Switching from hills boosts water savings and yields, but challenges abound

By Renee Stern
Contributing Editor

A group of Western potato researchers and growers is looking at flattening out conventional hill plantings in hopes of reducing water and power use while increasing yields.

Growers in humid areas developed the hilling method for extra drainage to prevent tuber rot and other damage, says Bradley King, an agricultural engineer with the U.S. Agriculture Department’s Agricultural Research Service in Kimberly, Idaho.

Better drainage also might boost early-season soil temperatures to promote quicker plant emergence, he says.

But in the West’s arid, irrigated potato fields, hills can shed too much water, causing it to pool in the furrows. “You’re not capturing all your water,” King says.

Increasing competition for water and rising prices for farmland in coming years will put more pressure on growers to look at more efficient alternatives, says John Taberna, research agronomist at Western Ag Research in Blackfoot, Idaho.

Promising results, but still a lot to learn

He and King have teamed to study the feasibility of planting in flat beds without conventional hills. Taberna’s company has developed five- and seven-row planters for this method, available to growers to buy or lease.

Several growers have signed on to test the beds in a portion of their fields. This year they planted 10 varieties on a combined 3,000 acres.

Results are encouraging, but both men point out that with less than five years’ work, they’ve barely begun to figure out the ideal parameters.

“Our production systems have been optimized around hills,” King says. “We’ve been doing irrigated potato research for over 60 years.”

Side-by-side comparisons between bedded fields and conventional hills to date have showed equal or better results in about 75 percent of the beds, Taberna says. While promising, that’s not yet a percentage that will sell full-scale conversion.

Achieving desired tuber sizes is the biggest hurdle. King and the others have focused on determining optimal seed spacing.

“When you plant in beds, you have the potential for slightly higher populations,” resulting in smaller tubers, he says.

That’s a selling point for such varieties as reds, Yukon Golds or seed potatoes, where buyers prefer smaller size profiles, Taberna says.

But many seed potato growers use two-row equipment, which doesn’t mesh easily with the modified five- and seven-row planters, King says. The 12-foot-wide beds are designed to work with most equipment growers already have on hand, minimizing conversion cost, he says.

The flat-bed method needs more refinement when it comes to russets, where size matters most. Gene Bair, agronomist at Walters Produce Inc. in Newdale, Idaho, signed on for the trials four years ago.

“I can’t say we’ve hit a home run every year,” he says. “We’ve got an awful lot to learn yet.”

Beds boost tuber uniformity

One plus to the bedded fields: They tend to produce more uniform tubers, he says.

This year Bair tested the method on a full pivot of russets in hilly ground that’s prone to heavy runoff. In August the field looked promising, despite a late start to the season likely to hold down tuber size. But a final judgment would have to wait for harvest.

Last year’s longer growing season resulted in “great size,” he says.

Richard Tominaga, co-owner of Tominaga Farms Inc. in Blackfoot, Idaho, put in five-row plantings of Rangers and Burbanks this year on 70 acres; two years ago he tried Alturas Russets, with yields averaging 300 hundredweight higher per acre.

Those plantings were intended for processing contracts, where gross yield rather than tuber size is the primary goal, he says.

Water, power savings, too

The main benefit comes from water savings, Taberna says. On sandy soils, growers can cut irrigation by 10 percent to 15 percent. Soils with more silt use up to 8 percent less water, although with hand lines, savings there can reach 15 percent.

But those reductions require more oversight to maintain proper soil moisture.

“It’s a very intense management program,” Bair says. “I enjoy that kind of challenge so we get along well with it—though that’s not to say we don’t lose sleep over it.”

Tominaga says Western Ag Research provided solar-powered soil-moisture monitors at no charge to help keep irrigation schedules on track.

With lower water use, growers who fertigate also apply less fertilizer, providing added savings given rising nitrogen costs, King says.

Bair says he’s been able to reduce water use across the full growing season by 20 percent, with similar reductions in fertilizer.

Power rates have increased 15 percent this year, Taberna says. “Add five more years of inflation and that 10 percent (in water savings) is going to be a ton of money.”

Growers also cut out a tractor operation by not hilling their fields, King says.

Every run through a field costs $15 to $20 per acre in fuel, Tominaga says.

Hills can break up herbicide spray coverage, Taberna says. Bedded fields show improved weed control. By spacing plants better both in rows and laterally, growers see some gains in light optimization, King says.

Tominaga says his test fields have experienced less wind erosion, thanks to more flat surface instead of contours on his sandy soil.

“When that sand starts moving, no one wins,” he says.

“We don’t want to overstate claims,” Taberna says. Plenty of work remains, particularly in tackling sizing issues.

But the savings hold out promise. “With the way expenses are going, if you can save 10 percent on your water and 10 percent on your fertilizer, and get the same or better yields, that’s going to keep you going,” Tominaga says.