Rice Farming

As the state of California expands restrictions on aerial herbicide applications, a growing number of growers are switching to ground rigs, and more recently, machines with rubber tires or tracks.

Although many of the growers who have gone to ground report good results, they say they’ve had to change their management practices.

And using ground rigs may not be for everybody. Fields with lighter or alkali soils or where growers can’t reflood quickly may not be suited for the application method.

“The biggest thing guys are going to have to consider is they are going to have to dry the fields down much more than they are accustomed to,” says Rick Geddes, a senior sales representative with Dow AgroSciences in Yuba City, Calif. “It’s going to have to be down to a light crust to support the application equipment. But you still want to have enough subsurface moisture to assure the weeds are still growing and not stressed.”

Using ground rigs to apply herbicides is not new, with growers first adopting the application methods when the California Department of Agriculture restricted aerial propanil applications in the 1990s. (Since then, the California Department of Pesticide Regulation has taken over enforcing pesticide laws.)

During the 2004 season, county agricultural commissioners banned aerial applications of Dow’s Clincher herbicide in Sutter County north of Sacramento, Calif. For the 2005 season, the agricultural commissioners have essentially banned any aerial application of Clincher anywhere in California’s rice belt because of concerns about drift onto neighboring permanent tree crops. Regiment can only be applied by ground in Sutter County.

While many growers were used to using steel-wheeled rigs to apply propanil, the rigs aren’t suitable for the early application window required by Clincher, Geddes says.

Clincher is typically applied when watergrass is at the one to four-leaf stage. “Steel wheels tear up the ground too much—there’s too much disruption in that early stage,” Geddes says.

Propanil, on the other hand, is applied 35 to 40 days after seeding. By then, the rice plants are large enough to support the steel wheels, and growers don’t experience as much rutting.

So many growers have looked at alternative ground-application equipment, with Steve Butler, president of the Sutter Basin Corp. near Robbins, Calif., being one.

Right on track
During the 2004 season, he used two rigs, each comprising a 400 cc four-wheel-drive ATV pulling a 100-gallon tank on rubber tracks equipped with a 30-foot spray boom. Although he had the two tanks on tracks specially built by PBM, the Chico-based company now builds a complete unit on tracks for about $7,500.

Butler equipped one of his two rigs with a GPS (global positioning system) guide bar, which would help the driver avoid overlapping or making skips in the spray pass. The first rig applied Clincher.

A second rig applying propanil followed either hours or a day later, following in the first rig’s tracks. The separate applications are needed because you can’t tankmix propanil and Clincher.

Butler drained his rice about 25 days after planting, waiting a week to 10 days to allow the surface to dry and just begin to crack before he put the rigs into the field.

With the two rigs together, he was able to spray between 150 to 200 acres during a 10-hour day, weather permitting. The actual acreage also varied, depending on whether the driver hit muddy patches.

Although the rigs temporarily knocked the rice plants down, Butler says they spring back once the water is applied one to five days later. The only damage he saw to the rice was where the four-wheelers got stuck in the mud, and the spinning wheels ripped up some plants.

“We didn’t have a lot of trouble,” Butler says. “If you have trouble with your wheels slipping and spinning, you just come back in a day or two.

Butler says he obtained satisfactory grass control with Clincher, but his sedge control wasn’t as good as he’d like with the propanil. Last year, he applied it in 10 gallons of water per acre—this year, he’ll increase it to 15 gallons per acre to get better coverage of the small sedges.

Based on last year’s results, Butler purchased a second GPS guide bar. That way, both rigs can apply Clincher simultaneously, then return a few days later to make the propanil application.

He’s also purchased rate controllers for both rigs that will maintain a set application rate, regardless of the speed.

Where the rubber meets the road
Steve Boggs has gone a slightly different route. The Colusa, Calif.-custom applicator has designed a spray rig based on a John Deere 5520 series tractor equipped with large floater tires, a 200-gallon spray tank and up to an 85-foot spray boom.

The rigs come equipped with a GPS guidance system and rate controller. He’s also designed a larger unit, featuring a John Deere 6400 series tractor and a 300-gallon spray tank.

Boggs, who has been using steel-wheeled spray rigs since the mid-1990s, used a flotation-tired unit last year on 30,000 acres of rice.

One of the benefits he’s seen with the flotation tires is they don’t leave the ruts and the berms on each side of the ruts like the steel wheels.

If you’ve got downed rice at harvest, the ruts can become an issue as the rice gets into the crevasses.

Compared to the 5.5 to 6 miles per hour you typically can drive with steel-wheeled rigs, the flotation-tired units cruise at 12 to 15 mph, more than doubling the acres you can treat in a day.

You can also use the flotation-tired units to spray other crops, such as processing tomatoes and wheat.

But don’t expect to get the same results just by putting some flotation tires on a tractor. Boggs spent more than year designing the unit to ensure the wide tires matched the tractor’s gear ratio. He has a proprietary purchase agreement with the tire’s manufacturer.

Surprisingly, a 5520 tractor-based rig has less soil compaction potential with 3.9 pounds of pressure per square inch compared to the ATV-based rig’s 4.1 pounds of pressure per square inch, he says.

And as Boggs points out, the units aren’t for every field. “You have to look at your conditions—the conditions of your fields, whether you can afford to drain your fields for rice spraying,” he says.

Fields with light or alkali soils, for example, may not support the rigs.

