Starch-based product moderates soil moisture, enhancing plant growth and yields

By Vicky Boyd


Jeff Mason, production manager at Hermiston, Ore.-based Hale Farms, admits he was skeptical when he first heard about a corn-starch-based product that would moderate irrigation moisture loss and boost yields.

“I didn’t think it would work because we have irrigation water and we control how much water we put on,” Mason says. “I couldn’t see how something like this would work in an irrigated situation.”

Two years of experimenting with Zeba—the name under which Absorbent Technology Inc. of Beaverton, Ore., markets the polymer—convinced him to expand its use.

In 2006, Mason applied the granular product to half of the operation’s 1,000 acres of potatoes. In 2007, he used it on all of the spud acreage except for a few strips that he left untreated so he could gauge the benefits.

“We had positive results every time we tried it,” Mason says of his trials. “We went to half of our potatoes the third year, and everything still came out positive. So we went ahead and did everything this year.”

Mason says he used a rate of 8 pounds per acre, applied with a Gandy box in-furrow at planting. In the early-season potatoes, he saw yield increases ranging from 3 percent to 8 percent. In the late-season potatoes, he saw increases of 5 percent to 10 percent.

“So when it’s that positive all of the time, it pays for itself,” Mason says.

This winter, Mason says he plans to conduct trials involving Zeba applied to bluegrass and wheat, although at much lower rates.

Several years in the making

The technology on which Zeba is based was developed in the 1970s by a team led by Bill Doane, a biochemist with the Agricultural Research Service in Peoria, Ill. The team married a synthetic polymer with a starch-based one, creating a product it dubbed the Super Slurper.

The USDA has entered into cooperative research and development agreements with more than 40 companies, including Absorbent Technologies, to develop and market products containing Super Slurper technology.

Synthetic polymers, such as cross-linked polyacrylamide--or PAM--absorb liquids and don’t readily release it. Zeba, on the other hand, absorbs up to 400 times its weight in liquid and then releases 90 percent to 95 percent of it in response to plant root capillary action, says Gary Olson, Zeba vice president of sales in Beaverton. And it can do so several times during the growing season.

“It’s kind of like a sponge underground,” he says.

Because the product moderates peak and low soil moisture levels that occur between irrigations, it helps reduce plant moisture stress, Olson says.

In newly planted crops, the product helps promote improved seed germination and more uniform stand establishment, he says. But Zeba also can help larger plants.

“In season when you have a full crop out there--big potato plants with lots of potatoes--and you are under center-pivot, it will take three to 3 1/2 days to circle around. When you get into the 95- to 100-degree days, we are providing a buffer between irrigations,” Olson says.

Putting the polymer to the test

In most of the trials the company has conducted, Olson says the product has increased average yields of various crops by 7 percent to 8 percent. That equates to at least a three-fold return on investment, he says.

In a trial conducted in a grower’s commercial cucumber field near Delray Beach, Fla., rows treated with 8 pounds of Zeba yielded 124.5 bins per acre compared with 115.5 bins per acre for untreated rows over three pickings. A bin contains about 32 1/2-bushel buckets.

Treated peppers, however, seem to respond slightly better, and some growers have seen average yield increases of 10 percent to 15 percent, Olson says.

“For some reason, peppers seem to be very responsive to the product, more than just about any other crop,” he says.

Glades Crop Care of Jupiter, Fla., conducted a replicated pepper trial at its Jupiter research facility, comparing untreated rows to rows treated with 8 pounds per acre of Zeba. The study also compared application methods.

One treatment involved broadcasting the product evenly over the field before bed formation. In the second, Zeba was banded at 16-inch spacings, centered across the bed, just ahead of the bed former.

The third involved injecting the material 5 inches below the soil surface using two shanks. The shankings were placed at 16-inch spacings centered across the bed.

All of the treated plots yielded 10 percent to 20 percent more pounds of fruit than the untreated check. But only the shank treatment showed statistically significant increases in the total number of fruit harvested--193 versus 155 for the untreated plots.

The shank treatment also yielded 33.3 pounds of fruit during the third harvest, significantly more than the other treatments and the 20.2 pounds from the untreated check



subhead: How to use Zeba


Mike Harowitz, Zeba Southeast regional manager in Palm City, Fla., says the product was first available commercially in Florida during the 2006-07 growing season.

A few growers applied it to 5 to 10 acres and were encouraged.

“Based on those results, those growers are coming back with 50 to 100 acres that they are treating this year,” he says.

Zeba also needs to be placed where its moisture-holding capabilities will benefit plant roots—typically 4 to 6 inches below the surface, Olson says.

The application method will differ among crops and cultural practices, he says. In Florida where growers use plastic-mulch-covered beds, about the only time growers can apply it is during bed formation before they’ve planted.

In potatoes, growers can apply it in-furrow at planting or during hilling. And in California, they have the option of applying it three to four weeks after transplanting crops, such as tomatoes and peppers.

To subscribe to the print version of The Grower, click here.