Phosphorus fertiliser has been a godsend for livestock and dairy farmers trying to build the fertility of our low-nutrient soils. Without it, Western Australian agriculture would be far less productive and profitable and count for little in terms of food security and the economy. So, when a soil test analysis recommends a zero requirement for phosphorus, it’s understandably met with some concern.
Recommendations have changed for most farms on the Swan Coastal Plain because their soil tests show that soil phosphorus exceeds critical values. These values have been developed from more than 250 experiments and 1,600 field sites across southern Australia and are supported by Western Australian research.
Excess phosphorus is now a common occurrence. Analysis of more than 100,000 tests show that 75 per cent of paddocks have enough soil phosphorus to achieve 95 per cent of maximum production with around 60 per cent of these containing 1 to 3 times more phosphorus than needed. In many cases, other nutrients such as potassium, sulphur and nitrogen are now more growth-limiting.
This excess phosphorus does not contribute to more production and is less likely to stay on farm. Instead, it is more likely to end up in waterways and estuaries where it can degrade water quality and lead to algal blooms and fish deaths. It’s certainly not the outcome that farmers want in terms of environmental stewardship or return on investment.
However, the decision to reduce rates or not apply phosphorus at all is seen as a significant risk by many farmers. A decline in pasture production could lead to an increase in feed supplementation costs or destocking that can end in financial disaster. So, any suggestion to change their system will be scrutinised closely to see how much uncertainty and risk is involved.
To demonstrate that risks associated with change are minimal, farmers need to trust the data they are using to make decisions. Unless they have a good history of effective soil testing on their own property and have a good handle on how their nutrient levels are tracking, farmers rely solely on recommendations based on experiments which they may know little about. The unfamiliarity of these experiments is enough for some farmers to question the relevance to their specific soils and pasture varieties, and therefore lack the confidence to use them as the basis for any significant change.
To address this shortage in confidence, numerous stakeholders have joined forces to demonstrate and trial phosphorus responsiveness in South West WA and compare against national datasets. Through funding from the Australian Government’s National Landcare Program, the Western Australian Department of Water and Environmental Regulation is collaborating with the fertiliser industry (manufacturers, retailers and Fertilizer Australia), the Department of Primary Industries and Regional Development, Murdoch University, independent agronomists, catchment groups, beef and dairy industry bodies, grower groups and farmers.
Earlier this year, 19 of an intended 36 trials commenced across a range of soil types in six catchments between Mandurah and Albany as part of a new four-year project called “uPtake”, referring to the uptake of fertiliser (by plants), partnerships and practice change, with a capital P for phosphorus. The project complements the existing Regional Estuaries Initiative Sustainable Agriculture Fertiliser Management program, which promotes soil testing, spreader calibration, and Fertcare® accredited advice.
The trial coordinator is former dairy farmer Rob McFerran, who says that the trials are working to address any unease farmers have with fertiliser recommendations.
“As a farmer myself I understand the drive to want what is best for the land, what is best for the animals and the anxiety that a potential drop in productivity can cause. uPtake has been a great opportunity for me to apply meaningful science to build fertiliser management knowledge and help local farmers,” Rob said.
Local fertiliser suppliers CSBP and Summit both see the project as a valuable source of data to help optimise fertiliser use efficiency. CSBP Fertilizer’s Garan Peirce says the independent study will make it easier for him to discuss with farmers the economics and risks associated with different options.
“I can have the trial results on hand when I visit farms to compare with a client’s soil test and give them more confidence that a particular rate will match their requirements.”
Summit Fertiliser’s Ralph Papalia sees more local and contemporary trials as being critical to building confidence in phosphorus recommendations.
“The more productive farmers chasing yield want to see how much phosphorus they need or don’t need. So, verifying critical levels and addressing any concerns people have with the current database is pretty important.”
Results from year one will be posted to the rei.dwer.wa.gov.au/uptake/ website by the end of the year. Farmers can also follow progress on social media by searching #uPtakeTrials or following the uPtake Updates twitter account.
Farmers from six catchment areas can also register interest in the whole farm nutrient mapping program at https://rei.dwer.wa.gov.au/strategies/sustainable-agriculture/soil-testing/
Enquiries about the trials should be directed to Rob McFerran at the Department of Water and Environmental Regulation on (08) 9781 0111.
This project is supported by South West Catchments Council, through funding from the Australian Government’s National Landcare Program and the Royalties for Regions Regional Estuaries Initiative.Tags: Fertiliser phosphorus uPtake Waterways