Study shows scope to exploit faster, lower-cost establishment methods

Oilseed rape (OSR) is traditionally sown in 125mm rows at a seeding rate of 50-80 seeds/m². However, recent interest in low soil disturbance, strip-till methods of establishment has resulted in some commercial growers opting for 600mm row widths.

Roisin Byrne, a PhD student at Teagasc Oak Park, has shown that there’s scope for Irish farmers to exploit faster and lower-cost establishment systems, such as strip tillage.

Byrne presented her research on OSR at Teagasc’s Crops and Cultivation open day in Oak Park, Co. Carlow, last week.

Establishment systems

The focus of Byrne’s study was to determine the impact of row spacing and seed rate on OSR development and yield.

Byrne looked at the three different systems of establishment typically used for OSR. These included: traditional plough-based; min-till; and strip tillage.

Row widths of 125mm to 750mm and seeding rates between 10 and 60 seeds/m² were evaluated over three years on varying yield-potential sites.

Byrne found that seed rate or row spacing didn’t impact significantly on yield and all systems can successfully establish OSR crops.

Her results showed pod numbers didn’t differ significantly when sown either at a wide (750mm) or a narrow (125mm) row spacing, even at lower seed rates.

Byrne attributed this to the crop’s ability to alter its canopy structure when growing at different plant densities.

A dense crop will have more pods nearer the top of the canopy, due to better light availability.

“A wider row width at a lower seed rate, however, allows the crop to branch out and fill pods lower down the plant which may not have filled to the same extent in a denser canopy,” Byrne explained.

However, where yield potential was high, Byrne found very wide rows (750mm) could limit the crop to some extent.

The PhD student’s research shows that wide-row, low-disturbance establishment systems are effective and can be used to reduce costs.

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