The Role Of polymersIn water Management

Practice field at Sunrise School in Salt Lake City, UT, before and 30 days after injection ofpolymers. Photo courtesy: RainSaver.

Water management will be the toppriority of the golf and sportsturf industries in this decade.

Turf managers are learning to managewater for irrigation to do their part intoday's climate of heightened environmen-tal awareness. Every tool that has the po-tential to save water must be put to work.

One such tool is a group of spongelikegranules known to many in the industry aspolymers. Long used in soil mixes for green-house and nursery production, the plastic-and starch-based particles have been triedby a number of golf course superinten-dents, sports field managers, and contrac-tors to increase the water holding capacityof soils for turf.

The use of polymers in turf has largelybeen limited to seed coating, sod and sprigestablishment, and incorporation into top-soil prior to seeding. However, the develop-ment of equipment to place the polymersinto the rootzone of established turf is nowopening up a whole new technology inwater management.

Transferring polymer use from the nur-sery to parks, golf courses,and athleticfields has been controversial and hamperedby a lack of university research. Withoutresearch data related specifically to turfuse, the education process involved in ex-plaining how polymers work and how theycompare has been slow and arduous. Thatresearch is now underway at a handful ofuniversities. However, a growing number ofsuccess stories and testimonials by turfmanagers who have tried polymers is nowconvincing municipalities, golf course ar-chitects, and sports field consultants tospecify polymers for new construction.

Polymers are created by chemical reac-tions which combine two or more smallmolecules (monomers) to form a larger,different type of molecule. Natural poly-mers include proteins and starches. The

continued on page 12

June, 1990 11

Fertilizer placed three inches below the surface by Yeager-Twose Bottom Dresser.

Polymerscontinued from page 11

first synthetic polymers were developedafter World War I and were later perfectedinto various types of plastic.

Pipe, valves, and sprinkler heads madeof plastic are widely used today for turf

irrigation. Plastic is also used for drainpipe,liners and covers, fibers for rootzone stabi-lization, and a growing number of light-weight components on turf equipment.

During the 1960s, chemists discoveredthat certain types of polymers in granularform could absorb very large amounts of

liquid, in some cases hundreds of timestheir weight. In the process, the polymersswell up many times their original size withmoisture, while still retaining their integ-rity. Their absorbency was eventually putto use in products such as baby diapers,wound dressings, kitty litter, and hazard-ous material collectors. As a result, a hugemarket for absorbent polymers has evolved.

Agricultural chemists began to exploreuses for polymers in crop production. Theiremphasis was not only on storage, it wasalso on how much of the stored waterpolymers would release and how easily. Byproviding a source of moisture for seedduring germination, sprigs or seedlingsduring establishment, or roots of plantsonce established, the health and productiv-ity of many crops has been enhanced.

When placed in the rootzone, polymerscould conceivably reduce the amount ofwater lost through percolation and evapo-ration, decrease the frequency of irrigation,and therefore reduce both water and laborcosts. Furthermore, dissolved nutrients,herbicides, or pesticides absorbed by somepolymers would remain where they wereneeded, and not be lost to leaching orevaporation. Finally, the expansion and

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contraction of the polymer granules withinthe rootzone helps create spaces for aera-tion and improves the texture of soils.

These concepts held so much promisethat the United States Department of Agri-culture (USDA) has carried out its ownresearch into polymers for many years. Thepolymers developed by the USDA havebeen designed to be economical and tobreak down within a growing season. Toaccomplish this, starch was grafted to asynthetic polymer. The final product is ap-proximately half starch and half syntheticpolymer. Soil organisms break down thestarch copolymer at a rate depending uponmoisture and temperature. Biologically ac-tive soils in warm weather can break itdown in a matter of weeks. However, starchcopolymers may persist for more than ayear in sterile soils in cooler climates. Dr.William Doane continues to work on poly-mers with the USDA Agricultural ResearchService in Peoria, IL.

When compared to completely syntheticpolymers, starch copolymers are softerwhen swollen and give up water more eas-ily, according to Cliff Marshall of Interna-tional Absorbent Products in Smelterville,10. The company's Polysorb is a starch-based copolymer developed and licensed bythe USDA that holds roughly 150 to 180times its weight of tap water and swells upto 40 times its original size, Marshall re-veals. He adds that Polysorb is roughly 60percent starch and 40 percent syntheticpolymer.

During production, Polysorb is treatedwith either sodium hydroxide or potassiumhydroxide in a process called saponifica-tion, Marshall explains. The potassium-treated polymers are generally preferredfor turf applications since a potassium re-sidual of about one percent remains.

