Emma Pearce and Matthew Miller
Climatic conditions in major crop-producing countries
At 28 August 2019 global production conditions were generally favourable.
Conditions for wheat development are generally favourable in Argentina. Conditions in Australia are mixed due to severe rainfall deficiencies across New South Wales and Queensland. In the northern hemisphere, winter and spring wheat harvesting is continuing under generally favourable conditions.
Growing conditions for maize are generally favourable in Brazil, Argentina, Mexico, China and India. Conditions are mixed in the United States, Canada, the European Union and Ukraine.
Growing conditions for rice are favourable in China, India, Indonesia, the Philippines, Japan and the United States. Wet-season rice conditions in Vietnam and Thailand are mixed due to below average rainfall.
Growing conditions for soybeans are generally favourable in China, India and Ukraine. Conditions in the United States and Canada are under watch due to delayed sowing. Final yields will depend on conditions during the remainder of the growing season.
Climate outlook for Australia
Dryness persists across much of Australia
From March 2018 to August 2019, much of south-eastern, and large areas of western and northern Australia recorded rainfall totals in the lowest 5 to 10 per cent of the historical record (severe deficient to extremely low rainfall). Much of northern inland New South Wales has been particularly dry with large areas having record low rainfall.
While large areas of south-western Western Australia recorded aggregate 18-month rainfall totals in the lowest 10 per cent of the historical record, timely rainfall during the peak growing season (April to October) has been sufficient to support average to above average crop production during 2018-19 and 2019-20.
Below average rainfall reduces crop prospects
The NSW wheat–sheep zone is on track to record decile 1 growing season (April to October) rainfall for 2 consecutive years for the first time since 1940 and 1941, and for only the second time in the last 118 years.
Winter rainfall was below average across large areas of Australia. Rainfall in June 2019 was variable across the country. Rainfall was particularly low across parts of south-eastern and central Australia. Cropping regions in Western Australia, South Australia and northern Queensland had an improved start to winter compared with 2018. Rainfall in these regions was average to well above average in June 2019. These falls enabled farmers to complete planting programs, supported crop and pasture growth and improved soil moisture levels.
In contrast, July 2019 was dry across much of Australia. Below average rainfall was recorded across cropping regions in New South Wales, southern Queensland, Western Australia and South Australia. Average July 2019 rainfall was recorded across cropping regions in southern New South Wales, Victoria and northern Queensland. This average rainfall and above average temperatures benefited crop and pasture growth in these regions. Elsewhere, stored soil moisture from June rainfall was sufficient to support continued crop development across much of Western Australia and South Australia.
Conditions in August 2019 were dry across much of south-eastern and central Australia. Severely deficient to well below average rainfall was recorded across New South Wales, southern Queensland, parts of the west of Western Australia, much of South Australia, northern Tasmania and the south of the Northern Territory.
Rainfall for August 2019 in winter cropping regions was average in parts of Victoria, northern Queensland and southern Western Australia. Rainfall was below average or lower across cropping regions in New South Wales, northern and eastern Victoria, southern Queensland, much of South Australia and northern Western Australia.
Soil moisture declined significantly through winter
Variable rainfall and above average temperatures during winter resulted in decreased soil moisture levels across Australia. Root zone soil moisture was below average to average across Australia during June, followed by well below average soil moisture in July and August.
In August 2019 soil moisture in cropping regions was extremely low to well below average in much of New South Wales, southern Queensland, Western Australia and western South Australia. For cropping regions in Victoria, northern Queensland and parts of eastern South Australia soil moisture was average to above average.
The low levels of soil moisture mean early spring rainfall will be critical for grain development in regions that had viable crops at the start of spring. Similarly, the planting of summer crops in these regions will require spring rainfall for crop germination and establishment.
Pasture growth below average for some livestock production regions
Below average winter rainfall and low soil moisture limited pasture production across large areas of southern, western and central Australia. For the 3 months to August 2019, modelled pasture growth was extremely low to well below average across large areas of New South Wales and South Australia, parts of southern Queensland, the south of the Northern Territory and parts of Western Australia. In contrast, modelled pasture growth was well above average to extremely high across parts of south-western Victoria, southern New South Wales, north-eastern Queensland, inland southern Western Australia and south-eastern South Australia.
Modelled pasture growth and soil moisture levels were extremely low over winter across much of New South Wales, southern Queensland and South Australia. As a result, livestock producers in these regions will be heavily reliant on spring rainfall and supplementary feed to maintain current stock numbers. In contrast, above average pasture production across much of Victoria, southern South Australia and north-eastern Queensland is likely to enable farmers to rebuild stock numbers and provide opportunities to replenish fodder supplies.
Sufficient rainfall likely for some winter cropping regions
The El Niño-Southern Oscillation is expected to remain neutral for the remainder of 2019. A positive Indian Ocean Dipole (IOD) is underway. Most climate models suggest it will remain the dominant driver of climatic conditions in Australia during spring. A positive IOD typically brings below average spring rainfall to southern and central Australia, and warmer days for southern Australia.
A prolonged negative Southern Annular Mode (SAM) event is also forecast to develop in spring due to a predicted sudden stratospheric warming event. This negative SAM is likely to intensify dry and warm conditions across eastern Australia during spring.
The Bureau of Meteorology's climate outlook for October to December 2019 (released 5 September 2019) indicates that a drier than average spring is likely across most of the country. Across parts of the north and west of Western Australia and Tasmania, there is no strong shift towards a wetter or drier than average 3 months.
The Bureau of Meteorology's climate outlook suggests drier than average rainfall across large areas of Australia. In areas where soil moisture is close to average to above average for this time of year, there is still a significant chance of recording rainfall totals sufficient to sustain crop and pasture production through spring.
In October 2019 cropping regions in eastern New South Wales, southern Victoria, south-eastern Queensland, far southern Western Australia and central South Australia have a 75% chance of receiving rainfall of between 10 and 25mm.
Between October and December 2019 cropping regions in eastern New South Wales and much of Queensland have a 75% chance of receiving rainfall of between 50 and 100mm. Smaller areas may receive up to 200mm. Cropping regions in western New South Wales, much of Victoria, far northern and south-western Queensland, southern Western Australia and eastern South Australia are also likely to receive rainfall of between 25 and 50mm. Cropping regions in northern Western Australia and western South Australia also have a 75% chance of receiving between 10 and 25mm.
Prospects are poor for areas with low soil moisture for this time of year. For these regions, the forecast low 3-month rainfall totals are unlikely to be sufficient to sustain current levels of crop and pasture production, particularly as temperatures and evapotranspiration begin to increase in spring.
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