Hitting the ground running New application rigs help growers cope with herbicide restrictions
By Vicky Boyd Editor
As the state of California expands restrictions on aerial herbicide applications, a growing number of growers are switching to ground rigs, and more recently, machines with rubber tires or tracks. Although many of the growers who have gone to ground report good results, they say they’ve had to change their management practices. And using ground rigs may not be for everybody. Fields with lighter or alkali soils or where growers can’t reflood quickly may not be suited for the application method. “The biggest thing guys are going to have to consider is they are going to have to dry the fields down much more than they are accustomed to,” says Rick Geddes, a senior sales representative with Dow AgroSciences in Yuba City, Calif. “It’s going to have to be down to a light crust to support the application equipment. But you still want to have enough subsurface moisture to assure the weeds are still growing and not stressed.” Using ground rigs to apply herbicides is not new, with growers first adopting the application methods when the California Department of Agriculture restricted aerial propanil applications in the 1990s. (Since then, the California Department of Pesticide Regulation has taken over enforcing pesticide laws.) During the 2004 season, county agricultural commissioners banned aerial applications of Dow’s Clincher herbicide in Sutter County north of Sacramento, Calif. For the 2005 season, the agricultural commissioners have essentially banned any aerial application of Clincher anywhere in California’s rice belt because of concerns about drift onto neighboring permanent tree crops. Regiment can only be applied by ground in Sutter County. While many growers were used to using steel-wheeled rigs to apply propanil, the rigs aren’t suitable for the early application window required by Clincher, Geddes says. Clincher is typically applied when watergrass is at the one to four-leaf stage. “Steel wheels tear up the ground too much—there’s too much disruption in that early stage,” Geddes says. Propanil, on the other hand, is applied 35 to 40 days after seeding. By then, the rice plants are large enough to support the steel wheels, and growers don’t experience as much rutting. So many growers have looked at alternative ground-application equipment, with Steve Butler, president of the Sutter Basin Corp. near Robbins, Calif., being one. Right on track During the 2004 season, he used two rigs, each comprising a 400 cc four-wheel-drive ATV pulling a 100-gallon tank on rubber tracks equipped with a 30-foot spray boom. Although he had the two tanks on tracks specially built by PBM, the Chico-based company now builds a complete unit on tracks for about $7,500. Butler equipped one of his two rigs with a GPS (global positioning system) guide bar, which would help the driver avoid overlapping or making skips in the spray pass. The first rig applied Clincher. A second rig applying propanil followed either hours or a day later, following in the first rig’s tracks. The separate applications are needed because you can’t tankmix propanil and Clincher. Butler drained his rice about 25 days after planting, waiting a week to 10 days to allow the surface to dry and just begin to crack before he put the rigs into the field. With the two rigs together, he was able to spray between 150 to 200 acres during a 10-hour day, weather permitting. The actual acreage also varied, depending on whether the driver hit muddy patches. Although the rigs temporarily knocked the rice plants down, Butler says they spring back once the water is applied one to five days later. The only damage he saw to the rice was where the four-wheelers got stuck in the mud, and the spinning wheels ripped up some plants. “We didn’t have a lot of trouble,” Butler says. “If you have trouble with your wheels slipping and spinning, you just come back in a day or two. Butler says he obtained satisfactory grass control with Clincher, but his sedge control wasn’t as good as he’d like with the propanil. Last year, he applied it in 10 gallons of water per acre—this year, he’ll increase it to 15 gallons per acre to get better coverage of the small sedges. Based on last year’s results, Butler purchased a second GPS guide bar. That way, both rigs can apply Clincher simultaneously, then return a few days later to make the propanil application. He’s also purchased rate controllers for both rigs that will maintain a set application rate, regardless of the speed. Where the rubber meets the road Steve Boggs has gone a slightly different route. The Colusa, Calif.-custom applicator has designed a spray rig based on a John Deere 5520 series tractor equipped with large floater tires, a 200-gallon spray tank and up to an 85-foot spray boom. The rigs come equipped with a GPS guidance system and rate controller. He’s also designed a larger unit, featuring a John Deere 6400 series tractor and a 300-gallon spray tank. Boggs, who has been using steel-wheeled spray rigs since the mid-1990s, used a flotation-tired unit last year on 30,000 acres of rice. One of the benefits he’s seen with the flotation tires is they don’t leave the ruts and the berms on each side of the ruts like the steel wheels. If you’ve got downed rice at harvest, the ruts can become an issue as the rice gets into the crevasses. Compared to the 5.5 to 6 miles per hour you typically can drive with steel-wheeled rigs, the flotation-tired units cruise at 12 to 15 mph, more than doubling the acres you can treat in a day. You can also use the flotation-tired units to spray other crops, such as processing tomatoes and wheat. But don’t expect to get the same results just by putting some flotation tires on a tractor. Boggs spent more than year designing the unit to ensure the wide tires matched the tractor’s gear ratio. He has a proprietary purchase agreement with the tire’s manufacturer. Surprisingly, a 5520 tractor-based rig has less soil compaction potential with 3.9 pounds of pressure per square inch compared to the ATV-based rig’s 4.1 pounds of pressure per square inch, he says. And as Boggs points out, the units aren’t for every field. “You have to look at your conditions—the conditions of your fields, whether you can afford to drain your fields for rice spraying,” he says. Fields with light or alkali soils, for example, may not support the rigs.
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