Mallee seeps are a direct result of excess water passing through sandy rises and collecting as perched water tables on less permeable clay layers beneath, causing land degradation.
They have become more prominent in recent years as modern farming systems control deep-rooted perennial summer weeds on surrounding sandy catchment areas that contribute to the recharge water into the perched water tables where the seeps/scalds form. Our Mallee seeps project has been trialling how seeps can be managed on Eyre Peninsula.
Wet periods and high summer rainfall events strongly impact the initial seep development, while the extended dry periods increase capillary rise and evaporation that concentrate salinity in the surface layers.
Why do seeps need to be managed?
Seep areas can initially experience high crop growth, but can become saturated, yellow, and soon dominated by ryegrass and a hazard to heavy machinery. They may start off with fresh water, but in time concentrate high levels of salt in the surface layers, resulting in bare saline scalds patching out across a farmer’s most productive land. If left unmanaged, these areas can expand to many hectares of severe land degradation within a few years.
The longer this goes on, the greater the limitations become on ability to restore the land back to its previous productivity. This is why early identification and action are vital, particularly after the wet summer that much of the EP has experienced.
What do farmers need to look out for during seeding?
Farmers should take notice of any areas showing signs of water collection or that are unusually soft to drive through, particularly below sandy catchment areas and through paddock swales. With wet to saturated soil, it is initially hard to determine whether this will just result in patches of extraordinary crop but dry out over the season, or whether a prolonged perched water table is forming that could cause massive degradation in the future.
How can farmers determine the best course of action?
Take note and keep monitoring these sites through the season. For these new developing sites there are practical actions that can be employed straight after harvest that could prove vital to achieving positive outcomes, such as targeted summer cropping to provide living soil cover and use up excess moisture over summer and autumn.
The aim of all Mallee seep management is to get living soil cover over affected soil areas, and to stop the flow of recharge water into these zones by using targeted high water use options. There are numerous ways of achieving this that need to be matched to the farmer’s specific circumstances.
There are two good ways for EP farmers to find answers to their Mallee seep issues.
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Visit the recently released Mallee Seeps Decision Tree on the MSF website which is an interactive guide with lots of short farmer demonstration videos (including some from EP), that show practical solutions to the full range of Mallee seep situations.
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Come to the Managing Mallee seeps – turning your Mallee seeps around workshop to practically work through the steps of how you can assess and strategically manage your own Mallee seeps to stop their spread and bring them back to production. This is being held at Rudall on June 15. Register today.
Find out more about our Mallee seeps project or watch our YouTube videos about managing and identifying seeps or a creek-line salinity.
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