Restoring the condition of degraded black speargrass pastures in southern speargrass zone

Summary

Four sites were selected and established on commercial properties in the southern speargrass zone. These were: “Glencoe”, Monto; “Derarby”, Mundubbera; “Corrunovan”, Proston; and “Stanley House”, Esk.

A group of up to 20 producers were associated with each site. These producers were involved in project planning, decision-making, implementation, data collection and information dissemination.

When the project began in late 1993, there was a large difference in pasture compositions at the four sites. Speargrass comprised as little as 1% of pasture yield at Glencoe and as much as 39% at Corrunovan. Wiregrass ranged from 6% of yield at Derarby to 75% at Glencoe. Another unpalatable grass in the South Burnett, canegrass (Arundinella nepalensis), comprised more than 30% of yield at Corrunovan. The pastures would be classified as being in lower B or C condition using the ABCD Framework (Grazing Land Management workshop, EDGEnetwork®).

At each site the original paddock was subdivided into three paddocks. One was a control, with the same grazing management previously used on the property. The second was burnt and grazed at half that stocking rate. The third was burnt and grazed at strategically-adjusted stocking rates. The group of producers associated with each site decided the details of the third treatment.

Outcomes

• The project maintained strong producer involvement in decision making and planning. This lead to greater acceptance and adoption of the demonstration outcomes by participating producers.

• A review of the project, commissioned by MLA, found:

“The project has been successful in achieving its objectives and in particular:

- Has enabled producers to make better decisions about their pasture and stock management through the knowledge they have acquired of the principles involved.

- Has shown that restoration of degraded speargrass pasture to a sustainable speargrass pasture is practically feasible on commercial properties, and quantified the cost and time to do so.

- Has demonstrated that producers and researchers/extension staff can form a dynamic partnership when each group has a key role in the conduct of the project at hand.”

• Pasture composition recovered well at Derarby in both of the burnt and lightly grazed treatments. The heavy stocking rates used commercially meant that cattle liveweight gain responses to halving stocking rate were significant – liveweight gains averaged 96 kg/head/year in the unburnt control and 154 kg/head/year in the burnt paddock stocked at half the commercial rate.

• At Corrunovan, the amounts of wiregrass and canegrass increased in the paddock where fire wasn’t used.

• At Glencoe, the frequency of occurrence of black speargrass gradually increased from 9% in 1994 to 38% in May 2000.

• Weight gains per head were highest in the lightly stocked paddocks at all sites, the difference being dependant on how heavy initial stocking rates were in the controls – heavier stocking rates reduced liveweight gains per head.

• Data from the sites was used to model the economic returns from breeding enterprises typical of the Burnett and producing either store steers or older steers for finished markets. The outcomes showed that running fewer cattle and allowing pasture condition to recover could improve gross margins by 13% when store cattle production changed to higher value cattle for ‘finished’ markets.

• Field days held throughout the project attracted wide interest and helped with the dissemination of results and information to a broader audience. The effect this had on changing attitudes and management of producers outside participating groups remains unquantified but could be significant. Comments from some producers not involved directly in the project suggest a shift in attitudes in relation to the importance of native pastures.