Maize for Silage
Technical
Insight 323

ASSESSING MAIZE SILAGE DRYMATTER YIELD

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The following procedure can be used to assess maize silage drymatter yield for maize planted in 30” (76 cm rows). It will give an estimate of yield that can be used for feed budgeting or bunker size calculations. This method of assessing crop yield should not be used for crop trading. 

EQUIPMENT REQUIRED

  • Chain or tape (5.3 metres in length)
  • Scales
  • Machete or sharp knife

YIELD MEASUREMENT

1. Move from the headland into the crop

The outside rows (normally 24 rows) of the crop are known as the headland. The yield and drymatter in this area of the crop are not usually representative of the crop as a whole. Move into the centre part of the crop (normally planted up and down the field).

2. Draw a line across four rows in the crop

Measure 5.3 metres down the four rows starting from the line.

3. Count the plant population in each row

Record the number of plants in each of the four rows. This is the plant population per 1,000th of an acre. In a silage crop planted at 110,000 plants per hectare, there would usually be around 44 plants in the 5.3 metre length.

e.g.           Row 1  44

                  Row 2  44

                  Row 3  48

                  Row 4  40

4. Calculate the average plant population

Add the plant population of each of the four rows together and divide by 4 to get the average plant population.

 e.g.          Average population = 44 + 44 + 48 + 40 = 176          176 divided by 4 = 44

5. Cut the row with the population closest to the average

Using a machete or a sharp knife, cut the plants approximately 150 mm above ground level.

e.g.          Cut row 1 = 44 plants

6. Weigh the cut material

Use a set of scales (e.g. calf scales, bathroom scales, weighing platform) to weigh the material and record the weight.

e.g.          Cut 1   Wet weight = 32 kg

7. Select three representative plants for drymatter sampling

The best option is to send a sample to a commercial laboratory for drymatter testing. Alternatively you can do a microwave drymatter assessment. See Pioneer Technical Insight titled “Microwave Drymatter Testing of Maize Silage” for further details.

8. Repeat the procedure at least twice

Move to a different place in the crop and repeat the procedure. The more times a yield cut is made, the more accurate the yield assessment will be. Crops that have a large plant population variation (e.g. insect damaged crops) or plants with a large variation in plant size (e.g. drought stressed or weedy crops) will require more cuts to achieve an accurate yield estimation.

9. Calculate the wet weight per hectare

Multiply the wet weight (from Step 6) by 2.471. This will give the wet weight (in tonnes) per hectare.

e.g.          Cut 1 = 32 kg x 2.471 = 79.072 kg wet per hectare

                 Cut 2 = 38 kg x 2.471 = 93.898 kg wet per hectare

                 Cut 3 = 37 kg x 2.471 = 91.427 kg wet per hectare

                 Cut 4 = 30 kg x 2.471 = 74.130 kg wet per hectare

10. Calculate the average drymatter yield

Once the drymatter percentage has been determined, multiply the wet weight (Step 9) by the drymatter percentage. Calculate the average drymatter yield by adding together the drymatter yield from each cut and dividing by the number of cuts.

 

e.g.          Cut 1 = 79.072 kg x 32% drymatter = 25.3 tDM/ha

 

                 Cut 2 = 93.898 kg x 31% drymatter = 29.1 tDM/ha

 

                 Cut 3 = 91.427 kg x 34% drymatter = 31.1 tDM/ha

 

                 Cut 4 = 74.130 kg x 33% drymatter = 24.5 tDM/ha

 

                 Total = 25.3 + 29.1+ 31.1+ 24.5 = 110

                 Average = Total divided by 4 = 110 divided by 4 = 27.5 tDM/ha



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Revised: June 2015
Expires: June 2018