Successful corn crops in Western Canada begin with getting the soil as warm as possible prior to seeding.
That’s according to Wilt Billing, corn and soybean line manager with Nutrien Ag Solutions, speaking at this summers’ Ag in Motion Discovery Plus virtual farm show. Billing told viewers that warmer spring soils would enable the crop to get properly established, a major challenge for the region.
“Corn is a C4 crop and thus requires heat to grow,” he said. “So anything we can do to warm those soils will help aid maturing corn establishment.”
Without getting into mathematic formulae and calculating corn heat units, it’s advisable to plant into warm, trash-free soils. The general rule of thumb is for soil temperatures to be around 10 C. Billing notes that as corn develops through its vegetative stages, the rate of development is dictated by warmth, so an early planting date will have less effect on development than a warm soil.
Planter maintenance and calibration are also crucial in sustaining uniform seeding.
“We need to precision plant these seeds since we are not planting millions of seeds per acre — as we would with some smaller grains,” Billing said, noting that corn is in the range of only 30,000 to 36,000 seeds per acre.
“We want to give each one of those kernels an equal chance to reach optimal yield potential so seed placement is very important — especially to ensure that we get germination uniformity.”
He notes that a corn plant that emerges 48 hours later than an adjacent corn plant will essentially become a weed — drawing resources from the surrounding plants, but not producing a harvestable ear.
“So make sure planter calibration is part of your pre-spring routine,” Billing said.
Soil temperature is of key importance, but even if planting in warm soils, you’re still not out of trouble.
“If you plant into warmer dry soils and that condition is followed by an icy rain, the corn can exhibit cold inhibition,” Billing said.
Cold inhibition, or chill effect, is when the dry seed absorbs cold water. This is often indicated by the coleoptiles emerging from the seed like a corkscrew.
“It will want to grow towards heat. When it corkscrews like that, it is because it can’t find what direction the heat is.”
Cold inhibition may result in stunted plants, runts and missing plants.
“Planting corn earlier, is not always better,” cautions Billing. “By waiting until the soils warm up a little bit, the corn pops up a lot quicker, a lot healthier and a lot more uniformly.”
When corn is planted 1.5 to two inches deep, Billing said that the nodal roots will want to develop about three-quarters of an inch below the surface, which he says is ideal. At planting depths less than one inch, nodal roots will develop at or just below the soil surface. Billing says this can cause slow or uneven emergence due to soil moisture variation.
“I always aim for two inches. You can go as deep as 2.5 to three inches if you’re chasing water. However, never plant your corn less than 1.5 inches into the ground.”
Billing recommends planting about five to 10 per cent above target populations to account for seeding losses. He says for extreme or challenging environments (cold or trashy soil), increase targets by an additional five per cent. When planting in areas with perennial drought stress, Billing says seeding rate targets can be reduced by 10 per cent or so because fewer plants will require less water.
He also points out that different hybrids have different optimal plant populations.
“Most corn companies are doing plant population studies to develop optimal targets, so it’s important to talk to your seed dealer,” Billing said.
Until it hits the rapid growth stages (just before it’s knee-high) corn will not compete well with weeds, so early weed control is critical. Billing notes that corn yields are dramatically reduced by weeds that are allowed to grow past four inches. “This is a general rule of thumb and obviously weed pressure will influence this as well,” he says. “After your weeds hit four inches tall, you’ve already lost corn yield.”
Harvest moisture depends mainly on what you’re doing with the grain after harvest. For silage, 33 to 40 per cent is recommended, 29 to 32 per cent is recommended for high-moisture corn (a high-value feed that is currently popular). For corn grain, Billing recommends 24 to 26 per cent moisture.
“Yes, we’ve had years where we had to go in a little bit wetter, but keep in mind that your drying costs will be a little higher,” he said.