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Daniel J. Wofford, Jr.
Western Polyacrylamide, Inc.
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February 5, 1990


Western Polyacrylamide, Inc. (WPI) (HYDROSOURCE) is a small Oklahoma-based firm dedicated to the research and development of cross-linked, gel-forming polyacrylamide, a water-absorbing polymer which can absorb up to 400 times its weight in deionized water, and which has a known life span of over seven years. WPI is currently involved with more than eighty research projects at thirty-one U.S. and two foreign universities. This paper summarizes some current and projected research on cross-linked polyacrylamide for soil conservation uses, and the research we feel should be initiated to establish the parameters of its use.

WPI is currently engaged in a fast-expanding tree planting program with Soil Conservation Districts, state forest services and others in a nine-state area in the Rocky Mountains and Western Great Plains. The basic technique used is to dip the bareroot seedlings, and put a cup to a pint of hydrated polymer in the backfill of the planting hole. This quantity of hydrated polymer is added to both bareroot and container-grown seedlings at time of planting.

1. Gel-Seeding Machines for Drilling Grass and Shrub Seeds

While current native grass planting techniques are generally adequate in the Western United States for most farmers and ranchers during specific Spring and Fall “windows”, such establishment continues to pose serious problems for mine reclamation projects, semi-arid pasture and wildlife revegetation, and off-season plantings under bond. For example, many spring construction projects are completed in summer and turned over to planters when grass stands are very difficult to establish.

Numerous researchers over past years have had successes with gelseeding, but the technique has not caught on – probably due to a combination of high gel prices, lack of gel-seeding equipment, and (sometimes) poor quality of gels. Our goal is to get guaranteed stands at less than $20 per acre, and by using deionized water (snowmelt or rainwater) to hydrate the gel, we hope to further reduce the costs. We speculate that as little as 5 lbs. of polymer per acre (which will hydrate more than 200 gallons of rainwater) may prove suitable.

We propose a concentrated research effort into gel-seeding (which might also benefit certain dryland crops) to prove the validity and economics of the method. Once the gel-seeding technique is validated for dryland grass planting, then a grant could be given to the ag-engineering department of a university to modify the best of current range drills or even build a new drill from scratch.

Points of Contact: Dr. Terry Booth (USDA/ARS, Cheyenne, (307) 772-2433) has considerable gel-seeding experience with pre-germinated seed and uses a homemade, single-row gel-seeder for this work. Dr. Ed DePuit (University of Wyoming range scientist, (307) 766-2196) and Dr. James L. Smith (Head of Department of Agricultural Engineering at the same school, (307) 766-4970) are also interested in researching gelseeding and modification of a range drill for gel-seeding. Their interest is amplified by the fact that the greatest single water problem in Wyoming, Colorado and other nearby areas is eroded sediment from over-grazed rangeland, so gel-seeding for rangeland revegetation to control erosion could become an important spin-off from this gel-seeding research.

There are many different gels on the market, and no one really knows how to differentiate between good and bad gels, both for gelseeding and bareroot dipping tree/shrub seedlings. We suspect the difference may be the ability of the root or seed to breathe through the gel, and that gel-forming, cross-linked polyacrylamide due to the angular shape of its crystals (even in pulverized form) may prove superior. To launch this research, Dr. Booth is attempting to obtain funds to purchase a respirometer for this and other research. Using both the respirometer and electron/regular microscopes, it is hoped that Dr. Booth’s proposed research will allow development of methodology to identify the characteristics of the most effective gels. Hopefully, follow-up field trials would validate these conclusions, and allow both industry and users to concentrate on the most promising gels.

2. Systemic, Bio-degradable Game Repellents

A Surrey, British Columbia firm (T.S. Research, Ltd.) has developed a series of systemic game repellents based on the only one of the world’s 10 most bitter substances which is water soluble. These products (produced by Ani-Pel Silviculture, Ltd.) include a pellet (Ani-Pel), a spray (Ani-Spray), a pellet for aerial reseeding (E-Caps), a salve, and a new water-soluble tablet used in water before hydrating with crystals or pulverized granules (used in bare-root dipping.) If these products work as the manufacturer believes, they have the potential to play a major role in our efforts to control both above- and below-ground animal damage.

