12 June 1998

Undersown maize being tried on site

SOWING Italian ryegrass under a maize crop, before it reaches the 10 leaf stage, could cut pollution risks and provide valuable forage during the five months the field would otherwise be bare.

Maize Growers Association director of operations, John Morgan, says undersown maize will be part of its regional demonstration sites this year, and on the MGA demonstration at the National Forage Maize site at CEDAR, Reading.

"All maize growers should consider catch cropping to reduce pollution risks, even if the crop is then ploughed under."

But forage produced from undersown grass can be valuable, possibly producing 1.3t/ha (0.5t/acre) of dry matter at a cost of just £18/t DM. Cost of establishment is estimated at £24.50/ha (£10/acre) for one pass of the field to broadcast seed sown at 12kg/ha (4.9kg/acre).

But precise guidelines for establishing grass under maize cannot be given because growers have not had enough experience and individual field conditions will also vary, he stresses.

"Undersown ryegrass is a catch crop, so it should not compete with the maize for moisture and nutrients, potentially causing a reduction in maize silage yield."

Italian ryegrass seed will be sown on the CEDAR maize plots when maize is at the eight to 10 leaf stage, because there is less risk of competition once maize reaches this stage.

"Sowing any earlier would also leave a shorter gap between atrazine herbicide applications and grass establishment. Atrazine takes time to break down in the soil and establishment is more successful when less of it is left in the soil.

"The aim is for good grass seed germination, with the resulting seedlings surviving in the micro-climate created by the maize canopy. Grass seedlings should remain spindly and yellow under the maize and grow on following maize harvest in the autumn."

Catch crops of grass should be used for spring grazing. Taking the grass off late or as silage may reduce the moisture available to the following maize crop.

&#8226 The National Maize Forage Day – including protein crops – is on Thur, Sept 3. It is sponsored by Midland Bank, CEDARand FARMERSWEEKLY.