From the beginning of the South Australian Colony landowners searched for productive pasture plants. An Acclimatisation Society was formed which introduced grasses such as timothy, Chewings fescue and cocksfoot and compared them with native grasses such as the spear grasses (Stipa spp), wallaby grass(Danthonia spp) and kangaroo grass (Themeda spp). All were found to be unproductive and unstable when compared with European pastures. In Europe fertile soils, mild temperatures and reliable rainfall made it possible to maintain permanent/perennial pasture swards year in and year out.
In South Australia, modest rainfall, dry, hot summers, combined with what we now know is the lack of nitrogen in the soil and low levels of other elements, phosphorus, molybdenum, copper and zinc meant that pastures had to be very carefully managed and re-established each year unless irrigated. Weed invasions were a constant challenge.
As farming systems stabilized across the state three pasture zones developed namely:
- the dry “pastoral zone” where no pasture improvement was attempted and the country was grazed in its natural state
- the “Cereal Zone” where pastures were an integral part of the ley farming system
- The “High Rainfall Zone” where perennial and annual pastures utilized the higher rainfall and became developed as permanent pasture areas.
Following WW2, when landowners and agricultural scientists alike had a deep commitment to providing food for the world, the improvement of pastures and grazing systems became urgent. The use of legume based pastures in conjunction with more productive grasses such as rye grass (Lolium spp) and phalaris (Phalaris spp) regularly top-dressed with superphosphate proved to be the answer.
The subterranean clovers (Trifolium spp) were found to be the most useful legumes for pastures on acid soils in higher rainfall areas. Medics (Medicago spp) were developed for the sandy, low rainfall, alkaline soils. Their hard seed coats ensured there were seed supplies in the soil in subsequent years giving the pastures an element of sustainability.
Combining or rotating these pastures for livestock with cropping systems dramatically increased grain yields. This became known as the ley farming system. For further reading see “Ley Farming in South Australia ()”, Bulletin No 15/77, Department of Agriculture and Fisheries, South Australia
Comprehensive information about pasture development in South Australia can be obtained from Dr David Smith’s book, Natural Gains in the Grazing Lands of Southern Australia. In this he covers the research and development programs carried out across the state which established the best plant species for particular soil types, their establishment and the care needed to maintain productive and sustainable ley farming as a basis for South Australian livestock and grain industries.
Smith David (2000) Natural Gains in the Grazing Lands of South Australia. UNSW Press.