An Ani-Pel tablet inserted into the planting hole is said to give at least two-and-a-half years protection. In addition, we have about 10 small tests underway to determine whether or not the use of this bittering agent will also cause plants to repel insects. These tests range from an Iowa State University effort to use the Ani-Pel to repel honeysuckle aphids to an Oklahoma State Forestry attempt to use it for control of the pine tipmoth.

Some of the most promising uses of the Ani-Pel family of repellents are:

a.) Growing bareroot nursery stock with polymer hydrated with liquid Ani-Pel products. The goal is to produce nursery seedlings immune to all above- and below-ground animal damage. Given the newness of this technique, no one yet knows how long the Ani-Pel-loaded polymer will protect the nursery-grown seedlings.

b.) Spraying tree and shrub seeds (used in direct seeding) with the Ani-Spray bittering agent might prevent rodents from eating the seeds before germination can occur. Tests are underway to validate this technique.

c.) Using the dibble method with Ani-Pel tablets, it might be possible to retrofit valuable established trees where animal damage is becoming serious. Once the tablet is inserted into the root system of a new seedling, it takes only 3-4 weeks for the bittering agent to become effective within the leaves and limbs of the tree.

d.) Use of a newly-developed, water-soluble tablet to make water bitter for hydration with crystals or pulverized granules (for bareroot dip). Again, no one knows how many months’ protection this will give the new plant, but it offers an easy-to-use application technique for nursery seed stock not grown in the Ani-Pel-loaded polymer.

e.) Treatment of wood with Ani-Spray could eliminate cribbing by horses, protect Third World granaries from rodent damage, and stop dogs from chewing through wooden fences.

f.) Use of the bittering agent to protect seedlings grown from E-Caps, the pellet designed for aerial reseeding of trees and shrubs.

g.) The salve containing the Ani-Pel bittering agent should be tested on the necks of young lambs to determine whether the bittering agent can be used to ward off coyotes. Since the systemic effect takes effect within seconds, it is possible that the salve could lower lamb losses. (Note: Accidental biting of a contaminated fingernail caused instantaneous bittering of the entire mouth, and the bad taste lasted 4-5 hours despite five vigorous brushings and two meals.)

Most of these Ani-Pel products are new, and have not yet had the benefit of extensive testing. Given the proven characteristics of the bittering agent, we are encouraging as many customer and replicated research trials as possible. To date we have approximately 35-40 foresters, SCS’ers, and university researchers interested in using and testing the bittering agents, but we need a focal point for all users to forward their test results in order to cut several years off normal validation time.

Point of Contact: The USDA/SCS Plant Materials Center at Los Lunas, New Mexico, would make an ideal focal point for this research, as they have been researching animal repellents for several years. They are co-located with a New Mexico State University team. New Mexico has a wide variety of serious animal problems which threaten their efforts for proposed significant expansion of tree and shrub plantings. Contact Morris Houck (USDA/SCS) at: Plant Materials Center, 1036 Miller St., SW, Los Lunas, NM, 87111, tel: (505) 8654684. Not only is Mr. Houck involved in such research on a continuing basis, but is interested in contact with others researching the Ani-Pel family of repellents. The same goes for Garth Baxter, USFS Forest Pest Management, 324 25th St., Ogden, UT 84401, tel: (801) 625-5258.

Company Contact for Ani-Pel Products: Ken Turpin, T.S. Research, Ltd., 13550 106th Avenue, Surrey, BC, Canada, V3T 2C5, tel: (604) 5854514, FAX: (604) 585-2873.

3. Polymer Research Center for Arid and Semi-Arid Lands:

WPI is already involved with the Bureau of Land Management, Bureau of Reclamation, USDA/SCS, Utah State University, and other related agencies in Utah, Arizona, Wyoming, Colorado and New Mexico interested in tree and grass plantings at sites in the 4-10″ rainfall range. Utah State is an ideal focal point for research into polymer used for cool desert grass and shrub establishment, (dryland/irrigated) fruit trees, landfill capping, etc.

In addition, Utah State is located only 50 miles from the manufacturer of one of the compressed air guns (Aqualife – Gene Siefert, Ogden, Utah), and this close proximity would allow them to experiment with injection of polymer (both dry and hydrated) into the ground to create large water storage systems for dryland orchards and roadside park plantings.

Points of Contact: Dr. Philip Rasmussen – Utah State Department of Plants, Soils & Biometeorology, tel: (801) 750-2257; Dr. James Dobrowolski – Utah State Dept. of Range Science, (801) 750-2759; and Howard Horton – USDA/SCS at Utah State, (801) 750-3079.

