Finding out what makes for a top crop of maize

21 August 1998

Finding out what makes for a top crop of maize

Its been a difficult year for

many maize growers

throughout the country, but

there are lessons to learn

from it, says MGA

agronomist Simon Draper

WHY are some crops the best ever and others the poorest? Thats what discussion sessions at the National Forage Maize Day will attempt to discover.

We will be analysing management practices contributing to crop success and failure, hoping to learn from the mistakes.

Seed-bed conditions are one of the factors contributing to poor maize crops. Past experience and trial work means we know maize has poor rooting power and, therefore, little tolerance of soil compaction.

No-one would want to drill maize into wet, waterlogged soil, severely rutted by slurry tankers and compacted further by the weight of thousands of gallons of slurry.

But thats exactly what happened to a large proportion of the maize fields this year, and producers have had to cope with these seedbed conditions.

Some of the site at the National Forage Maize Day was in this condition, with a portion of the field flooded in late April.

Given these conditions, what are the best methods to reduce risk of damage and produce an acceptable crop of maize from an unpromising start.

Several areas need to be looked at if we are to learn from this season:

&#8226 Do we have to apply manure/slurry in the spring?

Applying large amounts of organic manure in spring can cause rutting and compaction. The resulting poor drainage will delay cultivation, drilling and harvest. Applying manure and slurry in autumn will reduce compaction risks.

&#8226 Successful subsoiling in extreme conditions.

Subsoiling in poor conditions can often do more harm than good. The soil can be too soft to allow the desired cracking, and so wet that a smeared layer is left under the surface. Subsoiler set-up and correct working depth is vital.

&#8226 Cultivating and seedbed preparation on waterlogged land.

Seed to soil contact is essential if maize is to germinate evenly and quickly. Firm, fine seedbeds, without compaction, are crucial. Getting it wrong may cause uneven or delayed germination, making harvest more difficult to manage.

&#8226 Variety choice for cold soil conditions.

Seeds planted in wet, cold soil will soon deteriorate. Early seed vigour is therefore important, helping the plant to get going. When conditions dictate late drilling, early maturing varieties should be used.

&#8226 Seed rates for poor conditions.

Lower seed rates will speed up maturity and allow poorer ground to produce higher starch levels when drilling late. However, in poor seedbeds, seed rates may need to be increased to compensate for low germination rates.

&#8226 Fertiliser and trace element requirements.

Maize needs nutrients that are easily available to its root system. Combining this requirement with the fact that organic manure breaks down more slowly in wet, cold conditions leads to the conclusion that correct fertilisation of maize grown in less than ideal conditions is vital. Fertiliser placement works well in poor seedbeds.

&#8226 Season-long weed control.

Weed competition is the last thing maize needs when attempting to survive. A little and often approach with the sprayer means it will be possible to tackle late flushes of weeds at least cost.

&#8226 Harvesting date for a slow growing crop.

This years harvest will be more difficult that usual. The extended drilling period will lead to a long and late harvest period. Compromising on maize harvest date may be necessary to maximise performance of following crops.

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