19 March 1999

Giving best start in life

By Jessica Buss

PREPARE maize ground for drilling in spring with just one pass of cultivation equipment to get the crop off to a quick start and minimise compaction.

Gordon Spoor, Silsoe College, Beds, warns that any check in maize growth is serious, and the crops success depends on a good seed-bed.

When preparing a seed-bed avoid soil moisture loss, capping, compaction and poor drainage.

"Moisture loss is caused by excessive cultivation, capping occurs when the surface is too fine, and compaction is entirely from wheel traffic. Drainage is poor when there is a fine tilth over a coarse one," says Prof Spoor.

He says his ideal method for cultivating a maize field is to plough, or use deep tines, follow with a press and then power harrow once before drilling.

Most growers plough, either in autumn or spring, and when that ploughing is of poor quality it is difficult and costly to repair. Furrows should be tightly packed with a level surface and no cavities, he says.

Where fields have been autumn ploughed this can allow direct drilling, requiring no more than one spring operation even on difficult soils, he advises. But deep working can remove moisture from soils and brings up unwanted clods, he warns.

When direct drilling, he recommends avoiding excess penetration by setting discs carefully, using specialist machinery and not setting spring tines too deep.

On light soils that are ploughed in spring it should be possible to use a plough press and then drill. "But on heavier soils you may need to work deeper after the plough, but with good depth control to avoid going too far down," says Prof Spoor.

Even though you cover wheelings they are still there, he says. Reducing the number of passes by combining operations will help cut wheelings and, therefore, compaction.

Power harrowing after ploughing can create a good seed-bed. But the first pass into undisturbed plough furrows does most good; a second pass is less effective and may increase compaction.

"Adjust forward speed to get as close to a perfect seed-bed as possible in that first pass," he advises.

Wheelings made on each pass are influenced by tyre pressure, which can often be reduced to half the normal rate to cut compaction. Pressure on the ground is never less than the tyre inflation and will depend on the tyres ply rating.

"Always operate at the lowest possible tyre pressure, but never too low for safety reasons."

Prof Spoor suggests a gauge should be used to check tyre pressures are appropriate for each operation. That includes checking front tyre pressures which can also cause compaction. Alternatively, buy small, low pressure tyres, which are inexpensive.

Avoid making a fine seed-bed over coarser material which will not drain well and can become waterlogged in wet weather. Also be aware that discs will create a pan at working depth after a number of passes, warns Prof Spoor.

SEED-BED PREPARATION

&#8226 Neat ploughing.

&#8226 One subsequent pass.

&#8226 Lower tyre pressures.