(Authors note: Although several university researchers in the hot desert areas, i.e. Texas, New Mexico, Arizona, California, Nevada and some related areas are engaged in polymer research, we are not yet familiar with their work.)

4. Pelletized Tree and Shrub Seeds for Aerial Reseeding (E-Caps)

T.S. Research Ltd. has developed these promising pellets (called E-Caps) by using customer-supplied seeds, fertilizer, a game repellent and a fine grind of cross-linked polyacrylamide which allows the pellet to expand 200-300 times in size when hydrated by rainwater or snowmelt. The seeds are dropped from airplanes or helicopters, and soil-to-pellet contact is increased by the high falling velocity. Each of the 1 1/2-gram tablets will swell to more than 3″ in diameter and 1″ high. Fertilizers (i.e., potassium) are coated on the outside of the pellets, and this washes off onto the nearby ground as the pellet begins to swell. More than 100,000 seeds of the principal conifers in British Columbia have been seeded by air or hand-sown, and the manufacturer reports successes of up to 70% or more survival.

No one yet knows how this technique will fare outside the high rainfall areas of British Columbia where daily showers are commonplace, but we plan to test about 5000 of the pelletized seed with the USFS in Louisiana, the Colorado State Forest Service in Colorado, and 2-3 smaller users. Hopefully, these small tests will give us a quick but rough idea of whether the pelletized seed will prove useful in 3-4 typical areas of the U.S.

Given the tremendous potential of this aerial seeding technique, it is imperative that the USFS, USDA/SCS, USDA/ARS and other concerned parties launch a significant coordinated research and field test effort. Since this is a first generation product, the pellet will undoubtedly undergo several design changes. In this context, we are already thinking about possible changes which could improve pelletized seed survival in drier areas.

Point of Contact: We do not yet have good contacts developed for this within USDA/SCS, but Dr. James Barnett – USFS Southern Forest Experiment Station, Pineville, LA 71360, tel: (308) 473-7216 – will be testing more than 2,000 of the pelletized seeds this Spring.

5. Polymers as Carriers for Fertilizers, Micronutrients, Pesticides, Herbicides, Fungicides, Nematocides, Insect Repellents, Allelopaths, Etc.

The use of both starch polymers (short-term) and cross-linked polyacrylamide (long-term) as a delivery system for a host of materials is a very promising field. (Author’s note: The research below simply reflects some of what the author has stumbled across during the past years in pursuit of cross-linked polyacrylamide research. We know of some proprietary research in these areas, but suspect our knowledge only reflects the tip of the iceberg. For instance, we’ve only recently learned that a major U.S. agriculture research facility is preparing to launch a significant research effort into this area.)

a.) Fertilizers: TVA’s National Fertilizer and Environmental Research Center has increased plant size as much as 50% in preliminary greenhouse applications when fertilizer was added as gelled nitrogen, (utilizing Aquastore cross-linked polyacrylamide) compared with nitrogen alone. In addition, nitrogen conversion of these plants was up to 40% higher as a result of gelling the fertilizer. Point of Contact: Dr. Rob Mikkelson, NFERC, F-137, Muscle Shoals, AL 35660, tel: (205) 386-3625.

b.) Micronutrients: Loading of micronutrients on polymers is a natural extension of fertilizer loading, and several U.S. companies are experimenting with this technology. Point of Contact: Dr. Mikkelson, above, as some of this research is also being planned at the NFERC.

c.) Pesticides: Several companies and university researchers are also working on loading pesticides, producing more effective insect kills with less than 10% the normal pesticide dosages. For example, Dr. Lance Meinke – Dept. of Entomology, 202 Plant Industries Bldg., University of Nebraska/Lincoln, Lincoln, NB 68583, tel: (402) 472-2123 – is loading starch polymers with insect attractants and 10% or less of the normal pesticide dosage. The results are better and with more selective kills. Dr. Meinke believes that further reductions in pesticide dosages may be possible using this technique, which he is working on with the USDA/ARS in Brookings, SD, and Dr. Thomas Metcalf of the University of Illinois.

