Farmers turn to science for fertiliser advice

A large number of farms in the South West and South Coast are expected to save money on fertiliser after testing has revealed a bank of excess phosphorus in soils.

Oyster Harbour Catchment Group officer Bruce (left) interpreting soil test results with local farmer Ian (right)

Now in its ninth year, the soil testing program – currently supported by the $20 million Regional Estuaries Initiative – has helped hundreds of farmers increase their productivity through independently accredited soil testing, ensuring nutrients stay on the farm and out of waterways and estuaries.

In the latest round of workshops held recently across the South West and South Coast, more than 170 farmers unearthed how to maximise their nutrient requirements thanks to a program providing soil sampling, testing, agronomic advice and plant tissue testing.

Deborah Holtham, Sustainable Agriculture Project Officer, Department of Water and Environmental Regulation said that the long farming history across the South Coast had seen some nutrients build up in the soil beyond requirements for many farms.

“Soil that has had a phosphorus fertiliser applied every year for the last 50 years often can’t hold any more phosphorus. As a result phosphorus can be washed into nearby waterways where it can damage the environment.

DPIRD officer interpreting soil test results with farmer in Pinjarra

“Knowing the level of nutrients already in the soil enables farmers to estimate how much of which nutrient is needed and when to apply,” Ms Holtham said.

David Weaver, Senior Research Officer, Department of Primary Industries and Regional Development, said soil testing was essential for farmers to identify which soil conditions are limiting production.

“Of the 220 000 hectares that we have sampled, 65 to 80 percent of paddocks have more than enough phosphorus, while 80 to 100 percent are too acidic.

“When soils get too acidic, certain nutrients become less available to plants. By treating soil acidity, nutrient availability can increase, leading to improved plant growth.

“Around half of the paddocks tested had insufficient potassium and/or sulfur, providing an opportunity to redirect money that may have been spent on phosphorus fertiliser to address other limiting nutrients,” Mr Weaver said.

Peel-Harvey catchment farmer workshop in Pinjarra

Jim and Anne-Marie Offer have a beef property in the Leschenault catchment and attended the recent workshop in Bunbury.

“The level of detail and knowledge that’s provided in the program and workshop is fantastic and really useful – we would definitely recommend the program to others,” Anne-Marie said.

“What we found most useful in the workshop was the way that all of the science and evidence is explained along with how to calculate what that means for us. It’s complicated, though the workshop went through step-by-step what is in our soil now, what was measured and why it’s important.

“The farm maps we received are very applicable and we can use the tools shown to us to calculate what it means for the management of fertiliser and soils on our farm. We were surprised to find that we had built up a bank of phosphorus in the soil and now do not need to apply more phosphorus for a number of years.”

The latest round of workshops were held in Pinjarra, Albany, Busselton, Bunbury and Alexandra Bridge with the next round of the soil testing program opening for expressions of interest in June.

For more information visit our soil testing page.

  • The soil testing program is a partnership between the Department of Water and Environmental Regulation, Department of Primary Industries and Regional Development and local catchment groups; Peel-Harvey Catchment Council; Leschenault Catchment Council; GeoCatch; Lower Blackwood Landcare; Wilson Inlet Catchment Council; and Oyster Harbour Catchment Group.
  • The Regional Estuaries Initiative fertiliser management program partners farmers and industry groups with local catchment groups to reduce the nutrient run-off from farms to benefit both farmers’ productivity and water quality in our estuaries.