Reprinted with permission from Miner Institute, written by Ev Thomas
Photo Credit: Photography by Tiwago via Compfight
Several considerations as you get your corn planter ready to roll.
- First, will you plant enough seed to produce high yields if growing conditions are good? If not you may be limiting yields before you even start. With normal ear and kernel size you’d need about 32,000 plants per acre — not kernels — to get a yield of 200 bushels per acre. Assuming 10% seed loss that’s about 35,000 kernels per acre. This assumes ears averaging 550 kernels or about 0.3 lbs of grain. Recent research found that the ideal seed population for 100+ RM hybrids is 32,000-33,000/acre, and for less than 100 RM it’s 34,700.
- Speed kills, and planting too fast may kill your chances for top corn yields. Corn planter operator manuals may state that corn can be planted at 7-8 mph, but this could be at the expense of plant uniformity — and doubles and skips reduce yields. (Take particular care when planting small rounds with some corn planters.) Planting at 5 mph is fast enough for many conditions, and if you have all other parts of the system working efficiently will result in a lot of acres planted per day. John Deere’s newest MaxEmerge corn planters reportedly will plant corn at 10 mph, and in one trial corn planted at 13 mph resulted in the same population and uniformity as that planted at 5 mph. This sounds promising, but it’s unlikely that trial was planted in a field infested with stones sitting just below the soil surface. If you’re going to plant fast in stony conditions you’d better stock up on welding rods.
- Finally, planting depth: Don’t plant corn less than 1.5” deep, and then only with early planting into cold soils. With May planting 2” is preferable. Last year Cornell University got the highest populations when planting at 1” and 1.5” in early April (!), but that was on well-drained soils in Central NY. Research by Dupont-Pioneer (10 sites over 2 years) found that a 1½” planting depth resulted in the same grain yields as a 3” dept, while yields were much lower when corn was planted ½” deep. Much of the difference was due to lower plant population and many more small, low-yielding plants. Of course nobody is recommending that you plant corn at under 1” depth, but especially with notill it can happen by accident. Also, planting into cloddy fields may result in very uneven soil coverage. The only way to make sure that you’re planting to the desired depth is to get off the tractor seat and dig around until you find several seeds. A farmer who winds up a day’s planting without any soil on the knees of his trousers is making contact in the wrong places!
