Atmosphere Theme Report
Australia State of the Environment Report 2001 (Theme Report)
Lead Author: Dr Peter Manins, Environmental Consulting and Research Unit, CSIRO Atmospheric Research, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06746 9
Climate Variability and Change (continued)
Climate and major crops [A Indicator 1.15]
Wheat is the major crop in Australia. Its total production has increased substantially from the mid-1950s to the present because it pays higher returns than other farm enterprises. There is strong variability in cultivated area, yield and total production. The year-to-year variability is influenced by rainfall and price fluctuations (Figure 46). Rainfall is influenced by large-scale climatic factors, such as the Southern Oscillation.
Figure 46: Area of wheat cultivation in Australia from 1957-1958 to 1996-1997
Source: ABARE (1997)
There may be a link between recent climatic trends and wheat yield increases from the 1950s (Figure 47). Nicholls (1997) attributes part of this increase in yield to a decrease in frost frequency associated with an increasing trend in minimum temperature in eastern Australia. In recent years, wheat crops in north-east Australia have also been sown, where possible, to avoid frost at flowering. This practice may also be contributing to part of the increase in yield.
Changes in rainfall and soil moisture also affect yield. Droughts (1972-73, 1982-83 and 1991-95) associated with El Nio have at times caused significant reduction in wheat production. Other contributing factors are improvements in wheat varieties and farming practices.
Figure 47: Wheat yield and total production in Australia
Source: ABARE (1997)
Long-term variations, such as decadal-to-century scale variations in ENSO also have a substantial influence on wheat yield (Nicholls 1997).
Total production of other crops such as sugar and rice has also increased substantially during recent decades. Rice yield has increased slightly and has shown strong year-to-year variations, but depends largely on irrigation (see the Land Theme Report), which in turn is linked to rainfall variations. Total rice production shows a strong increase, which is largely attributable to increases in the area under cultivation. Year-to-year variations in rice production since 1980 are large compared with previous years (Figures 48 and 49). For total sugar production (Figure 50), the area under cultivation and the total amount of cane crushed also increased steadily, with less year-to-year variability than for rice production. Sugar production is often affected by extreme rainfall events during spring and early summer.
Figure 48:Rice yield and total production in Australia from 1954-1955 to 1996-1997.
Source: ABARE (1997)
Figure 49: Rice and sugar cultivation area from 1954-1955 to 1996-1997.
Source: ABARE (1997)
Figure 50: Annual crushed cane and total production from 1954-1955 to 1996-1997
Source: ABARE (1997)