The Effects Of Reinforcement Inclusions On Wear Tolerance, Playing Quality And Physical Properties In A Silt Loam And Sand Rootzone Matrix

Transcription

1 University of Connecticut Plnt Science Articles Deprtment of Plnt Science July 2005 The Effects Of Reinforcement Inclusions On Wer Tolernce, Plying Qulity And Physicl Properties In A Silt Lom And Snd Rootzone Mtrix Willim M. Dest University of Connecticut Deprtment of Plnt Science Krl Guillrd University of Connecticut Deprtment of Plnt Science, krl.guillrd@uconn.edu Scott Edon University of Msschusetts Amherst Deprtment of Plnt nd Soil Science Follow this nd dditionl works t: Recommended Cittion Dest, Willim M.; Guillrd, Krl; nd Edon, Scott, "The Effects Of Reinforcement Inclusions On Wer Tolernce, Plying Qulity And Physicl Properties In A Silt Lom And Snd Rootzone Mtrix" (2005). Plnt Science Articles. 9.

2 Interntionl Turfgrss Society Reserch Journl Volume 10, THE EFFECTS OF REINFORCEMENT INCLUSIONS ON WEAR TOLERANCE, PLAYING QUALITY AND PHYSICAL PROPERTIES IN A SILT LOAM AND SAND ROOTZONE MATRIX Willim M. Dest*, Krl Guillrd nd Scott Edon ABSTRACT Reinforcement inclusions hve een dvocted to llevite wer, compction, nd unstle surfces in sports fields, ut little reserch on the effects of these mterils hs een conducted in the USA. Experiments were estlished on ntive silt lom nd snd rootzone mtrix, seeded with Kentucky luegrss (Po prtensis L.) lend, t the Joseph Troll Turf Reserch Center, University of Msschusetts, Amherst, USA to determine the effects of reinforcement inclusions on wer, surfce hrdness, trction, ll roll, ll ounce resilience, wter infiltrtion rte, soil ulk density, ir porosity, totl porosity, nd root weights. Three types of reinforcement inclusions (Sportgrss, Netlon, Turfgrids) were tested long with non-reinforced control in three yer study. The tretments were set out in rndomized complete lock design with four replictions in oth soils. No inclusion provided less wer or greter infiltrtion or ir-filled porosity reltive to the control. Reinforcement inclusions showed significnt differences, however, in surfce hrdness, trction, nd ll roll reltive to the control, lthough this vried with the time of yer. Infiltrtion rtes, irfilled porosity, totl pore spce, ulk density, hrdness, trction, ll roll, nd ll reound were greter on the snd rootzone thn on the silt lom. Significnt correltions were present etween soil ulk density, surfce hrdness, trction, nd ll roll. Bsed on our study, the use of reinforcement inclusions to provide etter wer tolernce for snd or ntive soil thletic fields is not wrrnted. Certin plying surfce chrcteristics, however, my e slightly improved with the use of reinforcement inclusions. The use of snds for sports surfces is justified sed upon the improvement in plying qulity chrcteristics nd soil physicl properties importnt to good plying surfce. Keywords ir porosity, ll roll, hrdness, infiltrtion, root weights, trction INTRODUCTION Turfgrss wer, soil compction, nd n unstle surfce re recurring prolems on nturl grss sports fields. Snd sed construction techniques for uilding sports fields hve een developed to llevite some of the soil compction resulting from continued trmpling nd to promote etter dringe nd ir movement into nd through the soil profile. One of the first methods developed using snds ws the USGA Green Section method with detiled specifictions s to prticle size, hydrulic conductivity under sturted flow, nd pore spce distriution (Ferguson et l., 1960 nd Ferguson, 1965). Snd construction methods hve lso een found to sustin more usge efore losing their grss cover compred to construction using nturl soils such s sndy loms (Bker nd Gis, 1989). However, prticle stility remins prolem on snd rootzone constructed fields prticulrly when vegettive cover is worn wy through continued use. Furthermore, fields uilt from nturl soils Willim M. Dest nd Krl Guillrd, Deprtment of Plnt Science, University of Connecticut, 1376 Storrs Rod, Unit-4067, Storrs, CT , USA. Scott Edon, Deprtment of Plnt nd Soil Science, University of Msschusetts, Amherst, MA , USA. *Corresponding uthor: profdest@ol.com (sndy loms, loms, silt loms, etc.) will hve the sme prolem occurring when soil moisture is ner or ove field cpcity. This especilly tkes plce t the ltter prt of the plying seson in the fll when precipittion exceeds evpotrnspirtion. Adms nd Gis (1994) descrie the three types of synthetic reinforcement inclusions s 1) intct frics or crpets, 2) mesh frgments, nd 3) individul fiers. These mterils hve shown promise in some situtions in providing stle plying surfce, incresing wer tolernce of sports fields, nd improving the plying performnce of the surfce. However, the mterils re lrgely used in fields uilt using snd constructed techniques. Adms nd Gis (1989) reported the enefit of VHAF, needlepunched-geotextile fric, in providing stility nd trction on snd constructed fields where the vegettive cover ws worn wy. Smller divot openings nd n increse in turf recovery were noted using interlocking mesh elements incorported into snd rootzone compred with the control y Berd nd Sifers (1990). However, they found no difference in ll reound, nd trction vlues were inconsistent etween tretments on Tifwy ermudgrss [Cynodon dctylon (L.) Pers. x C. trnsvlenis Burtt Dvy] turf. Cnwy (1994) reported n increse in trction nd hrdness nd

