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Start planning for drilling

Written By Sarah Barnes, Maize Growers Assosciation (MGA) Office

To get your crops off to the best start there are several factors you need to think about and now is a good time to start for 2023’s crop.

Soil Temperatures

Check the soil temperature at drilling depth at 9am and aim for three consecutive days of at least:

  • 8⁰C on light land
  • 12⁰C on heavy clay land.

If maize is going to be planted under film the temperature can be much lower, at 6⁰C as the film warms the soil up. To get the most benefit from the film drill as early as possible when soil conditions allow.


If drilling early in the season then a rougher seedbed will benefit the crop as it will promote drainage and maize seed does not like wet or waterlogged soils. However if drilling later in the season for example after a cut of grass then the seedbed will need to be finer to prevent excessive moisture loss. If the soil is particularly dry then a pass with a roller will help retain as much moisture as possible to start the seeds off. Remembering not to cap the soil as this may impede seedlings breaking through the surface.

Seed Rate

Accurate seed placement is essential; ensure the drill metering mechanism is accurate. Most drills metering are based on forward speed. A standard drill speed would be at or below speeds of 10 km/hr – but modern drills will work well up to 14 km/hr.

Even spacing within the row and even seed depth is also important to reduce competition between plants. Speed of drilling is important here alongside seedbed quality. An uneven seedbed will likely make the drill bounce and as such vary the seed depth. Any seed drilled at different depths will emerge earlier or later than the rest and will result in competition between the seedlings.

Seed rate adjustment

When drilling in cold and wet conditions you can expect higher seed loss of at least 10% consequently more seeds should be planted to mitigate the loss.

Starter fertiliser

Our MGA Agronomist Jon Myhill says “Starter fertiliser trials over the years have delivered mixed results in terms of crop yield. Tonnage aside, what starter fertiliser does seem to do is increase the rate of crop maturity, allowing maize to tassel about four days earlier than would otherwise be the case. The four days may mean the difference between reaching ideal harvest maturity or not.

Rates of starter fertiliser should take full account of the nutrient supplied via organic manures, including digestate, and that available from the soil. In high soil phosphate situations (Index 3 or above) there is little justification for starter P unless perhaps growing conditions are particularly challenging. If starter P is to be applied in these higher soil P situations application rates should be reduced (50 kg/ha of DAP). Recent trial results suggest that biostimulent alternatives to starter P fertiliser have achieved simlar results.

Weed control

Jon continues “Where grass weeds are present (and notably blackgrass), then a clean start is crucial. An application of glyphosate to take out any young grass weeds is very important. These grasses tend to get through the cultivations, which are then too big to be controlled via the pre-emergence herbicides and present problems to the main post-emergence grass treatments.

Once drilled, the crop should be treated with a pre-emergence herbicide. You have two options:

  1.  A cheaper first spray followed by a more expensive one at the 1-2 leaf stage of the maize.
  2.  An expensive start followed by a less expensive one at the 1-2 leaf stage.

The choice depends on the weed spectrum present, but as a general rule, a cheap option is Pendimethalin at around 3.0l/ha (dependent upon product). Under dry conditions, this will still give some control, but a more expensive follow up may be required. For improved, more expensive, pre-emergence control, either Pendimethalin + dimethenamid P (e.g. Wing P) or Pendimethalin + S metolachlor (e.g. Stomp + Dual gold) should be considered.”


The maize crop will require sufficient nitrogen to optimise yields while abiding by regulations such as the NVZ N max limit of 150 kg/ha. More applied nitrogen will result in more yield to a point, beyong that point crops remain green and take longer to mature, possibly delaying harvest. If you would like to use the MGA Nitrogen Predictor service get in touch with the MGA.