To further extend the life of polymers,chemists developed totally synthetic ver-sions. These can vary widely in their chem-ical makeup, but may be loosely dividedinto two groups, cross-linked polyacrylatesand cross-linked polyacrylamides,

The chemical reaction used to makesynthetic polyacrylate polymers producesits own energy, explains David Keen, na-tional sales manager for agricultural chem-icals for American Colloid in Stuart. FL,maker of Hydrozorb. Because of this, pro-duction costs are lower than for polymersrequiring more energy to produce. Keenadds that his polymer holds up to 260 timesits weight in tap water and releases it to thesoil as well as to roots coming into contactwith the polymer. Hydrozorb is approxi-mately 15 percent potassium. Depending

Manypolyacrylamide

polymers performfor five to sevenyears or longer

depending on saltsin the soil.

upon the soil, it lasts from seven months tonearly two years before breaking down.

The most durable polymers are cross-linked polyacrylamides. Companies market-ing polyacrylamide polymers say theyperform (hydrate and dehydrate) for five toseven years. They point out cases wherepolymers still work to some degree after tenyears. They absorb from 100 to 300 timestheir weight in soil moisture and swell upmore than 40 times in size, as noted byWally Boilek, national sales manager ofTerra-Sorb for Industrial Services Interna-

continued on page 14

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14 Golf & Sports TURF

RainSaver injects a gel of starch-based polymers into the rootzone.

Polymerscontinued (rom page 13

tional, Inc., in Bradenton, FL. The companyhas marketed polymers since the late '70sand also makes a starch copolymer.

Broadleaf P4 is a cross-linked polyacryl-amide from Broadleaf Industries, SanDiego, CA. Since 1984, the company hasemployed Dr. Dean Piper, a retired profes-sor from California Polytechnic Universityin San Luis Obispo, to gather and refineinformation on superabsorbents. Much ofhis focus has been on determining properapplication rates for polyacrylamides insoils.

With proper selection and installation,Piper reveals that synthetic polymers canstore an extra inch of rainfall or irrigationin turfgrass rootzones, and release 95 per-cent or more of this water upon demand.Figuring an evapotranspiration rate of .25inch per day, this extra storage amounts tonearly a four-day supply of water. This doesnot account for reduced losses to evapora-tion, runoff, and drainage.

To achieve such storage, figuring ab-sorption of 150 times by the granule, morethan 30 pounds of polymer should be uni-formly mixed into the top six to eight inchesof soil in a 1,000-square-foot area. That isroughly 1,300 pounds per acre, which is farhigher than rates currently used for injec-tion equipment on established turf.

"You get more impact than the amountof polymer you use," points out Dr. GarnWallace of Complete Green in Los Angeles,CA. "There is a synergistic effect broughtabout by improved soil porosity and adeeper root system." However, Wallacefeels that a rate of three pounds per 1,000square feet is "bare bones" if the intent is

to increase water storage capacity in manysoils. Technically, at the same absorptionrate as above, three pounds per 1,000square feet represents less than 1/10 inchof stored water. Complete Green markets adifferent type of polymer designed to im-prove water infiltration in turf and land-scaping.

Getting water to the polymers is essen-tial to their performance. "The crystals onlyabsorb free water," says Jerry Curtice, tech-nical services manager for Aquatrols Corp.,which markets Supersorb. Thatch or hydro-phobic soils can cause runoff and preventmoisture from ever reaching polymers inthe rootzone. Curtice believes that wettingagents can enhance the effectiveness ofpolymers by getting water to them.

Another factor in absorption is soil pres-sure, according to Ron Salestrom, nationalsales manager for Hydro Resources South-west in Mesa, AZ. The granules can swellmore in sand than they can in compactedclay soils, he says. The company's Hydro-Hold is a cross-linked polyacrylamide.

Agrosoke is a tightly linked polyacryl-amide that absorbs some 40 times itsweight in water. Janet Curry, president ofAgrosoke, Inc., Fort Worth, TX, says thepolymer does not absorb salts, as do thosewith higher absorption rates. As a result, itresists salt-induced degradation. She cred-its this characteristic for permitting thepolymer to perform longer than eight yearsin tests. The tighter bond with water alsolimits losses to evaporation.

Viterra Gelscape by AglukonAgriproducts in Congers, NY, is a uniquetype of polymer. It is a combination ofacrylamide, potassium acrylate, and an ad-juvant. Gelscape was designed to release

moisture easily to plants based upon need.It holds approximately 200 times its weightof tap water.

