Indian couch invasion: scope, production impacts, and management options

Abstract

Indian couch, after being introduced into Australia in the 1930s and 1950s, was promoted for amenity use as well as for land reclamation and as a pasture species for grazing. The grass (including different ecotypes) has since naturalised and has spread into grazing lands in eastern Queensland. A range of factors are contributing to its spread, including ecological attributes for competitiveness, land degradation, heavy grazing, adequate source of seed and means of spread, and climatic extremes in rainfall variability. Under severe conditions, such as heavy grazing coupled with drought, Indian couch can replace existing pasture species and change the production system. Understanding the implications of this to beef businesses was a key focus of the project, as was quantifying the extent of Indian couch invasion and testing and identifying possible management options.

Research findings, expert opinion, and producer knowledge showed that while Indian couch has some production value, a major impediment is its reduced drought tolerance. As one producer said, Indian couch is a “Less reliable feed source, as reasonable production only comes with good seasons”. In addition, the bioeconomic modelling showed average annual profits for an Indian couch pasture enterprise were much more variable than those for native pasture enterprises.

Indian couch mapping was conducted for grazing lands of eastern Queensland using new and existing datasets. An area of 9.6 million hectares, representing ~32% of the total area that makes up the Burdekin, Fitzroy, and Burnett-Mary catchments, was identified as being at risk of Indian couch dominance.

The project also consulted with producers, professional grazing sector advisors and scientists to collate best-management options for established Indian couch pastures, as well as options for minimising Indian couch incursions into native and sown pastures. In order to minimise Indian couch incursions, management options include avoiding over-utilisation of the pasture, maintaining high ground cover, and improving the competitiveness of existing pasture species. For pastures dominated by Indian couch, key strategies for improved production and ecological function include reducing stocking rates, applying more rest to pasture, and incorporating new grasses and legumes into the pasture where possible.

In summary, the project has raised awareness on the issue of Indian couch spread in eastern Queensland and provided an important foundation for future work to build on aimed at improving pasture resilience.