3 1050 in wter infiltrtion rtes y incresing the mount of mesh element inclusions in snd. A significnt increse in ir-filled nd totl porosity with susequent decrese in ulk density y the incorportion of mesh elements in snd compred with control ws shown in lortory nd field study y Richrds (1994). Bker nd Richrds (1995) found in lortory study tht the incorportion of fiers in snd produced greter totl nd ir-filled porosity s fier content incresed. Bker nd Richrds (1995) further reported n increse in trction, hrdness, nd ll reound in field tril on snd with incresed fier content therey supporting more stle surfce. However, they reported no effect on ground cover from the fiers reltive to the control (without fiers). Although most studies utilizing reinforcement inclusions hve een in snds, few studies hve een conducted on ntive soils (Bker et l., 1988; McNitt nd Lndschoot, 2001). Bker et l. (1988) using five reinforcement mterils in sndy lom nd snd crpet rootzone found etter overll wer nd trction on the sndy lom with most of the reinforcement mterils, while there ws very little effect from these mterils used in the snd rootzone when compred with snd rootzones without the inclusions. However, the surfce of the sndy lom ws reported to e uncceptly soft when it ws excessively wet regrdless of the reinforcement mterils, wheres the snd rootzone surfce ws slightly hrder with the reinforcement mterils thn snd y itself. Bker et l. (1988) found ll reound chrcteristics improved on the sndy lom soil in four of five reinforcing mterils in wet conditions, with ll reound within cceptle limits in the snd crpet rootzone regrdless of whether reinforcement mterils were used. A significnt difference in ll roll occurred only once during the two yer study due to reinforcement mterils. McNitt nd Lndschoot (2001) found limited enefits from reinforcement inclusions (Sportgrss, Turfgrids, nd DuPont Shredded Crpet) reltive to the control under three wer tretments tht included non-wer tretment on silt lom. They ssessed turf density, surfce hrdness nd trction, wter infiltrtion rtes, soil moisture content, nd soil ulk density. Differences in dmge from wer tretments cross ll inclusion tretments were negligile compred with the control. Sportgrss provided the est density of the four tretments ut on only one occsion ws it etter thn the control. The Bker et l. (1988) study indictes tht reinforcement inclusions my e of greter enefit to improving the plying surfce of nturl soils of which mjority of sports fields re constructed. Although McNitt nd Lndschoot (2001) were the first to ssess nd report these mterils in ntive soil for thletic field use in the United Sttes, no comprtive study of reinforcement inclusions on the difference in their effect on ntive soil nd snd rootzone hs een done here. The ojective of our study ws to investigte the effects of three synthetic reinforcement inclusions in silt lom nd snd rootzone to compre the effects of these mterils on the two soils s to: 1) wer tolernce of cool seson turf used for sports fields, 2) surfce plying qulity, nd 3) their influence on soil physicl properties. MATERIALS AND METHODS A field experiment ws conducted t the Joseph Troll Turf Reserch Center, University of Msschusetts, Amherst, USA over three yer period. Experiments were estlished in two soil types ( ntive silt lom (corsesilty mixed, noncid, mesic Typic Udifluvents) nd snd rootzone). The silt lom hd snd, slit, cly composition of 244, 666, nd 90 g kg -1, respectively, with n orgnic mtter content of 51.9 g kg -1. The snd rootzone hd snd, silt, cly composition of 975, 22, nd 3.0 g kg -1, respectively, with n orgnic mtter content of 13.5 g kg -1. Three types of reinforcement inclusions were tested in ech soil with control (no reinforcement inclusions). The reinforcement mterils were n intct fric Sportgrss (Sportgrss Inc., McLen, Virgini, USA) comprising polypropylene woven cking with 37 mm polypropylene fiers tufted into the cking, Netlon (Netlon Limited, Blckurn, UK) which is 50 x 100 mm rectngulr polypropylene grids with ris protruding from the edges nd Turfgrids (Stilizer Solutions, Inc., Phoenix, Arizon, USA) which re root hir like 37 mm long polypropylene fiers tht open to form netlike structure when mixed with soil. Tretments were set out in rndomized complete lock design with four replictions on ech soil. Plot size ws 1.8 x 7.3 m. A wooden frmework ws constructed to order the plots. The Netlon ws mixed with the soils offsite with ucket loder to chieve 0.74 kg m -2 of Netlon nd plced to 152 mm depth for ech plot. The Turfgrids were incorported t 0.68 kg m -2 to 152 mm depth with rototiller. Thorough mixing ws ccomplished y removing 76 mm of the soils for ech plot, mixing hlf the mount of Turfgrids into the ottom 76 mm of soil with the rototiller, returning the upper 76 mm of soil nd incorporting the remining Turfgrids into the top 76 mm. The Sportgrss ws cut to fit the plots, stpled nd then topdressed with snd meeting USGA specifictions (USGA Green Section Stff, 1993) nd rushed into the fiers. The snd ws topdressed in increments nd rushed in until only 6 mm of the fiers were showing. The wooden frmes were then removed. The plots were fertilized with 54, 42 nd 50 kg h -1 of N, P nd K respectively nd then sown on 17 Sept with Eclipse, Touchdown nd Impct Kentucky luegrss cultivrs t 90 kg h -1. The plots were estlished through Nitrogen, P nd K were pplied in six pplictions over the 1998 growing seson to supply totl of 312, 95, nd 213 kg h -1, respectively, on the snd rootzone. The silt lom plots received 205, 81 nd 162 kg h -1 of N, P nd K, respectively, over the sme growing seson. Nitrogen ws

