Farmers attending a Farm Field Walk at North Dandalup recently were shown that it pays to regularly test their soils before they order fertiliser or engage a fertiliser contractor. The Field Walk was part of a four-year Royalties for Regions Regional Estuaries Initiative project that has supported soil testing on 60 farms in the Peel-Harvey Catchment since 2016. 

The project involves the Peel-Harvey Catchment Council, Department of Primary Industries and Regional Development and Department of Water and Environmental Regulation working with farmers to test paddock soils and provide advice and recommendations on future fertiliser applications. The PHCC has provided farmer extension support throughout the project, including interviewing farmers to assess farm fertiliser practices and convening workshops to assist farmers to make best use of soil testing results.

On the Field Walk farmers visited sites on two farms where soil testing had been conducted in 2017 to measure the nutrient status of individual paddocks. On each farm, fertiliser demonstration plots had been established earlier this year to assess pasture growth responses to different amounts of superphosphate fertiliser, potassium and sulphur.

One farm, where testing revealed high phosphorus levels in 2017, showed no extra growth by applying superphosphate in 2018.  The other farm, which tested low in phosphorus in 2017, showed good responses to superphosphate at moderate levels, informed by the soil test results.

The key message from the Field Walk for farmers and landholders was test your soils before you order fertiliser, or you could be wasting your money.

One interesting finding from the demonstration plots is that paddocks with high phosphorus soils may get a response from applying fertilisers like superphosphate. This is attributed to the sulphur in superphosphate, not the phosphorus. In these cases, the farmer could save money by applying cheaper forms of sulphur such as gypsum, or other fertiliser products high in sulphur but without phosphorus.  This approach has added benefits of reducing phosphorus entering groundwater and local waterways.

Department of Primary Industries and Regional Development Officer David Rogers who was involved in establishing the trial sites explained that through testing around 600 paddocks across 40 farms in the Peel-Harvey since 2016, the project has found that at least 70% of paddocks already have enough phosphorus stored in the soil for several years from past superphosphate applications . An additional 23 farms will be tested this year.

”These paddocks don’t need more phosphorus to get a pasture growth response. Often though, they may have other constraints like soil acidity (pH), or other nutrients that are limiting production. Soil testing helps farmers determine what is needed, and reduces the risk of wasting money on nutrients that will not give a production response.   Applications of phosphorus based on soil tests can assist to maximise pasture production and minimise the amount washed into groundwater, waterways and the Peel-Harvey Estuary” said Mr Rogers.

PHCC Acting Chairperson Jan Star has been impressed with the strong farmer involvement in Fertilising the Farm.  “We have already had 60 farmers sign up to soil testing over the past 3 years, and had to turn away farmers for the first time this year,” said Ms Star.

“A great aspect of the Project is that it has consistently set new standards in soil testing, paddock mapping and analysis of test results” said Ms Star. “This helps to increase farmer confidence in how to use the test results to make fertiliser decisions for their farm.”

The Field Walk was part of the Fertilising the Farm project, a cooperative initiative Peel-Harvey Catchment Council, Department of Primary Industries and Regional Development and Department of Water and Environmental Regulation. Fertilising the Farm is part of the Regional Estuaries Initiative, a $20 million State Government program to improve the health of six key South-West estuaries, including the Peel-Harvey Estuary.


Media Contact:  Jane O’Malley, Chief Executive Officer, Peel-Harvey Catchment Council,, (08) 6369 8800

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