Is Mustard Bad News For Weeds

22 April 2007
By Johnny Caldwell
BBC News website

Farmers in Northern Ireland or anyone else for that matter may never look at a jar of mustard - be it Dijon, Bavarian or plain old English - the same again. A host of golden mustard plants makes for a spectacular view.

Scientists at Greenmount Campus believe they have confirmed a theory currently doing the rounds that the planting of a mustard crop can help reduce weeds in a field thereafter. They grew a mustard crop for eight weeks and then ploughed it into the soil.They then compared this with a control area, which had significantly more of the gardening and horticultural nuisance.

In addition to its scientific benefits, the experiment also produced a glorious bright yellow crop which could be seen for miles around the Antrim seat of learning. Mustard crops are normally used for green manures to add organic matter to the soil, but recent research in the US and elsewhere in Europe has suggested that they also have the potential to suppress weeds as well as soil-borne pests.

Dr Raja Harun says Greenmount's confirmation that the planting of mustard definitely reduces one of these is "very good news for the farming community in Northern Ireland."

"Mustard is incorporated into the soil at the flowering stage, it then releases isothiocyanate gas and this kills the seeds of weeds," he said. "After a four-week period, the number of weeds was much lower in the area where the mustard crop had been ploughed in compared to the control. "With regards to the bigger picture this means farmers could reduce the use of the amount of herbicides they have to use. "The other benefit of this is it adds organic matter to the soil, and this improves its structure which also benefits the next crop planted there."

Despite what he believes is proof that mustard is bad news for weeds, Dr Harun said he and his team "need to confirm this with another experiment". "It looks like a winner, and hopefully farmers, especially organic ones, will be interested in what we've discovered. "Although considering the time constraints it mightn't suit every crop," he added.

Mustard as a winter crop takes 25 weeks from an autumn sowing to incorporation in early April, however, as a summer crop it only takes only eight weeks before it's ready to be ploughed in. Whether or not the planting of mustard crops to reduce weeds catches on here only time will tell. After all farmers in Northern Ireland may not be that keen.

Greenmount Campus is part of the College of Agriculture, Food and Rural Enterprise (CAFRE).