First-timers using crop sensor systems for variable-rate nitrogen (N) sidedress applications often are surprised by pokey field speeds needed to apply higher N rates with traditional spray nozzles.

They soon tire of honks from rate controllers warning them to slow down to achieve application goals, says Russ Linhart, GreenSeeker/WeedSeeker specialist for Trimble.

“You cannot use traditional nozzles effectively if you want to sidedress N in corn at 12 to 14 mph with a self-propelled sprayer,” Linhart says. “You have to cut field speeds and reduce acres per hour with traditional nozzles. The lack of field capacity ultimately drives many growers to change nozzles. It’s all about speed.”

Linhart says it is not unusual for active crop sensor systems — GreenSeeker from Trimble (www.trimble.com/agriculture); OptRx from AgLeader (www.agleader.com); and CropSpec from Topcon (www.topconpa.com) — to call for sidedress N rate swings of 30 gal./acre in corn. Traditional nozzles are able to double output (by quadrupling pressure), but often that rate range is not wide enough unless you are willing to slow down to make heavier applications.

The solution: Switch to nozzles designed for variable rates.

Variable-rate nozzles solve the rate-range challenge by using pressure-activated springs to vary orifice sizes. This allows rates to flex as much as 10X (10 to 100 gal./acre, for example) as pressure roughly triples, depending on the nozzle.

VeriFlow

The Hi-VeriFlow 1 nozzle from SprayTarget can deliver 3.5 to 39.3 gal./acre at 12 mph with a 30-in. nozzle spacing. The low rate is delivered at a pressure of 20 pounds per square inch (psi) and the high rate at 70 psi. The Hi-VeriFlow 1 is recommended for fertilizer applications with self-propelled sprayers. The VeriFlow 1, a lower-rate-range nozzle, is recommended for use with sidedress toolbars. Other models are available for planters, according to Qui Bui, SprayTarget president.

Both streaming nozzles can be converted to apply spray patterns needed for herbicides, insecticides and other pesticides. Compared to conventional nozzles, which must be disassembled for cleaning, blocked VeriFlow series nozzles can be automatically flushed by boosting pressure to 50 psi.

The suggested retail price for the VeriFlow 1 is $43/nozzle. The Hi-VeriFlow 1 nozzle retails for $46. For more information, contact SprayTarget, Dept. FIN, Box 177, Rosemount, MN 55068, 651/485-2410, or visit www.spraytarget.com.

TurboDrop

The TurboDrop variable-rate fertilizer nozzle from Greenleaf Technologies is available in three rate ranges. The TDVRF 015 delivers between 4.5 and 20 gal./acre at 8 mph (based on 20-in. nozzle spacing) at pressures ranging from 20 to 140 psi. The TDVRF 02 delivers 5.6 to 30 gal./acre at 8 mph, while the TDVRF 03 has a rate range of 8.2 to 40 gal./acre at 8 mph and 5.4 to 27.2 gal./acre at 12 mph.

The TurboDrop fertilizer nozzles deliver fertilizer through six streaming orifices, single and double flat fans or a hose barb. In addition to use on toolbars and self-propelled sprayers, they also are used on planters, according to Will Smart, Greenleaf Technologies president.

The suggested retail price of the TurboDrop variable-rate fertilizer nozzle is $38.50, with a street price as low as $23. For more information, contact Greenleaf Technologies, Dept. FIN, Box 1767, Covington, LA 70434, 800/881-4832, or visit www.turbodrop.com.