4 1051 pplied t 214 kg h -1 to oth rootzones in four pplictions over the growing seson in the yers 1999, 2000 nd Phosphorus ws pplied t 19, 13 nd 3 kg h -1 nd K t 97, 138 nd 81 kg h -1 to oth rootzones in 1999, 2000 nd 2001 respectively. The plots were mowed t 32 mm cutting height on weekly to twice weekly schedule depending upon the seson nd growth rte. Grss clippings were returned. The plots were irrigted s required to mintin ctive growth. Wer ws simulted using differentil slip wer mchine (Cnwy, 1976) fitted with footll clets. Wer tretments egn in August Wer ws imposed from lte August through mid-decemer in 1999, 2000 nd Plots received wer on Tuesdy nd Thursdy ech week irrespective of the wether. Three psses were mde over the plots ech time wer ws imposed. Tretments were ssessed for 1) turf properties (wer, recupertive potentil, nd root weights), 2) soil physicl properties (wter infiltrtion, ulk density, irfilled porosity, nd totl porosity), nd 3) plyer-to-surfce nd ll-to-surfce properties (surfce hrdness, trction, ll roll, nd ll ounce resilience). Wer nd recupertive potentil were rted visully on scle of 1 to 9 in Octoer, Novemer, nd Decemer of ech yer. A rting of 1 indicted no wer nd 9 complete loss of ground cover. Rtings of less thn 5 indicted lef injury with loss of color nd rting of 5 or greter indicted lef injury nd loss of density (thinning). Rtings for recovery were tken in the spring following the previous fll wer in My nd June. A rting of 1 indicted 0 to 20% of the plot recovered nd 9 rting indicted 91 to 100% recovery. At the termintion of the study, 6 cores (3.1 cm 2 ech) were tken to depth of 15 cm to mesure root weights. The cores were plced on screen nd the soil wshed from the cores. The reinforcement mterils nd eril portion of the plnts were removed y hnd fter the soil ws wshed from the roots. The roots were dried t 70º C until constnt weight ws otined. The roots were weighed nd then shed t 600º C for 2 hrs. The sh weight ws sutrcted from the oven dry weight to otin the weight of the roots. Wter infiltrtion ws mesured using doule ring infiltrometers (Bertrnd, 1965). The inside nd outside rings were 305 mm nd 610 mm, respectively. The rings were inserted 25 mm into the ground with mesurements tken from the inside ring. The inside ring ws filled to 100 mm nd the level of drop inside the cylinder mesured t intervls nd then refilled to the 100 mm level fter ech intervl. Infiltrtion ws recorded once the rte ecme constnt over three mesurements. In no instnce etween intervls ws the wter llowed to drop elow 50 mm. Mesurements were mde in the summer, 1999 efore wer ws imposed on the plots, t the end of Septemer 2000 nd in June nd Octoer, At the termintion of the study, two undistured cores 53 mm in dimeter y 30 mm in length were otined with rss cylinder fitted inside metl tue from ech plot for determining ulk density (Blke, 1965), totl porosity (Vomocil, 1965) nd ir-filled porosity (Vomocil, 1965; ASTM F , 1999). Thtch nd soil were removed to 38 mm elow the surfce efore inserting the metl tue with the rss cylinder. This included removing section of the Sportgrss just elow the cking, so tht the core smples could e otined. Air-filled porosity vlues for the silt lom were determined t -10 kp nd t -3 kp for the snd rootzone. Surfce hrdness ws mesured using Clegg Impct Soil Tester (Clegg, 1976). An ccelerometer ws fstened to 2.25 kg missile dropped from height of 300 mm with the pek decelertion mesured in grvities (Gmx). Mesures were tken in the lte spring nd fll of 1999, 2000, nd Four redings were mde per plot ech time mesurements were tken. Trction ws mesured y device descried y Cnwy nd Bell (1986). The device comprised 150 mm steel disc with six footll studs spce t intervls round the disc. The disc ws weighted with 34 kg nd dropped from 152 mm height so tht the studs fully penetrted the surfce. The torque required for the studs to ter the surfce ws mesured nd is reported in N m. Four mesurements were tken in ech plot in the lte spring nd fll in ech of the three yers. Bll roll vlues for the different tretments were determined y relesing Didor FIFA-pproved soccer ll inflted to 70 kp down 45º inclined rmp (Bell nd Holmes, 1988; British Stndrd, 1989). The ll ws relesed from height of 1 m nd the distnce mesured from where the ll first met the surfce to where it cme to rest. Three redings were mde in one direction nd then repeted in the opposite direction in ech plot. Mesurements were mde in the fll, 1999 nd in lte spring nd fll of 2000 nd Bll reound resilience ws mesured y relesing Didor FIFA-pproved soccer ll inflted to 70 kp from height of 3 m nd then mesuring its reound height (Bell nd Holmes, 1988; British Stndrd, 1989). Four redings were tken in ech plot. Mesurements were mde in the fll of 1999 nd 2000 nd in the lte spring nd fll of The results re reported s rtio of the reound height over the relese height expressed s percentge. The dt were sujected to the ANOVA procedure of SAS (The SAS Institute, 1990) using the comined nlysis of vrince cross sites (soils). Tukey s Honestly Significnt Difference test ws used to seprte mens when the F-test ws significnt for tretment effects. Correltion coefficients were determined for the reltionships of ulk density to surfce hrdness, trction, nd ll roll, nd the reltionships of ir porosity to infiltrtion nd root weights.

