Management of Saltbush

Tuesday, April 21, 2020

To maximise production from saltbush stands it is important that they are managed appropriately.

Forage shrubs (mainly Old-man saltbush) need to be grazed every year, not just kept as a drought reserve. A small patch of shrubs will not provide enough grazing days to have a significant impact on profitability. Livestock need time to become accustomed to the saltbush.
Traditionally Old-man saltbush was planted in dense blocks with minimal pasture growth between the shrubs. Forage shrub systems consist of forage shrubs planted in rows with wide inter-rows (> 5m) to allow other pasture species to grow and provide a more balance diet.

Forage shrub systems can be grazed by either sheep or cattle. To ensure livestock graze a mixture of the inter-row and forage shrubs, rather than just the inter-row pasture it is important to use:

  • High stock density, as high grazing pressure encourages animals to be less selective and eat a wider range of plants
  • Livestock in reasonable to good condition, as they will tend to eat a more diverse range of plants
  • Experienced animals, which have experienced grazing shrubs on a regular basis from an early age.

Grazing forage shrubs
Forage shrub systems (with Old-man saltbush) should not be continuously grazed (set-stocked ) as livestock initially have rapid weight gain as the most nutritious plants are selected, but then lose weight as less nutritious plants are eaten. Forage shrubs also require recovery periods where they are rested from grazing as they cannot support intensive and continuous grazing or set stocking.

In contrast, rotational grazing management of forage shrub systems may limit livestock selectivity of palatable and nutritious forage and inter-row pastures.
Rotational grazing with moderate to high grazing pressure and moving animals into new paddocks allows them to adapt their grazing behaviour and incorporate shrub foliage into their diet before the inter-row pasture is overgrazed.

Areas of forage shrubs being grazed, should be small enough so that they can be grazed within a short timeframe e.g. one week, before being moved to another shrub area. This is a substantial change from previous thinking that areas be grazed for 6-8 weeks and livestock moved when forage shrub plants start to reshoot. Intense short grazing does not damage or bare out the inter-row pasture, leaving adequate ground cover which prevents erosion and unpalatable plants such as onion weed becoming dominant. The stocking rate recommended for forage shrub systems is ~10 DSE/ha, and a stock density of 30-55 DSE/ha to intensively graze forage blocks.

The recovery period will vary depending on how hard shrubs are grazed, and the time of year grazed. If plants are grazed hard with little leaf remaining they will need at least 6 months to recover, however with only moderate grazing they may only need 3 to 4 months to recover. Forage shrubs are generally summer active or C4 plants which grow mainly in spring and summer with only slow growth during winter.

Pruning/Slashing of Saltbush
It is important to manage forage shrubs to stop them becoming woody and tall, as shrub growth above 1.5 m is not available to grazing sheep. If plants become too tall, it is recommended to initially prune to approximately 60 cm above the ground, and then raise the height of pruning as the plants age. Trials on Old-man saltbush have shown that cutting at 80 cm produced the largest amount of regrowth.

Experience has shown that it is preferable to slash or cut the bushes before grazing when the bushes have good leaf area. Tall growth will be removed and this will be available to grazing animals on the ground. Pruning after grazing can result in significant shrub deaths as they do not have enough leaf area to recover.