One great thing about having a yield monitor and yield-mapping capability is that you can compare one product or practice with another. But you need to know with certainty that the test plots have been treated equally.

Split-planter comparisons can make that possible, says Tom Doerge, precision farming agronomist with Pioneer Hi-Bred International. This type of test sets up the comparison in alternating strips across a field.

Pioneer, through its sales force, offers help in establishing valid comparisons. The company also analyzes the results at no cost to farmers.

Some of the more common comparisons are between two corn hybrids or soybean varieties, two seeding rates or seed treatments, starter fertilizer vs. no starter and one tillage method against another. These are just a few of the possibilities.

Setting up a split-planter comparison can be as simple as placing different corn hybrids, for example, in each half of the planter. Be certain both are set at the same seeding rate.

When harvesting, it's best to have a combine header that's half the planter's width, Doerge says.

On the yield monitor, assign a specific "load" or variety to each hybrid. "It's essential to keep a detailed planting map or plot plan in the combine. That helps ensure that loads are properly labeled."

If possible, he says, combine both hybrids in the same direction, especially in sloping fields.

Also, it's best to collect yield data at one-second intervals.

Pioneer prepares three sets of maps for participating growers. The first is an overall yield map that shows major trends across a field. The second shows the yield for both hybrids individually. And the third shows the yield differences between the two hybrids across the field.

The farmer or his crop consultant can do the analysis if he chooses, says Doerge. Several commercial software systems are available to do this.

Pooling the results with those from similar comparisons done at other locations increases their credibility, he adds.