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Dijon Trip – October 2012


October 2012

Back in October, 26 Crop Management clients and agronomists packed their bags and headed to France to explore the benefits of companion cropping. Richard Wood & Simon Roberts from Syngenta who sponsored the travel and accommodation were also in attendance.

The first visit took us to a Syngenta research station just outside the small town of Dijon in western France.

At the site we learnt that only around 10-20,000 ha of the total 1.5million hectares of oilseed rape in France are drilled with a companion crop. The research scientists at the experimental farm were exploring the benefits of companion cropping and the best ways to manage them

Companion Cropping Benefits

Although, the work is very much at its early stages, the perceived benefits of companion cropping are hoped to be:-

  • Reduced herbicide use – particularly in terms of reducing the competitiveness of geranium species.
  • Increased yields (increases of around 1T/ha have been shown)
  • Reduced Nitrogen use

The later benefit is of particular interest to French farmers as they are not allowed to legally apply artificial Nitrogen fertilisers in the autumn months for water quality reasons.

In their work, the French scientists have found that using leguminous companion crops such as common vetch, red vetch and alexander clover can fix upto 30 units of Nitrogen – a clear potential benefit for French farmers.

Dijon Trip Report

Companion Crop Types & Management

The most common companion crop mixtures used in France are:-

  • Common vetch, red vetch and Alexander clover
  • Lachrose, fenurgreek and red vetch

Seed costs were typically 30 – 40 Euro’s per hectare (£24-32/ha). Interestingly, similar mixtures are costing British farmers £50 – 70/ha!

In terms of plant populations the French suggest aiming for a total of 40 combined companion and osr plants per linear metre at a row spacing of 45cm.

The scientists were also looking at the effect on commonly used pre and early post emergence herbicides on both individual companion crop species and mixtures.

In order to destroy the companion crop, the French rely on their regular heavy frosts of below -5 degrees. In a ‘normal’ year, it is obviously envisaged that the companion crop will die off before stem extension of the oilseed rape crop in early spring.


Anything that has the potential to reduce input costs obviously cannot be ignored. However, there are still question marks over:-

  • cost of seed – at £50-70/ha this is way more than a 30kg/ha application of bagged N costing around £27-30/ha. 
  • weed control in crops where companion crops have been sowed – more and more work is being done and we should have some more reliable data soon.
  • ease of establishment – how can we limit the hassle factor of sowing these additional crops?

A very interesting concept – watch this space……….