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How to Snap Up Wheat Yields
When it comes to crops, wheat must feel like the proverbial middle child sandwiched between corn and soybeans. Row crops glean much of the attention at the neglect of this golden grain.
It doesn’t have to be that way, though. Wheat can be a major player in a crop rotation under improved management. Here are some ways to do it.
Agronomists like those at the University of Nebraska recommend basing wheat seeding rates on seeds per acre – not pounds per acre.
That’s because the number of seeds per pound can vary widely between wheat varieties.
Even when using the seeds-per-acre benchmark, though, optimal seeding rates can differ. In Nebraska, optimal seeding rates can vary from 600,000 to 900,000 seeds per acre in the panhandle of Nebraska to 1 to 2.5 million seeds per acre under irrigation.
“Every region has its (seeding) target,” says Kyle Okke, a WinField United agronomist.
The amount of seed per pound multiplied by the germination rate on the seed tag is a solid number, Okke says.
Estimating stand loss is a grayer area, though. Much depends on how soil moisture levels – whether too wet or too dry – impact development of plant diseases and insects.
“These can be quite variable across the field, so it’s hard to account for them,” says Okke.
Seeding depth is one factor influencing stand loss.
“Some wheat farmers in the Dakotas will say 1½ to 1¾ inches,” says Okke. “Some in South Africa plant wheat as shallow as ½ inch. Some growers in Texas will say they plant wherever the moisture is!”
Planting on the shallow side of ½ inch can work, as spring moisture normally is present at this depth, says Okke. Be wary of shallow depths in Northern Plains areas like the Dakotas and Montana, though.
“Shallow seeding will subject seedlings to chill imbibition which will affect vigor, mortality, and emergence dates,” says Okke.
Wet and/or cool soils boost the chances of infections via diseases like Pythium root rot and common root rot. The good news is these diseases become less virulent as plants grow. That’s because it’s more difficult for fungal diseases to penetrate older, tougher roots.
Root diseases aren’t the sole province of wet and cool soils. Root disease like Fusarium crown rot also can result in drier environments. Bob Bohl, WinField United technical seed manager, advises retaining records of seeding rates over the years. Over time, this can help fine-tune them, he says.
“In the Northern Plains, many acres of wheat are planted with no seed treatment,” says Bohl. That guarantees stand losses in many cases, for a seed treatment can protect a seed investment from stressors like disease, he says.
“Seed treatments don’t always equate to a yield increase, but every time you put on a seed treatment, there is a response – a decrease in the incidence of root rot,” Bohl says. “If you are a winter wheat grower in Texas and do some winter grazing, seed treatments don’t always equate to increased yield. They do help plant vigor, however, and there are plant emergence benefits that help during the season.”
Uniform seeding rates
This starts at planting. “Some guys will say singulation doesn’t matter with wheat,” says Okke. “But if you go so fast that row units aren’t in the ground, good seed-to-soil contact won’t result.”
In turn, uneven planting keys uneven emergence. “As seed is planted shallower or deeper than targeted depth, the emergence of that seed is invariably affected,” says Okke. “Seed planted at shallower than average depths will emerge sooner while seed planted at deeper than average depths will emerge more slowly. This can result in up to a few days’ difference in emergence in the same field.”
Uneven emergence and growth can come back to haunt wheat farmers later in the season.
“If you have a five- to seven-day difference in head emergence, applying fungicide to manage Fusarium head blight (scab) is difficult,” says Okke. “Slowing down to ensure an even planting depth can make a world’s worth of difference when it comes to managing those diseases.”
Okke advises getting out of the tractor occasionally at planting to ensure the field is planted at a uniform depth. At the very least, make adjustments when traveling between fields, as each plot is likely to have different soil types that can impact depth control, says Okke.
Starter fertilizers like 11-52-0 and 10-34-0 are crucial for supplying essential phosphorus (P) for early-season growth. There’s a catch, though. Phosphate starters contain salts that can injure young seedlings. To prevent excessive salt toxicity while still gleaning early growth, phosphate fertilizer must be 1½ to 2 inches away from wheat seed, says Okke.
“Under average soil conditions planting wheat and placing fertilizer in a 1-inch furrow with 60 pounds of MAP (11-52-0), you need to expect a bit of stand loss tallying up to 5%,” says Okke. “In many cirucumstances, it makes sense to place more fertility in the same furrow as seed. If this is the case, even more mortality will be expected due to salt toxicity. So, you have to figure out how many seeds you will lose from putting the fertilizer down.”
Normalized difference vegetation index (NDVI) imagery can help monitor fields. “NDVI correlates highly with yield,” says Ethan Wyatt, WinField United technology manager.
In a high rainfall year, NDVI imagery can show you how increased topdressed N rates might help take advantage of an improved yield climate. In a dry year, though, NDVI imagery can tell you that increased N applications won’t pay, says Wyatt.
There’s a benefit outside of yield, too. As a rule, when yields rise, protein content decreases. In 2016, for example, dryland wheat fields that yielded 110 bushels per acre in Colorado and Kansas had a low protein content of 8%.
“Those were high yields, but there was not enough N to supply (additional) protein,” says Wyatt.
NDVI maps showed that topdressed N rates of 50 to 60 pounds of N could raise protein levels to 12% and help those farmers garner a protein premium.
“The NDVI imagery can help you determine what to spend your money on,” Wyatt says.