University Extension and research scientists say cotton yield monitors, although not perfect yet, provide farmers with information they can use to increase yield and improve production efficiency.

John Wilkerson, who has been working with yield monitors for six years at the University of Tennessee, says precision technology leads to precision information and to increased profit.

"Farmers can do profit/loss mapping with yield monitor data," says Wilkerson, who developed the technology for the Ag Leader system.

"We can identify loss areas in a field. We look at nutrient levels, soil characteristics, slope and other factors."

He says one test indicated two distinct zones in a field. "One zone made a profit every year in a five-year study," he says. "The other zone never made a profit in five years."

He says farmers can improve harvest efficiency with yield monitors, especially when they have multiple pickers or strippers running in one field. "If a module is nearly full, we can use a yield monitor to identify which picker has the pounds on board to fill the module.

"They're also important in scrapping decisions. If yield monitors indicate too little lint to justify a second pass across the field, we can move on to another field without wasting time and energy in one that's not profitable," he says.

He says monitors also help farmers make in-field picker adjustments to improve efficiency.

Alex Thomasson, Mississippi State University, says remote-sensing technology is improving. "Even with errors, farmers can get a good idea of variability in a field," he says.

Thomasson tested monitors in Weslaco, Texas, South Georgia, and Mississippi and says results show some error but also indicate that yield monitor data is accurate enough to provide valuable information for farmers.

The highest margin of error, compared to yield weight measurements, was 26.6 percent. That came from the Texas location and was the first load analyzed in the day. Thomasson says that load included a lot of weeds, and was harvested early in the morning, when temperatures were cooler. Average margin of error for the Texas location was 5.6 percent.

Average for the South Georgia sites was 0.9 percent. The worst load here, a 24 percent error, also came early in the morning.

"We think temperature may be a factor in accuracy," he says.

The Mississippi tests were set up to judge reliability. "We found the monitors to be easy to use and reliable," Thomasson says.

He says industry should continue to improve reliability and accuracy and provide a unit that compares to grain yield monitors.

Steve Searcy, Texas A&M, says stripper monitors differ from picker-type units.

"We've evaluated commercial monitors and weigh-type systems," he says. "We want to know how accurate, from point-to-point, stripper monitors are. We compare monitor data with hand-picked cotton."

He says results from 1999 were not promising. "But we de-designed the system and got significantly better results."

Calvin Perry, University of Georgia, says the Ag Leader monitor appears to be "the most user-friendly system we've tested."

He also has evaluated Farm Scan and Zycom. "Each has days in which it performs better than on other days. The same is true for different fields," he says.

He recommends farmers re-calibrate cotton yield monitors any time harvest conditions change dramatically.

"Each system will perform and produce useful yield maps, if properly calibrated and maintained," he says.