Technology | Spring 2009
Go big or go fast?
By Scott Garvey
Should you go just a little faster to stretch the performance of your sprayer? And if it's possible to speed up, does it make sense to scrimp on boom width to save a few dollars on the price of a new sprayer?
With ever-increasing pressure to cover more acres per season, these are valid questions. But don't rely on higher spraying speeds as a matter of routine. They come at a cost, say the experts.
“On the whole, lower speeds are better. Travel as slowly as you can afford to, given your workload,” says Tom Wolf of Agriculture and Agri-Food Canada's Saskatoon research centre. Going faster to compensate for narrower booms is counterproductive.
“Given the choice, opt for boom width over travel speed to increase your capacity,” adds Wolf. As sprayer speed increases, it gets tougher to achieve good herbicide coverage. For example, penetration into a mature crop canopy diminishes with speed. Orienting nozzle tips straight down, along with lower travel speeds, brings the best results here. But in general, pointing nozzles slightly forward works best for most herbicide applications.
A higher travel speed also generates more dust that can interfere with water droplets behind the sprayer. High speeds create other potential problems, too. “With a tractor (and pull-type sprayer) you can get kind of a burn in behind you. It creates kind of a venturi effect,” says Dale Gryba, a grain grower at Gilbert Plains, MB. After switching to a self-propelled, high-clearance sprayer, he hasn't noticed the same problem. His high-clearance SP machine works better than a pull-type at higher speeds.
But Gryba finds the biggest impediment to good application is usually weather rather than equipment. “Every day it's a trade-off. It's seldom a perfect day. Losing efficiency because of speed is one of many factors to consider,” he says. Often, just getting the job done becomes the objective. “A poor job beats no job at all,” he adds.