5 1052 Tle 1. The men wer rtings for the min effects of reinforcement inclusions nd soils on turfgrss wer rtings in 1999, 2000, nd Oct. Nov. Dec. Oct. Nov. Dec. Oct. Nov. Dec. Wer rtings Inclusions Sportgrss Turfgrids Netlon Soils Snd rootzone Silt lom F test Inclusion (I) NS NS NS ** ** * ** ** ** Soils (S) ** NS NS ** ** NS ** ** NS I x S NS NS ** * NS NS NS NS NS CV% *,**,NS Significnt t P < 0.05, 0.01, nd not significnt (P > 0.05), respectively. Visul estimtes of wer 1 = no wer; 9 = complete loss of ground cover. A rting of less thn 5 indictes lef injury with loss of color; 5 or greter indictes lef injury nd loss of density. Mens within column for inclusions followed y the sme letter re not significntly different ccording to Tukey's Honestly Significnt Difference test (α = 0.05). RESULTS AND DISCUSSION Turfgrss Wer nd Recovery Fll turfgrss wer rtings for 1999, 2000, nd 2001 re shown in Tle 1. None of the reinforcement inclusions resulted in less wer thn the control cross the two soils, with the exception of Decemer 1999 (Fig. 1). Sportgrss plots hd significntly less dmge from wer Wer rtings Silt Lom Snd Rootzone Sportgrss Netlon Turfgrids Figure 1. Effect of reinforcement inclusions x soil on wer in Decemer Visul estimtes of wer 1 = no wer; 9 = complete loss of ground cover. A rting of less thn 5 indictes lef injury with loss of color; 5 or greter indictes lef injury nd loss of density. Mens for inclusions within soil followed y the sme letter re not significntly different ccording to Tukey s Honestly Significnt Difference test (α = 0.05). thn the control in the silt lom, ut there ws no difference etween the two tretments in the snd rootzone for the lst rtings tken in Decemer Wer on the Sportgrss ws significntly greter on the snd rootzone thn the Netlon tretment (Fig. 1). In Octoer 2000 (Fig. 2), oth control nd Netlon hd significntly less wer thn Sportgrss in the snd rootzone plots. There ws no effect of the inclusions in the silt lom. Wer rtings NS Silt Lom Snd Rootzone Sportgrss Netlon Turfgrids Figure 2. Effect of reinforcement inclusions x soil on wer in Octoer Visul estimtes of wer 1 = no wer; 9 = complete loss of ground cover. A rting of less thn 5 indictes lef injury with loss of color; 5 or greter indictes lef injury nd loss of density. Mens for inclusions within soil followed y the sme letter re not significntly different ccording to Tukey s Honestly Significnt Difference test (α = 0.05).

6 1053 All the tretments showed loss in turf density (wer rtings 5 or greter) s the fll seson dvnced into Decemer of ech yer (Tle 1). There ws significntly greter wer on the Sportgrss thn ll the tretments in Novemer nd Decemer 2000 except etween Sportgrss nd Netlon t the Decemer rting. This trend continued from Octoer through Decemer McNitt nd Lndschoot (2001) reported tht Sportgrss provided etter wer tolernce thn severl other tretments including Turfgrids in two out of five dtes tht rtings were tken. However, Sportgrss gve etter wer only on one out of five dtes reltive to the control. The study ws crried out on silt lom. The only dte tht Sportgrss gve etter wer thn the control in our study ws on the silt lom in Decemer Bker nd Richrds (1995) found little difference on ground cover using fire-reinforcement inclusion on snd rootzone in which significnt differences in fire inclusions were found only on two out of 10 dtes when rtings were tken. The silt lom provided significntly etter wer thn the snd rootzone soil in erly to mid fll in 1999 nd 2000 (Tle 1) in three out of the six dtes rtings were collected. However, the opposite occurred in 2001 when the turf growing on the silt lom ws showing significntly more wer thn the snd rootzone in Octoer nd Novemer. This my e ttriuted to the ingress of nnul medow-grss (Po nnu L.) into the silt lom plots. The silt lom plots comprised 42% nnul medow-grss t the eginning of imposing wer in August 2001 (dt not Tle 2. The men recovery rtings for the min effects of reinforcement inclusions nd soils in 2000, 2001, nd My June My June My June Recovery rtings Inclusions Sportgrss Turfgrids Netlon Soils Snd rootzone Silt lom F test Inclusion (I) NS NS ** ** NS NS Soils (S) NS ** ** NS NS NS I x S NS NS NS ** NS NS CV% Recovery rtings 1 = 0-20% vegettive cover; 9 = % vegettive cover. Mens within column for inclusions followed y the sme letter re not significntly different ccording to Tukey's Honestly Significnt Difference test (α = 0.05). shown). The snd rootzone hd less thn 3% nnul medow-grss. There ws no tretment y soil interction for nnul medow-grss infesttion. Averged cross soils, the Sportgrss tretment hd significntly less nnul medow-grss (17%) thn the control (29%). However, even this did not ccount for the Sportgrss hving significntly more wer thn the other tretments in There ws no significnt difference in wer etween soils t the lst rting in ll three yers. Recovery Recovery rtings for My nd June 2000, 2001, nd 2002 following the wer imposed the previous fll, 1999, 2000, nd 2001 for the min effects re shown (Tle 2). The only significnt inclusion y soil interction occurred t the June 2001 rting (Fig. 3). There ws no significnt difference in recovery etween the inclusion tretments in My nd June of 2000 nd Recovery in My 2001 for the control nd Netlon tretments cross oth soils ws significntly greter thn the Sportgrss tretment. The reinforcement inclusion y soil interction on June 2001 (Fig. 3), shows no difference in recovery mong the inclusions on the silt lom. The recovery of turf on the Netlon nd Turfgrid tretments, however, ws significntly greter thn the Sportgrss on the snd rootzone y the June rtings, lthough the recovery from these