The second repetition of the Farm Progress Companies/Precision Planting plots were planted last Wednesday, June 8, at the Purdue University Research Center, the Throckmorton Farm, near Romney. An identical set of plots were planted on May 20.
This is a follow-up study to last year's first attempt to determine how planting could be affected by changes in seed depth, downforce on row units, and changes in planting speed. The study was planted during the last week of May last year. The goal was to plant by May 1 and after May 20 this year, but the weather didn't cooperate.
However, soil temperature at the 40-inch depth was 65 degrees when the first set of plots was planted. Last year it was already over 75 degrees. Last year's one-time results indicated that seeding depths deeper rather than shallower were better. And although planting speed affected spacing, even at 6 miles per hour, plant spacing was still good enough that there was no yield loss, according to statistical analysis.
To go deeper, the plot factors were expanded this year. A fourth depth, 4 inches, and a fourth downforce treatment were added. The planter has four manual downforce settings, and all were included this time. According to the 20/20 Seed Sense monitor purchased from Precision Planting, the downforce pressure varied from about 350 to 600 pounds per square inch.
A faster driving speed, seven miles per hour, was also added this year. The goal, says Jeff Phillips, Tippecanoe County Extension ag educator and former research assistant for Dave Mengel, then soil fertility specialist at Purdue, was to test the outer limits of these parameters.
Judging by the irregularities showing up on the monitor during the first planting, there should be more doubles and skips when the plots are examined. The first set of plots have emerged. Phillips reports some water damage from a heavy rain after the first planting, especially on the depth plots. However, he's confident that even that part of the study can be salvaged. The option may be harvesting shorter rows than were previously planned. The original row length was about 160 feet this year. At least on those plots, it may be necessary to shorten harvest length to get a fair trial. Water also affected the plots last year, and the results were adjusted to exclude the water-damaged areas.