Pasture Biomass Sensor

Use distance sensors and an Arduino to collect information on pasture structure to convert into estimates of biomass

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Pasture Biomass Sensor

Overgrazing leads to changes in pasture composition, erosion and in some cases desertification: It is a global scale problem.
Matching animal numbers feed available is the issue. But how much biomass do you have? Availability = area * kg/ha biomass
How to estimate kg/ ha biomass that’s more tricky and time consuming than it seems!

Use an array of 4 distance sensors connected to an Arduino to get information about the density of grass leaf and stem and convert this to biomass

How to estimate kg/ ha biomass that’s more tricky and time consuming than it seems!

  • (1)Cut quadrats and weight (slow, needs scales & drying oven) few samples
  • (2)Botanal / visual estimates plus cut standards (see 1) plus have to set up regression model.
  • (3)Estimate from photo standards (some people are very good others are hopeless, need a big range of photo standards green dead plus minus trees etc.), need to record.
  • (4)Remote sensing measuring cover not mass (although calibration possible)
  • (5)Capacitance type meters sensitive to moisture content
  • (6)Weighted disk meters – measuring height and relating to biomass – problems in grass with strong stems or very sparse tussocks can be difficult.
  • (7)Modelling, like remote sensing needs calibration (and good inputs like climate data)
  • (8)Lidar (too expensive at the moment)

Pretty much biomass estimated only done by scientists (e.g. in specialist grazing trials) and amount of assessment is quite limited by time and resources.

Proposed solution:

  • Estimate pasture sward density parameters and relate to mass.
  • Measure density and construct density to mass calibration equations and test for generality over various sward types.
  • Mass is concentrated near the bottom of the sward so extra sensing needed here


  • Needs to be a robust gadget that can be used in the field
  • Needs to be inexpensive (< $150 AUD)
  • Should be able to make measurements at the quadrat scale (typically 0.5m*0.5m) for calibration and consistency with established research practice.
  • Should record data and / or upload to a mobile phone
  • Should be upgradable so can integrate with GPS information.
  • Should be able to be carried on a motor bike.
  • Should have one handed operation.


  • 1 × Rotary Encoder KY-040 (20 positions)
  • 4 × Distance Sensors E18-D80NK-N Adjustable Infrared Sensor
  • 1 × Arduino Leanards
  • 1 × Sensor Shield V4
  • 1 × SD card shield

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  • Pasture Biomass Sensor

    John Carter08/20/2014 at 07:26 0 comments

    Grass_stick V1.1 Aluminium channel

    Grass_stick V1.2 25mm PVC

    Grass_stick V1.21 bottom end cap too small for encoder use T-piece, use sensor shield on Arduino

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