tretments ws no etter thn the control. The turf growing in the silt lom soil showed significntly greter recovery thn in the snd rootzone on two out of the six dtes (Tle 2). This is proly due to the nturl fertility of the silt lom nd its etter moisture holding cpcity compred with the snd rootzone. Plying Qulity Chrcteristics The men vlues for the min effects of the reinforcement inclusions nd soils on surfce hrdness, trction, nd ll roll re shown in Tle 3. Becuse the trends for these three vriles were similr for the three yers, the dt were comined nd nlyzed cross yers for the spring nd fll periods. Bll reound results re reported for the fll 1999 nd 2000 nd the spring nd fll 2001 (Tle 3). Hrdness Sportgrss resulted in significnt increse in surfce hrdness reltive to Netlon nd the control in the spring, however, there ws no difference etween Turfgrids nd Netlon or etween Netlon nd the control during the sme period (Tle 3). There ws significnt inclusion y soil interction for fll hrdness tht showed Sportgrss providing significntly hrder surfce thn the control in the silt lom nd greter hrdness thn the control nd Netlon in the snd rootzone (Fig. 4). Surfce hrdness in the Netlon, Turfgrids, nd the control tretments did not differ in the silt lom, nd Turfgrids hd significntly hrder surfce in the snd rootzone thn either Netlon or the control. There ws no difference in firmness etween

7 1054 Tle 3. The mens for surfce hrdness, trction nd ll roll for reinforcement inclusions nd soils cross three yers, nd reound resilience vlues for 1999, 2000, nd Reound resilience Surfce hrdness Trction Bll roll Fll Fll Spring Fll Spring Fll Spring Fll Spring Fll Inclusions Gmx N m m % Sportgrss Turfgrids Netlon 52.1c c Soils Snd rootzone Silt lom F test Inclusion (I) ** ** ** ** ** ** NS NS NS NS Soils (S) ** ** ** ** ** ** NS NS ** * I x S NS * NS NS NS NS ** * NS NS CV% *,**,NS Significnt t P < 0.05, 0.01, nd not significnt (P > 0.05), respectively. Mens within column for inclusions followed y the sme letter re not significntly different ccording to Tukey's Honestly Significnt Difference test (lph = 0.05) Recovery rtings NS Silt Lom Snd Rootzone Sportgrss Netlon Turfgrids Figure 3. Effect of reinforcement inclusions x soil on turf recovery in June Recovery rtings 1 = 0 20% vegettive cover; 9 = % vegettive cover. Mens for inclusions within soil followed y the sme letter re not significntly different ccording to Tukey s Honestly Significnt Difference test (α = 0.05). Hrdness (Gmx) Silt Lom Figure 4. Effect of reinforcement inclusions x soil on surfce hrdness for fll rtings. Mens for inclusions within soil followed y the sme letter re not significntly different ccording to Tukey s Honestly Significnt Difference test (α = 0.05). Snd Rootzone Sportgrss Netlon Turfgrids the control nd Netlon t ny time. Richrds (1994) reported tht the difference etween Netlon nd control tretments for hrdness were non-significnt except for one out of four months in which the control registered significntly firmer surfce thn Netlon. The study ws crried out on snd rootzone using Clegg soil impct tester with 0.5 kg missile. In our study, the missile weight of the Clegg meter ws 2.25 kg. Surfce hrdness could not e compred to the stndrds for hrdness suggested y Cnwy et l. (1990) due to differences in the missile weight (0.5 kg) used y Cnwy et l. nd the missile weight of 2.25 kg used in our study. The snd rootzone gve significntly greter hrdness thn the silt lom soil over ll inclusion tretments in the spring nd fll (Tle 3). This is proly result of the difference in soil moisture content etween the two soils. Dest nd Guillrd (1999) reported significnt negtive correltion (r = 0.78, P <0.01) etween soil moisture nd hrdness on soccer fields. Trction The men trction vlues for inclusions cross oth soils for the spring nd fll show significnt differences (Tle 3). Sportgrss gve significntly greter trction thn the control in the spring lthough trction did not differ from the Netlon nd Turfgrids tretments. However, in the fll seson Sportgrss provided significntly greter trction thn ll the other three tretments, even though the Sportgrss hd shown significntly more wer compred with the other tretments, prticulrly during the fll of 2000 nd McNitt nd Lndschoot (2001) reported greter trction with Sportgrss compred with DuPont Shredded Crpet,

8 1055 Tle 4. Person correltion coefficients (r) relting ulk density, surfce hrdness, trction, nd ll roll for spring nd fll dt, nd ir-filled porosity to infiltrtion nd root weights. Spring Hrdness Trction Bll roll Bulk density 0.85** 0.73** 0.82** Hrdness 0.91** 0.91** Trction 0.81** Fll Hrdness Trction Bll roll Bulk density 0.78** 0.77** 0.75** Hrdness 0.87** 0.85** Trction 0.82** Infiltrtion Root weights Air-filled porosity 0.75** 0.48** ** Significnt t P < Turfgrids, nd control over severl dtes, lthough the significnce of the vlues vried etween tretments sed on the dte trction ws determined. There ws significntly greter trction in the spring nd fll on the snd rootzone thn the silt lom. However the trction vlues we found in the silt lom soil re well ove the preferred minimum of 25 N m reported y Cnwy et l. (1990), with men vlues of 46.2 N m nd 41.3 N m for spring nd fll respectively. The inclusion y soil interction ws not significnt in either spring or fll. Bll Roll Vlues for ll roll re shown in Tle 3. Similr to wht ws found with the hrdness nd trction, ll roll significntly incresed on Sportgrss reltive to the control. In ll instnces, the distnce rolled on Sportgrss ws significntly greter thn the other inclusions except for the spring vlues when there ws no significnt difference etween Sportgrss nd the