d.) Herbicides: Many herbicides will not hydrate, but some do, thus opening the way for possible inexpensive weed and grass control for establishment of Living Snow Fences, windbreak plantings, etc. For example, a Texas high school science teacher hydrated Prowl (herbicide made by American Cyanamid and used for weed control in cotton), and we plan some tests in Colorado using this and other herbicides hydrated with the polymer. What makes this promising is that each pound of cross-linked polyacrylamide (standard) contains approximately 70,000 individual crystals. Thus one pound spread over 1000 square feet would deploy some 70 crystals per square foot. Point of Contact: None yet identified.

e.) Fungicides and Nematocides: Several university and government researchers are experimenting with the loading of both fungicides and nematocides onto the polymer. Because of growing fungus problems with tree seedlings, this could become an important research focus. Point of Contact: None yet identified.

f.) Insect Repellents: Certain natural plant products may be worth close examination for loading on polymer as insect repellents. For example, a Colorado State entomologist cut Russian aphid damage to wheat by 50% by hydrating a liquid garlic (50%) solution, and we are looking at some of the other natural repellents including hot peppers, marigolds. etc.

g.) Allelopathic Weed Control: A researcher should examine all allelopathic plants (i.e. walnuts, pine trees) for possible use in controlling weeds.

h.) Miscellaneous: There are many other possibilities such as color alteration of flowers by loading dye on crystals, altering fragrance by loading specific items (i.e., peppermint) on polymer and possibly loading nitrogen-fixing bacteria.

Summary: All the research above must be carefully planned to avoid unwelcome environmental pitfalls. For instance, the use of the systemic bittering agent (Ani-pel) as an animal repellent on certain plants might also repel the bees needed for cross-pollination of that particular species of plants. Also, despite the fact that crosslinked polyacrylamide is anionic and anything which is absorbed can be pulled out by plant roots, carryover of pesticides and herbicides (especially the latter), may create some potential problems which must be carefully studied before practical field applications are possible.

6. Capping of Landfills

The cross-linked polyacrylamide shows promise in capping landfills, both as a barrier material and for establishment of vegetation cover over the landfill. The initial leaching column work at Colorado State University focused on putting a thin layer of the polymer (mixed with the pulverized polymer) directly on top of the 2′ clay cap, and then covering it with 10″ of topsoil in which the polymer crystals would be incorporated.

In the CSU leaching column tests a dry barrier one-eighth inch thick swelled 1″, creating an impervious barrier and physically lifting the 9-10″ sand column 1″ in height. Subsequent tests of the same technique at the U.S. Bureau of Mines in Salt Lake City resulted in the shattering of glass leaching columns, as the expanding polymer blew the glass apart rather than lifting the heavy sand overburden. In theory this capping system would allow absorption of large amounts of water in the polymer storage layer, and the water would be sucked out by the landfill cap vegetation as it went into dry spells.

Point of Contact: Dr. James Dobrowolski, Watershed Leader, Dept. of Range Sciences, Utah State University, Logan, UT 84322-5230, tel: (801) 750-2759.

7. Placement of Polymer Crystals in the Soil:

As noted in the attached paper, “Use of Cross-Linked Polyacrylamide in Agriculture for Increasing Yield or Reducing Irrigation”, the principal problem facing introduction of cross-linked polyacrylamide into agriculture is probably the correct placement of the crystals to achieve maximum benefit. The second problem is determination of most economical rates for a particular site.

Point of Contact: No real focal point for this type research has yet emerged, although the National Fertilizer and Environmental Research Center has considered such research. Dr. Rob Mikkelson (mentioned in fertilizer loading section of this paper) is knowledgeable of this problem.

8. Severe Erosion Control for Farmland

We are working with several companies to develop new and cheaper methods of hydro-seeding by using the pulverized (powder) cross-linked polyacrylamide crystals as a binding agent for wood fiber and grass seed. If this proves satisfactory, then the technique might be helpful for some severely eroded farmland.

Point of Contact: None identified.

9. Growing Seedlings in a Mixture of Hydrated Crystals and Soil Mix

It appears possible to raise tree and shrub seedlings (both bareroot and container) in a soil mix consisting of 10-20% hydrated polymer and 80-90% soil, with each seedling having 50-150 hydrated crystals attached to the root system for actual planting. With the seedling root systems growing through the hydrated crystals, we suspect it may be possible to increase survival – especially on bareroot stock. The addition of the Ani-Pel game repellent to the polymer may also give protection against all above- and below-ground animal damage for an unspecified time period (probably at least one year?).

