Potential for Natural Zeolite Uses on Golf Courses - Zeolite Products

RESEARCH UPDATE:<strong>Potential</strong> <strong>for</strong> <strong>Natural</strong> <strong>Zeolite</strong> <strong>Uses</strong> on Golf Coursesby A. MARTIN PETROVICAssociate Professor of Turfgrass Science, Cornell University, Ithaca, New YorkTHERE ARE MANY IMPORTANTcharacteristics of a desirable turfgrassroot zone material, namely: minimumcompaction tendency, good water infiltrationand percolation rates, adequate aeration <strong>for</strong>deep rooting, high cation exchange capacity(CEC), and adequate moisture retention.However, due to the heavy traffic that puttinggreens and tees receive, sand is themajor mix component. If properly chosen, itprovides <strong>for</strong> good drainage, resistance tocompaction, and good aeration. By itself,though, it generally lacks adequate cationexchange capacity and water-holding capacity,and it allows excessive percolationrates.Typically, sands are amended with some<strong>for</strong>m of organic matter to create a rootzone mix, and peat is the most widely usedorganic amendment. In some situations,locally available organic matter sources areused. Rice hulls, sewage sludge, and lumberwaste materials are all possibilities. Theadvantages of amending sand with organicsinclude increased water retention, increasednutrient retention (cations), and some pesticidebinding (reduced pesticide leaching).On the down side, organic amendments decomposewith time and are of limited effectivenessin retaining nitrate from leaching.Though not routinely used, some inorganicamendments, including fIred clay, colloidalphosphate, sintered fly ash, vermiculite,perlite, and calcined clay have receivedsome attention. Inorganic amendments canincrease moisture retention to a limiteddegree, but generally do not improve nutrientretention. Some break down over time as aresult of weathering or traffIc. Thus, there isa need <strong>for</strong> an amendment that will increasewater-holding capacity and nutrient (especiallynitrogen) and pesticide retention whilestill remaining stable over time. A naturalzeolite like clinoptilolite may be such anamendment.<strong>Zeolite</strong>s are alumino-silicate minerals fIrstdiscovered in 1756 by Swedish mineralogistBaron Axel R Cronstedt, who named theporous mineral from the Greek wordsmeaning "boiling stones." There are morethan 40 natural zeolites, six of them in largedeposits: anacline, chabazite, clinoptilolite,erionite, mordenite, and phillipsite. Clinoptiloliteis of importance in agriculture becauseof its abundance and its chemicalproperties. Extensive deposits of clinoptiloliteare found in the western United States,the <strong>for</strong>mer Soviet Union, Bulgaria, Hungary,Yugoslavia, and Japan. It has a crystallinestructure with many minute internal poresthat retain water and nutrients such asammonium and potassium. It has a very highcation exchange capacity (from 100 to 230cmol/kg). The pores are large enough toallow cations to pass in and out, but are toosmall <strong>for</strong> bacteria, especially bacteria thatconvert ammonium to nitrate. Water andnutrients held in the pores remain available.Thus, clinoptilolite amendment of sand actsas a mechanism <strong>for</strong> slowly releasingnutrients and water.As seen in Figure 1, clinoptilolite is a rockthat can be ground into sand-size particles.Figure 1. A piece of clinoptilolite zeolite be<strong>for</strong>e processing.It can be mixed with sand, as shown in Figure2, <strong>for</strong> the purpose of increasing both theefficiency of water uptake and nutrientutilization while reducing nitrate leaching.Other Research FindingsSeveral other researchers have studiedthe effects of clinoptilolite on creeping bentgrassgrowth and establishment. Researchconducted at Washington State University(Nus and Brauen, 1991)studied the effects ofvarious amendments (sawdust, sphagnumpeat, and a gravel-sized clinoptilolite) atseveral amendment volumes on the establishmentof creeping bentgrass on sandbasedputting greens. They added sawdust at5%,10%, and 20% by volume; peat at 20%to 33% by volume; and clinoptilolite at 33%JANUARY/FEBRUARY 1993 11

PropertyTABLE!Physical properties of clinoptilolite zeolite-amended sand(CZ-sand) and sand used in the greenhouse experimentHydraulic conductivity, cm hr- ITotal porosity, % (by v)Water availability, %(between -0.003 and -0.1 MPa)Aeration porosity, % (at -0.003 MPa)Bulk density, g cm- 3Particle density, g cm- 3Particle size analysisGravelTotal sand:SiltClayVery coarseCoarseMediumFineVery Finemm>22 ~ 0.052~11 ~ 0.50.5 ~ 0.250.25 ~ 0.10.1 ~ 0.050.05 ~ 0.002