Turfgrids tretments. The ll rolled greter distnce in the fll compred with the spring which my e ccounted for y wer tking plce t tht period with its susequent lef dmge nd thinning the turf. A negtive correltion ws found etween ground cover nd rolling distnce y Holmes nd Bell (1986) nd Dest nd Guillrd (1999). The snd rootzone gve significntly greter rolling distnce over ll inclusions tretments thn the silt lom in the spring nd fll periods (Tle 3). This my e result of the snd providing firmer surfce. There ws highly significnt correltion etween hrdness nd rolling distnce in the spring (r = 0.91) nd fll (r = 0.85) Reound resilience (%) NS Silt Lom Snd Rootzone Sportgrss Netlon Turfgrids Figure 5. Effect of reinforcement inclusions x soil on ll reound resilience for Mens for inclusions within soil followed y the sme letter re not significntly different ccording to Tukey s Honestly Significnt Difference test (α = 0.05). Reound resilience (%) NS Silt Lom Figure 6. Effect of reinforcement inclusions x soil on ll ounce resilience for Mens for inclusions within soil followed y the sme letter re not significntly different ccording to Tukey s Honestly Significnt Difference test (α = 0.05). (Tle 4). There ws no inclusion y soil interction for ll roll in either the spring or fll periods (Tle 3). Bll Reound Resilience There ws n inclusion y soil interction for ll reound resilience in the spring 1999 nd fll 2000 (Fig. 5 nd 6). Bll reound on the Sportgrss tretment ws significntly higher thn the Netlon on the snd rootzone in oth yers. Although reound mesurements determined on the silt lom showed reverse effect etween the Sportgrss nd Netlon, the differences were not significnt. The control nd Turfgrids were not significntly different in reound resilience to either Sportgrss or Netlon in oth soils in 1999 nd There ws significnt difference in ll reound due to soil type over ll inclusions in the spring nd fll 2001 (Tle 3). The snd rootzone resulted in significntly greter resilient surfce in oth sesons thn the silt lom. This my e due to the snd hving firmer surfce nd Snd Rootzone Sportgrss Netlon Turfgrids

9 1056 Tle 5. The men infiltrtion rtes, ir-filled porosity vlues, totl pore spce, ulk density, nd root weights for reinforcement inclusions nd soils. Infiltrtion rte Spring Fll Air-filled Totl pore porosity spce Bulk density Root weights mm h -1 % % g cm -3 mg Inclusions Sportgrss Turfgrids c 1.25c 143 Netlon c Soils Snd rootzone Silt lom F test Inclusion (I) NS NS NS * ** ** ** NS Soils (S) ** ** ** ** ** ** ** ** I x S NS NS NS NS NS NS * NS CV% *,**,NS Significnt t P < 0.05, 0.01, nd not significnt (P > 0.05), respectively. Mens within column for inclusions followed y the sme letter re not significntly different ccording to Tukey's Honestly Significnt Difference test (α = 0.05). lower moisture content thn the silt lom. Gis (2002) nd Dest nd Guillrd (1999) reported negtive correltion etween ll reound resilience nd soil moisture lthough only 15 to 20% of the chnge could e ccounted for y soil moisture in oth studies. Soil Physicl Properties Infiltrtion Rte The men infiltrtion rtes for inclusions nd soils re shown in Tle 5 for 1999, 2000, nd There ws no inclusion y soil interction for infiltrtion. Differences mong inclusions were oserved only in the fll 2001, when Sportgrss hd significntly higher infiltrtion rte thn the control nd Turfgrids, while there ws no significnt difference etween the control, Netlon nd Turfgrids. The snd rootzone conducted wter two to three times the rte of the silt lom (Tle 5). This is not unexpected given the difference in soil texture nd irfilled porosity differences etween the two soils (Tle 5). Further, there ws significnt correltion (r = 0.75) etween ir-filled porosity nd the infiltrtion rte mesured in the fll 2001 (Tle 4), which ws t the sme time tht oth infiltrtion ws determined nd undistured soil smples tken to determine ir-filled porosity vlues. At lest 55% of the infiltrtion vrition etween the two soils cn e ttriuted to ir-filled porosity vlues. However, given the difference in the mgnitude of infiltrtion rtes etween the soils, the infiltrtion rte for the silt lom sed on reltive clsses descriing soil permeility (USDA Soil Survey, 1962) is modertely rpid to rpid (61 to 245 mm h 1 ). The excellent flow in the silt lom ws proly function of tuulr flow cused y erthworm ctivity. Erthworms re in undnce on the silt lom soil t the reserch center. Addition of erthworms hs een shown to increse infiltrtion (Kldivko et l., 1986). Air-Filled Porosity, Totl Pore Spce nd Bulk Density There ws no inclusion y soil interction for either ir-filled porosity or totl pore spce. However, there ws significnt difference in ir-filled porosity nd totl pore spce due to inclusions cross soils nd soil differences cross ll inclusions (Tle 5). The men ir-filled porosity vlue for Sportgrss ws significntly less thn for Turfgrids. There ws no difference in vlues etween Turfgrids, Netlon, nd the control, nor did ir-filled porosity in the Netlon nd control tretments differ significntly from the Sportgrss. This ws lso reflected in the totl pore spce vlues, except in reverse, where the totl pore spce in the Sportgrss tretment is significntly lrger thn the Turfgrids tretment. There ws lso significnt difference in mens for totl pore spce etween the control nd Turfgrids. The difference in ir-filled porosity etween the snd rootzone nd silt lom ws significnt (Tle 5). Airfilled porosity in the snd rootzone ws 25.8% compred

