Climatic and agronomic conditions

​​Australian Crop Report: June edition

Autumn rainfall in 2020 was above average to extremely high in most cropping regions in New South Wales and Victoria, and average to well above average in cropping regions in South Australia. In contrast autumn rainfall was extremely low to below average in most cropping regions in Queensland and Western Australia (Map 1). However, rainfall during February and March in Queensland and Western Australian cropping regions provided generally favourable conditions leading into the winter crop season in these regions.

Map 1 Australian rainfall percentiles, 1 March 2020 to 31 May 2020

Note: Rainfall percentiles are displayed for cropping regions only.
Source: Bureau of Meteorology

During May 2020, rainfall was generally average to below average in most cropping regions (Map 2 ).

Map 2 Australian rainfall percentiles, 1 to 31 May 2020

Note: Rainfall totals are displayed for cropping regions only.
Source: Bureau of Meteorology

Map 3 and Map 4 show the relative levels of modelled upper layer (~0.1 metres) and lower layer (~0.1 to ~1 metres) soil moisture for cropping zones across Australia for May 2020. Soil moisture estimates are relative to the historical long-term average (1911 to 2016) and presented in percentiles.

Upper layer soil moisture responds quickly to seasonal conditions and often shows a pattern that reflects rainfall and temperature events in the days leading up to the analysis date. Lower layer soil moisture is a larger, deeper store that is slower to respond to seasonal conditions and tends to reflect the accumulated effects of events that have occurred over longer periods.

Relative upper layer soil moisture in May 2020 was around average for this time of year in most Australian cropping regions (Map 3).

Map 3 Upper layer soil moisture, May 2020

Note: Relative upper layer soil moisture is displayed for cropping regions only. The extremely high band indicates where the estimated soil moisture level for May 2020 fell into the wettest 10 per cent of estimated soil moisture levels on that day each year between 1911 and 2016. The extremely low band indicates where the estimated soil moisture levels for May 2020 fell into the driest 10 per cent of estimated soil moisture levels on that day between 1911 and 2016.
Source: Bureau of Meteorology.

Relative lower layer soil moisture in May 2020 was average to extremely high for this time of year in most cropping regions in the eastern states and South Australia. In contrast lower layer soil moisture was average to extremely low for this time of year in Western Australian cropping regions (Map 4).

Map 4 Lower layer soil moisture, May 2020

Note: Relative lower layer soil moisture is displayed for cropping regions only. The extremely high band indicates where the estimated soil moisture level for May 2020 fell into the wettest 10 per cent of estimated soil moisture levels on that day each year between 1911 and 2016. The extremely low band indicates where the estimated soil moisture levels for May 2020 fell into the driest 10 per cent of estimated soil moisture levels on that day between 1911 and 2016.
Source: Bureau of Meteorology.

The rainfall outlook presented here provides an indication of how favourable conditions for agricultural production are likely to be over winter. The latest three-month rainfall outlook (June to August), issued by the Bureau of Meteorology on 4 June 2020, suggests that winter rainfall is likely to be above average in most cropping regions in Queensland and New South Wales and there are roughly equal chances of higher or lower than average winter rainfall in most other cropping regions in Australia (Map 5). It is likely rainfall will not be evenly distributed over winter with lower than average rainfall likely in June in most cropping regions and more favourable conditions in the remainder of winter.

Map 5 Chance of exceeding median rainfall June to August 2020

Note: Rainfall outlook is displayed for cropping regions only.
Source: Bureau of Meteorology

There is a 75% chance of between 50 and 100 millimetres of rainfall in most Australian cropping regions and a 75% chance of between 100 and 200 millimetres in most cropping regions in Western Australia and southern cropping regions in New South Wales, Victoria and South Australia. (Map 6). It is highly likely these rainfall totals will be enough winter rainfall to sustain crops through to spring in regions where crops were in a good position at the start of winter.

There is a 75% chance of rainfall between 10 and 50 millimetres in northern and western cropping regions in Queensland. In areas with low soil moisture at the start of winter these probable low three-month rainfall totals are unlikely to be sufficient to sustain crop production.

The outlook for maximum and minimum temperatures for June to August 2020 indicates that daytime temperatures are likely to be average in most cropping regions in Victoria and South Australia, and warmer than average in cropping regions in other states. Night-time temperatures are expected to be hotter than average in most cropping regions with the exception of southern cropping regions in South Australia and Victoria.

Map 6 Rainfall totals that have a 75% chance of occurring, June to August 2020

Note: Rainfall outlook is displayed for cropping regions only.
Source: Bureau of Meteorology

Map 7 shows modelled water availability levels that have a high chance of occurring by the end of October 2020. Water available for crop growth comes from water stored at sowing time and in-crop rainfall. On average, the total water requirement to achieve the national 5-year average wheat yield of 2.0 tonnes/ha is 235 millimetres, based on a conversion rate of 16kg of wheat per millimetre of water. The total water requirement to achieve 3.0 tonnes/ha, 2.5 tonnes/ha, 1.5 tonnes/ha, 1.0 tonnes/ha and 0.5 tonnes/ha based on this same conversion rate have been estimated to be 295, 265, 205, 175 and 140 millimetres, respectively.

ABARES estimated the winter cropping areas likely to achieve 295, 265, 235, 205, 175 and 140 millimetres of water availability. These indicative estimates are based on modelled plant available soil moisture as at 30 April 2020, recorded rainfall totals as at 31 May 2020, an estimate of rainfall totals with a 75% chance of falling during winter derived from the Bureau of Meteorology latest rainfall outlook released on 4 June 2020 and assumed average September and October rainfall totals.

The crop yield associated with a specific level of water availability varies across regions with variations in soil characteristics. The indicative estimates presented above, abstract from this complexity by assuming a conversion rate of 16kg of wheat per millimetre of water and a standard soil evaporation loss factor of 110 millimetres. As a result the implications of the analysed threshold values of water availability may be quite different across regions. Additionally, in some seasons the responsiveness of crop growth to water availability will be better than average (around 22kg/mm) and in other years it will be worse (around 6kg/mm) as responsiveness depends on factors such as temperature, humidity, soil nutrition and the timing of rainfall.

Map 7 Modelled water availability levels that have a 75% chance of occurring by the end of October 2020

Note: Modelled water availability is displayed for cropping regions only.
Source: ABARES & Bureau of Meteorology

Statistical tables

Last reviewed: 9 June 2020
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