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Live Long and Revolutionize Forage Measuring

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Posted Oct. 22, 2013

Remote sensing for pastures seems like science fiction, but Noble researchers are taking today's technology where it has never gone before

Research Associate Josh Pittman drives a vehicle equipped with remote sensors to take forage measurements in a pasture.
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If you grew up in the days of "Star Trek," you know it wouldn't be long into any episode before Dr. McCoy would pull out a tricorder, wave it in the direction of Captain Kirk and rattle off a laundry list of medical readings. (Followed by, "I'm a doctor, not a [fill in the blank].")

The device was imaginary, but the concept couldn't be more real - people have long tried to perfect ways to gather data on subjects too inaccessible or too delicate to disturb. It's called remote sensing, and it is the idea behind military satellite surveillance or sonar that explores the depths of the ocean floor.

Remote sensing also provides vital information about human food crops like corn, soybeans or grapes - from harvest estimates to the levels of nitrogen or chlorophyll in the soil and leaves. Farmers have even used remote sensing for damage assessment after hailstorms. But, for all its potential, the technology has been largely overlooked for alfalfa, rye and other crops that sustain livestock. Remote sensing of forages hasn't been seen as feasible or necessary. So most remote sensing of pastureland is still done the old fashioned way: ranchers relying on their eyes and years of experience.

But scientists from Noble Research Institute are working to bring remote sensing of forages into the 21st century. Not only could remote sensing be a tool for developing hardier lines of plants, but perhaps one day the technology could also supplement a rancher's judgment with something scientifically precise. "To me, it's a no brainer to use it," said Josh Pittman, a research associate in the Noble Research Institute's forage agronomy laboratory and a Ph.D. candidate at Oklahoma State University (OSU).

At first glance, Pittman's remote sensing equipment looks a little like NASA meets the PGA: a TV-antenna-sized collection of instruments and cables mounted onto the front of a souped-up golf cart. As it drives along scanning the field, the sensors collect data about the chemical and physical properties of the plants around them. The sensors being used are all commercially available with some focused on similar applications in agriculture. The difference here is the use of multiple sensors in combination for a comprehensive on-the-go approach to data collection. This prototype system is unique to the Noble Research Institute, but was born from collaboration.

Bringing it all together
In late 2011, Associate Professor Twain Butler, Ph.D., became aware of the use of sonar as a forage biomass estimation instrument. Butler and Pittman began to examine the various types of instruments used in industry and academia for remote chemical analysis and dimension measurement.

No single unit seemed to fulfill the pair's desired outcome - a comprehensive data collection unit. Thus, the idea was born to use numerous sensors simultaneously.

Pittman contacted Drs. William Raun and Brian Arnall, both with the Department of Plant and Soil Sciences at OSU.

Both professors are well known for their expertise in spectral sensing applications in agriculture. In fact, Raun was one of the original individuals involved with development of the GreenSeeker variable rate application technology. This system scans a plant to determine the amount of nitrogen it needs and applies fertilizer based on those readings.

Raun suggested a joint set of research projects between OSU and Noble, as well as the development of a doctoral program for Pittman, focused on integrating numerous sensors into a single system.

From this joint effort, Butler and Pittman reviewed OSU's equipment to examine the utility and limitations Noble's project could encounter. The pair ran preliminary tests to evaluate what components to incorporate and which to leave out.

In February, Noble's efforts received a boost from an interaction with Jesse Poland, Ph.D., a research geneticist at Kansas State University. Poland provided counsel about certain components.

"Great ideas usually aren't born from one person," Pittman said. "In our case, we have a handful of outstanding minds, all supporting the development of this technology."

But what does this technology actually do?

In many ways, Pittman's remote sensing acts as a kind of CSI technology for plants. On television, detectives often use a device called a mass spectrometer.

The CSI team puts a sample into the machine, which then produces a big revelation about the evidence - this blood has sulfur in it! (And does so with remarkable speed; real life mass spectrometry takes much more time.)

Generally speaking, spectrometry identifies a substance by breaking down a sample into its basic molecular components and measuring how much of each component is present. It would be like an artist studying a shade of purple paint, trying to figure out the proportion of red, blue and other tints that created it.

The remote sensing Pittman uses is also an analysis of color; in this case, the wavelengths of light reflected off the leaves. Like mass spectrometry, it's a measurement based on the sum of its parts. If you're wondering what color says about the health of a field, think of an aerial view of a baseball diamond. One can tell a lot by the ratio of green grass in the infield and outfield to the brown, bare soil of the baseline.

In addition to the color of vegetation, remote sensing can also detect the location, temperature and height of plants. Ultimately, remote sensing systems record a huge volume of information for a relatively small area. The sensors on Pittman's prototype collect anywhere from 10 to 200 readings per second. The sheer volume of information creates a challenge for analysis after the fact, so resources at the Noble Research Institute were tapped for a solution. Yinbing Ge, a software developer in the Computing Services group at the Noble Research Institute, worked with Pittman to develop a unique piece of software which enables the information from all of the sensors to come together seamlessly.

Most importantly, the technology does all of this without cutting a single stem.

A second new system
Cutting is primarily the way scientists now measure a pasture's biomass or the amount of vegetation it contains (and one of the more important aspects to know about a field). Researcher Mark Newell, assistant professor at the Noble Research Institute and a small grains expert, set up a series of sample plots 5 feet wide and 10 feet long, shortly after his arrival at Noble in 2012. His research goal is to find plants that are better able to withstand and recover from drought, grazing and other stresses.

The traditional way to calculate biomass is to cut the field, allow the plants to dry and weigh the straw that remains. When the time came for Newell to collect data about his fields, he and his team began the process of clipping and drying. It was not long before he realized the process was way too slow. At the rate he was going, he wouldn't even be able to measure all of his experimental plots before the heat of summer started killing them off.

"After I got off the clipper, I thought, 'This isn't a good measurement of how much forage there is anyway,'" he said.

For one thing, a mowed field doesn't look like a grazed one. An animal will eat down to nubs no blade could ever touch. Clipping also doesn't allow scientists to measure the reseeding and regrowth time - because the crop you're trying to measure is gone. "Noble works on forage crops," he said. "If we can't accurately measure how much forage there is, that's not a good thing."

Newell is working on remote sensing technology that differs from Pittman's in at least one approach to design. Instead of a golf cart, Newell will use a tractor with a high axle and wheels that leave the field relatively undisturbed as it rolls through.

Once the scientists establish that the system works with good precision on the basics, they will start to see if it can obtain information now almost impossible to easily gather. Pittman envisions the day when ranchers can scan a field and use remote sensing to not only tell how much forage they've got, but what kinds of plants are in the mix, because each kind of crop has its own unique color signature.

And he says that science will soon come up with a smartphone app that could download the data from a remote sensor with a touch of the screen.

Still ideas in the making, but it would be the closest to a tricorder a rancher will ever get.