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Farming by Satellite

Kentucky farmers are challenged by highly variable land. Slight differences in soil structure, elevation, slope, fertility, and drainage can frustrate a farmer trying to decide the correct types and quantities of seed, fertilizer and chemicals to apply to his crops.

To help these farmers optimize production, researchers at UK's College of Agriculture are experimenting with new and evolving "precision agriculture technologies." Precision agriculture helps producers recognize the variations of their land and helps them adjust inputs to the land to optimize production.

"Precision agriculture has been described by other researchers as doing the right thing, in the right place, at the right time," says Scott Shearer, biosystems and agricultural engineer at UK.

The focus of precision agriculture in Kentucky has been on grain production, and the key is the Global Positioning System. The Department of Defense developed this satellite system for the United States' security interests. Since then, civilians have used the satellites much more than the developers anticipated. Agricultural professionals have become one of the primary groups to use GPS.

An analogy might help to illustrate how this system works. You can estimate the distance between yourself and lightning by counting the seconds between the flash and the thunder. GPS is much the same; the difference is that GPS is a space-based navigation system. A satellite generates a radio signal that is transmitted to a GPS receiver on Earth. The receiver measures the time it takes that signal to travel from the satellite to the receiver. With four signals from separate satellites, the position can be accurately fixed.

"GPS allows farmers to locate their position in a field within less than one meter," Shearer says. "This means they can go back to that same spot, within one meter, time and time again. This is the beauty of the technology."

Before, when farmers applied chemicals or fertilizer, they made decisions on a field-average basis. They used to apply the same amount of fertilizer over the entire field. With new technology, this is no longer the case. Now, with high-tech farming, the farmer has a GPS receiver on his machinery, which is connected to a laptop or task computer that already has a stored database of optimal field requirements for fertilization. The computer runs a program that controls the mixing of nutrients—nitrogen, phosphorous and potassium—for fertilization and spreads them as needed as the farmer drives across the field. "With GPS, producers can identify the exact places that soil fertility changes," says Shearer.

He estimates that about one-fourth of Kentucky's grain producers are using some form of precision agriculture technology, and he expects that percentage to increase. Many farmers already are using sophisticated bookkeeping and accounting practices. Some have networked computers in their farm offices. So adding a technology such as precision agriculture does not seem like a stretch to them.

Precision agriculture research continues in the College of Agriculture. This fall, a new, indoor yield-monitoring test facility will open. It will be the most sophisticated facility of its kind in the world. Also, studies on electrical conductivity of the soil and the use of satellite imagery are ongoing. "The college will continue to work with producers to gain important real-life pictures of how precision agriculture is helping them be more efficient with their resources," Shearer says. "This technology has opened a whole new avenue for researchers and producers."

—Aimee D. Heald, Extension Communications Specialist