by Professor Ross Kingwell – AEGIC Chief Economist.
- In a drying and warming climate across most grain-growing regions of Australia, wheat yields continue to increase.
- The best endeavours of plant breeders, agronomists, farmers and agricultural engineers are generating higher wheat yields in most grain-growing regions of Australia.
- In more southern or higher rainfall regions, higher rates of wheat yield gain are observed.
Australian wheat is rain-fed, not irrigated, so the amount and timing of rain is crucial for wheat production. Yet it is widely known that many Australian grain-growing regions are experiencing a drying trend that means wheat crops are increasingly constrained by the availability of water (Figure 1).
Figure 1: The drying trend affecting grain-growing regions in Australia: 1970 to 2018
Source: BOM (2019)
Temperatures can also affect grain yields. Frosts during flowering can greatly diminish grain yield and crop quality. Excessive heat during grain-filling can also restrict yield and affect grain quality. Many grain-growing regions are experiencing an overall warming trend that increases the likelihood of excessive heat during grain-filling (Figure 2)
Figure 2: The trend in maximum daily temperatures in spring in Australia: 1970 to 2018
Source: BOM (2019)
Besides rainfall and temperatures, many other things influence wheat yield, including:
- soil quality
- time of sowing and timeliness of sowing
- weed, pest and disease control
- amount and type of fertilisers applied
- varietal superiority
- efficiency of harvest operations.
These factors that influence wheat yields in turn are affected by investments in R,D&E that enable incremental innovation, efficiency gains and practice change that boost wheat yields. Production of wheat in Australia has greatly benefited from the R,D&E investments of the Grains R&D Corporation, state government agricultural agencies, commercial wheat breeders, and machinery manufacturers.
Given all these influences upon wheat yields, what trends in wheat yields across Australia are observed? David Stephens from Agrometereology Australia has compiled a range of data sources and modelled changes in wheat yields across Australia. He has constructed a yield map, compiled for AEGIC, which reveals an interesting spatial pattern of wheat yields trends across Australia (Figure 3).
Figure 3: Spatial time trends in wheat yields in statistical sub-divisions across Australia from 1990 to 2017. (Source: https://www.agromet.com.au/ )
Over the period 1990 to 2017, most grain-growing regions display positive, yet small (in absolute terms) annual increases in wheat yields. In more southern or higher rainfall regions, higher rates of yield improvement are being observed. Australia’s major grain handlers have noted these spatial changes and accordingly have adjusted their investments in grain handling and storage facilities.
So, despite the challenges of the drying and warming trend in climate, plant breeders, agronomists, farmers and agricultural machinery manufacturers have enabled wheat yields to improve. Water increasingly is being used more efficiently. More of the rain is being turned into grain.