Orbiting Eye Will See Where Crops Need
Within 3 years, plans call for launching the first commercial satellites for
delivering crop information to farmers within a day after it's obtained. An
airplane-carried prototype already flies.
Countdown to the satellite launch began several years ago at an Agricultural
Research Service (ARS) laboratory in Weslaco, Texas. By summer 1999, four
satellites could eyeball every crop acre on Earth about twice a week, from 450
Data from their digital sensors will stream to two receiving stations on the
east and west coasts of the United States. From there, computer-processed
information will bounce off existing communications satellites and be snagged
by small satellite dishes linked to computers.
Farmers and farm advisers will view the images, print out color maps, run
statistical analysesand know exactly where on the farm to find the
problems the imagery has spotlighted.
The result should he a fast track to more informed, timely
decisionsand fewer regrets along the lines of "if I knew then what I
Agronomist John LeBoeuf, who is, with Fordel, Inc., in Mendota, California,
has used the airplane prototype since 1993. RESOURCE21, Inc., which will build
and launch the satellites, supplies the service to LeBoeuf and dozens of other
farm advisers and growers.
Fordel, a grower, packer, and shipper, has 5,000 owned or leased farm acres
in California. The plane-carried prototype of the Earth-orbiting system matches
over about 1,700 Fordel acres, mostly in cantaloupe and honeydew melons.
How does the information help? LeBoeuf ticks off some examples. "It
identifies areas getting too much or not enough irrigation water," he
says. "It lets us find nutrient deficiencies in the plants, so we can
remedy them. It points us straight to weed, nematode, aphid, and salt problems
that almost certainly would worse without attention. We also use the
information to pinpoint outbreaks of plant diseases such as Fusarium
wilt and vine decline." Is remote sensing something only big farms could
No," LeBoeuf says. "It's conceivable almost any size farm
would find useful. While farmers dont need to how the cameras and
satellites work, they do need to know that the system picks up changes before
the human eye can. It usually won't tell what the problem is, but it will tell
you where to find it. Then you apply your fanning knowledge and
Since 1985, ARS range scientist James H. Everitt and the learn he leads at
Weslacos Subtropical Agricultural Research Laboratory have assembled,
tested, and refined approaches to using remote sensing for monitoring crops and
the environment. Now they're seeing their high-tech dreams played out as part
of the everyday business of agriculture.
Most U.S. farms using RESOURCE21's system are in the 1,000- to 2,000-acre
range. Farm remote-sensing services are also available in other countries.
AGRO-SAT Consulting, Ltd., based in Berlin, Germany, uses the basic system
designed by Everitt's team to help German farmers with fertilizer
Until recently, turnaround time has been a chief drawback to using satellite
data on farms. It took days, weeks, or months to convert imagery to a form that
would have been usefulhad it reached farmers promptly.
Everitts team at Weslacos Remote Sensing Research Unit has long
been in the vanguard of developing remote sensing for farming using videotape
and low-flying planes. [See "Airborne VideoA Ride on ARS' Own Air
Force 1, Agricultural Research, February 1991, pp. 4-9.]
In 1991, Weslaco's setup used three video cameras attached to a portable
frame and placed so they peered at the land through a port in the plane's
floor. Each camera had a different light filternear-infrared, red, and
yellow-green. To human eyes, these video images would look black and while.
But studies by Everitt, remote-sensing specialist David Escobar, and others
at Weslaco had established spectral "signatures" for dozens of plant,
soil, and water conditionssuch as weeds, excess salts, and infestations
of plant diseases or insect peststhat showed up best on one or another of
the three filters.
The ARS team had also drawn on decades of research on interpreting satellite
and aircraft data by others at ARS as well as by the National Aeronautics and
Space Administration (NASA), universities, and private industry
From the three taped images, the ARS scientists produced composites, called
color infrared. They could interpret the colorsbased on known signatures.
They knew, for example, that a color infrared image of a sorghum field would
show healthy plants as magenta and areas with chlorosis, an iron deficiency, as
The ARS team made faster progress once higher resolution Super-VHS video
recorders became available in the late 1980's. "But," Everitt
recalls, "after a flight, we had to spend hours and hours converting
videotape images to digital format. Only than could we use the computer lo
break down the information into useful statistics."
Tuning in a Space Channel
George May knew about the Weslaco research. May is director of the Space
Remote Sensing Center, a part of the Institute for Technology Development
(ITD). The center is located on the Gulf of Mexico about 20 miles west of
"We went to Weslaco in 1991 to see how their aircraft-based video
system operated." May says, "But we wanted to get it up to space. You
can't cover the whole world from small airplanes."
A nonprofit company, Space Remote Sensing Center entered a cooperative
research and development agreement with ARS in 1988. The center receives some
funding from ARS, NASA, and private industry. But its goal was to stimulate
creation of a company that would generate its own financing to launch a space
"We put together a business plan and created RESOURCE21. To show
growers and industry that a space-based farm surveillance system would work, we
started with planesflying basically the same system Jim's team had
developed, except we used digital cameras," May explains.
The system's resolutionthe area shown by one bit, or pixel, of digital
informationis 10 meters, or one-fortieth of an acre, forming a square
with sides of 33 feet.
"In 1995, we had four planes flying the systems in six
statesCalifornia, Illinois, Indiana, Iowa, Missouri, and Nebraska,"
The customers get images before planting season and once a week thereafter.
A standard 11-by-17-inch color map printout shows four views of each land area,
which typically covers 160 acres.
One imagetaken before planting but used for reference all
seasonis the soil color map. It reflects soil differences, mainly in
organic matter and ability to hold moisture. Two vegetation maps show crop
growth; one discriminates 16 gradients in vegetation, from bare to dense. A
fourth map shows how much change has occurred since the time of the previous
"The maps and the computer generated statistical analyses let growers
make decisions based on comparisons of the same field from week to week and
year to year," May says.
When information points to problems in small areas, spot treatments can cut
needs for fertilizer, chemicals, and wateror ensure that a deficient area
gets the extra it may need.
"Since 1991, about 170 farmers have paid for the service and also
invested their time to help improve the products. This year, RESOURCE21 will
cover about 50,000 acres," he says. "We anticipate that several
hundred million dollars will be invested by the partners that make up
The current partners are Agrium Ltd., Boeing Commercial Space Company,
Farmland Industries, Inc., GTD Systems, Institute for Technology Development,
and Pioneer Hi-Bred International.
Next fall, RESOURCE21 plans to begin building five 1,200-pound,
solar-powered satellitesfour to launch, plus a spare. Each will grab a
wide swath of digital data during its several daily orbits.
And in Weslaco, research continues. "We're beginning to study a
12-digital-camera system," says Everitt. "Some bands, such as
mid-infrared and thermal infrared, are available from satellite. But
agricultural researchers need to find out how to interpret them in ways farmers
and others can use."
May notes that the number of cameras deployed on future satellites will
depend partly on the Weslaco experiments.
"The RESOURCE21 venture," says May, "coming about because of
the achievements of Everitt and his research team. will provide the United
States a capability that does not exist anywhere else in the world."
By Jim De Quattro, ARS.
Agricultural Research Laboratory, 2413 E. Highway H3, Weslaco TX
"Orbiting Eye Will See Where Crops Need Help" was published
in the April
1996 issue of Agricultural Research magazine.