Fernando Erazo, president of Aglukon,explains that Gelscape maintains its absorp-tion and release properties for two to threeyears, but the polymer itself does not bio-degrade. "Basically, its absorption capacity[after this period] drops to that of clay orpeat moss, about 20 times its weight inwater," he states. Recommended ratesrange from 1/2 to 3/4 pound per 1,000square feet, or roughly 20 to 30 pounds peracre. "The focus of our product is to im-prove the speed and uniformity of establish-ment through seed coating, and thenmaintain good soil texture and porosity inhigh-wear areas, with subsequent periodicapplications in topdressing or as an amend-ment during core aeration," Erazo says.

Most polymer companies offer two ormore sizes of granules. The size of thegranule is important, stresses DanielWofford, general manager of Western Poly-acrylamide, Inc., Castle Rock, CO. Fine crys-tals (less than 500 microns) are best suitedfor root dipping and seed coating. Largercrystals (between 500 and 1,500 microns)are better for soil amendment.

"They are identical products, yet their

Olathe's Polymer Planter is designed for dry polymers.

properties are so different in use that weshould consider them dissimilar," saysWofford. "The standard [larger] crystalshydrate to form large, individual lumps ofgel with resulting high pore space, whilethe fine material forms a sticky mass." Hewarns that larger granules should be uni-form in size and free of fines or dust. Thecompany markets HydroSource, anothercross-linked polyacrylamide.

He has been gathering data on polymers

from more than 30 universities and de-scribes some of the benefits revealed todate. Improved root development andstress reduction may account for dramaticresults with a number of crops, includingturf. There is some evidence that polymershave a cooling effect on soils, as well asimproving texture and aeration. Further-more, dissolved fertilizers, root stimulants,and micronutrients are temporarily ab-

continued on page 16

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Circle 122 on Postage Free Card June, 1990 15

Polymerscontinued from page 15

sorbed and released by some of the poly-mers. Used on slopes, they may reducerunoff of water and nutrients.

In addition to storing water, polymersmixed into soil appear to act as a cap forwater moving toward the surface by capil-lary action. By holding capillary moisturebeneath the surface, it is not exposed asmuch to evaporation caused by wind andheat. This effect can backfire in sites withpoor drainage, impervious subsurface lay-ers, or perched water tables. Capillary waterwill keep the polymers swollen and renderthe area too soft. But the right combinationof drainage and polymer may soften hardsoils enough to reduce the potential forsports-related injuries. All these areas arebeing studied at various universities at thepresent time, and preliminary results arepromising.

One researcher involved in polymerstudies is Dr. Jeff Nus, assistant professorof turf science at Kansas State Universityin Manhattan. He points out that the usefullife and water-holding capacity of most syn-thetic polymers is reduced by salts and/orpoor-quali ty water, such as effluent. Soil pHis also a factor in their performance.

Nus is one year into rate determinationstudies for low-maintenance sports fields.He has also begun researching polymerrates and types for United States GreenSection (USGA) spec greens. Various poly-mers were incorporated into the top sixinches of a green profile after the bentgrasssod was removed. The sod was then placedback over the amended rootzone. Unfortu-nately, heavy rainfall this spring has ham-pered initial results.

Dr. Anthony Koski has been studyingthe effects of incorporating polyacrylamidepolymers into the rootzones of Kentuckybluegrass and tall fescue turf at ColoradoState University in Ft. Collins. Koski islooking at four different areas, includingrooting, water infiltration, compaction re-sistance, and irrigation reduction. LastJuly,different brands of polymer were rototilledinto the top eight inches of soil at rates upto 80 pounds per 1,000 square feet.

"We want to find out which polymersand rates will allow turf managers to reduceirrigation to 50 percent of the ET rate," heexplains. Koski will also be testing the plotsfor compaction resistance, using a pene-trometer and a Clegg impact monitor. Hisinitial data will be produced this summer.

"Comparative polymer testing pro-grams, such as those at Kansas State andColorado State, are absolutely essential tothe successful, widespread adoption ofpolymers within the turf maintenance in-dustry," Wofford points out. "If the rightcombinations of equipment, comprehen-sive testing, and polymers are worked out,this will happen."

The greatest potential for polymers ap-pears to be for established turf. Polymercompanies and equipment manufacturersare searching for economical methods toinject them from one to six inches belowthe surface. At the present time, three com-panies have polymer injectors on the mar-ket. At least another three companies hopeto introduce theirs within the comingmonths.

