Nutrient-rich manure (otherwise known as effluent) from dairy cows is a valuable resource to farmers. Through the Dairy for Healthy Estuaries project, Western Dairy and the Department of Water and Environmental Regulation (the department) have been working together to improve dairy effluent management in Western Australia (WA) and protect waterways. Western Dairy recently completed a business case to assess the return on investment from using dairy effluent as a resource for fertiliser and irrigation.
A tool has been developed from the investigation to help farmers and financiers interpret the cost benefits of an effluent system upgrade.
Dan Parnell, Western Dairy Project Manager, said farmers who use their farms’ effluent smartly are most likely to benefit.
“At a farm level, those most likely to profit from effluent management investments catch and reuse a higher proportion of effluent; apply it to responsive soils instead of fertiliser; and gain some irrigation advantage”, said Mr Parnell.
Fertiliser and imported feed pricing are uncontrollable at the farm gate, and water is a critical resource, so financial rewards for effluent reuse are likely to continue.
The payback period for an average-sized dairy herd and effluent upgrade was estimated to be seven years when the nutrients in the effluent were valued against high 2023 fertiliser prices. If a modest pasture growth response from irrigation was included, the estimated payback period reduced to five years.
To support the business case, demonstration trials are in progress to measure how using effluent can optimise pasture growth. This could help dairy farmers reduce supplementary feed costs, particularly during shoulder seasons. The trial also explores whether the additional organic matter from the effluent has benefits for soil health parameters such as organic carbon and soil pH.
The business case analysis also considers commercial incentives for effluent systems upgrades.
“Milk price incentives or capital grants for best practice effluent management can reduce the payback period for farmers, and we have definitely seen this help our industry with effluent management in recent years” Mr Parnell said.
“Good progress has been made, though continued efforts are needed within the industry to ensure dairy farms are meeting the Code of Practice and managing effluent effectively,” he added.
The Code of Practice for Dairy Farm Management in WA (the Code) was updated in 2021 and establishes industry-agreed best-practice standards that are commercially and environmentally responsible. Dairy farmers are encouraged to have an effluent management plan and effluent system review completed by an accredited system designer, supporting them to meet the standards in the Code.
During the period 2016–20, 31 farms received dairy effluent system upgrades funded as part of the Regional Estuaries Initiative and Revitalising Geographe Waterways. This included an investment of $3.5 million collectively by the program and landowners. Since 2020, the project has continued under Healthy Estuaries WA, with a focus on supporting farmers to meet the Code.
Healthy Estuaries WA also works to reduce nutrient input to waterways through fertiliser management, stock exclusion fencing and revegetation, and soil amendments.
For more information, contact: estuary@dwer.wa.gov.au