yield
Choice vital to maximising
yield
Selecting the right maize
variety for your farm can
boost margins by £90/ha.
Emma Penny reports
TOO many maize growers are sacrificing yield by selecting varieties which are earlier than the optimum on their farms.
Better variety choice would increase yields, reducing the area of maize which has to be grown on-farm, explains NIABs head of forage crops Jim McVittie.
"Maize has to be harvested at 30-32% to make good silage. According to some of our trials, cutting a crop on Sept 15 reduces yields by 8% – about 1t/ha. Thats a loss of about £90/ha.
"Selecting the right variety will reduce losses, or means producers could grow a smaller area to obtain the same tonnage," stresses Dr McVittie.
He advises considering your farms situation. "The Descriptive List covers the whole of England and Wales. Consequently, some varieties are very suitable for some areas and unsuited to others.
"Consider the potential of your maize field to produce silage of the correct dry matter and at the ideal harvest date."
Factors influencing this include soil type and conditions, height above sea level, aspect and which area of the country you are in.
Dr McVittie says that this should be given serious consideration, even in mainstream maize areas. "Some producers are growing varieties which are too early, and are therefore not getting the maximum benefit."
He urges growers not to get stuck in the trap of choosing an early variety where conditions are suited for later harvest.
"Although I cant criticise producers who want their maize in early, later maturing variety will obviously have longer to grow, and therefore more time to accumulate yield. Early maturity doesnt come free – you have to pay for it."
He warns that growers regularly harvesting in mid-September are losing yield. Maize continues to accumulate DM until late September, after which light intensity reduces and so DM accumulation slows.
Once growers have decided which maturity group to choose from, selection isnt so daunting. "Then you are restricted to five or six varieties, so its a choice between older varieties, which will have a proven reliability, or new, higher yielding varieties."
But for producers in marginal maize areas, he says that there is no option but to select an early variety. "There are four points to consider when selecting a variety in a marginal area – what you have grown in the past, NIAB maturity rating, harvest date, and DM content or cob ripeness."
He recommends choosing a variety with good early vigour. "When maize germinates it tends to sit and look yellow for about a month and then starts to grow. A variety with good early vigour will come out of this yellow stage more quickly – an important factor in marginal areas."
Dr McVittie also advises deciding whether maize is being grown for its nutrient value or for its bulk.
In mainstream areas, where nutrient value – maximum starch yield – tends to be the aim, a high cob ripeness figure is vital.
Digestibility
But in marginal areas, where it may not be possible to get high starch levels, maize will still help to increase intakes and maximise production from forage, and it will make sense to consider whole plant digestibility rather than starch content.
Digestibility is strongly correlated with intake; highly digestible maize spends less time in the rumen, meaning cows can eat more, so increasing intake.
According to Dr McVittie, digestibility of varieties on the Descriptive List varies from 6.7-7.2, equating to a 67-72% range.
"This doesnt seem like much of a difference, but its reasonable to assume that digestibility and intake figures for grass are much the same for maize, so a 1% rise in digestibility will increase output by 5%. But that benefit will only be seen where cows are challenged with forage and do not have a high concentrate intake." *
VARIETY SELECTION
• Appropriate maturity.
• Consider farm potential.
• Yield or starch required.
NIABs Jim McVittie: Selecting the right variety will reduce losses.