Update on Landscaping Uses of Cross-Linked Polyacrylamide

Posted by on 9/27/2015 to Library

(Reference “Landscaping Uses of Cross-Linked Polyacrylamide

in the Western United States” by Daniel J Wofford, Jr.,
Western Polyacrylamide Incorporated – WPI – for the
Central California Xeriscape Conference on 4 May 1989)

20 February 1990

Low Water-Use Lawns: The Colorado Springs lawn test at 30 and 45 lbs. polymer/1000 sq. ft. (seeded fescue mix) produced an excellent stand. Water cost savings over similarly maintained lawns was estimated at $190 for the season on the 3000 sq. ft. lawn, and they expect to save more this summer as the grass becomes better established.

The Douglas County Park plot (seeded fescue, 50 lbs. polymer/1000 sq. ft.) showed two to four times more grass seedling sprouts during the first two months, but later both control and treated died out. (Succeeded by a healthy crop of weeds!) Apparently, initial attention must be given to get the fescue stand well established. It may still be possible, (but probably not in Colorado) to produce no-water lawns in other parts of the country. A parks department in Annapolis, Maryland, planted several non-irrigated median strips at 20 lbs./1000 sq. ft. in Spring 1989. The park supervisor reported that the strips remained green all summer, except for some stress damage during a 3 week drought period in August.

The turf study at CSU headed by Dr. Tony Koski (planted May 1989, bluegrass trials and fescue trials at polymer rates up to 80 lbs/1000 sq. ft.) should define the limits of this technique for Colorado and some other Western states. No attempt was made to stress the tests in 1989 until September when watering was suspended for fescue trials.

Due to reduced ET rates no water stress was observed in Fall 1989, however differences in compaction were dramatic; soil with polymer being loose and friable, control very compacted. Having seen a significant increase in the root volume of plants grown with polymer, Dr. Koski is suggesting that this may increase organic matter in the soil as the extra root mass decomposes.

Polymer as Substitute for Soil-Prep Agents: One WPI residential customer tried rototilling 25 lbs. Hydrosource standard and 8 lbs. Scott’s Fertilizer (no other soil amendments)/1000 sq. ft. into a hard clay soil for a 60/40 bluegrass/fescue seeding. and got an excellent stand. The polymer’s ability to keep clay soil loose, and prevent water stress to plants may have led to this initial success.

Installing Polymer in Existing Sod: In the week of February 12, 1990, we tested the new Olathe Model 831 Polymer Planter at California State/Bakersfield on approximately 6000 sq. ft. of existing, compacted sod (sandy loam). Most early problems in the machine appear to have been eliminated except for some clogging in the slit seeder. No firm date has been given for the release of the upgraded prototype, however a machine should be available from WPI for testing by April 1990. Olathe is now recommending a 40 hp or higher tractor be used to pull it. (The machine disk aerates in 2 – 4 1/2″-deep slits on 6″ centers, and deposits the polymer behind, via slit seeders.)

Trees/Transplants: Colorado State Forest Service is now entering its sixth year of seedling planting using cross-linked polyacrylamide; By bareroot-dipping all stock with Hydrosource fine and planting seedlings with one cup to one pint of hydrated standard crystals (at a total cost of 5-10 cents/seedling) they continue to get high survival rates.

As a trial, one Colorado Living Snow Fence was planted using this survival planting technique on half the seedlings and drip irrigation at $1/tree cost on the other half. The half planted with polymer is reportedly doing as well as the irrigated portion. This survival tree planting program has spread via Soil Conservation Districts, forest services and others to eight other Western states.

We feel the polymer could well be used to facilitate midsummer transplants of trees and shrubs. One hopeful note on this possibility was struck last summer when the Utah Department of Transportation was forced to make an emergency transplant of 17 Joshua trees (4-14 ft. tall) in July, when daily temperatures ranged to 108 degrees F.

They were moved using a tree spade, all exposed roots were swabbed with a slurry solution of Hydrosource fine at time of lifting, and hydrated standard crystals were included with the backfill in the planting holes. After four months the 17 trees showed 100% survival. In a similar transplant 20 years ago the same trees were moved during fall under ideal conditions, and thirty of sixty trees died.

Even more promising is the possibility of growing trees and shrubs with polymer in the soil mix from the beginning, such that each seedling would have a steady water supply from several to several hundred crystals (depending on the size of the stock) attached to its roots.

In January and February 1990 WPI removed two Ponderosa pine seedlings from the styro blocks they had grown in from seed since last May, washed the dirt off, and sent them to two forestry conferences where they were handled by dozens of people. After 6-7 days each of living in baggies, the seedlings were replanted and appear to be alive. This correlates with observations of numerous researchers noting a several-fold increase in wilt time of plants with crystals attached to their roots, both in and out of the soil they’re grown in.

Accelerated Growth: In almond and grape seedling trials in the San Joaquin Valley, California, (Spring and Summer 1989) cross-linked polyacrylamide was mixed with the backfill on planting. Twelve-ounce trials (almonds) and two-ounce trials (grapes) gave accelerated growth of 20-30% in foliage, canopy and caliper through the summer. By late fall differences had narrowed between treated and untreated to 15% on the almond trees, but a single almond tree cross-trenched showed double the lateral root system of the control.

