Environmental concern over popular maize
THE growing popularity of maize silage as a complementary forage for grass silage is leading to increased concern about the environmental implications, according to Scottish Agricultural College expert Arnoud Hameleers.
"Fields used for maize are fallow for six or seven months a year, and leaching, run-off, erosion and weed infestation can be a problem," he told an alternative forage conference at Dumfries (see p38).
He advocated the use of cover crops to counter those problems and to give winter grazing.
"Dutch research has shown that cover crops, sown after the maize harvest, can take up 30-70kg/ ha of nitrogen (24-56 units/acre) of which anything from 11 to 63% was used by the next maize crop if the cover was ploughed in," said Mr Hameleers. "In Britain, by the time the maize is harvested it is too late to establish a cover crop. It needs to be sown within the maize."
Intensive work on the subject is now under way at Crichton Royal Farm, with Italian ryegrass and stubble turnips being used as cover crops.
"We have a commercial trial in its second year using Italian ryegrass for winter grazing with sheep. The first year indicated herbage production of 1.5-2t DM/ha (0.6-0.8t DM/acre). In addition, less nitrogen will leach into ground water, there will be less soil erosion and there should be less soil compaction," said Mr Hameleers. *