South Coast Sandplain WA – Pastures
Pasture trends of the South Coast Sandplain
Pasture composition in the South Coast Sandplain of WA varies with rainfall and soil type. Annual grasses and legumes are the most common pasture species with annual ryegrass and sub clover dominant. There are also significant areas of mixed ryegrass and serradella pastures, mainly on the poorer sandy soils as well as smaller areas of medics.
In the areas receiving >550mm of rainfall the sub tropical perennial grass kikuyu is common with approximately 153,000ha present in the south west of Western Australia making it the most widely planted perennial in WA . This is especially the case in areas receiving more than 600mm where kikuyu is most likely the dominant pasture along with ryegrass and sub clover.
There are smaller areas of other perennial grasses, legumes and shrubs across the region with approximately 58,200ha of mixed species across the south west of Western Australia. Temperate perennial grasses like perennial ryegrass, tall fescue and phalaris can be found in the high rainfall (>600mm) areas. Lucerne is mostly found in the medium to lower rainfall cropping dominant areas receiving less than 500mm of rainfall, however it is still a relatively minor pasture species with approximately 33,400ha across the south west of Western Australia. Small areas of chicory can also be found, however these are mainly as part of mixed pasture swards.
There are small areas of other mixed and single species including Rhodes grass, setaria and other temperate grasses. These tend to be on poorer soils in mixed pasture systems.
Suitable perennial pasture species for the South Coast Sandplain
Tropical perennial grasses
Well drained sandy and gravelly soils in the region support tropical grasses like kikuyu. Unlike many tropicals however, kikuyu will also thrive on waterlogged sandy duplex soils making it a very versatile plant for WA. This combined with its ability to tolerate acidic soils and heavy grazing make it the most wide spread perennial in the zone. Panic (Panicum maximum) is another tropical grass that has potential in these soils. It is not widely planted however it does have the potential to produce large amounts of biomass in well drained sandy and gravelly soils.
Perennial herbs and legumes
Lucerne is better suited to the moderate to shallow duplex soils. Where waterlogging and low soil acidity is not limiting, the pasture can grow well and produce substantial amounts of quality dry matter. Chicory also fits into this niche however, compared to lucerne, it is better able to tolerate soil acidity which may make it more suited to the south coast sand plain.
Temperate perennial grasses
The temperate grasses are better suited to the medium to high rainfall areas of the south coast sand plain (>550mm). Winter active tall fescue and phalaris have shown considerable promise and have the potential to extend the growing season. There are small areas established throughout the South Coast Sandplain and in the high rainfall zone there is potential for increased plantings on more fertile soils.
Shrubs and salt-tolerant options
Tagasaste is a common fodder shrub. It is grown in small areas through the Sandplain, primarily in the areas receiving <600mm of rainfall. It is mainly grown on very poor easily eroded sands where cropping and conventional pasture species struggle to be productive, however on these sites in has proven to be a grazing tolerant and productive option.
Saltland pastures are grown in small pockets throughout the zone, though they are more common in the lower rainfall areas where salinity is more evident. These include tall wheat grass and puccinellia mixed swards and in more saline areas alleys or block plantings of saltbush with oldman (A. nummularia), river (A. Amnicola) and wavy leaf (A.undulata) being the most common saltbush species. Tall wheat grass is found throughout the agricultural region and is grown down to 350mm annual rainfall on a range of soils. It is mainly targeted at saline soils but may have application outside of these areas.
Rules of thumb
The Perennial pastures: rules of thumb table provides an indication of the suitability of different perennials species to differing soil types and purposes for WA.