SFS/BWBL - Tropical pastures

Summary

Producers in Gippsland have begun to use tropical grasses in their pastures and have a need to find productive feeds that fill feed gaps in summer and autumn. With the region receiving summer rainfall, having milder climatic conditions and the potential for more summer rainfall in the future, it is beneficial for producers to find species that utilise these conditions.

The aims of this project has been to evaluate the establishment, performance and persistence of tropical grasses and possible companion legumes, whilst considering potential animal performance of these pastures in Gippsland. This project is a MLA's Producer Research Site program, a component of MLA's southern Feedbase Investment Plan. In particular, this project supports the MLA funded project B.PSP.0001 – Increase feedbase production and quality of sub-tropical grass-based pastures.

There were three sites established across central to eastern Gippsland to cover different soil types and climatic conditions. At each site the tropical grasses, Panic, Digit, Bambatsi, and Rhodes, were compared against Kikuyu and summer active Fescue to provide feed over the summer and autumn.  Six companion legume species were also sown at each site, with variety selection determined by site soil and seasonal parameters.

The project found that all tropical grasses tested can establish, but invasion of annual grasses and broadleaf weeds over the winter compromised their persistence, especially the grass species with erect growth habits.

Slow establishment of the different species was an issue. Each trial lost a number of plants due to weed competition. Soil fertility and weed seed burdens on each site played a key role in establishment success.  This was particularly evident in the success of the Bairnsdale trial site, which had good soil nutrition and had been cropped prior to sowing, unlike the other trial sites. The lower soil fertility at Seaspray and Bengworden restricted plant growth which may have allowed weeds to establish.

Continental Tall Fescue, used as a comparative species at all trial sites, unexpectedly persisted and produced well in both clay and sand textured soils, was the pick of the species trialled - provided good soil fertility can be maintained. Panic, Digit and Rhodes grass were not suitable in the clay soils, and only Bambatsi and Kikuyu maintained plant numbers. In lighter textured soils where Panic, Digit and Rhodes grass are already adapted, they failed to persist because of competition from annual grasses and Kikuyu and Tall Fescue maintained levels within the pasture.

For companion legumes, the trial found that Subterranean clovers, Arrowleaf clover and Persian clover were the best performing clovers. These legumes were found to be the most suitable for establishment planting in autumn, through established summer active pastures. However, where there was competition from existing pastures, establishment was still poor. A better approach would have been to use herbicide suppression of the grasses at sowing.

This project received additional collaborative support from Agriculture Victoria, allowing the group to increase the scope of the research undertaken.