There’s an art to determining the optimum plant population for a particular field — the sweet spot where there are enough ears per acre without being too many for the plants to fill. Though researchers and their computers are chewing through mountains of data to try to create automated tools to help match populations to patches of soil, it’s still a decision based largely on experience and instinct.
Over the past couple of decades, breeders have focused on selecting shorter hybrids with fewer, more upright leaves; smaller tassels; better synchrony between silk emergence and pollination; and improved endurance. The combination of those traits allows today’s hybrids to flourish in higher populations.
The key is planting higher populations where you expect to harvest high yields.
The magic number
According to a Dekalb review of field trials in four states, the sweet spot for most Midwestern fields with high yield potential and good management practices is between 32,000 and 39,000 plants per acre, or ppa. Plant more than optimum populations and you may just be burying money that won’t deliver more yield. Plant too few seeds and you could be cutting your crop short.
In all, it’s better to err on the high side, notes Peter Thomison, Extension corn specialist at Ohio State University.
“In the absence of major environmental stresses, most research suggests that planting a hybrid at suboptimal seeding rates is more likely to cause yield loss than planting above recommended rates, unless lodging becomes more severe at higher population levels,” Thomison says.