According to grass seed breeder Barenbrug UK, some growers may be keen to keep valuable nitrates in the soil this year by undersowing maize with a grass or legume-rich cover crop.

However, the company’s team of agronomists is pointing out that caution is needed to receive the full benefit of the practice.

Recent years have seen a growing interest, particularly in the UK, in undersown maize as a means of ‘locking up’ nitrate residues, reducing winter soil loss from bare fields, and preventing watercourse pollution. 

“This year, growers will see that, in addition to valuable winter grazing opportunities and meeting environmental obligations, a grass catch-crop can also generate a positive economic yield; a reduction in next year’s bagged nitrogen requirement,” explained Barenbrug’s Roger Bacon.

“For those growers not already planning to undersow this year’s maize, it’s not too late to make plans.

“And there are several ways to achieve it, even without specialised equipment.

“But more important than the method of drilling, is your choice of the undersown variety. The wrong selection can have such a detrimental effect on the maize crop that you’ll completely wipe out any benefit you’ve gained from retaining soil nitrogen,” he warned.

Undersowing maize

“The agronomist explained that maize if often thought of as a rather robust crop, but it is surprisingly vulnerable in its early growth stages.

"Undersowing with a variety that’s overly competitive can have a deleterious effect on final yield, so anything you’ve gained from nitrate retention and winter grazing might be wiped out by the depressed yield. You’re robbing Peter to pay Paul," Bacon stated.

But can such an approach work under Irish conditions?

“We are not just there yet,” commented Maizetech’s John Foley.

“In the first instance, the vast majority of maize crops established in Ireland are sown out under plastic.

“In addition, weed control is very much a post emergence-related challenge.”

Significantly, Foley does see the potential to undersow grass into established forge maize crops in Ireland. But this may be about to change.

“Maize will always be the primary crop that is grown here. So, in theory, grass seed could be broadcast into an existing crop, once it is about knee high in term of its height.

“New compostable maize films are being brought to market at the present time.

“They have the added advantage of decomposing when maize crops are about seven to eight weeks established.

“And, under those circumstances, it would be more than feasible to undersow grass within an existing maize crop.”