Sunday, December 28, 2008

UW Ag students use satellite images to evaluate crop- & range-land

Source: UW Extension Service's press release
By: Steven L. Miller, Senior Editor
Date: 28 Dec 2008

Agriculture students in a University of Wyoming class used remote sensing information to analyze crop and rangeland they are either familiar with or farm and ranch upon. 

The class, taught by Ramesh Sivanpillai, remote sensing scientist with the Wyoming Geographic Information Science Center (WyGISC) in the College of Agriculture building, examined crop and pasture lands using satellite images obtained through WyomingView. 

WyomingView is a consortium, headed byWyGISC and the University of Wyoming, aimed at increasing opportunities for remote sensing through outreach, data distribution, education, training and research activities in Wyoming. WyomingView is part of AmericaView, which is funded by the U.S. Geological Survey (USGS). 

Student Vince Holton wanted to eye his crop land in northern Colorado and pasture he leases between Laramie and Cheyenne. He could not obtain free satellite images for his Colorado cropland for the years he was interested in, but images collected by Landsat satellites of his Wyoming pasture were available through WyomingView. 

He had a “prove it” attitude. “I wanted to see how it worked; if it actually showed what I had observed on the ground,” he said.  The images provide variations in light reflectance of vegetation, which can show levels of plant vigor. 

“That tells you if it’s real productive, dormant or dead,” said Holton, of Greely, Colo. “But you have to know what you are looking at. You can’t take somebody else’s place; not having been there, you only can guess. You still have to do the groundwork to know what you are looking at. It works slick on farm ground, but it works good on rangeland, too. But you need help on which satellite image to use and how to configure it so you get the right values. It’s not something you can jump on and pop it out.” 

Holton said he’d like to use remote sensing in future operations. “I’d like to get more advanced so I know what I’m doing,” he said. “I got enough out of it I sure could see a heckuva value, especially in farming.” 

Garrett Klein and his lab partner, Laramie Wigington, both of Pavillion, northwest of Riverton, used the class to look at center pivots on Klein’s family land near Fort Washakie. 

“We changed from flood irrigation to pivot irrigation in 1998,” said Klein. “I wanted to see if the crop yields were increasing or if helping improve the ground (fertility).” 

The project was of particular interest to both. “I grew up a half-mile away from the ground,” said Wiginton. “We worked on the same ground together since elementary school.” 

They examined Landsat images from July and August from 1998 to 2006. The software program illustrates crop vigor through the years. “It allows us to see if an area of the field is consistently good or consistently bad,” said Klein. 

Klein, familiar with the farm ground, said he remained a skeptic of the process while using the program. “So far, it’s been correct,” he said. 

In the satellite images, they were able to match the growth patterns observed in the barley and alfalfa fields and distinguish areas where barley grew well and poorly due to alkaline soil, said Sivanpillai. “However, Landsat images were less useful when portions of the field were covered with weeds. For smaller farms, they concluded that high-resolution imagery taken at right time of growing season could be more helpful.” 

Landsat images are useful for monitoring crop growth, although the information content are less than the images seen in programs such as Google Earth, Sivanpillai noted. Landsat images are updated every 16 days, and the USGS is planning to make the entire Landsat image archive (going back to early 1970s) free in a year or two, enabling everyone to use these applications for monitoring their agricultural lands.