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Texas Agriculture Archive

March 1, 2002

Tech Tips
Variable-rate seeding: A good fit?

Now that some of the "new" has worn off of global positioning systems (GPS) technology, growers have stopped asking "What'll they think of next," and have started asking "What'll this cost me and when will I see a return?" Receiving special attention from efficiency-minded producers are implements using variable-rate technology, specifically map-based, variable-rate seeding systems that allow computer-controlled, on-the-go changes in seeding rates.

Though the specifics of variable-rate seeding systems differ between manufacturers, most systems use several common components. A GPS receiver mounts on the roof of the tractor or combine, and is used to plot the location of the equipment. During harvesting operations, the receiver may work in conjunction with a yield monitor to plot a yield map of a particular field. Before planting the next season, that yield information, along with other data, can be used to set up a seeding-rate prescription on a data card. The data card is then placed in the processor on board the tractor during planting. The processor controls the variable-rate drive on the planter, putting down less seed in low-yielding, or low-potential areas and more in high-yield, high-potential areas. A monitor in the cab tells the operator what the system is doing, and allows for manual override.

The question on growers' minds, of course, is one of economics: Does variable-rate, map-based seeding pay?

"The cost-effectiveness of the system depends to a large extent on the way it's used, as well as the grower's commitment to getting maximum benefit from the technology," says Mike Albaugh, project manager, Ag Management Solutions, John Deere. "Used by itself, without the benefit of a yield map, soil-type map, or other data, a variable-rate seeding system isn't much more than a monitor. It can be useful, but considering the cost...the grower isn't likely to see a quick return on his investment.

"But when you incorporate map-based seeding into a larger precision-farming effort, with soil-type information, yield mapping, and variable-rate chemical or fertilizer application, the entire system can return the investment much faster, just through more-efficient use of seed and chemicals. And there's real value to the information the system gathers."

Precision farming technology can pay in other ways besides just agronomics, Albaugh adds. Seeding monitors and variable-rate planter drives take a lot of the guesswork and fatigue out of planting, and can help simplify recordkeeping. Your GPS equipment could also work with an implement guidance or automatic steering system that can help further reduce fatigue, and possibly allow you to use a less-qualified operator during any operation that involves driving down, or across, rows or other activities requiring precision.

Still, says Albaugh, there are plenty of other considerations, including the source of the equipment. Though individual components are available from independent manufacturers, there are advantages to using a single company's system.

"There are definite advantages to using equipment, systems and technologies that are completely and fully integrated," Albaugh notes. "Take the GreenStar® system, for instance. The advantage is that the common components _ the StarFire^TM position receiver, the GreenStar display, and the mobile processor can be used on any GreenStar-ready John Deere tractor, combine or sprayer, for any field operation."

Also, consider how you'll use the system to its fullest abilities, and how you expect it to benefit your operation.

"As far as map-based seeding is concerned, yield history isn't enough to base your seeding rate on; you'll want to consider soil-type information as well as moisture and nutrient availability, so that information has to be collected and entered into your system. There's a lot to learn about using the machinery and the software; count on spending some time figuring it all out. And because of the cost of the equipment, knowing how to use it to its fullest potential will give you the best results and fastest returns on your investment."