11 September 1998

Crop yields up 20% with later maturing types

There was much to learn

about maize growing

techniques, variety choice

and feeding at last weeks

National Forage Maize Day.

Jessica Buss reports

WHEN producers are regularly harvesting maize in mid-September, choosing a later maturing variety could increase crop yield by up to 20%, says Jim McVittie of the National Institute of Agricultural Botany, Cambridge.

Dr McVittie told visitors at the National Forage Maize Day, held at CEDAR, Reading, Berks, that unless growers had good reason to complete harvest in mid-September, such as heavy, wet soils, many are missing out on yield potential by using the wrong variety which matures too early.

"Crop yield increases by 10% a week during the last two weeks of September. Growing a crop to harvest in late September could result in 20% more yield." But yield increases are unlikely to occur in October.

"As plants mature, sugars in the plant are transfered to the cob and turn to starch. But this process does little to increase total plant digestibility," he explained.

Whole-plant digestibility, therefore, stays constant during September, while total yield of digestible organic matter rises. Actual crop digestibility is a variety trait, results of which are available to MGA members.

Starch content usually rises from 15% to 32% during the main maturity period. But it is more important to harvest maize crops at 30-32% dry matter for optimum feed value. Later harvest means a later maturing variety will be required to avoid harvesting a crop which is too dry, he advised.

Crop dry matter will continue to increase by 2% a week in September and October. Selecting a variety for harvest two weeks later means choosing one which is 4% wetter than that now grown. All variety maturity groups on NIABs Forage Maize list are harvested on the same date. Producers can, therefore, select those with 4% less dry matter or a score of two less points on maturity rating than the current variety grown.

For example, where you are growing Nancis but want to harvest two weeks later, consider Melody, Lincoln and Facet. Then check each of these varieties for other traits such as standability and cob ripeness to ensure they suit your growing conditions and intended crop use.

Harvest for the different maturity groups listed by NIAB has generally been on the same date, so there is little difference in % dry matter scores between the groups. This makes it possible to select from a later maturing group using this method, he added.

VARIETY SELECTION

&#8226 Aim to harvest late Sept.

&#8226 Yield increase 10% a week.

&#8226 DM increases 2% a week.

Choosing a late-maturing variety would increase maize crop yield, NIABs Jim McVittie told visitors to the National Forage Maize Day.