Make the most of your fertiliser budget with the Four Rs

Best practice crop nutrition seeks to make the most of your fertiliser budget and minimise environmental impact. The ‘Four Rs’ is a nutrient management framework that aims to match nutrient supply with crop needs.

The Four Rs

The four components of the framework are:

  • The RIGHT source fertiliser  
  • At the RIGHT rate
  • At the RIGHT time
  • In the RIGHT place

But first, you need the RIGHT information. Soil tests, tissue tests and paddock history help guide crop nutrition decisions.

Agronomists and growers can work together to develop crop nutrition programs. Your 4R program should be specific to your paddock and crop:

  • The right source fertiliser addresses macro and micronutrient requirements.
  • The right rate is determined by the predicted crop demand and the nutrient source. It aims to maximise yield without waste via losses such as runoff or leaching.
  • The right time(s) to apply fertiliser depends on the crop, fertiliser, seasonal conditions and predicted yield. Splitting some fertiliser applications through the season gives more potential to match nutrient supply to crop demand.
  • The right place means getting nutrients into the active root zone. Variable soil might require different application rates within the paddock.

Your 4R program evolves with each season and crop. If one part of the plan changes, other parts may need to adapt. Changing the fertiliser source, for example, might mean changing the placement and timing of application as well. Other practices such as no-till, cover crops, use of recycled organics and tailored irrigation affect the 4R regime.

Use paddock fertiliser test strips to:

  • confirm the current application rate and fertiliser type
  • support decisions to change the rate, application method, timing and type.

Regular equipment calibration and record keeping are part of good farm management. Use past application rates, times, yield responses and nutrient use efficiencies to improve crop nutrition practice.

Read more about the Four Rs:

Acknowledgements

Photo courtesy of the Fertiliser Institute

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