Nitrogen Fertiliser Calculator

The Nitrogen Fertiliser Calculator determines the optimum nitrogen fertiliser application for cereal crops, for a range of potential yield outcomes.

Read about our selection process for including tools on Climate Kelpie

 

Who this tool is for

Wheat and sorghum farmers in Queensland and selected sites in northern New South Wales.

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Questions this tool answers

What is the likely wheat or sorghum yield response to nitrogen, for a given starting soil moisture and regional rainfall projections?

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What this tool does

The Nitrogen Fertiliser Calculator is part of the ‘Smart N Decisions’ package for central and southern Queensland, which also includes a best-practice reference manual (The Nitrogen Book) and a user guide.

The calculator determines the optimum nitrogen fertiliser application rate based on the difference of the demand and supply of nitrogen for cereal crops:

  • Demand is calculated from desired crop yields using WhopperCropper.
  • Supply is calculated from soil test analysis results or entered directly into the calculator.
  • Yield is calculated for four season types.
  • Nitrogen fertiliser rate can be adjusted to compare the effects on gross margin.

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Inputs

You enter the following data into the Nitrogen Fertiliser Calculator:

  • soil nitrogen test results
  • expected planting time
  • stored soil water
  • expected season type (e.g. poor, average)

The calculator uses WhopperCropper to calculate nitrogen budgets.

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Outputs

The Nitrogen Fertiliser Calculator estimates:

  • nitrogen mineralisation from soil sampling to planting
  • crop demand for nitrogen
  • soil supply of nitrogen
  • nitrogen fertiliser rate required

The calculator also estimates the losses you will incur if the season turns out differently than expected.

The inputs and results are displayed on a single screen. Figure 1 is an example.

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Reliability

The Nitrogen Fertiliser Calculator can be used for a limited range of commodities, and is applicable more at regional than paddock scale.

Because it is based on existing climate data, as our climate changes the tool is likely to become less reliable.

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History

The Nitrogen Fertiliser Calculator was developed by Howard Cox with programming by Alastair Doherty from Department of Agriculture, Fisheries and Forestry (Queensland).

The Nitrogen Book was compiled by Howard Cox and Wayne Strong from the Department of Agriculture, Fisheries and Forestry (Queensland) in association with the Central Queensland Sustainable Farming Systems Project and South Queensland Farming Systems Project.

The Grains Research and Development Corporation assisted with funding of these projects.

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Support available

Support is provided by Howard Cox, Department of Agriculture, Fisheries and Forestry (Queensland).

Email: howard.cox@daff.qld.gov.au

Phone: 07 4688 1381 or 0418 708 278

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Where to get it

Department of Agriculture, Fisheries and Forestry (Queensland) - Business Information Centre

Phone: 13 25 23

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Cost

Free

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