Verify New Planter Performance
We evaluate many corn stands for Peterson Farms Seed’s Plus20 Agronomy Club members. We look at several things, including plant spacing, the emerged versus planted population, and emergence variability. Plus20 Club members are top corn growers, and many have relatively new planters that don’t have a lot of acres on them yet. But we still find a disappointing number of variable corn stands.
Many researchers have studied the uniformity of in-row plant spacing to determine if it relates to yield. Studies have come out on both sides of the question, but there seems to be a correlation to better yields with more uniform stands.
Most of the stand issues we see are a result of planting too fast. Our research has shown a 9.3-bushel-per-acre advantage over seven years from planting at speeds less than 5 mph compared to more than 5 mph. University of Wisconsin research shows yields dropped from 183 bushels per acre at 4 mph to 180 bushels per acre at 6 mph, which is a statistically significant difference. This was conducted over 12 different locations with both air and finger seed delivery systems.
Purdue agronomist Bob Nielsen studied the effect of corn stand uniformity on yield by measuring the standard deviation of the plants in plot rows. Plots with a zero deviation yielded 192.4 bushels per acre. Plots with the highest deviation, 8, had a yield of 178.5 bushels per acre. There was a 2.2-bushel-per-acre reduction in yield for every inch increase in standard deviation.
The plots we looked at last spring with our Plus20 group had deviations that ranged from 0.82 to 4.11. We like to see at least 80% of the plants within 2 inches of the targeted spacing (6.5 inches for a 32,000 population on 30-inch rows, for example). Only half of the plots were in this range. Plots that were planted under 5 mph averaged over the 80% threshold and plots planted over 5 mph averaged well under the 80% threshold. We also looked at each plot and estimated the doubles and skips. Doubles normally result in a barren ear on one of the plants, and skips underutilize soil and sunlight falling on the field. No grain is produced in the open space.
We found population to be another problem. Seven percent of the plots we looked had more than a 100% emergence rate. In other words, more plants came up than what the operator thought he or she was planting. This could be due to doubles, but most of these plots had low standard deviations, and speeds were less than 5 mph. It’s important to verify before you get to the field how much seed the planter is dropping. It may be different from what the book says.
Clearly, money and time spent on planter maintenance this winter can turn out to be a very good investment. I urge you to go through your planter units and check all chains, sprockets and fittings. This spring, check to make sure the planter is doing what you want it to do. Verify how it is performing early, before you have issues throughout the farm.
Adam Spelhaug is our Agronomy Manager at Peterson Farms Seed, and writes a monthly column in the Dakota Farmer.
