101 Questions answered
Reclaiming Mallee Seeps: What It Takes to Crop Again and How Long It Might Take
Yes it is possible to fully rehabilitate a seep, but how long it takes depends on how severe the salinity is, how big the catchment is contributing to the water table, and how quickly you can dry out the water table.
If you catch a seep early, before bare patches have appeared, it’s not too much effort to stop the progression and crop with limited loss to productivity.
Sowing lucerne immediately around the seep, or into the interception zone (where water runs in from) to bring down the water table might be enough and there will be almost no ‘down time’ caused by the seep.
Seeps that are very difficult to rehabilitate:
- are “severe”, with large, bare, degraded, unproductive saline scalds
- have a highly saline water table close to the surface
Seeps with a highly saline water table close to the surface are hard to ‘desalinate’ enough to get a crop to grow. The aim at first is to stop them spreading. These seeps often need trees to use up the excess saline water, as well as lucerne in a perimeter around the seep, and tall wheat grass and/or puccinellia on the seep to try and get some soil cover. Results with these tall wheat grass and puccinellia are variable, but some cover is better than no cover.
Some severe scalds have been fixed without trees where the water table wasn’t too saline. In these cases, the seeps were dried out with high water-use options like lucerne.
In other cases, applying sand mulch meant a wheat crop was grown immediately. However, these still require intervention with high water-use crops such as lucerne, otherwise over time the new sand topsoil will become saline.
In any situation where a seep is forming, there needs to be at least a minor change to farming practices by including lucerne in the interception zone to use up the excess water and stop the seep from progressing.
Use the Mallee Seeps decision tree to work out the best management options.
