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Topics : Pastures : Determining Pasture Yield

Determining Pasture Yield

Additional pasture information via the Forage Information System (FIS)


How to calibrate indirect methods

The methodologies for calibrating the pasture ruler and for the rising plate meter are slightly different. Both methodologies are easy but time consuming.

Pasture Ruler

Necessary elements:

  1. Hand/electric shear
  2. Ruler
  3. Pasture ruler
  4. Big cloth or plastic bag
  5. Scale

Procedure:

  1. Walk through the paddock in a W pattern.
  2. At a pre-set interval (could range from 20 to 35 footsteps) collect a hand clipping to ground level in an area of 3 ft by the shear width.
  3. Insert clippings into the bag.
  4. Measure and record sward height.
  5. Repeat steps 2 to 4 throughout the W pattern. If paddock is small at least 15 samples are needed.
  6. Weigh bag. This is the total wet weight (TWw).
  7. Take a sub-sample from the bag of approximately one pound.
  8. Weigh the sub-sample. This is the wet weight (SubWw).
  9. Dry sub-sample (for information on how to dry forage refer to fact sheet I-106).
  10. Weigh sub-sample. This is the dry weight (SubWd).
  11. Calculate % of DM content of sub-sample (%DM) = SubWd/SubWw * 100.
  12. Obtain total DM (total DM) = TWw * %DM.
  13. Calculate the clipped area = Shears width (ft) * 3 ft * number of samples/43560.
  14. Calculate lb DM/A = total DM/clipped area.
  15. Calculate average pasture height = Sum of individual heights/number of samples.
  16. Calculate average lb DM per plant height = step14 / step 15.

 

Rising Plate Meter

Necessary elements:

  1. Hand/electric shear
  2. Ruler
  3. Rising plate meter
  4. 15 – 20 bags labeled (numbered)
  5. Scale

Procedure:

  1. Walk through the paddock in a W pattern.
  2. At a pre-set interval (could range from 20 to 35 footsteps) collect a hand clipping to ground level in an area of 3 ft by the shear width.
  3. Insert clippings in individual bags. Bags have to be labeled with the order they are collected.
  4. Push down the rising plate meter and record the accumulative pasture number.
  5. Repeat steps 2 to 4 throughout the W pattern. If paddock is small at least 15 samples are needed.
  6. Weigh each bag. This is the bag wet weight (bagWw).
  7. Randomly select three bags.
  8. Weigh selected bags (SubWw).
  9. Dry selected bags (for information on how to dry forage refer to fact sheet I-106 [PDF]).
  10. Weigh selected bags. This is the dry weight (SubWd).
  11. Calculate % of DM content of selected bags (%DM) = SubWd/SubWw * 100.
  12. Calculate average %DM.
  13. Obtain bag DM for each bag (Bag DM) = bagWw * average %DM.
  14. Calculate the clipped area = Shears width (ft) * 3 ft /43560.
  15. Calculate lb DM/A = Bag DM/clipped area.
  16. Click here and follow instructions (mouse over red marks on cells to see instructions).