Monday, 29 August 2016

Competitive cultivation strategies: Who dares wins

Cultivation for all


NIAB CUF has conducted a range of experiments over the years on cultivation and this makes sense as a topic to investigate. 

Not everyone can choose their soils. Not all have access to water for irrigation. But all growers can manipulate their pre-planting cultivations and all aim to do the best possible job.

From 75 experiments over five years the conclusion is that 270 mm is the optimal depth for a destoned bed prior to planting, allowing the job to be done at a good speed without yield reduction compared with deeper cultivation. 

The trouble is that these results suggest that many growers don’t have things quite right, and this bone of contention can only be settled one way.


Olympics over but SPot still provides fierce competition



As a school kid Mark Stalham was seriously competitive, putting in 20 hours a week swimming practice. As a mature researcher with NIAB CUF he’s not lost the competitive streak, and it looks as though he’s now trying to beat the farmer. 

Setting himself up against James Daw’s experience makes me wonder, is this the excess bravado associated with certain sportsmen? 

270 mm versus 300 mm, the narrow field of battle


Standard practice at this farm is for the bedformer to provide 530 mm of cultivated soil, followed by bedtilling to 460 mm on the heavier land and then use of a destoner to give a final ridge 300-330 mm deep.  

Mark Stalham’s recommendation is use of a bed former to provide 370 mm depth, with the destoner giving 270 mm final soil depth and eliminate the bedtiller.



So Field 33 at Thorpe Constantine has been tilled according to standard practice, but with Mark’s ‘shallower is better’ style on six beds each 600 m long, crossing two major soil types.

Who is taking the risk?


Mark says he’s putting his 'neck on the line over this one’. 
James feels that, more to the point, it’s his money on the line.

Odds in favour of Mr Daw


Farming though, is no athletic competition where the stop watch measures the winning performance. 

Each season's decisions have to be made essentially blindfolded, not knowing what weather will unfold, so often tend towards a safe outcome whatever the season brings. 



Our starting position is always that standard practice is best. In this case, James Daw said he’d not risk moving to cultivations as shallow as Mark Stalham would recommend. 

That position gives him the advantage in this competition. 

If yields turn out to be less under shallow cultivations, he wins. 
If yields end up equally good under shallow and deep cultivations, the deeper 300-330 mm final bed depth could be seen as a careful insurance tactic.

Credit to Dr Stalham


James Daw doesn’t think that Mark Stalham gives sufficient weight to the need for an insurance margin in fields with variable soil types. He says he has responded to Mark's good research and advice and has ‘dramatically shallowed off,’ but Mark is ‘going too far’.

However where both James and Mark agree is on not going too deep, because the cost is unnecessary, and only brings up clods that don’t need to be brought up. 


250 mm is too shallow


Visitors to SPot Farm West this year saw what happens in the extreme case of shallow cultivation providing only 250 mm of cultivated soil. 

There wasn’t space for the tubers and excessive greening resulted.




Reliable measurement


It is no use at all knowing the ideal depth of cultivated soil if in practice it's not well controlled. 

At the Daw’s farm, four de-stoners are operating at the same time, so its vital they work to the same accurate standard. 



James has introduced a system where the machine operators stop twice each day at random times and check each other’s depth of working and other aspects of quality. 

They take pride in getting it right.  

Reason to repeat a SPot Farm topic


Depth of, and timing of, cultivation was a topic last year at SPot Farm West, and is a topic this year at SPot Farm Scotland and next year at SPot Farm East. 

It takes several experiences in different conditions to test a technique.


There’s no doubt that competition adds interest to a trial and we look forward with anticipation to the final yield and quality figures from all sites.  

This year's final farm walk at SPot Farm West is set for September 22, slightly later to enable further harvest digs and samples to be undertaken, allowing us to share more of the findings and results of this season’s work. 

Come join us to discuss how the demonstrations and trials have come to fruition: potatoes.ahdb.org.uk/events 

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