Two basic methods are being tried. Thefirst involves placing a band of dry polymercrystals in the soil, using a modified seeddrill or vibratory plow. Olathe in IndustrialAirport, KS, Yeager-Twose in Hillsboro, OR,and Hydro Resources Southwest have in-jectors working in the field.

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Circle 114 on Postage Free Card

the polymer is fed into the slits throughchutes. The rate of injection ranges from20 to 250 pounds of polymer per acre. Thecompany is exploring new versions, includ-ing one that will cut grooves on closercenters. The current model covers a four-foot-wide swath on each pass and requiresa 40-hp tractor.

"Higher rates are possible by going overan area more than once," Olathe's TomMelton explains. He adds that more infor-mation is needed on rates according to soiltypes and drainage. That is why the com-pany is supporting Nus' research at KansasState.

Yeager-Twose recently adapted its TurfConditioner to create the Bottom Dresser.Vibrating blades spaced ten inches apartopen a channel from two to eight inchesdeep. A chute on the back of each bladedeposits a row of dry polymer at rates fromfive to 500 pounds per acre. The machinecan plant up to three acres of polymer perday.

Hydro Hold Applicators by Hydro Re-sources Southwest extend the width of thepolymer band by lifting the sod and blowingthe crystals underneath. The lifting actionis created by horizontal V-shaped blades

Yeager-Twose Bottom Dresser injects rows of dry polymer.

cavity through a fan-shaped nozzle behindeach blade. In this way, polymer reaches adistance of 12 to 14 inches on both sides ofthe blades.

spaced 28 inches apart. The blades createa cavity at any desired depth between 2-1/2inches (for Kentucky bluegrass) to 4-1/2inches (for berrnudagrass), Polymer from ahopper on the tractor is blown into the continued on page 18

ROOT WATERING CRYSTALS.The Most Revolutionary Product Since Water

AGROSOKE was originally developed and patented for plant water maintenance.

FERTILIZER COMPATIBILITYFertilizers applied to the soil in any form are compatible with AGROSOKE. Unlike other polymers which release their waterand lose the ability to maintain rated water retention in the presence of nutrient salts, AGROSOKE is unaffected. Fertilizerions are retained and available to the plant along with the water. Since AGROSOKE provides free exchange, salt buildupswithin the polymer are not possible.

REDUCTION OF CONTAMINATED GROUND WATER RUN-OFFAGROSOKE incorporated in the mixes will reduce the frequency of water and nutrients being applied therefore reducing therun-off by a minimum of 50%. In addition, when the water, fertilizer, and chemicals are applied the AGROSOKE absorbs alarge percent of what would normally run through.

NONDEGRADABLEAGROSOKE is a small synthetic anionic polymer (polyacrylamide) crystal. It is NOT starch based! Since the polymer wasdesigned to ONLY absorb 40 times its weight in water, the cellular walls are still quite strong when fully expanded. Thesefactors provide for a physically stable, stronger product, even under heavy traffic areas, such as in golf course installations.

AGROSOKE, unlike starch based and most superabsorbing polymers, is not affected with chemical degradation in thepresence of nutrient or other additives. In fact, it absorbs water even more rapidly once the initial expansion has been ac-complished. Since it is permanent, it is ADDED VALUE providing benefit to the plant for the entire life cycle. ThereforeAgrosoke provides a tremendous value to golf courses, sports turf, landscaping, & tree planting.Agrosoke has been tested by Conlee Seed Co. using the USGA recommended greensmix - significantlyfavorable results were obtained in water savings, turf quality, percolation, and cold tolerance.

Complete test results are available upon request.MARKETED BY AGROSOKE INC. - 817-284-9831

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June, 1990 17Circle 119 on Postage Free Card

Polymerscontinued from page 17

The company's 90-inch-wide applicatorpowered by a 60-hp four-wheel-drive tractorcan treat up to four acres of turf per hour,says Salestrom. It also makes a 30-inch-wide model which can cover about one acreper hour when attached to an l Shp, four-wheel-drive tractor. Salestrom has foundthat rates between 100 and 200 pounds peracre are effective. His equipment is de-signed to apply only the cross-linked syn-thetic polymers, not starch-based ones.