10 1057 Bulk density, g cm Silt Lom NS Snd Rootzone Sportgrss Netlon Turfgrids Figure 7. Effect of reinforcement inclusions x soil on ulk density. Mens for inclusions within soil followed y the sme letter re not significntly different ccording to Tukey s Honestly Significnt Difference test (α = 0.05). with 13.6% in the silt lom. However, given the men irfilled porosity vlue of the silt lom, the vlue of 13.6% ws still ove the minimum vlue of 10%, vlue elow which ertion porosity cn ecome deficient (Grle, 1971). The snd rootzone hd significntly lower totl porosity thn the silt lom (Tle 5). There ws n inclusion y soil interction for ulk density (Fig. 7). Turfgrids significntly lowered the ulk density in the silt lom compred with ll other tretments. There ws no effect on ulk density in the snd rootzone from inclusion tretments. The ulk density vlues found in our study do not indicte soil compction occurred over the durtion of the study. Bulk densities of the silt lom soils t the reserch center tht we hve mesured rnge from 1.19 to 1.27 g cm -3. The ulk density on the snd rootzones mesure from 1.46 to 1.52 g cm -3. Root Weights None of the reinforcement inclusion tretments hd significnt effect on root growth compred with the control tretment (Tle 5). There ws no inclusion y soil interction. The men root weight in the snd rootzone ws significntly greter thn in the silt lom soil. This is prtilly result of improved ertion porosity of the snd rootzone s shown y the reltionship etween ir porosity vlues nd root growth in which there ws highly significnt positive correltion etween the two (Tle 4). CONCLUSIONS Although ll the tretments showed incresed dmge from wer s the fll seson progressed, none of the reinforcement inclusions improved wer tolernce reltive to the control except on the silt lom in Decemer 1999 when there ws significntly less dmge on the Sportgrss tretment compred with the control. However the difference in turfgrss wer etween the two tretments did not ffect the rte of recovery in the spring There ws significntly less dmge from wer on the silt lom plots erly in the fll thn on the snd rootzone in the first two yers of the study, likely result of the nturl fertility nd etter moisture holding cpcity of the silt lom resulting in etter growth fter ech wer tretment. However, this chnged in 2001 with the snd rootzone providing significntly etter turfgrss wer compred with the silt lom. This ws result of ingress of nnul medow-grss in the silt lom in which 42% of the turfgrss community comprised nnul medow-grss compred with 3% of the popultion in the snd rootzone suggesting n dvntge of snd rootzone in keeping nnul medow-grss popultions low or the need to mnge ntive soils to reduce the ingress of nnul medow-grss. Sportgrss nd Turfgrids significntly incresed surfce hrdness reltive to the control in the spring nd fll while there ws no difference in hrdness etween Netlon nd the control in either the spring or fll seson. There ws lso significnt difference in surfce hrdness in the fll etween Turfgrids nd Netlon on the snd rootzone, however there ws no difference etween the two tretments on the silt lom soil. This could e due to the higher soil moisture content of the silt lom exerting greter influence over surfce hrdness thn the two tretments. The ddition of Sportgrss significntly incresed trction reltive to the control in the spring nd fll while no difference in trction occurred mong the Turfgrids, Netlon nd control over the sme periods. Although there ws no significnt difference in trction mong Sportgrss, Turfgrids nd Netlon from the mesurements mde in the spring, Sportgrss significntly incresed trction compred with these two tretments in the fll seson. This my hve resulted from the closer contct of the footll studs with the polypropylene fires s result of decresing turf density from wer. The distnce the ll rolled incresed significntly on the Sportgrss compred with ll other tretments in the spring nd fll except for the spring when there ws no significnt difference etween the Sportgrss nd Turfgrids tretments. The greter rolling distnce chieved with Sportgrss ws due to the greter turfgrss dmge from wer in the fll with loss of density nd the slower rte or recovery in the spring 2000 nd 2001 compred with the other tretments. Surfce hrdness, trction nd ll roll were significntly improved in the spring nd fll on the snd rootzone compred with the silt lom. This is indictive of the firmer surfce provided y the snd rootzone nd shown y the positive correltion etween ulk density nd hrdness, trction nd ll roll. Bll reound resilience ws less ffected y tretments thn the other plying qulity chrcteristics except in the spring nd fll 2001 when the snd rootzone provided surfce with significntly improved resilience

11 1058 compred with the silt lom. This ws due to the snd rootzone s firmer surfce nd lower moisture content. Although some of the reinforcement inclusions nd the snd rootzone ccounted for improved plying chrcteristics; trction, distnce rolled nd reound resilience in the control nd silt lom soil were within the proposed stndrds for Associted Footll y Cnwy et l. (1990). Infiltrtion rtes were not ffected y the ddition of reinforcement inclusions with the exception in the fll 2001 when the infiltrtion rte ws significntly incresed y Sportgrss reltive to the Turfgrids nd control tretments. Although not unexpected, the snd rootzone conducted wter 2 to 3 times the rte of the silt lom. The greter mount of ir-filled pores in the snd rootzone compred with the silt lom ccounted for 55% of the increse in infiltrtion. However, given the difference in the infiltrtion rte etween the snd rootzone nd silt lom, the silt lom ws still conducting wter t reltively rpid rte due to the undnt erthworm ctivity. Erthworm ctivity hs een shown to enefit ntive soils y incresing infiltrtion