LOOKING UP: Robin Goymour has been keeping an eye on the sky.PHOTO/BEVAN CONLEY 010915WCBRCWEA02
LOOKING UP: Robin Goymour has been keeping an eye on the sky.PHOTO/BEVAN CONLEY 010915WCBRCWEA02
The effect of jet vapour trails on the way plants grow needs more research, Robin Goymour says.
"I see too many crops that must be disappointments to the people who put them in."
The 87-year-old from Rata has been growing plants and watching the weather all his working life. For30 years he worked in James Bull's Hunterville potato business, learning as it expanded.
He's been photographing the way vapour trails spread into cloud and measuring the resulting changes in light with a meter.
On January 19 this year, he said light didn't come up to optimum levels for plant growth until nearly 9am. By that time the temperature was high enough to shut down clover and pasture plants.
On another day the cloud begun by vapour trails had formed "a virtual heat shield" over Wanganui by evening.
He's convinced the extra cloud cover reduces light for photosynthesis - the process plants use to convert sunlight to food. And he thinks it also traps more heat, which can make conditions too hot for growth.
Jet vapour trails only form in cold, moist air conditions. He said planes could choose to fly higher or lower, or on different routes to avoid creating them.
It worries him that farm consultants and the National Institute of Water and Atmospheric Research (Niwa) advise farmers on fertiliser and irrigation without taking the effect of vapour trails into account.
"You see urea going up the road and you know that the ground temperature isn't good enough."
Farmers could be over-fertilising, or applying water at the wrong time, he said.
"All I really think should be happening is Niwa should be measuring the varying light effects created by aircraft. They say they're going to give all this advice to farmers, but they don't have enough information."
But three Niwa scientists, consulted last week, say jet traffic over New Zealand is low compared to that over the US or Europe. They also say it dissipates quickly under prevailing strong westerly winds.
They haven't been funded to research the effect of vapour trails and didn't think it would be considered important enough for public funding.
