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Am I wasting phosphorus?
A Literature Review by Glenn Bailey, Rural Solutions SA
edited by Felicity Turner, MacKillop Farm Management Group
Phosphorus fertilisers are expected to get more expensive as demand overtakes supply.
Key Points
• Fertiliser applied phosphorus can be lost rapidly on some sandy soils. There are some simple tests
that can be done to indicate the risk of this happening.
• In other soils, phosphorus is fairly immobile and won’t be lost to leaching.
• Building up the soil reserves of phosphorus will make P more plant-available, regardless of how or
when it is applied.
• The total phosphorus in the soil has value to you, not just the more readily available phosphorus.
• Generally if you maintain a balanced phosphorus regime, you will use everything that you apply in
the long run.
• Phosphorus is fixed by most soils. This is a generally a good thing as it prevents leaching losses, so
unless you have ‘high risk soils’, don’t be concerned about “lockup”.
• Don’t buy into alternatives to phosphorus fertilisers that claim to improve access to phosphorus
stored in the soil.
