Rice Farming

Although remote sensing and the accompanying variable-rate application of chemicals are taking off in cotton, they’re still in their infancy in rice.

Researchers are currently trying to determine whether the technology, which is used in cotton and other crops, has a place in rice. The technology involves measuring how much infrared and near-infrared light plants reflect to determine variability in plant health and vigor.

In cotton, growers are using remote sensing to guide variable-rate applications of mid-season plant growth regulators, such as Pix, as well as fertilizer, insecticide and end-of-season defoliants.

Another hurdle, which recently was overcome, was developing affordable variable-rate liquid application equipment for airplanes, says Matt Peterson, director of operations for InTime Inc., a precision agriculture product and service provider in Cleveland, Miss.

Unlike cotton that is irrigated intermittently, rice is permanently flooded in mid-season, typically eliminating ground applications of liquid products, such as fungicides.

“It’s going to take the increase of variable-rate aerial application equipment being available to the rice producers before they realize the true benefit of variable-rate technology,” Peterson says. “Everybody sees the benefits of [remote sensing]. They know what the imaging can do.”

Once that occurs, Peterson sees several applications in rice, such as determining crop nitrogen needs, identifying disease and weed outbreaks before they become severe, and checking on water distribution uniformity, to name a few.

Moving variable-rate to the air
Del Norte and Satloc, two manufacturers of aerial application equipment, earlier this year released new variable-rate controllers for airplanes. Most of the units sold so far have gone into planes serving cotton growers.

Satloc Inc. of Phoenix, Ariz., early this year unveiled the AerialACE, a variable-rate controller that sells for less than $5,000. It allows applicators to apply either a constant rate of liquids across a field or vary the rate, based on a prescription, says John Bohlke, Satloc product market manager.

“There had been different types of flow control systems prior to this, but they were very expensive and they didn’t do variable rate too well,” Bohlke says. “That’s where the AerialACE fits in.”

A fit in rice?
Despite the lack of variable-rate aerial application equipment in the field, some people are still giving remote sensing a look in rice.

“A lot of people are looking at it just to see how their crop is doing and the relative differences,” Peterson says. “It’s not so much targeting applications but is my crop uniform or not.”

Allen Wrather, a professor in the University of Missouri’s plant science unit in Portageville, Mo., for the past two seasons has been studying the technology to see whether it has applications in rice.

With only one year of data so far from his small-plot trials, he’s hesitant to make any predictions. But he says he plans to continue the research in 2005.

“We are in the initial experimental stages to determine if remote images can predict nitrogen needs of mid-season rice and stress due to disease,” Wrather says. “We can’t say right now whether or not it will be useful. That is what we are trying to determine.

“They’ve been working with this in cotton for the last 10 years, and it’s just getting to the point where it’s taking off. We have a ways to go.”

Some challenges ahead
Tim Walker, a Mississippi State University assistant research professor, has only one year of experience with remote sensing in rice under his belt. Two areas he’s investigating involve mid-season nitrogen and fungicide applications.

“It may be that the technology is here to sense differences in the vegetation, but do we have technology in our spray sensors to make a variable-rate application from a plane going 130 mph?” says Walker, who’s based at the Delta Research and Extension Center in Stoneville, Miss. “There are definitely some challenges, and we have work to do. But that’s what research is all about.”

In fields infested with sheath blight, for example, the disease isn’t spread evenly throughout the field. Instead, it tends to be clustered.

“If we could just treat a portion of the field with a fungicide, it would be much more economical than treating the entire field,” Walker says. “If we could detect it from the air prior to a consultant seeing it with his naked eye and then apply a fungicide using variable rate, it might make economic sense.”

Walker plans to continue his research in 2005. Another technology he’s seeking more information on involves real-time “on-the-go” sensors being developed by Oklahoma State University for detecting nutrient variability in wheat. The OSU research also involves making simultaneous variable-rate nitrogen applications based on the nutrient variability.