Two other dry-polymer injectors are inthe final stages of development. GreenCareInternational in Huntington Beach, CA, hasdesigned its version in conjunction withBroadleaf P4. Tye Manufacturing in Lub-bock, TX, has been working with Agrosokeon an injector. Jerry Hutchinson, presidentof Turf Specialists Corp. in Holbrook, NY,has also developed an injector by adding aGandy Air Flow machine to a Moore Uni-Drill. His contracting company has used thedevice to inject starch copolymers on low-maintenance sports fields on Long Island.

"The potential for this type of equip-ment is tremendous, since it puts turf chem-icals below the surface, where they are not

Hydro-Hold Applicator lifts soil and sprays a28-inch-wide band of dry, synthetic polymer.

exposed to players or weather," Hutchin-son states. "We've seen instances wherelower rates of chemicals have achieved ex-cellent results."

The second approach is to use a pumpto spray polymer gel beneath the surface.RainSaver, Inc., of Walla Walla, WA, haspioneered this technology. A starch copol-ymer gel is pumped under low pressurethrough tubes into slits made by colterblades cutting as deep as 2-1/2 inches. Theinjectors are spaced either three or sixinches apart. The rate of application recom-mended by RainSaver so far is about 25pounds per acre. Despite the comparativelylow rate, company founder Richard (Dean)Culbertson says his customers report watersavings between 20 and 50 percent.

The company makes three models, twoself-powered and one trailer version.Culbertson envisions his product as havingapplications beyond polymer injection. Hesees a growing need to inject insecticidesbelow the surface to reduce exposure andlower rates. "A large portion of surface-ap-plied pesticides are tied up by thatch beforethey reach the pest in the soil," he adds."Many times they need to be watered in. Byinjecting insecticides, you can apply lowerrates and reduce exposure."

"We have discovered that the polymerplanter is a better aerifier than coring ma-chines," says Nus. "Some of the improve-

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Circle 115 on Postage Free Card

18 Golf & Sports TURF Circle 116 on Postage Free Card

ment in the soil can be linked to theaerifying effect of the devices." Nus has justinstalled plots to test rates up to 2,500pounds of polymer per acre. Each plot hasindependent irrigation to enable him toevaluate water retention and irrigation fre-quency.

"Each time a polymer granule expandsand contracts it is providing a form ofaeration," Salestrom explains. "If you aer-ify mechanically, the improvement lasts fora few months. The polymers continue to·aerate the soils for years. You are providingtwo forms of aeration with polymer plant-ers."

The bulk of experience in polymer injec-tion is with rates from 25 to 200 poundsper acre. Calculated at an absorption rateof 150 times the weight of polymer, 200pounds of polymer will store nearly 5,000gallons of water per acre. This is the equiv-alent of .18 inches of water. If the daily ETis .25 inches, technically the polymer pro-vides less than one day's reserve. However,test results have shown considerably longereffects.

Whether or not polymers are holding asignificant amount of irrigation or rainfalldoes not prove or disprove their value.Superintendents have used them success-fully to improve the condition of turfaround sand traps and on slopes. Sod grow-ers and park superintendents have in-creased the speed and germination rate ofseed during renovation. Groundskeepershave noticed a reduction in the hardness ofhigh-wear areas of sports fields. Reducedwater consumption is essentially a bonus toan already useful product.

"If you doubt whether polymers work,"says Salestrom, "put in a test strip in a turfarea. Then turn the water off. Watch to seewhich area stays green longer."

The evidence of water conservation hasbeen convincing enough for a number ofmunicipalities to try polymers on parks andgolf courses. "When an area is hit with awater shortage, the local government hasto do more than implement restrictions forresidents," Salestrom adds. "They have toset an example. Successful use of polymersby municipalities has been a big help ineducating others that they work."

"Education is the greatest hurdle thatpolymer and polymer injector manufactur-ers have to clear," Wofford points out. "Weneed to realize that modern 400x cross-linked polyacrylamide polymer for horticul-ture has been around less than ten years.It's not easy to understand how and whythey work. Universities are now carryingout the type of research needed to clear up

doubts, determine rates, and quantify sav-ings. There is a mounting base of evidenceto document the effectiveness of theseproducts. We need to get this informationout to the sports turf industry."

The evidence is showing that, when usedproperly, polymers can be an important toolfor water management in the future. Whencombined with other water-saving technol-ogy and the utilization of improved,drought-tolerant turfgrasses, billions of gal-lons of water could conceivably be savedwithout sacrificing the quality, playability,and safety of recreational turf facilities. @

"Eachtime apolymer granule

expands andcontracts it is

providing a form ofaeration. "

GRfJOND NfJG INC.

Circle 117 on Postage Free Card

June, 1990 19