nd dding erthworms is recommended in some situtions. Bsed on our study, the use of reinforcement inclusions to provide etter wer tolernce for thletic fields, whether snd rootzone or ntive soil, is not wrrnted. Certin plying surfce chrcteristics my e slightly improved with the use of reinforcement inclusions, ut the gretest effect on plying qulity chrcteristics nd some of the physicl properties of the soil importnt to good plying surfce were gretly improved y the use of snd construction methods. Therefore, snd construction methods or the use of snd topdressing on ntive soils to provide for firmer surfce nd etter plying qulity chrcteristics should e encourged. ACKNOWLEDGMENTS The uthors thnk Tom Griffen, Mnger of the Joseph Troll Turf Reserch Center for his ssistnce in constructing the plots nd for their susequent mintennce over the life of the project nd Lesley A. Spoks, Reserch Assistnt, Deprtment of Plnt, Soil nd Insect Science, University of Msschusetts for her ssistnce nd use of the lortory for determining pore spce distriution. REFERENCES Adms, W.A., nd R.J. Gis The use of polypropylene fires (VHAF) for the stiliztion of nturl turf on sports fields. p In H. Tktoh (ed.) Proc. of the Int. Turfgrss Res. Conf., 6 th, Tokyo, Jpn, 31 July 5 August Int. Turfgrss Soc. nd Jpnese Soc. of Turfgrss Sci., Tokyo, Jpn. Adms, W.A., nd R.J. Gis Nturl Turf for Sports nd Amenity: Science nd Prctice. CAB Interntionl, Cmridge, 404 pp. ASTM Stndrds F Stndrd test method for sturted hydrulic conductivity, wter retention, porosity, prticle density nd ulk density of putting green nd sports turf root zones in Annul Book of ASTM Stndrd v Americn Society for Testing Mterils, West Conshohocken, PA, pp Bker, S.W., A.R. Cole, nd S.L. Thornton The effect of reinforcement mterils on the performnce of turf grown on soil nd snd root zones under simulted footll-type wer. J. Sports Turf Res. Inst. 64: Bker, S.W., nd R.J. Gis Levels of use nd the plying qulity of winter gme pitches of different construction types: cse studies t Nottinghm nd Wrrington. J. Sports Turf Res. Inst. 65:9-33. Bker, S.W., nd C.W. Richrds The effect of firereinforcement on the qulity of snd rootzones used for winter gmes pitches. J. Sports Turf Res. Inst. 71: Berd, J.B. nd S.I. Sifers Fesiility ssessment of rndomly oriented, interlocking mesh element mtrices for turfed root zones. p In R.C. Schmidt et l. (ed.) Proc. of the Symp. on Chrcteristics nd Sfety of Plying Surfces (Artificil nd Nturl) for Field Sports, Phoenix, AZ. 6 Dec Americn Society for the Testing of Mterils, West Cohonshocken, PA. Bell, M.J., nd G. Holmes The plying qulity of ssocition footll pitches. J. Sports Turf Res. Inst. 64: Bertrnd, A.E Rte of wter intke in the field. p In C.A. Blck (ed.) Methods of Soil Anlysis, Prt 1. Agron. Monogr. 9. Americn Society of Agronomy, Mdison, WI. Blke, G.R Bulk density. p In C.A. Blck (ed.) Methods of Soil Anlysis. Prt 1. Agron. Monogr. No. 9. Americn Society of Agronomy, Mdison, WI. British Stndrds BS 7044: Section 2.1: Methods for determintion of ll/surfce interction. British Stndrds Institute, London, UK. Cnwy, P.M A differentil slip wer mchine (D.S.1.) for rtificil simultion of turfgrss wer. J. Sports Turf Res. Inst. 52: Cnwy, P.M A field tril on isotropic stilistion of snd root zones for footll using Netlon mesh elements. J. Sports Turf Res. Inst. 70: Cnwy, P.M. nd M.J. Bell Technicl note: An pprtus for mesuring trction nd friction on nturl nd rtificil plying surfces. J. Sports Turf Res. Inst. 62:

12 1059 Cnwy, P.M., M.J. Bell, G. Holmes nd S.W. Bker Stndrds for the plying qulity of nturl turf for Assocition Footll. In R.C. Schmidt et l. (ed.) Proc. of the Symp. on Chrcteristics nd Sfety of Plying Surfces (Artificil nd Nturl) for Field Sports, Phoenix, AZ. 6 Dec Americn Society for the Testing of Mterils, West Cohonshocken, PA. Clegg, B An impct testing device for in situ se course evlution. Austrli Rod Reserch Bureu Proc. 8:1-5. Dest, W.M., nd K. Guillrd Developing plying qulity stndrds for nturl turf thletic plying surfces. p In 1999 Agron. Ast. Americn Society of Agronomy, Mdison, WI. Ferguson, M.H., L. Howrd, nd M.T. Bloodworth Lortory methods for evluting putting green soil mixtures. USGA. J. of Turfgrss Mngement 13(5) Ferguson, M.H After five yers: The green section specifictions for putting green. USGA Green Section Record 3(4) 1-7. Gis, R.J Effect of Loksnd fire-reinforcement on snd crpet rootzone under cool seson nd wrm seson turfgrss mngement. J. Sports Turf Res. Inst. 78: Grle, A.R Effects of compction on content nd trnsmission of ir in soils. p In K.K. Brnes, W.M. Crleton, H.M. Tylor, R.I. Throckmorton, G.E. VndenBerg (eds.) Compction of Agriculturl Soils. Am. Soc. Agric. Eng., St. Joseph, MI. Holmes, G., nd M.J. Bell A pilot study of the plying qulity of footll pitches. J. Sports Turf Res. Inst. 62: Kldivko, E.J., A.D. McKy, nd J.M. Brdford Erthworms s fctor in the reduction of soil crusting. Soil Sci. Soc. Am. J. 50: McNitt, A.S., nd P.J. Lndschoot The effect of soil reinforcement inclusions in n thletic field rootzone. Int. Turfgrss Soc. Res. J. 9: Richrds, C.W Effect of mesh element inclusion on soil physicl properties of turfgrss root-zones. J. Sports Turf Res. Inst. 70: SAS Institute SAS/STAT User s Guide. Vol. 1 & 2. Version 6. 4 th ed. Cry, NC. USDA Soil Survey Soil survey mnul. USDA-SCS Agric. Hndook No. 18. U.S. Government Printing Office, Wshington, D.C. USGA Green Section Stff USGA recommendtions for putting green construction. USGA Green Section Record 31(2): 1-3. Vomocil, J.A Porosity. pp In C.A. Blck (ed.) Methods of Soil Anlysis, Prt 1. Agron. Monogr. 9. Americn Society of Agronomy, Mdison, WI.