A tractor-mounted real-time variable-rate nitrogen sensor

The Yara N-Sensor ALS-2 enables real-time variable rate application of fertilisers by measuring a crop’s nitrogen status in a precise, easy-to-use, and cost-efficient system.

The system is the culmination of over 20 years of development work at Hanninghof in Germany, through extensive testing and trial work.

With the sensor fitted you can:

  • Measure crop nitrogen requirement as the fertiliser spreader passes across the field
  • Automatically adjust the fertiliser application rate in real-time.

Which means you can:

  • Apply nitrogen variably in exact amounts, only where it’s needed
  • Improve yields and reduce costs
  • Improve harvest performance and combine rates

How does the N Sensor work?

The N-Sensor determines the nitrogen demand by measuring the crop’s light reflectance covering a total area of approximately 50m/ sec.

Measurements are taken every second with the system designed to operate at normal working speeds and all bout widths.

Unlike other sensing technology in ag that are based around NDVI, the Yara N-Sensor measures light reflectance at specific wavebands related to the crop’s chlorophyll content and biomass, therefore it calculates the actual N-uptake of the crop.

Optimum application rates are derived from the N-uptake data and sent to the controller of the variable rate spreader or sprayer, which will adjust fertiliser rates accordingly.

The whole process of determining the crop’s nitrogen requirement and application of the correct fertiliser rate happens instantaneously, with no time delay. This enables “real-time agronomy and application” to be possible.


  • Nitrogen savings of up to 14% have been recorded where N-Sensor was used
  • The first nitrogen sensor to have ‘dew suppression’ to further improve sensing accuracy
  • Cereal yields increased by 3.5% where the same intensity of fertiliser was used
  • Oilseed yields increased by 3.9% through the Absolute-N calibration
  • An 80% reduction in lodging rates (compared with crops where nitrogen was applied under conventional practices)
  • Combine performance was increased by 12-20% due to reduced lodging, lower losses and faster intake speeds
  • Protein levels in cereal crops showed greater consistency averaging 0.2-0.5% above target
  • Increases in nitrogen use efficiency have reduced the carbon footprint by 10-30%

Source: Yara UK Ltd

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