Farm Table says:
What is the problem?
Predictions are for a warmer and drier environment in southern Australia, with the average temperature forecast to rise by up to38C by 2050 in some regions and annual rainfall changes of –20 to +10%.
This study focused on the effect of warming on perennial ryegrass which is a temperate grass, and kikuyu which is a subtropical grass.
What did the research involve?
The objective of this study was to
• use a model well suited to grazing systems in SE Australia—the Sustainable Grazing Systems (SGS) Pasture Model
• to assess the average monthly and annual ME yield of a kikuyu pasture under warmer climate scenarios in this region in comparison to perennial ryegrass.
What were the key findings?
If conditions in SE Australia become warmer in the future, this study suggests that in terms of annual pasture production, on average, kikuyu grass is unlikely to provide a greater source of ME per hectare compared with perennial ryegrass, at least until temperatures increase by 18C at more temperate locations such as Bega, Dookie, Hamilton, Ellinbank,and Elliott.
Even with predicted increases in ME yield per hectare with warming, the higher coefficient of variation associated withthe kikuyu pasture would make it a less reliable feed source than perennial ryegrass at temperature increases of up to 38C.
In winter-dominant rainfall regions, replacing a winter-active pasture with a summer-active pasture where future climate predictions do not change the winter-dominant rainfall pattern means that kikuyu will never reach its full warm-season production potential.
The nutritive value, seasonal distribution of growth, total annual production, and its variability are all important considerations for producers when selecting pasture species.