Native couch grasses for revegetating severely salinised sites on the inland slopes of NSW. Part 2

Abstract

Perennial ‘couch’ grasses that reproduce from rhizomes and or stolons have some advantages on scalded saline sites where they can reproduce in situations that are often hostile to germination and establishment of obligate seeders. Promising couch grass species from an earlier evaluation at Wagga Wagga and Manildra were Cynodon dactylon, Paspalum vaginatum, Sporobolus virginicus and, to a lesser extent, Sporobolus mitchellii. This paper reports results of a subsequent evaluation of these species as well as Eragrostis dielsii and Distichlis distichophylla at 3 other saline sites (Burrumbuttock, Cudal and Cundumbul). All accessions were established vegetatively and assessed for vigour and survival (all sites), groundcover production and its relationship with EC and pH (2 sites), biomass production, forage value and the effect of regular cutting on groundcover (1 site). S. virginicus appeared the most tolerant to saline conditions and produced high levels of groundcover and biomass but was sensitive to regular defoliation. At the 2 alkaline sites, C. dactylon and D. distichophylla generally outperformed the other accessions in terms of persistence and groundcover but appeared to be relatively low in forage value, and D. distichophylla appeared to have significant weed potential. Paspalum vaginatum produced high groundcover and relatively high biomass of moderate forage value at Burrumbuttock but performed poorly at the other sites. S. mitchellii and E. dielsii persisted on the more benign sites producing only low amounts of dry matter and groundcover and may be useful for environmental plantings where low weed potential is paramount. Despite spatially intensive testing of the topsoil chemistry, there were no obvious relationships between EC or pH and plant performance at the 2 main trial sites – a possible consequence of vegetative propagation.