Rapid-growing maize ready to be undersown
By Marianne Curtis
MAIZE may have gone in late this year, but rapid growth since planting means those planning to undersow should plant grass no more than a week later than usual, says ADAS Bridgets agronomist Martin Froment.
"The critical time for undersowing is just before the maize canopy closes. Recent wet and sufficiently warm weather means late-sown maize has come up quickly, reaching the four-leaf stage within 10 days."
Undersowing too early means grass will compete with the maize crop, whereas sowing too late allows insufficient time for grass to establish before the maize canopy closes.
"This year undersowing may be delayed by a week, meaning it takes place in mid to late June," says Mr Froment.
Leaving enough time between atrazine application and sowing is also important, he adds. "Allow four to six weeks after using atrazine before undersowing, otherwise grass will be killed."
Grass variety is not critical, but Italian ryegrasses do tend to be cheaper. They also provide early bite, says Angus Golightly of the Maize Growers Association.
"It is not advisable to graze undersown grass in the autumn, but a producer in Oxon began grazing on Jan, 22 this year and managed two grazing cycles before grass was ploughed in for the following maize crop."
Mounting pressure from the Environment Agency is another reason why producers should consider undersowing, says Mr Golightly.
"There is concern from the Environment Agency about water and soil run off between maize crops polluting rivers. Unless we work with them to reduce these concerns, its rules could overtake us.
"Research from the Institute of Grassland and Environmental Research shows a 20-fold reduction in run-off over the winter period from maize crops undersown with grass."
Undersowing other crops such as linseed is also under discussion by MGA, but Mr Golightly questions whether this will be successful.
"In theory linseed may provide a protein source to balance the high starch content of maize. However, harvesting when both crops are ready is tricky and one crop may compromise productivity of the other." *
• Sow before maize canopy closes.
• Avoid competition with maize.
Maize is growing fast despite late drilling, so only delay undersowing grass until mid-June, says Martin Froment (left).