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John Goff’s seven-year-old daughter Jill checking out potatoes planted with 34-inch rows spacings. Photo: John Goff.

Tighter Row Spacings

Expert views on best management practices in potato production.

Growers and processors are always looking at how to improve farming practices that will boost yields in potato fields. Could using a narrower row width when planting potatoes be one way?

Spud Smart asked the following four experts to share their views on tighter row spacings in potato production and how growers could stand to benefit: processing potato producers John Goff and Sheldon Wiebe and McCain Foods agronomists Scott Graham and Rhett Spear.

Wiebe grows 1,300 acres of Russet Burbank, Umatilla Russet and Innovator potatoes on his farm, J.P. Wiebe Ltd., in McGregor, Man. He switched over from 38-inch row widths to 34-inch row widths five years ago.

Goff grows 1,500 acres of Russet Burbank and Ranger Russet potatoes at his farm, Corduroy Plains Ltd., in Carman, Man. He made the move from 38-inch-wide rows to 34-inch-wide rows in 2014 (a year in which he also grew Innovator potatoes).

Wiebe and Goff were among the growers invited by Graham, the McCain potato agronomist for Manitoba, to talk about their experiences with tighter row spacings at a November meeting of McCain’s Manitoba producers.

Spear, a McCain agronomist based in Burley, Idaho, was also invited to the meeting to present research results from recent potato row spacing work in the Columbia Basin in the U.S. Pacific Northwest.

Improved Yields

In addition to discussing the U.S. research results, Spear was also asked to review data on yield and quality and row width comparisons that was collected from McCain Manitoba growers from 2009 and 2015 and provide an assessment. He indicated that both sets of data indicated a significant increase in yield with decreased row spacing.

According to Graham, Spear’s presentation was designed to bring to growers’ attention that row width spacings in the province are traditionally wider than many other potato-producing areas. Most Manitoba producers utilize 38-inch row widths in their potato fields.

“We also wanted to enlighten them and bring to the forefront that we have to think of new ways to increase yields in Manitoba,” he says, “Reduced row widths means increased plant populations, which is one of the contributors to increased yields.”

Goff says his yields have risen in the past two years but how much of that can be precisely attributed to tighter row spacings is difficult to gauge “because we changed so many other things at the same time. Our irrigation practices got better, our fertigation practices got better — all these other things happened in parallel, so it’s really tough to say.”

Moving from 38-inch to 34-inch rows widths did mean an 11 per cent increase in plants per acre, he says, “and I didn’t see a reduction of yield per plant.”

Wiebe says since making the switch to 34-inch rows in 2010 his yields have increased by roughly 10 per cent. He notes much of that’s due to planting 10 per cent more seed, made possible by having more potato rows per field as a result of narrower spacings.

“With that 10 per cent more yield, we can plant on fewer acres or increase our contracts without planting more acres,” he says.

Like Goff, Wiebe stresses that improvements in his farm’s fertility and watering practices accompanied the move to tighter row spacings. “All of those things go hand in hand with higher plant populations,” he says. “I would emphasize that doesn’t just happen by itself. You have to have everything else lined up as well.”

Improved Quality

According to Graham, the research data indicated that while plant populations went up with narrower row spacings, other factors such as average number of tubers per plant, average stems per plant and average tuber weights did not change appreciably.

However, he points to “better distribution up the middle” with tighter row spacings — meaning fewer under and oversized sized potatoes and more No. 1 grade payables in the bin.

Graham says a more uniform tuber size and fewer jumbo potatoes have the added benefit of reducing defects like hollow heart, brown centre and greening. Goff notes that cutting down on bigger potatoes also helps to reduce bruising during handling.

Both Goff and Wiebe report more uniform tuber sizes since switching to tighter row spacings, making their crops more marketable and obviously helping the bottom line.

“You get paid more for that more consistent weight and size,” says Wiebe.

Goff says the main driver behind his switch to narrower row spacings was to help eliminate sugar ends, which makes processing potato less marketable.

“I mainly did it for quality purposes,” Goff says. “I decided that I would get better protection from soil heating earlier in the year because of the quicker row closure, and that would reduce my sugar ends.”

Wiebe says he’s also seen a reduction in sugar ends in his crop. “With our shorter growing season, you want to reach row closure as soon as possible,” he says. “With our canopy closure sooner … we feel we’re getting away from that early heat that can cause sugar ends in potatoes, especially in Russet Burbanks.”

Equipment Concerns

Changing row widths will obviously affect machinery used in potato production.

Goff says he’s had to modify some of his equipment. Tires on tractors and other implements had to be changed to 380 size or smaller to accommodate the narrower row widths, and the inner row spacings on some equipment also needed to be reconfigured. But he notes, “That’s not a huge challenge.”

Wiebe has made similar adjustments but says it hasn’t been too onerous. “You have to make sure you have narrower tires on your tractors and your sprayer, but other than that it hasn’t really changed much. We use our regular width of harvesting equipment and it works in the narrower rows,” says Wiebe.

Graham says using 34-inch row widths may mean growers have to be a little more precise when harvesting, to avoid catching vines and digging up neighbouring hills.

