About a decade ago, work by Bob Nielsen at Purdue University woke people up to the notion that how their planter performed could affect yield. If stalks were very irregularly spaced, due to poor kernel spacing, yield could be affected. Keeping the planter in top shape is still important. However, results of a recent study indicate that either today's planters work better than befoe or farmers are paying more attention to setting planters properly, or both.
"Ideally you would have a standard deviation of zero," Nielsen explains. Standard deviation is a measure of the uniformity of spacing between stalks, taken by counting distance between stalks at several locations, then applying statistics to the numbers.
In the real world, 95% germination, insect damage, even if small, and other factors usually result in about 2 inches of variation in spacing between plants, Nielsen suggests. If numbers get much higher than that, indicating lots of skips, doubles and triples, or all three, the number could rise easily to 3,.0 or 4.0 or even higher. Yield drops can occur when spacing are that varied, Nielsen says
In the Indiana Prairie Farmer/Precision Planting plot at Throckmorton Research Center, Jeff Phillips, Tippecanoe County Extension ag educator, took data on plant spacing and calculated standard deviation. The difference was from just under 2.0 for 4 miles per hour to just about 2.5 for 6 mile per hour.
"Those three speeds were statistically different from one another," Phillips says. But when the plots were carried to yield, there was no significant difference. In fact, the 4.0 mile per hour plots were on the borderline of yielding significantly lower than the other two speeds, where yields were almost identical.
Instead of having an explanation, Nielsen simply says that the yield difference could be due to chance. At least Phillips wasn't 90% confident that if you plant at 4 miles per hour, you will get less corn. However, he was 90% confident based on this trial to say that if you plant 4 miles per hour vs. 5 or 6, you will likely see better stands.
Look for more reports on this plot in the future. Other factors were tested in the trial.