Mallee seeps

Working together with Eyre Peninsula farmers to manage mallee seeps

We supported a three-year project up to June 2023, to provide support to farmers facing the rising degradation of Mallee seeps on Eyre Peninsula.

The initial two years of the project was funded by the Australian Government’s National Landcare Program with a 12-month project extension funded by the Board.

Mallee seeps expert, Farming Systems Consultant Chris McDonough from Insight Extension for Agriculture, led the local trials.

What is a Mallee seep?

A Mallee seep is an area affected by a localised perched water table that brings water and salt to the surface soil layers that can result in surface ponding and bare saline scalding over time.

Mallee seeps generally begin when too much fresh water is present in the soil. The soil saturation leads to salinisation and land degradation if no management actions are taken. The issue for farmers is that soil health declines to the point that it no longer functions to support life.

A farmer’s bottom line is affected by Mallee seeps, the paddock is changed and productivity is affected.

The key to managing and restoring Mallee seep areas is to establish living soil cover over bare ground and to target high water-use strategies to reduce perched water tables. Read this case study from a Lock farmer about how he's been able to manage seeps.

Applying strategic management can result in:

  • stopping the spread of the degradation;
  • achieving good soil cover and grazing; and
  • restoration back to full crop production, in some cases.

However this will depend greatly on how severe the seep scald has become at the time of applying intervention strategies - early identification and thoughtful action is the key to achieving optimal outcomes in Mallee seep management.

The project

The project trialled management options suited to both mixed farmers and cropping-only farming systems to explore remedial options. The objective was to slow the increase in unproductive saline land in farming systems where farmers apply highly productive cropping techniques that increase paddock water use efficiency through the effective control of summer weeds.

A key message from the project report is that future farmers need to continue to look, monitor and act early, rather than allow degraded areas to form, expand and go out of production. The worst current scenario is to allow areas to remain damp and bare over the hot summer and autumn. Sowing summer crops such as sorghum and millet directly over these patches to obtain and maintain living cover and use up excess moisture through to seeding time is an acceptable management strategy. This ensures reduction of salts rising in the soil profile, and is an option for a cropping system. Ultimately though, stopping the recharge of these areas using deep rooted perennials such as Lucerne, has proven to be the best management strategy.

Resources for farmers

A series of videos have been created to outline Mallee seep management options.

Some of the methods used during this project to reduce unproductive Mallee seep areas include planting strategic strips of Lucerne up slope of the Mallee seep, establishing puccinellia on the seep to slow osmosis, adding sand layers to improve saline scalded topsoils and pumping water out of the seep to use elsewhere on-farm.

Video #1 - Creek-line salinity identification and management

Creek-line salinity is different to Mallee seeps but important to identify and manage to avoid spread into paddocks. Farming Systems Consultant Dr Chris McDonough explains how to identify creek-line salinity and outlines the management strategies of planting salt-tolerant trees and saltbush.

This video has also been included within the Mallee Seeps Decision Tree which is an interactive on-line guide to all aspects of Mallee seeps management.

Video #2 - Fixing a Mallee seep with Lucerne and Puccinellia

This video shows how quickly a growing Mallee seep scald can be turned back to production using strategic lucerne plantings and puccinellia. It includes footage and results from our trial on a Kimba farm.

Video #3 - Bringing a large recent bare scald back to life

See how a bare scald at Rudall now has cover with puccinellia successfully growing to help stop the seep spreading, improve soil and stop soil accumulating on the surface. Lucerne was also planted but wasn’t as successful yet. Chris McDonough explains what actions they will take to get lucerne to grow, which will help bring the land back to full agricultural production.

Video #4 - Fixing a developing seep before it becomes a scald

A trial site on a farm at Lock has come back to life from a developing Mallee seeps scald. The developing scald area had degraded over a few years – from being a noticeably wet spot in the paddock to not being productive at all. Watch how the trial project has progressed from a spreading scald to rehabilitated land that will be used for production again.

Mallee Sustainable Farming (MSF) brings together farmers and researchers to build more efficient, profitable and sustainable farming businesses in the low-rainfall Mallee region across New South Wales, Victoria and South Australia. Their website is a useful resource including details of current projects.

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