Extra Costs

In addition to equipment, there are a number of agronomic implications to narrower row width spacings. Some of them involve extra costs, with the biggest one being seed.

“Obviously you have to buy more seed because you’re putting more plants in the ground,” says Spear.

Goff, for example, says his seed costs went up 11 per cent, which corresponds with his 11 per cent yield increase.

The extra plants produced with tighter row spacings also means more fertilizer is required. Wiebe says he’s paying “a little bit more” for fertilizer now while Goff says the increase in his fertilizer costs is similar to the rise in his seed costs.

Rhett Spear (left) plants potatoes as part of row width field trials at Washington State University Research Farm in Othello, Wash. in 2013. Photo: Rhett Spear.

Rhett Spear (left) plants potatoes as part of row width field trials at Washington State University Research Farm in Othello, Wash. in 2013. Photo: Rhett Spear.

Both Wiebe and Goff report no increases in fungicide and herbicide costs as a result of tighter row spacings. Wiebe says his insecticide costs have risen because he uses seed treatment and there are more seed pieces being planted now. Goff says his insecticide seed treatment costs have also increased in direct proportion to his higher seed volume.

Also, with more plants per acre, it makes sense that more water is required to nourish them.

Wiebe says he’s seen irrigation water usage go up on his farm, particularly early in the season. So has Goff, and while noting that “water is a tough thing to measure,” he says this increased usage likely has an impact on fuel and labour costs. “That’s hard to quantify but those costs are there,” Goff says.

In Wiebe’s experience, having to pay slightly more for such things as seed potatoes have been outweighed by the benefits he’s seen with tighter row spacings. “Not just yields but in quality as well,” he says. Goff agrees that any additional costs have been more than offset by increased profitability.

Agronomic Management

According to Graham, “You’ve got more plants per acre so you’ve got to a little bit more on top of your agronomic management,” says Graham.

He stresses that proper soil types as well as good seedbed preparation and astute fertilizer, chemical and irrigation management are key considerations for growers mulling over a move to tighter row spacings. Graham recommends they consult with an agronomic expert and even talk it over with their neighbours first.

Spear says disease is an important consideration for growers moving to tighter row spacings. “Having those rows closer, you’re going to have that canopy be a lot more thick, and if it stays wetter longer you can have the potential for foliar disease, late blight or white mould or things like that,” he says.

According to Graham, sprayer tires may crowd the sides of hills with narrower row spacings, which could contribute to greening. In addition, any deep ruts the tires leave behind could accumulate water that also poses as a disease threat. For this reason, growers might be better off utilizing aerial spraying in-season, he says.

Goff used to ground spray his potato fields throughout the growing season but he’s now switched to aerial spraying after an initial herbicide application.

Over on Wiebe’s farm, “we do that anyways. We only spray for our herbicides and then after that we spray everything by air,” says Wiebe. He adds his agronomic practices haven’t changed very much since the move to tighter row spacings.

However, one important thing he’s learned is that “with more plants in the field you do have to have to be on the ball sooner with [irrigation] because it will dry out faster on you,” Wiebe says.

Goff says he saw good results in terms of yield and quality with all three varieties he has grown with the narrower row spacings [Russet Burbanks, Ranger Russets and Innovators]. “I saw the best results on Innovators,” he says. “It has a more vertical plant structure, a more vertical set, and doesn’t naturally have a big sprawling plant like the Burbank does.”

Growing Season

When it comes to length of growing season for potatoes, Manitoba’s is shorter than most. It’s one reason why some growers might be reluctant to give tighter row spacings a try, particularly, if “they get caught in a year where it rains a lot early and they can’t get on the land,” Graham says.

“My argument would be to just manage your in-row seed spacing,” he adds. “In a year of late planting, you can drop your seed down differently within the row. You can go wider with your in-row seed spacing and that would achieve size. … In an early season, you can go tighter because you’re going to have more time for those potatoes to get bigger.”

Wiebe says this is something he always keeps in mind. “If we get into the middle of May with planting, we will widen out our in-row spacing. We’ll go from 13-and-a-half inch to 14-and-a-half inch, maybe 15,” he says.

Soil type is another important consideration. Both Wiebe and Goff farm potatoes on lighter, sandy soil, which Graham maintains is more conducive to getting size more quickly than soils that are more heavily textured.

“I don’t believe the jump to 34-inches is for everybody in Manitoba,” he says, adding it makes the most sense for farms on sandy, well-drained soils. Graham maintains it’s likely that most growers in the province would benefit from moving to 36-inch row width spacings regardless of their soil type.

Both Goff and Wiebe will attest the move to tighter row width spacings has worked well for them. “I’m at 34 inches to stay,” says Goff. My neighbours are considering it, and I’ve got one who’s going to switch to 34 inches for next season.”

However, Goff agrees that a 34-inch row width isn’t necessarily for everyone. “Conditions are different throughout the province — different soil types, different numbers of heat units. I just to want them to hear what I’ve done, and if they think it’ll work in their conditions, than that’s definitely something they could try,” he says.

“It’s worked well for me. I may go so far as recommending it to my neighbours next door, but in different growing conditions I think a grower would need to make his own choice on that.”

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