Companions give OSR a helping hand

Article taken from the Farmers Guardian, written by Martin Rickatson

With low seed rates creating open spaces in and between oilseed rape rows, Agrovista has been conducting research on companion cropping as part of its GrowCrop Gold trials.

This technique involves sowing a beneficial, non-competing crop to grow with the OSR during the early part of the season.

Not only does this reduce room for weeds to establish but it also locks up nitrogen over autumn, when it would otherwise be lost through leaching, before the frost-susceptible companion crops die off over winter, releasing N as they break down in spring.

Agrovista technical manager Mark Hemmant says: “It’s a technique that was developed in France, where it has been shown to improve autumn crop growth and offer potential weed suppression benefits, and is increasing in popularity on farms there, where nitrogen use is heavily restricted.

The 2012-13 season was the first year the GrowCrop Gold trials included a companion crop assessment, and despite planting at many of the trial sites stretching into September due to the weather – with crops failing to grow sufficiently in the autumn to capture enough nitrogen to make a significant difference to crop yield – the results have been encouraging.

In the Agrovista trials the benefits of the two-pant mix were shown as the vertical growth habit of the smaller seeded berseem clover, which emerged first, meant it did not compete with crop at early stages.

Meanwhile, larger-seeded vetch, which has a more prostrate growth habit, emerged later and filled the inter-row spaces.

“We achieved good establishment of both crop and companion mix at all sites bar Stoughton, where surface trash levels were high.  At the earliest sown site [August 15] at Morley, plots sown with companion plants showed significantly more biomass in autumn, peaking in late October, and this was reflected by an increase in SNS class of 1.0 when soil mineral nitrogen testing was carried out in February.

“The extra 29kg/ha N captured, which assuming an average 60 per cent efficiency factor is equivalent to about 50kg/ha bagged N, exceeded comparable French trial results.  It had a head start though, from a poultry manure application before drilling.”


Best harvest response from companion plant inclusion was at the Croft (North Yorkshire) site, where yield was improved by 0.33 tonnes/hectare to 0.5t/ha (0.1t/care to 0.2t/acre).  At Morley (Norfolk), yield benefit of companion plant inclusion appeared to depend on OSR seed rate, with a 0.5t/ha (0.2t/acre) gain where the rape (Quartz) had been sown at the optimal wide-row seed rate of 15 seeds/metre.  At higher rates, there was no effect on yield, positive or otherwise, while at sub-optimal plant populations the companion plant inclusion appeared to have an adverse effect.

At Morley (Quartz sown August 15) and Croft (DK Extrovert sown August 23), plots sown with rape alone yielded 4.7lt/ha (1.9t/acre) and 3.66t/ha (1.5t/acre) respectively, while plots sown with companion plants yielded 5.29t/ha (2.1t/acre) and 4.16t/ha (1.7t/acre).

“In addition to comparison of establishment methods for the companion plants, we plan to do further work on seed rates and herbicides screening to assess the effects on companion plants of various herbicide strategies,” says Mr Hemmant

Growcrop Gold Trials
More details from the trials at:


16 December 2013

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