Mark McNabb's guidance system for spraying ultra-narrow-row cotton is not high tech, but it gets the job done and saves money in seed costs, too.
The Somerville, Tenn., cotton producer spent about $750 to install electric solenoid clutches on two units of his UNR cotton planter, configured for 10-inch rows. The two units correspond to the tractor tire path on McNabb's UNR spray rigs.
The clutches are controlled by a switch in the tractor cab. When engaged during planting, the two units shut off, creating a guide path for his spray rigs to follow during the season. Each 20-inch wide path provides more than enough wiggle room for the rigs' 13-inch tires.
McNabb points out that he could have created the guide tracks by simply running over planted cotton. But seed costs are too high these days to waste that much cotton seed. By not planting cotton in the rows, McNabb figures, he reduced his seed costs by around 2.7 percent, or roughly $5,000 across his entire farm. That's nothing to sneeze at.
McNabb's sprayer is 60-feet wide and his planter is 20 feet wide, so the planter driver must lay down the guide tracks on every third pass (after initial setup). To minimize confusion, McNabb added two orange “dummy” lights to the switch box as memory aids for the driver. A third red light on the panel indicates that the clutches are engaged and creating a guide path.
As the operator begins the first pass after the guide tracks are laid down, he shuts off the red light and turns on the first orange light. As he begins the next pass, he flips on the second orange light. On the third pass, he flips off both orange lights and flips on the red light.
“No foam markers, no GPS needed,” said McNabb. “We were thinking about spending $18,000 for GPS guidance for two tractors, and I spent $750 for this system. It works perfectly, around curves, up hills. Our driver, David Thompson, did 1,650 acres and never missed a track.”