Estimating pasture growth on your farm

To complete feed budgets for your farm, you need to be able to estimate pasture growth rates throughout the year. Estimates of pasture growth in different regions of Australia are provided here (Regional pasture growth rates). However, measurements on your farm in your paddocks will always be more accurate than generalised regional data.

There are several ways pasture growth can be estimated on farms. The procedure set out below is based on the change in height of the pasture over a 30-40 day period while the paddock is spelled from grazing. Alternatively, small cages or areas of the paddock need to be fenced off so that stock do not graze the areas being measured.

Equipment needed

  • One pasture ruler, marked at 1 cm intervals than can be easily read in a photograph
  • Twenty wire pegs with a numbered tag

Procedure

  • On the first measurement day (Day 0), place the numbered wire pegs in a line every 10 metres in the paddock so that they can be easily found at the time of the second measurement.
  • At each location, set the ruler next to the wire peg with a tag listing the peg number attached to the side of the ruler (See Figure 1 below).
  • Estimate the height of the pasture. and take a photo of the quadrat showing the pasture height, density and tag number, and most important the date of the measurement. Most smart phones and cameras have this feature inbuilt. Photos will help ensure that you do not lose the data.
  • At the second measurement (Day 30-40), use the ruler and camera to again to record pasture height.
  • For each peg, work out the change in pasture height between Day 0 and the date of the final measurement.
  • Estimate the change in Feed On offer (FOO) from the change in pasture height
    • Dense high rainfall, high fertility 100% green pasture 1 cm = 300 kg/ha
    • Lower density, lower fertility pasture 1 cm = 200 kg/ha
    • Open, low density pastures 1 cm = 150 kg/ha
  • The AWI Feed On Offer Library can also be used to estimate FOO values
  • Divide the change in FOO values by the number of days to work out the pasture growth that has occurred at each peg location.
  • Average the pasture growth values to determine the average growth for each paddock.

pasture_ruler
Figure 1: Wire pegs are used to ensure exactly the same location is measured on each occasion. A numbered tag is attached to the peg to ensure that the pasture height data can be matched with the earlier results.
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