with Pencross creeping bentgrass <strong>for</strong> thegreenhouse studies. The green profiles werefertilized with ammonium sulfate as thenitrogen source at yearly rates of 2, 4, and 6lbs. N/I,OOO sq. ft. Unfertilized profileswere used as check treatments. Ammoniumwas selected as the nitrogen source becauseit is easily retained on the zeolite. The profileswere 1)properly watered and 2) wateredto excess (to produce leachate) on a weeklybasis. To track the applied fertilizer nitrogenin the putting green system, the profiles weremowed weeky at Yi-inch and the amountof fertilizer nitrogen retained in the clippingswas determined. The weekly leachatesamples were analyzed <strong>for</strong> concentrationsof nitrate and ammonium.As seen in Figure 3, the amount offertilizer N that accumulated in the clippingsvaried with the N application rate and zeoliteamendment. As the amount of N appliedincreased, the percentage of applied N thataccumulated in the clippings decreased. Forthe sand profiles, the percentage of appliedfertilizer N that was recovered in the clippingsranged from 62% to 70%. The additionof zeolite to the sand resulted in a greateramount of the fertilizer N ending up in thebentgrass clippings (75% to 93% of theapplied N). This difference was most noticeableat the lower N application rate.As seen in Figures 4 and 5, adding zeoliteto sand also resulted in substantially lessnitrate leaching. The concentration of nitratein the leachate from the putting green profiles,as shown in Figure 5, reveals that inno case was the nitrate level in excess ofthe drinking water standard (10 mg/I) whenthe sand was amended with zeolite. However,water with much higher nitrate levels wasnoted leaching from the sand-only puttinggreen profiles at all N application rates,especially at the highest N rate (6 lbs.N/I,OOO sq. ft.). In this case, the leachatehad nitrate concentrations in excess ofdrinking water standards at least one thirdof the time.Water Use StudiesIn the same greenhouse experimentdescribed above, the amount of water usedby the creeping bentgrass plants was determinedthree times per week by measuringthe change in weight of the lysimeters. Asseen in Figure 5, applying N to creepingbentgrass increased the shoot growth ratenearly ten times with little or no effect onthe water use rate. Shoot growth was alsoincreased by the addition of clinoptilolite tosand, without a substantial increase in theamount of water used by the plant. Thus,better shoot growth can be achieved in puresand putting greens with the addition ofclinoptilolite, and this can be accomplishedwith less water and less total N.Summary and ConcernsAmending sand putting greens with azeolite like clinoptilolite was shown, fromEil.l10080Zil.l a 60:::l ~CZl.~ ~~ Z..... 40;80~2002FIGURE 3these studies, to result in several importantadvantages. First, nitrate leaching from sandbasedputting greens can be reduced. Second,the shoot growth rate and the amountof fertilizer N that ended up in the clippingswas enhanced by the addition of clinoptiloliteto sand. Third, the improved growth ofSand• CZ-sand mixtureTotal N application rate, Ibs/1000 ftzFigure 3. The influence of clinoptilolite amendment of sand and nitrogen application rate on theamount of nitrogen accumulate in the clippings of creeping bentgrass.108il.l~ "'d...l:: .~Co)0..6c\l~ 0..c\l.s Z~~..... 40~20FIGURE 4Figure 4. The influence of clinoptilolite amendment of sand and nitrogen application on thepercentage offertilizer nitrogen leached from putting greens.4Sand• CZ-sand mixture2 4 6Total N application rate, Ibs/1000 ftz6JANUARY/FEBRUARY 1993 13

Q).....co:ll--,~ co:ll-< "0100003.53.02.52.0E-- 8 1.5~ 81.00FIGURE 6246expense of using more water. The creepingbentgrass plants were more efficientin usingwater and N to produce growth.With such strong findings, coupled withthe results from previously published research,it appears that clinoptilolite couldmake an excellent amendment of sand <strong>for</strong>putting greens. Some words of cautionshould be noted, however. To my knowledge,only a handful of golf courses haveused clinoptilolite to either amend newgreens or to use as a topdressing on existinggreens. To date the results have beenencouraging. The long-term stabilityof thecrystalline structure is one major questionthat stillneeds to be addressed. If the zeoliteweathersor is crushed by traffic,will itremain a sand-size particle or become silt/clay size, clogging the highly pervioussand? We are initiating several short- andlong-term studies to answer these questions.Long-term evaluation on actual golf courseswith clinoptilolite-amended sand greens isnecessary.Another point to consider is that theproperties of clinoptilolitecan vary between,and possibly within, deposits. There aresome deposits that are naturally high insodium, potassium, or ammonium, and somecan contain some clay.High-sodium-contentclinoptiloliteshould be leached to removethe sodium be<strong>for</strong>e using it with low-salttoleratinggrasses. The hardness of theclinoptilolitealso varies with each deposit.Some are very hard and would be lesslikely to be damaged by traffic,whereasothers are soft and are more easily crushed.The results of the next series of studieswill help establish guidelines in selecting asource of clinoptilolitebased upon measurableproperties.LITERATURECITEDFerguson, G. A., 1. A. Pepper, and W. R. Kneebone.1986. Growth of creeping bentgrass on anew medium <strong>for</strong> turfgrass growth: c1inoptilolitezeolite-amended sand. Agron. J. 78: 1095-1098.Huang, Z. T. 1992. Clinoptilolite zeolite as anamendment of sand <strong>for</strong> golf green root zones.Ph.D. Thesis. Cornell Univ., Ithaca, NY.Nus, 1. L., and S. E. Brauen. 1991. Clinoptilolitezeolite as an amendment <strong>for</strong> the establishmentof creeping bentgrass on sand media. HartSci.26:117-119.Sand• CZ-sand0.50.002 4N rate, Ibs/1000 ft26(Above left)Figure 5. The influence ofclinoptiloliteamendment of sand and nitrogenapplication rate on the concentration of nitratein the water draining from putting greens.(Left) Figure 6. The influence of clinoptiloliteamendment of sand and nitTvgen applicationrate on the shoot growth rate and evapotranspiration(ET) rate of creeping bentgrass.14 USGA GREEN SECTION RECORD