From airplane image to variable-rate map
Every week during the season, planes flying for InTime take images, which are then available for viewing and downloading on the Internet within 24 hours. To access the information, InTime subscribers simply type in their individual password, and they can view any or all of their maps.

Each map costs $1.50 per acre, says Michael Seal, president of InTime Inc. Users pay for only the fields they want mapped, not for an entire image “scene” like the satellites shoot. And InTime users are not charged additional fees if they want to view or download the same maps several times.

The Web site also contains easy-to-use software to create scout maps and variable-rate prescription maps for both ground and aerial application equipment.

Using the scout mapping software, for example, users can take the red-hued aerial images and change the colors to something more relevant. Using the default colors, dense, vigorous vegetation could be represented by dark green; weak vegetation by brown.

Equipped with an iPaq or other personal digital assistant with GPS (global positioning system), consultants or agronomists can take the maps to the field to ground truth. Typically, they establish management zones, which involve areas of the field with the same map color.

With the field data in hand, they return to the office and the InTime Web site. A few clicks of the mouse, and they’re able to assign chemical or fertilizer rates to each management zone and create a variable-rate application map.

Contact Vicky Boyd at (209) 571-0414 or vlboyd@att.net.

What is remote sensing?

Remote sensing involves images captured either by an airplane or a satellite that are separated using filters to isolate given bandwidths. In the case of InTime, it’s an airplane flying at 12,000 feet above ground level. At that resolution, each pixel represents a 6-foot-by-6-foot block.

Vegetative biomass or density is represented by different shades of red. The images measure the amount of infrared and near-infrared light waves reflected or absorbed. Lush, healthy plants reflect more near-IR light wavelengths and absorb more red light wavelengths than weak or stressed plants.

And the opposite is also true—weak or stressed plants reflect less near-IR light and reflect more light in the red wavelengths. Because the images also pick up subtle variations in plant vigor typically not discernable by the human eye, they can alert growers and scouts to small problems, such as a disease outbreak, before they’ve grown out of hand.

The images also are coupled with GPS (global positioning system) coordinates, so a scout can take the map, go to the field and find the same location.

