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28 August 2018 Gary Bosley

Getting it right from day one

You only get one chance to get a crop in the ground at the right time, and that is the first day you do it.

If you have to come back and re-sow, you have lost weeks of productivity and yield. Planning is critical for success. Crop type and time of planting are key, but ask yourself, why do you want to grow a brassica?

In most cases, a brassica crop serves two purposes:

  1. To fill a feed deficit that is left by existing pasture at a particular time of year.
  2. To use as a tool to take out and renew old pasture after the brassica crop has finished.

A brassica crop not only delivers quality feed for livestock, but also allows us to break a pasture rotation by using the opportunity to tidy up perennial weeds that do not need clover safe chemicals.

So a few questions need to be asked:

  • Are the paddocks earmarked for the crop suitable?
  • How did they come through the winter?
  • Are any last minute adjustments needed?

Once you have confirmed the paddock location and have taken a soil test, the next step is to decide what type of brassica you are going to grow: leafy turnip, bulb turnip, rape, raphanobrassica, kale or swede. Then work backwards from the planned grazing date using the number of days that it takes from planting to grazing as per the suppliers’ recommendation.

When you receive your soil test results, if your pH is out, come up with a fertiliser plan and apply lime at the earliest opportunity. Remember, lime can take around six months to correct pH. If possible, plan your spray-out date four weeks before your planting date. This allows plenty of time for old vegetation to die back especially in no-till situations.

There will be less unwanted plants to deal with and it will be easier to create a nice clean seed bed if you plan to cultivate. Whilst it is always tempting to try to get the last graze out of the previous pasture, this can be false economy as you need around 10 cm of actively growing plant leaf to take up the glyphosate effectively. Grazing to the dirt before you spray leads to disappointing results.

Cultivate a firm, flat and fine seedbed to drill into. Remember that brassica seeds are small and do not have much energy inside them. They should be sown with enough good seed soil contact, which supports rapid and even seedling emergence to optimise establishment and achieve canopy closure. Most small seeds should be sown between 10 to 15 mm depth, and always use a slug-bait at sowing in no-till situations.

Spray an appropriate post-plant pre-emergence herbicide, especially if you have difficult weeds or you are sowing a long-term crop such as rape, raphanobrassica, kale or swede. This takes away any seedling competition with weeds emerging at the same time as the crop. Monitor regularly for further weeds and pests and deal with accordingly.

For advice around sowing brassica this spring, contact your local PGG Wrightson Technical Field Representative.

Gary Bosley

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