September 12, 2003

Australia:  Winter Wheat Yield Potential Increases

July and August Rainfall Revives Crops

Summary

On September 11, USDA's official forecast of Australia's 2003/04 wheat production was set at 24.0 million tons, up 1.0 million or 4 percent from last month, and up 14.6 million or 156 percent from last year. This large year-to-year production increase is the result of higher area and yield. This forecast is 3.2 million tons or 17 percent above the five-year average and is third largest on record.  The current 2003/04 wheat area forecast is 12.0 million hectares, unchanged from last month but up 1.17 million hectares or 11percent from last year.

NOAA satellite image composites from August 2003 and 2002.
Wheat Areas, 2003	Wheat Areas, 2002

Above are NOAA satellite image composites from August 2003 and 2003. Click on the images to see them in full resolution.  The infrared band, sensitive to vegetation,  is displayed as visible red.  The more photo-synthetically active vegetation, such as vigorously growing crops, is represented in the brighter red areas.  The white areas are clouds. The wedge in the 2003 scene is missing data.  The green outlines represent Australia's continuous wheat belt.  The scene on the left is the current season while the corresponding image from last year is shown on the right.  Note the strong difference in infrared reflectance between the two years, particularly in the wheat belt.

Season Update

The previously anticipated effect of a delayed start of season in the eastern wheat producing states of Queensland, New South Wales, and Victoria has been mostly offset by excellent growing conditions during July and August.  Rainfall to date in nearly all growing areas has been favorable, with many regions of the winter grain belt having received normal to above-normal rainfall amounts for the period July 15 through September 1. The temperatures and precipitation pattern of the last six weeks has now improved yield prospects feared lost in the earlier dry weeks of the season. 

Australia tentatively stepped out of the devastating drought of 2002 earlier this season with beneficial April rains in many areas.  To the surprise of climatologists and the disappointment of farmers, the rains dried up in the eastern states just as winter grain sowing was about to commence.  Patchy rainfall allowed some areas to plant under less-than-optimal conditions.  However, the incentive to plant was fueled by farmers trying to recoup financial losses of last season. Producers were caught between economics and weather, as the increased desire to sow more land into winter grains was rebuffed by a mostly dry planting season. The end result being a 11-percent increase in wheat area and 14 percent for barley.  This is in sharp contrast to a historic area rebound of 28 percent for wheat in the year following a severe drought. 

The current crop assessment is based on weather station rainfall observations and satellite derived vegetation indexes.  Vegetation indexes were calculated for the current and numerous past seasons. The current season vegetation index values were compared to previous seasons in order to select the best analog. The following graph shows the current season's cumulative vegetation index value and several previous seasons for the New South Wales wheat area.

The analog season, yield value, and an average yield by state are shown in the following table. In New South Wales, as of September 1, 2003, the current 2003/04 season is tracking most similar to the 2001/02 season,  which yielded 2.36 tons per hectare, 19 percent higher than the 5-year average yield of 1.99 tons per hectare.

Background Information on Australian Wheat

Wheat is Australia’s most important crop, having a seasonal gross value approaching three billion Australian dollars. Australian wheat is a major competitor for U.S. wheat exports. Australian wheat is grown as a winter crop (autumn-winter-spring), often in rotation with some form of pasture. Wheat production is concentrated on the mainland in a narrow crescent known as the wheat belt, which receives approximately 400 to 600 mm average annual rainfall. Areas with less than 400 mm per year are too dry to support winter grains, and areas receiving greater than 600 mm develop pest and disease problems in winter grains. The eastern portion of the wheat belt stretches in a curve, inland of the dividing range, from central Queensland through New South Wales, Victoria, and southern South Australia. The western portion of the wheat belt continues around the south west area of Western Australia. The area planted to wheat during the recent season has averaged 11.9 million hectares producing 20.6 million tons. Much of the wheat growing region is in the sub-humid and semi-arid zones.

Australian wheat is primarily grown between the two extreme climatic zones. The interior edge of the agricultural crescent is formed by the exceptionally dry and erratic precipitation pattern of the interior, and the geographical outer edge of the wheat belt crescent is created by the excessive moisture of the coastal climate. Winter rains over this narrow belt can be highly variable though in most years provides the needed moisture levels for crop growth. The 2002 season experienced one of the worst droughts on record. Virtually all of Australia wheat is rain fed. Irrigation is applied to higher value crops such as cotton and rice.

For more information, contact James Crutchfield  
of the Production Estimates and Crop Assessment Division, FAS, at (202) 690-0135.