EARLY PLANTINGS yield bonus
LAST years trials at Dumfries have shown a difference of 2t DM/ha (0.8t DM/acre) between sowing on April 25 and May 10. "There is concern about frost damage to early sown crops. But there is a big yield penalty, and the cob index was also reduced from 70% to 56%, for the later sown crop – both under plastic," says Mr Hameleers.
On the question of whether or not to use plastic, which costs £250/ha (£101/acre), he advises producers try the crop for a year or two and then decide whether it is for them. "If the answer is yes, then consider plastic. It does look as if the potential is there if the farmer has decided that high quality maize is to be a major part of his forage crop. But he must claim the 10-day earlier sowing that plastic allows to get the benefit."
On that subject he urges maize growers to prepare well for the crop. "In marginal areas as soon as April 20 is reached be ready to go when the soil temperature is 8C at 10cm," he says.
He seeks more research using uncut plastic on the crop. "There do seem to be advantages in the early growth of maize. I dont know if the early benefit would be maintained to harvest. It does work for sweetcorn crops in the south but I would also be a bit worried about the public attitude to plastic flapping about all over a field," says Mr Hameleers.
"The main problem is that we do not have the right equipment to try whole plastic but I think it is a growing technique that deserves further investigation," he adds.
Trials at Dumfries have shown that some of the newer varieties have an erect leaf habit and give a positive dry matter yield and percentage response to increasing plant density.
Mr Hameleers reports that pushing plant density from 80,000 to 100,000/ha (32,300-40,500/acre) gave an extra 1.4t DM/ha (0.56t DM/acre) and the DM rose from 25.1 to 25.9%. In the control trial using non-erect leaf varieties, dry matter yield and percentage were both reduced by increasing plant populations. *
Producers must claim the 10-day earlier sowing that plastic allows to get the benefit.