Some fertilizer dealers are apparently spreading the word that the hula-hoop method for measuring soybean stands only works if you are in 7.5 inch rows. Many people today are in 15-inch rows, using split-row planters. Shaun Casteel, Purdue University Extension specialist and soybean information specialist, says the hula-hoop method still works in 15-inch rows, regardless of what you may have heard.
"Sure, you can use the hula-hoop method on 15-inch rows," he says. "It will still work."
Using the method requires knowing the diameter of the hoop. Diameters can range from 27 to 36 inches. The larger hoops may get a better distribution, especially in 15-inch rows. The difference in diameter is accounted for in the factors that are used to determine how many thousand plants per acre are in the spots that you check.
The secret to the hula-hoop method or any other cou8ntign method is to take several counts, and take them at random. That's why many crop consultants have a set pattern. They pace to a certain spot in the field, then roll the hoop and do the count where it lands. Otherwise, it might be easy to bias the results by placing it down on good on good spots rather than counting at random.
The other important factor, specialists say, is to do a number of counts in any one field. If only part of a field is having stand problems, you may want to take several counts in that one spot, then average them to arrive at a reasonable estimate of the population there.
If you don't want to use the hula-hoop, you can count off feet of row, as many people do when estimating corn yield, Casteel says. Again, it's important to pick the spots that you count at random.
One method is to count off 17 feet and 5 inches, which represents one/ one thousandth of an acre in 30-inch rows. Lay out the tape between two soybean rows, then count both sides, since rows are only 15 inches apart. Or if that's more measuring and counting than you want to do, use half of 17 feet, 5 inches to compute your counts, counting plants on both sides of the tape. Then double the average count.
However you do it, you should come out at about the same estimated population, the specialist says.