Restoring native pasture after fire

Native pastures play an important role in livestock nutrition for some farmers.

There are about 1,000 native grass species in Australia; species that are well adapted to the country’s harsh and varying climate and low-fertility soils. As a result, there are situations and environments where native pastures can be a well-adapted, sustainable and suitable choice for livestock production.

Research shows that to restore native pastures you need to implement deferred grazing. While this is something most farmers do traditionally, it is particularly important to carry out this strategy after fire. Restoring native pastures will help maintain population density and avoid invasion by undesirable species such as onion grass, broadleaf weeds and annual grasses.

There are many deferred grazing regimes including optimised deferred grazing, short-term deferred grazing, long-term deferred grazing, timed grazing and strategic deferred grazing.

The aim of deferred grazing is to:

• ensure ground cover remains about 70 per cent up to mid-January
• increase native perennial plant density
• reduce annual grass seed germination
• increase perennial germination and seedling survival
• increase root biomass down to 60cm
• increase subsequent years herbage mass.

Optimised deferred grazing

Optimised deferred grazing is one of the most effective strategies to alter pasture composition and lift perennial grass population and production while suppressing annual grasses. This strategy requires a high stocking rate, with animals grazing dry and lower quality feed.

Care needs to be taken with the class of stock grazing these pastures to ensure their needs are met. Supplementary feeding may be required to meet nutritional requirements.

With optimised deferred grazing, the withholding time from grazing depends on the growth stage of the pasture plants, with grazing generally prevented from spring to late summer depending on seasonal variations.

The period of time that paddocks need to be rested for optimised deferred grazing will depend on the pasture growth stage and seasonal variation. Generally, this occurs in spring to late summer.

This deferred grazing starts after annual grass stems elongate, but before seed heads emerge so the growing points of undesirable annual plants can be effectively removed by close grazing. The completion of the paddock resting phase for this grazing strategy depends on pasture conditions of the desirable perennial grasses (seed set, growth and herbage on offer), which are generally ready for grazing from late summer to early autumn.

This strategy aims to reduce the amount of seed produced by annual grasses and alter pasture composition – lifting the proportion of perennials while suppressing the annual grasses.

To implement optimised deferred grazing, farmers need to have a clear understanding about pasture composition, growth stage, seasonal constraints and expected outcomes.

Optimised deferred grazing should be used when:

• There is a reasonable amount of desirable perennial species (>20 per cent)
• There is the capacity to intensively graze a paddock (adequate fencing and stock requirements).

Timing is crucial, as heavy grazing is required when most annual grass stems have elongated in late winter and early spring but before the seed heads emerge.

Deferred Grazing (DG) Quick Reference Guide