While we’re still changing our seeding rate approach from bushels per acre to thousand kernel weight, Phil Needham of Needham Ag Technologies, has moved on to thinking about heads per square yard.
An agronomist originally from Britain and now based in Kentucky, Needham has made a name for himself advising farmers on how to increase wheat yields. This June, Needham spoke to a group of farmers and agronomists at the Farm Progress Show in Regina, as part of the SaskWheat (Saskatchewan Wheat Development Commission) annual meeting.
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Needham began with a photo of a wheat crop in Lincolnshire, U.K. A crop that yielded 211 bushels per acre. While the U.K. is surrounded by water and has a more temperate climate and longer growing season than the Canadian Prairies, Needham pointed out that Lincolnshire is on a similar latitude to Saskatoon. While we do have yield limitations here, Needham doesn’t think we’re pushing our wheat fields hard enough.
The head count
When we’re setting seeding rates, we typically think of the ideal wheat crop in terms of plant count — plants per square metre or plants per square foot. Instead of counting plants, Needham thinks in terms of the number of heads of wheat in a square yard. He said an ideal wheat crop has between 500 to 600 heads per square yard. “If you get much over 600,” Needham says, you’ll have lodging and reduced yield. With fewer than 500 heads per square yard, you’ll have a lower-than-optimal yield.
What does this look like? Manitoba Agriculture’s website suggests a plant population of 23 to 28 plants per square foot, and notes that some farmers are pushing this up to 30 or 35 plants per square foot. With nine square feet in a square yard, 25 plants per square foot is 225 plants per square yard. Three heads per plant would be a crop with 675 heads per square foot, well over the top of Needham’s optimal range.
Prairie wheat fields often have three or more heads per plant. However, we don’t tend to see as much lodging as Needham’s math might lead us to expect. Mitchell Japp, Saskatchewan Agriculture’s cereal crops specialist, says this is due to the varieties we’re growing — “we have pretty good varieties, with strong straw,” he says — and to our climate. “Our environment tends to be a little bit drier than some of the places Needham has worked.” However, in some cases when there are too many heads per plant, wheat plants may not have enough resources to fully fill all of the heads.
Research from Eastern U.S. has shown an optimal range of 470 to 900 heads per square metre (or 430 to 823 heads per square yard.) Japp he hasn’t seen any replicated trials in Saskatchewan focused on the optimal number of heads in the crop. “It would be nice to see some local research,” Japp says.
Tillering and nitrogen
Needham pays a lot of attention to tillering in wheat crops. The reason? Uniformity. Where there are tillers, not all heads are developing at the same rate. “We need to get a little bit better on the uniformity perspective,” Needham said. A uniform crop is necessary to allow you to apply fungicide at exactly the right time. “Prosaro, Caramba,” he said, “need the head fully emerged” for an effective application. If all of the heads are emerging at the same time, fungicide application can be more exactly timed.
If you’re sidebanding nitrogen so the fertilizer is available to the seed, “when that plant gets ahold of it early, you’re going to get a lot of tillers,” especially on varieties that tend towards tillering. So, he says, if you’re seeding at a higher seeding rate, you might want to consider delaying your nitrogen application (to mid-season), or applying nitrogen in a mid-row band, so the plants are a little more advanced when they reach the fertilizer. What you want, he says, is a delay in nitrogen availability.
Needham encourages his clients to top-dress nitrogen during the growing season rather than putting all of their nitrogen down at seeding. “How do you know how much you need?” he said. If you wait until midway through the growing season, you have an opportunity to add more nitrogen if the plant has enough moisture to be able to use it.
Again, here in Saskatchewan, the research is not fully in. To date, Mitchell Japp says, “the most consistent results are from nitrogen applied at seeding.” There are some years when Prairie crops could benefit from top dressing — Japp refers to 2013, when we started getting moisture during the growing season, and some crops could have used additional nitrogen to produce higher yields. However, the benefits of top dressing are limited to those times when additional rainfall comes after the nitrogen application. We can’t always rely on those post-application rains, and some years when crops would benefit from top dressing, it’s already too wet to get into the field to apply the nitrogen at the right time.
Residue management
Needham says another factor in growing a uniform wheat crop is residue management. A lot of variation in growth, he says, “can be carried right back to residue management.” Needham stressed the importance of spreading residue well out of the back of the combine, and recommended investing in special attachments if necessary. He also suggested not having a wider combine header than your straw spreader could reach.
“I’d really encourage you to spread the residue out the back. It’s going to be more money, but I’d rather you spend the money on a chopper than on a harrow.” He believes better technology for spreading residue from the combine is in the works. “We’re not there yet, but I think there’s some better options coming.”
Harrowing, he believes, can sometimes make residue management worse. Harrowing can detach residue from the soil surface and move it into piles, slowing down the breakdown of the trash. “Do not harrow is my suggestion,” he says
Start now
Of course, it’s too late to vary your 2019 seeding rate, but you can count heads per square yard (or metre) and compare variations in head count to yield variations in different fields, or different areas of the same field.
A lot of factors contribute to yield, including number of heads, number of kernels per head, and kernel weight. “Each of these factors can be influenced by the seeding rate,” Japp says.