Point of Contact: A number of such test plantings will be tried this Spring, but with the leading test being conducted by Dick Thatcher, USFS, Lucky Peak Nursery, HC33, Box 1085, Boise, ID 83706, tel: (208) 343-1977.

10. Polymer Injection Equipment for Trees

There are at least five manufacturers of compressed-air injection tools, plus one also producing mudpumps for injection of hydrated polymer into the ground. Basically, these guns fracture the earth 3′ deep and 10-12′ in diameter, physically lifting the ground 3″ to 5″ in height. These guns are becoming popular in landscaping, and will gradually move into agriculture. Three major uses will be rejuvenation of orchards and vineyards with compacted soils, fracturing ground and injecting polymer for new plantings, and injecting 1-10 pounds of polymer for large capacity water storage in arid regions. With one pound capable of storing 15-30 gallons of water under most conditions (depending on the soluble salts in the ground), large-scale water storage for individual trees is a possibility.

Point of Contact: An independent research facility (government or university) needs to evaluate these guns on a continuing basis. Ideally, this facility would be located in an area with a wide variety of soils available (including caliche!), and simultaneously be able to pursue long-term research into how tree growth can be stimulated by both the polymer and the resulting aeration of compacted soils.


a.) Olathe Manufacturing, Inc. – 100 Industrial Park, Industrial Airport, KS 66031 – Tel: (800) 255-6438 or (913) 782-4396.

b.) Condor Industries (Aqualife), Gene Siefert – 557 W. 4800 S., Ogden, UT 84405 – Tel: (801) 479-7546

c.) Grow Gun Corporation – 5322 Howell St., Arvada, CO 80002 – Tel: (303) 278-9112.

d.) Pitts Carbonic (Orchard/Vineyard) – 9827 S. Clovis, Fowler, CA 93625 – Tel: (209) 834-1591.

e.) R.E. Jarvis Co. (dealer for West German-built Terra-lift) – Rt. 9, Fayville, MA 01745 – Tel: (617) 485-6100

11. Cross-Linked Polyacrylamide Quality

The modern (400X) cross-linked polyacrylamide is a durable, high performance polymer which we view as the current best in the world for a wide range of agricultural, landscaping and nursery uses, yet it has some limitations. For example, soluble salts at certain sites may temporarily limit water storage capacity by 50% or more, and a growing body of evidence indicates that some permanent damage to the rehydration capability of the crystals may be caused by higher concentrations of certain water-soluble minerals, i.e., iron, magnesium, calcium carbonate. Several researchers are now working to identify these potential problems and the manufacturers have been alerted to the need to design an even better water-absorbing polymer.

12. Pump for Dispensing Hydrated Crystals off a Tree-Planting Machine

A long-time manufacturer of tree-planting equipment in Georgia has developed an attachment for dispensing hydrated crystals for its tree-planting machine. The company is:

R.S. Whitfield Manufacturing, Jim Whitfield, President – 6431 Gordon Circle SW, Mapleton, GA 30059 – Tel: (404) 948-1212


The 400X cross-linked polyacrylamide was developed in 1982, but gained little popularity during its first five years due to high prices and lack of a concentrated research effort. However, a combination of retail prices dropping below five dollars per pound (in 50-pound bags) and recent extensive research generated by WPI and others is creating the momentum needed to make this fine product practical and affordable for a wide range of uses.

(Author’s note: Since much of the data for this paper was collected from researchers by telephone, the author takes full responsibility for any resulting errors. The author also wishes to thank everyone who contributed the information which the above paper possible.)

Western Polyacrylamide, Inc.

Copyright 1990 by Daniel J. Wofford, Jr, and Dale Greenwood. 

Manufacturers of Polymer Injection Devices:

a.) Olathe Manufacturing, Inc. – 100 Industrial Park Industrial Airport, KS 66031 – Tel: (800) 255-6438 or (913) 782-4396.

b.) Condor Industries (Aqualife), Gene Siefert – 557 W. 4800 S., Ogden, UT 84405 – Tel: (801) 479-7546

c.) Grow Gun Corporation – 5322 Howell St., Arvada, CO 80002 – Tel: (303) 278-9112.

d.) Pitts Carbonic (Orchard/Vineyard) – 9827 S. Clovis, Fowler, CA 93625 – Tel: (209) 834-1591.

e.) R.E. Jarvis Co. (dealer for West German-built Terra-lift) – Rt. 9, Fayville, MA 01745 – Tel: (617) 485-6100