Gps Proves Useful Tool For Leopold Center Grazing Research

AMES, Iowa – While most people see cows when they look at a pasture, Iowa State animal scientist Jim Russell sees the potential for improving cattle production as well as a way to conserve soil and water.

For the past three years, Russell has been studying cattle preferences as part of a research project supported by the Leopold Center for Sustainable Agriculture. He used global positioning systems attached to cattle collars to track each animal’s movements within a pasture over two-week periods of time.
“We wanted to find out how much time cattle really were spending near waterways and if they were, why,” said Russell. “After three years, we noticed that they don’t spend nearly as much time in or near the water as people generally think.”
The location of cattle in relation to creeks or other sources of water is very important information for the Leopold Center’s grazing research program. It has been assumed that cattle in pasture-based systems are large contributors to the levels of sediment, nutrients and pathogens found in surface water.
Findings showed that the amount of time cattle spend in waterways varies according to specific pasture conditions. For example, size and shape are most important and smaller pastures generally mean more time in the water. But if all pastures are the same size, the shape will determine how long animals stay in the water. If all pastures are similar in size and shape, then shade placement becomes an important variable that influences more or less time in the water.
“In response to the shade, it seems pretty obvious, but with the different-sized pastures we had to begin with, we didn’t see any differences,” said Russell. “When we controlled for different variables, it was pretty easy to see that size and shape of the pasture can greatly reduce the risk of water contamination.”
The experiment called for recorded data on movements of two or three cows in eight different pastures on five cow-calf farms in the Rathbun Lake watershed area. Each cow wore a GPS collar for two weeks during the spring, summer and fall of 2007, 2008 and 2009. Temperature and humidity also were recorded.

One of the major obstacles of this project was finding several willing farmer cooperators. The amount of cattle handling was a turn-off for many producers.

“They were a little hesitant because of the amount of handling required,” Russell said. “We were limited by the two-week battery life on the GPS receivers in that respect. Several producers told us they would love to do it if we could put the collars on in May and take them off in September.”

Russell believes that cattle producers can take several steps right now from what he's learned through his research.

“Creating buffer strips between pastures, providing off-stream water sources or stable crossing points, or using rotational grazing are good places to start,” he said. “The size and shape of pastures does matter, and cattle don’t spend as much time in the water as we hypothesized so other factors may be contributing to the water quality, such as wildlife or even septic tank leakage. Sediment in the water is caused more by the hydrology than by cattle kicking it around.”

Russell said he will be collecting data from cattle at the ISU farm near Rhodes in central Iowa during the current grazing season. What has been learned from the project is included in a series of publications that Russell created entitled Guide to Managing Pasture Water. View the publications on the Leopold Center website at: (see Animal Management Forage).


This news release is from the Leopold Center for Sustainable Agriculture at Iowa State University. If you would like to add or change an address, or be removed from this list, please contact Laura Miller,

Leopold Center for Sustainable Agriculture
Iowa State University/209 Curtiss Hall
Ames, IA 50011-1050
(515) 294-3711; FAX: (515) 294-9696

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