The sampling procedure grain traders use to test loads of beans from farms has been called into question following concerns that existing methods may lead to inaccurate admixture results.

Current sampling protocols allow firms to use pneumatic “vacuum” spears which automatically draw a sample from the lorry. However, some people are concerned that such methods are biased towards smaller ‘rubbish’ material rather than heavier bean seeds and could therefore lead to higher admixture contents.

“There is a problem here,” Guy Gagen, the NFU’s chief arable advisor said. “There used to be separate sampling standards for cereals and beans, but it changed some time ago to allow the same [vacuum] sampling for both.”

Yorkshire farmer Peter Knaggs raised the issue with Farmers Weekly after he experienced problems with a load of beans destined for human consumption going into Hull docks.

Sampling by Frontier before the load left the farm revealed an admix content of 0.6%, but later testing at the dockside put it closer to 12.5% – equivalent to a deduction of 3.6t of rubbish, or £22.50 for that load, he said.

“After I found out, another sample was taken, which did come in lower at 5% admix, but this was still way above the initial test. I can’t believe there won’t be others who’ve had the same problem.

“Everyone knows it’s a problem, but no one has done anything about it. It should have been sorted a long time ago.”

Frontier’s trading director John Duffy declined to comment on specific cases, but said that all the firm’s stores followed the necessary sampling guidelines. Sampling beans with a spear on-farm was very difficult to do accurately and on-farm admix results should only be used as a guide, he said.

Mr Gagen, who planned to raise the matter with representatives from the grain trade, suggested farmers selling beans should try to negotiate what sampling method is used before contracts were signed. “It’s a lot easier to negotiate before signing, rather than after.”

Alternatively, if an unusually high result did come back, farmers should try to negotiate it down, he said.

Have you ever experienced such problems with beans, peas or any other crop? If so, we’d like to know about it, so why not tell us at the FWi forum, or email paul.spackman@rbi.co.uk