Effect of dry weather on winter cropping in Western Australia
Rain fed crops grown during winter, such as wheat, barley and canola, represent the bulk of agricultural production in Western Australia. The winter crop production of Western Australia in 2023-24 was 14.7 million tonnes. This is a reduction of 44% from the 2022-23 season (and 15% lower than the 10-year average). The reasons for the drop in production are thought to be persistent dry spring conditions, below average soil moisture and a drier start to the winter cropping season in 2023. On the up side, the winter crop harvest was faster than normal due to the drier and warmer finishing conditions.
El Nino Southern Oscillation vs Indian Ocean Dipole
Western Australia is again entering the winter growing season (April/May to September/October) of 2024. Although Australia experienced an El Nino event from September 2023 to April 2024, this has only a marginal effect in reducing rainfall in Western Australia as opposed to the East Coast of Australia where it has a major impact. The main driver determining the dry summer in Western Australia is the Indian Ocean Dipole – the Indian Ocean equivalent to the Pacific Ocean based El Nino Southern Oscillation events.
The Indian Ocean dipole is the difference between the Western and Eastern Indian Ocean surface temperatures. Cold ocean surface temperatures in the Eastern Indian Ocean and warm ocean temperatures in the Western Indian Ocean have led to a strong positive Indian Ocean Dipole which has suppressed rainfall for Western Australia while also increasing temperatures. The bumper crop witnessed in 2022-2023 was preceded by a negative Indian Ocean Dipole in 2022 resulting in higher than average rainfall. The Department of Primary Industries and Regional Development (DPIRD) is currently forecasting below median rainfall from April to June this year and the higher than average temperatures already witnessed for Autumn are expected to continue. Current advice from DPIRD is for farmers to prepare for a very dry growing season with current farm water supplies deemed inadequate in areas of the South-West and Wheatbelt.
Supplementing rainwater with groundwater
In the face of these drier climactic conditions, farmers are increasingly moving away from rainwater harvesting via dams and instead tapping into groundwater. Groundwater is increasingly being used around the world to supplement diminishing or polluted surface water sources. The groundwater of the South West Land Division is largely saline particularly near Esperance, Lake Grace, Gin Gin and Merredin so will require treatment prior to use. The best current technology for treating saline groundwater is brackish water desalination. This technology is increasingly being rolled out across Western Australia allowing farmers to treat saline groundwater to an appropriate standard for spraying and irrigation.
Moerk Water have extensive experience treating saline groundwater for agriculture and horticulture, particularly in the installation of remote groundwater treatment systems powered by renewable energy systems. To read more about our groundwater desalination projects supporting agriculture in Western Australia, follow the link here.
