There are two reasons to plant a test plot—to help sell seed or to find the most profitable hybrids for your farm.
"Only a small percentage of farmers who do not sell seed plant their own plots and use them for purchasing decisions," says Ken Ferrie, Farm Journal Field Agronomist. "With the cost of seed nowadays, most farmers will find it worthwhile to put out their own plots."
There’s a wealth of information to glean from a test plot—if you do it right. But if you do a plot wrong, it can do more harm than good.
To make your test plot a profit booster, rather than a mere showpiece or even a waste of time, keep the following tips in mind.
"Understand that your objectives may differ from your seed dealer’s," Ferrie says. "Your dealer wants maximum yield; you want data you can use on your farm."
To obtain useful data, locate your plot in an area that represents your farm’s predominant soil types. A yield map, or your consultant, can help you identify areas of uniform soil. The best spot may not be along the road.
"Avoid your highest-yielding area and small areas with several soil types," Ferrie says. "You may need plots in two locations, representing your heavy and light soils. You need two plots if you farm under irrigated and dryland conditions."
Treat the plot exactly the same as your own crop. "I’ve seen the same hybrid vary by 50 bu. to 90 bu. per acre because of different management practices in a test plot and a farmer’s field," Ferrie says.
You want to identify hybrids that respond to your management practices. If you sidedress your corn, sidedress the plot, too; ditto if you fall-apply anhydrous ammonia. If you apply starter fertilizer in your corn fields, apply it in the plot, also.
"Do the same tillage in the plot as in your fields," Ferrie continues. "I have seen farmers moldboard plow a plot or burn off the old-crop residue, even though they strip-till or no-till their fields. That makes for a good show plot, but it doesn’t yield information they can use on their farms."
Apply a fungicide. Consistent management also applies to fungicide applications. "I see test plots where a farmer sprayed the plot even though he never uses fungicide in his fields, and also the opposite," says Missy Bauer, Farm Journal Associate Field Agronomist. "Certain hybrids will get trashed in a plot if you don’t spray them. If you don’t apply fungicides, you may rule out some of the best-yielding new hybrids.
"If you’re not convinced about the value of fungicides, spray one end of the plot by going across the rows, and see how much difference it makes in yield," Bauer adds.
Fungicide application may rule out some plot locations. Don’t stick the plot next to your house where you won’t be able to spray.
If you grow continuous corn in some fields and rotate with soybeans in others, set up your test plot, if possible, so that half is planted into corn residue and half into soybean stubble. Otherwise, the results could be very misleading. If you can’t design the plot that way, you’ll need two plots.
"Ask your seed salesman what seed sizes he is bringing, use a test stand and calibrate your planter," Ferrie says. "If you don’t calibrate, seed distribution is likely to range from good to poor, and hybrids won’t yield to their potential. In a plot containing 50 hybrids, I was able to pick the yield winners at the V6 stage because of poor seed singulation, resulting in skips, doubles and triples."
Plant each hybrid at its recommended population. "A determinate hybrid may yield best at 36,000, while a flex-ear hybrid may max out at 32,000 and yield less at higher populations," Ferrie says.
Plant the plot in timely fashion. "It’s tempting to plant the plot first, just to get it out of the way, or to put it off until last," Bauer adds. "But planting date is a big factor in yield."
Avoid shading. When you design your plot, consider plant height and separate tall hybrids from short ones.
"We often see hybrids lined up in test plots from the earliest maturity to the latest, without taking height into account," Bauer says. "But the shading effect of taller hybrids works against the shorter ones. Conversely, a tall hybrid between two short ones benefits from the ‘outside-row effect’ because of greater light interception.
"If you can’t separate the shorter hybrids, plant a buffer around them or make the plot big enough that the short hybrids are not shaded. Taller hybrids may also need a buffer."
Save a seed sample from each entry in your plot, and store it in a refrigerator; it could prevent you from accidentally eliminating an excellent hybrid. "If a hybrid shows surprisingly low emergence or vigor, have the seed analyzed for quality," Bauer advises. "You may find the poor performance resulted from poor seed quality."
Study your fields. There are lessons to be learned from a test plot all season long. Ferrie calls the process "reading the plot."
After emergence, take stand counts. "See how close the hybrid came to your target population," Ferrie says. "If you find a problem, dig some roots and determine the cause.
"At the V6 or V7 stage, inspect the plot for diseases. Disease will be visible later in the season, but you want to see if it is getting an early start on certain hybrids. If disease sets in early on a hybrid, it may pollute the hybrids planted next to it."
Note which hybrids are most appealing to insects. "Aphids and corn borer are taster insects based on sugars in the plant," Ferrie says. "They like some hybrids better than others, so they sometimes infest one hybrid and don’t touch the one next to it."
Don’t forget to record problems that are not related to genetics, such as weeds and mechanical issues (cultivating plants or driving over them when sidedressing and spraying).
Take notes. If a hybrid comes up short when you take ear counts or at harvest, those notes will help you figure out why. "You don’t want to discover that one hybrid yielded 20 bu. per acre less than others and not know why," Ferrie says.
Harvest. A week before harvest, walk the plot and rate the best and worst hybrids on stalk quality, general appearance, ear shank, ear quality and ear mold. Split stalks and look for signs of disease. Give stalks a push test to make sure they’re not just a day or so away from falling down.
Harvest hybrids at the same moisture level at which you harvest your fields. That might be 18% moisture if you dry using only air or 28% if you have a dryer.
Watch what happens as hybrids dry down. "A hybrid standing tall at 32% moisture may be flat on the ground by the time it reaches 18%," Ferrie says. "You will find that some hybrids dry down faster than others—some may lose a point of moisture per day, but others only a tenth of a point. That’s important information if you dry corn in the field, but you’ll miss it if you harvest the plot at 28% just to get it out.
"To get this kind of information, you may need to harvest your plot several times, by maturity groups as the hybrids dry down—and that could be a deal-breaker if you’re working with a seed salesman," Ferrie says. "Discuss your harvest plans with him before you agree to put in a plot.
"After harvest, compare net yield to the physical appearance you observed earlier," Ferrie says. "You may find a hybrid yielded more but was 10 points wetter. Look for hybrids with standability and less ear mold, in addition to yield. If a hybrid yielded well but showed other weaknesses, realize that it’s going to require extra management, and don’t plant it on more than a third of your acres."