Winter oilseed rape has big potential to become the cornerstone of a good crop rotation strategy

Every year after the dust has settled on the harvest, Teagasc publishes its Harvest Report. The yields reported are calculated after consultation with farmers, advisors, discussion groups and grain merchants nationwide.

While yields vary from year to year, the one constant is that farms with good rotations record significantly higher crop yields than holdings where little or no rotation is practised.

While this can hardly be regarded as a ground-breaking discovery, it reinforces the need for resilient rotations to improve our soils, yields and overall profitability.

It is important that every crop contributes to the bottom line in its own right, but profitability should be viewed over the duration of the rotation and not just in any one crop.

Teagasc research has shown that rotations can improve profitability by increasing cereal yields (by up to 1.5t/ ha following break crops over continuous wheat) and decreasing input costs.

Rotations also reduce resistance to plant protection products.

We farm in an era where there is increasing pressure from consumers and policymakers to reduce inputs.

A cornerstone of the European Green Deal is the ‘From Farm to Fork’ strategy which proposes a 50pc reduction in pesticides and a 20pc reduction in fertiliser by 2030. Good rotations will contribute to this.

Winter Oilseed Rape

Winter oilseed rape is a very suitable crop for arable rotations and has large scope to increase from its current area sown of 8,500ha.

The area of winter oilseed rape grown has remained relatively stable in recent years. The market is diverse, with rape meal used for animal feed, oil for biodiesel, High Erucic Acid Rape (HEAR) for specialised markets and food grade oil.

While much of the oilseed rape produced in Ireland is exported, the price in recent years has remained consistent and less variable than cereals.

Oilseed rape provides an ideal opportunity to forwardsell a portion of the harvest at sowing as most buyers will offer contracts.

When target yields are achieved, winter oilseed rape is more profitable than spring feed barley in the Teagasc Crops Costs and Returns measure, notwithstanding the additional yield from the succeeding crops.

Timely sowing is crucial for successful establishment of winter oilseed rape.

The sowing window from mid-August to early September coincides with a busy harvest period, but successful oilseed rape growers use broken weather to prepare ground and typically plant after winter barley.

Research at Teagasc Oak Park on crop establishment trials showed that ploughbased, min-till and strip-till (including sub-soiler leg type) systems were all capable of achieving high yields, although establishment may vary.

Row widths up to 500mm or 600mm did not hinder yield potential in most of the trials but it may be sensible to increase seeding rate by 10-15pc when using strip till systems in wide rows.

Good establishment is critical for high yields and helps the crop withstand pest (slug/pigeon) attack and weed competition.

Varieties should be selected from the Department of Agriculture (DAFM) recommended list.

Varieties that performed well in the UK do not always perform well in Ireland.

All too often varieties are grown for one season and then discarded, at the grower’s expense.

Varieties on the DAFM recommended list have been grown in Irish conditions for at least three years so growers can be confident that these varieties are reliable.

Advances in breeding technology means that growers have access to varieties with excellent podshatter resistance, increasing disease resistance and Turnip

Yields:

When target yields are achieved, winter oilseed rape is more profitable than spring feed barley, according to the Teagasc Crops Costs and Returns measure

Virus Yellows resistance.

Sowing rate depends on soil conditions, but are usually in the range of 50-80 seeds/m², with conventional varieties at the higher end.

There are options.

Herbicides

pre-and-postemergence weed control

Herbicide choice depends on what weeds are expected, but crucially winter oilseed rape provides opportunities to control difficult grass weeds.

Clearfield (CL) varieties are hybrid varieties that can be grown where brassica weeds prevent “normal” varieties being grown.

These varieties can be treated with the herbicide Cleranda which will control volunteer oilseed rape and brassica weeds. Clearfield varieties are slightly lower yielding than conventional varieties, and beware of the control of volunteers.

As weather patterns are becoming more unpredictable, there is great comfort in having a portion of the next harvest in the ground and forward sold before the dust settles on this harvest.