Canola ameliorants

By Damian Jones, ICC

Key messages:

ICC_Trial_Summary_Book_ cover

  • Applications of gypsum and lime did not increase canola emergence in 2015.
  • This result was expected as May rainfall was not sufficient to induce slaking of the soil.

As the soil on the trial block is prone to slaking if overworked, this can become an issue when trying to establish canola, particularly when watering up.

Calcium, either as gypsum or lime, can assist in improving soil structure and hence reduce
soil crusting and slaking. Gypsum is widely used as it is available locally, saving transport costs. It does not affect soil pH and is relatively soluble compared with lime.

In 2014, rates of gypsum, lime, gypsum/lime and PAM (polyacrylamide, which acts in a similar manner to calcium in that it helps aggregate the soil particles) were applied to the soil surface (which was crusting after pre-irrigation) and incorporated by sowing. Plant counts were taken as representing the success of the ameliorants in reducing soil crusting.

The 2014 results showed an improvement in establishment where gypsum was used at 3t/ha over all other treatments. All other treatments except for the PAM were an improvement over the control (no ameliorant).

The trial was repeated in 2015.

Method

Plots were re-sown following pre-irrigation and relied on rainfall to ensure enough moisture for germination. Although rainfall was below average in May, there was enough for very good establishment. Target establishment was 50 plants/m².

Table 1: Ameloriant treatments.
Treatment

Rate (t/ha)

 plants/m²

Gypsum + Lime

1.5

58.7

Gypsum + Lime

3.0

82.9

Gypsum

1.5

65.3

Gypsum

3.0

69.5

Lime

1.5

68.6

Lime

3.0

68.0

No treat

74.3

PAM

5 kg/ha

65.1

P

LSD

CV

0.325

NS

14.3

Results

No treatment had any effect on establishment. This may not be that surprising, given the small rainfall events in May.

In order for the soil to slake post-sowing, it has to be wet enough to breakdown the soil structure. If it doesn’t get particularly wet, then the soil can resist slaking and the seedlings can emerge unhindered.GRDCLogoStacked_TM_CMYK

The stubble project – maintaining profitable farming systems in Victoria and Tasmania with retained stubble (project number BWD00024) is funded by the GRDC.

A printer-friendly version of this trial report can be accessed here.

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About BCG

Birchip Cropping Group Inc. (BCG) is a not-for-profit agricultural research and extension organisation led by farmers in the Victorian Wimmera and Mallee.
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2 Responses to Canola ameliorants

  1. Pingback: 2015 field trials | The stubble project: Victoria and Tasmania

  2. Pingback: Break crops in stubble retained systems under irrigation | The stubble project: Victoria and Tasmania

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