2 February 1996

allow roots to penetrate

MAIZE plants are deep rooting and can survive drought stress but only when the seed-bed is well prepared, says Maize Growers Association agronomist Simon Draper.

The plant has extensive root systems that can penetrate soil to a depth of 1.2m (4ft). This means it can use nutrients and moisture reserves deep in the soil as well as providing itself with adequate anchorage.

"Eliminating compaction is the main aim when creating the right seed-bed for maize to thrive. Crop failures in 1995 were caused generally by poor seed-beds," says Mr Draper. This was particularly where cultivations had not broken up pans which meant roots were unable to access moisture.

"For this reason the seedbed should be worked as little as possible," he says.

To tailor cultivation work to the needs of the bed, the first step is to dig a pit to assess the soil profile.

From this any cultivation pans, or panning from previous grass swards and their depth will be visible. When not redressed, stunting of the plant will occur and cob quality and yields will be affected severely.

"Setting the depth of the subsoiler is by trial and error. Set the subsoiler at the pan depth and make a trial run. Dig a pit and assess the extent to which the pan has been broken up," says Mr Draper.

"If a mole channel has been created beneath the pan, raise the subsoiler depth until it fractures the pan. Then set the subsoiler legs apart at a distance equating to twice the working depth," he says.

Subsoiling should preferably be carried out in dry soil in September so that the compacted soil shatters and winter frosts can further break down soil. But where slurry and/or FYM have been applied during the winter subsoiling in the spring will be needed to break up compaction caused by tractor and spreader.

"If drilling time is approaching and conditions are wet any wheelings could be taken out with a chisel plough/power harrow if they are not too deep. If, however, wheelings are 8in to 9in deep they should be subsoiled and clods power harrowed," says Mr Draper.

"On light land subsoiling could take place immediately before drilling. Subsoiling after ploughing will require less tractor power.

"Otherwise plough, power harrow and drill into a seed-bed with a fine tilth to a depth of about 3in. This will allow moisture to be drawn up from the soil below by capillary action," he says. &#42