Maize for Silage
ASSESSING MAIZE SILAGE DRYMATTER YIELDBack to Technical Insights
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.
- Chain or tape (5.3 metres in length)
- Machete or sharp knife
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