Eye in the sky Researchers explore remote sensing’s fit for rice
By Vicky Boyd Editor
Although remote sensing and the accompanying variable-rate application of chemicals are taking off in cotton, they’re still in their infancy in rice. Researchers are currently trying to determine whether the technology, which is used in cotton and other crops, has a place in rice. The technology involves measuring how much infrared and near-infrared light plants reflect to determine variability in plant health and vigor. In cotton, growers are using remote sensing to guide variable-rate applications of mid-season plant growth regulators, such as Pix, as well as fertilizer, insecticide and end-of-season defoliants. Another hurdle, which recently was overcome, was developing affordable variable-rate liquid application equipment for airplanes, says Matt Peterson, director of operations for InTime Inc., a precision agriculture product and service provider in Cleveland, Miss. Unlike cotton that is irrigated intermittently, rice is permanently flooded in mid-season, typically eliminating ground applications of liquid products, such as fungicides. “It’s going to take the increase of variable-rate aerial application equipment being available to the rice producers before they realize the true benefit of variable-rate technology,” Peterson says. “Everybody sees the benefits of [remote sensing]. They know what the imaging can do.” Once that occurs, Peterson sees several applications in rice, such as determining crop nitrogen needs, identifying disease and weed outbreaks before they become severe, and checking on water distribution uniformity, to name a few. Moving variable-rate to the air Del Norte and Satloc, two manufacturers of aerial application equipment, earlier this year released new variable-rate controllers for airplanes. Most of the units sold so far have gone into planes serving cotton growers. Satloc Inc. of Phoenix, Ariz., early this year unveiled the AerialACE, a variable-rate controller that sells for less than $5,000. It allows applicators to apply either a constant rate of liquids across a field or vary the rate, based on a prescription, says John Bohlke, Satloc product market manager. “There had been different types of flow control systems prior to this, but they were very expensive and they didn’t do variable rate too well,” Bohlke says. “That’s where the AerialACE fits in.” A fit in rice? Despite the lack of variable-rate aerial application equipment in the field, some people are still giving remote sensing a look in rice. “A lot of people are looking at it just to see how their crop is doing and the relative differences,” Peterson says. “It’s not so much targeting applications but is my crop uniform or not.” Allen Wrather, a professor in the University of Missouri’s plant science unit in Portageville, Mo., for the past two seasons has been studying the technology to see whether it has applications in rice. With only one year of data so far from his small-plot trials, he’s hesitant to make any predictions. But he says he plans to continue the research in 2005. “We are in the initial experimental stages to determine if remote images can predict nitrogen needs of mid-season rice and stress due to disease,” Wrather says. “We can’t say right now whether or not it will be useful. That is what we are trying to determine. “They’ve been working with this in cotton for the last 10 years, and it’s just getting to the point where it’s taking off. We have a ways to go.” Some challenges ahead Tim Walker, a Mississippi State University assistant research professor, has only one year of experience with remote sensing in rice under his belt. Two areas he’s investigating involve mid-season nitrogen and fungicide applications. “It may be that the technology is here to sense differences in the vegetation, but do we have technology in our spray sensors to make a variable-rate application from a plane going 130 mph?” says Walker, who’s based at the Delta Research and Extension Center in Stoneville, Miss. “There are definitely some challenges, and we have work to do. But that’s what research is all about.” In fields infested with sheath blight, for example, the disease isn’t spread evenly throughout the field. Instead, it tends to be clustered. “If we could just treat a portion of the field with a fungicide, it would be much more economical than treating the entire field,” Walker says. “If we could detect it from the air prior to a consultant seeing it with his naked eye and then apply a fungicide using variable rate, it might make economic sense.” Walker plans to continue his research in 2005. Another technology he’s seeking more information on involves real-time “on-the-go” sensors being developed by Oklahoma State University for detecting nutrient variability in wheat. The OSU research also involves making simultaneous variable-rate nitrogen applications based on the nutrient variability. From airplane image to variable-rate map Every week during the season, planes flying for InTime take images, which are then available for viewing and downloading on the Internet within 24 hours. To access the information, InTime subscribers simply type in their individual password, and they can view any or all of their maps. Each map costs $1.50 per acre, says Michael Seal, president of InTime Inc. Users pay for only the fields they want mapped, not for an entire image “scene” like the satellites shoot. And InTime users are not charged additional fees if they want to view or download the same maps several times. The Web site also contains easy-to-use software to create scout maps and variable-rate prescription maps for both ground and aerial application equipment. Using the scout mapping software, for example, users can take the red-hued aerial images and change the colors to something more relevant. Using the default colors, dense, vigorous vegetation could be represented by dark green; weak vegetation by brown. Equipped with an iPaq or other personal digital assistant with GPS (global positioning system), consultants or agronomists can take the maps to the field to ground truth. Typically, they establish management zones, which involve areas of the field with the same map color. With the field data in hand, they return to the office and the InTime Web site. A few clicks of the mouse, and they’re able to assign chemical or fertilizer rates to each management zone and create a variable-rate application map. Contact Vicky Boyd at (209) 571-0414 or vlboyd@att.net. What is remote sensing? Remote sensing involves images captured either by an airplane or a satellite that are separated using filters to isolate given bandwidths. In the case of InTime, it’s an airplane flying at 12,000 feet above ground level. At that resolution, each pixel represents a 6-foot-by-6-foot block. Vegetative biomass or density is represented by different shades of red. The images measure the amount of infrared and near-infrared light waves reflected or absorbed. Lush, healthy plants reflect more near-IR light wavelengths and absorb more red light wavelengths than weak or stressed plants. And the opposite is also true—weak or stressed plants reflect less near-IR light and reflect more light in the red wavelengths. Because the images also pick up subtle variations in plant vigor typically not discernable by the human eye, they can alert growers and scouts to small problems, such as a disease outbreak, before they’ve grown out of hand. The images also are coupled with GPS (global positioning system) coordinates, so a scout can take the map, go to the field and find the same location.
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