline scalds."
While management practices, such as delving, organic matter or clay spreading and even drainage, were suggested at the forum, Mr McDonough said from his years of experience, establishing living soil cover (plants) across the discharge zone was the best way to limit capillary rise and evaporation (scalding), while restoring soil health, and applying high water use plants within the interception zone to lower or dry up the perched water tables.
This included growing deep-rooted perennial lucerne or other high water use crops on the interception zone (above the seeps), to salt-tolerant grasses or summer crops on the discharge zone (where the water ends up), and even salt-tolerant trees on the more historic salt-established areas.
"This isn't necessarily about trying to grow the best lucerne stand, it's more about using up the water in a specific area at a specific time," Mr McDonough said.
"Once the roots of these plants establish and get into that water table, they are able to dry the area out before any more degradation of the topsoil occurs. Some of these areas on the EP will have water pouring out of these sand hills for a few years yet.
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"If you can get lucerne established in a year like this, when it's remained reasonably wet, it should help to address any potential seep forming.
"It doesn't have to be the whole paddock, just a strategic strip for 20-25 metres above some of these areas has shown to be enough to start intercepting recharge and reducing or even drying out perched water tables within a year."
Mr McDonough stressed early identification of a seep was key and where using the online Mallee Seeps Decision Tree was important.
The Mallee Seeps Decision Tree project was supported by MSF, with funding from the federal government's National Landcare Program and co-investment from the GRDC and Murraylands and Riverland Landscape Board levies, in collaboration with the EP Landscape Board's Mallee Seeps Project and AIR EP.
At the forum, Mr McDonough also highlighted they were looking into other seep management practices.
"There is a new project under way looking into dry saline land (magnesia patches) and whether incorporating organic matter, such as chaff, straw, sand or manures, into topsoil layers could help improve areas longer term after 'salt-leaching' wetter years," he said.
"It will be interesting to get a lot more detail on that."
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