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.
Potential animal intake can be estimated from animal size. A 450kg steer eats about 10kg of grass / day and it is safe to eat 20-40% of annual growth. 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!
- (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.
- 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.
Project Name Grass_stick
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
Sensor Shield V4
SD card shield
20 Position Rotatory Encoder with switch
IR distance sensor