Fertiliser: does applying autumn fertiliser to oilseed rape really stack up?

Early application of nutrients to oilseed rape (OSR) crops can help achieve prompt emergence and development. But losses each year from cabbage stem flea beetle (CSFB) and other pests, mean some growers are reluctant to make the initial investment.

Is it worth it?

Yara trials have shown a 40% increase in plants per m2 6 weeks after drilling, when autumn fertiliser was applied. Higher plant numbers can help reduce yield loss after CSFB damage.

What nutrients should you focus on?

Nitrogen, to ensure early growth, and phosphorus for good root development and energy transfer within the plant.

Nitrate Vulnerable Zones rules allow up to 30 kg/ha of nitrogen to be applied to the crop in the autumn.

Phosphate has very poor mobility in the soil, moving less than 1 mm. So it’s beneficial to apply fertiliser when drilling as it’s immediately accessible to the seed. Yara trials show that yield can be increased by 0.2 t/ha if fertiliser is placed with the seed, rather than broadcast.

Which products should you use?

DAP (18:46:0 NPK) is the most commonly used product, giving both N and P in a compound granule. However at 46% P there’s a risk of overapplying phosphate in unsuitable situations, which can cause eutrophication if lost into water courses from soil movement. 

Starter fertilisers can be applied as either microgranular or liquid. They’re applied at low rates and are targeted at the early growth stages. Other solutions can protect phosphate which prevents immediate lock-up in the soil and prolongs nutrient availability to the crop.

When should you order?

In our experience growers rarely need to order a full load (28.2 T) of OSR autumn fertilisers. It’s more likely you’ll be ordering smaller quantities and delivery will take longer than you’re used to with other products. Allow around 2-3 weeks for delivery, so order in good time to get your fertiliser on farm.

To place your order, email fertiliser@af.farm or call 01603 881 906. 

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