(Note: Twelve ounces was probably too much for the almonds, as it would have absorbed about twelve gallons of water and jacked the tree out of the planting hole had full hydration occurred. Most of the significant increase in root growth came from the six ounces of polymer deposited in the top ten inches of the twenty-inch augered hole, and the almond root system barely touched the six ounces mixed in the fluff at the bottom of the hole.

WPI feels that by designing methods of spreading polymer over a wider area, such as by one of the several air-injection devices now available, this accelerated growth could be promoted in trees and shrubs over several years, to bring landscape plants to earlier maturity.

Bareroot Dip: Pulverized fine has been experimented with as a medium for transporting bareroot stock in several states. Two Texas Forest Service nurseries have gone completely to this method, replacing the heavier, bulkier and more expensive peat moss they had used. In a blind test of 1000 seedlings bareroot-dipped in the polymer and sent out by UPS to purchasers from the Oklahoma State Forest Service, a follow-up check showed very good survival rates.

Desert Plantings: The Little Sahara (Utah) planting of 268 trees and shrubs reported in the earlier landscape paper showed roughly 50% survival after six months with virtually no precipitation. A site evaluation is planned for Spring 1990. The Central Arizona Project (125 seedlings planted 1 Dec 1988 at a 5-6″ rainfall site) was successful with 60-70% survival for the treated plants compared to 30-40% survival of the untreated plants. Ironically, the 2-ounce rate proved best for this planting of native species, with the 4-ounce rate marginal, and the 8- and 12-ounce rates pushing the plants out of the augered holes when fully hydrated. The same techniques will be used for the next phase of the project in 1990.

Native grasses: The technique of drilling low rates of polymer in with native grass seeds for stand establishment was used successfully at the Rocky Mountain Arsenal last summer (1989); 180 acres were planted with 15 pounds of polymer per acre. The planting fortunately occurred just before a spate of late spring/early summer rains. No outside irrigation was needed and the initial stand was deemed substantial.

Two test sites made by the Bureau of Land Management in Utah in Fall 1988 using polymer with a variety of grasses and drills showed mixed results. At Clear Spot, a severe Western Utah blowout area (6″ annual rainfall site), prostrate kochia, a low-growing edible shrub, showed 100% stand establishment with 40 lbs. Hydrosource per acre drilled in with a Tye no-till drill on 10-inch centers, 80% stand with 20 lbs. and 10% stand on the control. Results on others trials were less dramatic, however all trials showed increased stands with the polymer. BLM reports that 100% stands in the desert are almost unheard-of, and that the polymer appeared to open up tiny cracks in the soil in which the grass seedlings flourished.

About two hundred miles north at Whiterocks the results were completely reversed. In eleven of twelve trials stands were suppressed by the presence of the polymer. In analyzing these two tests we feel certain that the difference was caused by the polymer being hydrated at Clear Spot, and de-hydrated at Whiterock during the time the seeds germinated, thus highlighting the need to insure hydration during that crucial stage either by precipitation or watering.

Native grass establishment continues to pose serious problems for mine reclamation projects, semi-arid wildlife and pasture revegetation, and off-season plantings under bond, such as spring construction projects completed midsummer, then turned over to landscapers. Dr. Terry Booth (USDA-ARS) in Cheyenne, Wyoming, who has become interested in developing gel-seeding methods for native grass seeding using pulverized polymer, is gathering funds for a respirometer to measure oxygen flow-through of various grind sixes and brands of gel.

Researchers have had successes with gel-seeding, but the technique has not caught on, due to high gel prices and lack of gel-seeding equipment, among other things. Our goal is to get guaranteed stands at less than $20 per acre.

Use of Polymer as Carrier for Fertilizers, Pesticides, Fungicides, Growth-Retardants, Etc.: Due to some initial greenhouse successes in reducing rates of fertilizers by loading onto crosslinked polyacrylamide, the National Fertilizer end Environmental Research Center has decided to launch an intense research effort into this area. Plant size was increased as much as 50% in preliminary greenhouse applications when fertilizer was added as gelled nitrogen, compared with nitrogen alone. Several other examples of this loading technique show promise.

For instance, Dr. Lance Meinke, (University of Nebraska/Lincoln) loaded polymer (starch polymer, due to its short life-span) with insect attractants and 10% of the normal dosage of a pesticide, which was taken up systemically by plants. This treatment produced better and more selective kills (i.e., much reduced kill of beneficial insects, higher kill of the damaging insects).

One very promising substance for hydrating into polymer is AniPel (available from Ani-Pel Silviculture. Ltd., Surrey, British Columbia), a bio-degradable, systemic game-repellent which contains Bitrex (the only one of the world’s ten most bitter substances that is water-soluble). Its effect as a bittering agent is well-known, and there are now 7-8 experiments designed to test its efficacy as an insect-repellent, the chief one being made at Iowa State University against honeysuckle aphids which are destroying the honeysuckle bushes on campus (and has spread to several other Midwestern states.)

Bedding Plants: Flower Floral in Fountain, Colorado, which raises all its bedding plants outdoors to provide hardier stock, used half of WPI’s recommended soil mix rate of 2 lbs./cubic yard, in 1989. They were able to cut their watering labor in half, and produced the best stock they had ever had. They plan to increase the rate to 2 lbs./yard in 1990 and assume they will again halve their watering labor.

With questions about these or other landscape uses for crosslinked polyacrylamide, please contact:

Daniel J. Wofford, Jr.
Western Polyacrylamide, Inc.
Click Here For Current Contact Information

Copyright 1990 by Connie Lockhart Ellefson, and Dale Greenwood

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