EFFECTS OF ROOTZONE MATERIAL AND DEPTH ON MOISTURE RETENTION PROBLEMS IN UNDULATING USGA PUTTING GREENS (THE SLOPING GREEN)

TURFGRASS SOILS AND FERTILITY RESEARCH REPORT 2000 Kevin W. Frank and Thmas A. Niklai Department f Crp and Sil Sciences Michigan State University It seems hard t believe that my first year at Michigan State University is almst cmplete. It's certainly been a very busy year as I've fcused n establishing a research prgram and traveling the state t meet thse wrking in the turfgrass industry. Thrn Niklai served as my research technician fr my first 9 mnths but has nw taken a teaching psitin in the tw-year turf grass management prgram. It will be difficult t replace Thrn and I am grateful fr his assistance as I strived t establish my prgram. I have taken n tw graduate students wrking twards a Masters degree. Brian Leach started in June and is cncentrating his research n the Slping Green Research Prject. Kevin O'Reilly has recently started graduate schl and will be wrking n the Lng Term Nitrgen Fate Research Prject. I lk frward t cntinuing several research prjects this year and investigating new areas. I am als eager t cntinue my explratins f Michigan and establish relatinships with thse wrking in the turfgrass industry. The research results presented in this reprt are preliminary f data are necessary t make definitive cnclusins. in nature and additinal years EFFECTS OF ROOTZONE MATERIAL AND DEPTH ON MOISTURE RETENTION PROBLEMS IN UNDULATING USGA PUTTING GREENS (THE SLOPING GREEN) K.W. Frank, B.E. Leach, T.A. Niklai, J.R. Crum, P.E. Rieke, R.N. Calhun and B.R. Leinauer Intrductin The United States Glf Assciatin (USGA) intrduced guidelines fr cnstructing putting greens ver thirty years ag and since then the USGA green has becme the standard fr glf curse putting greens. The cncept behind the USGA recmmendatins fr putting green cnstructin is t build a green that prvides a measure f resistance t cmpactin in the rting zne and drains quickly t an ptimum sil misture level. If greens lacked slpes there is little dubt that mst, if nt all, USGA greens wuld perfrm well. Hwever with the slpes present n putting greens tday, the USGA greens d nt always perfrm ideally. Tw prblems that have cmmnly been encuntered n greens are "Lcalized Dry Spt" (LDS) and "Black Layer". These prblems are primarily assciated with extremes in sil misture in the rtzne f the green (Wilkinsn and Miller, 1978; Tucker et ai., 1990; Cullimre et ai., 1990; Berndt and Vargas, 1992). 15

Specificatins fr a USGA putting green require that the sandy rtzne mixture be placed at a unifrm depth f 30 cm (12"), acrss the entire surface f the green. Hwever, the unifrm rtzne mix depth des nt accunt fr the lateral flw f water in a slping rtzne. Lateral flw ccurs in slping sil prfiles when gravitatinal and surface tensin frces acting n the water becme larger than the attractin f water t the sil. This lateral flw causes lwer water cntents in high areas f the putting green resulting in dry sil cnditins and susceptibility t LDS. Water flws laterally t the lwer parts f the green causing higher water cntents clser t the surface in the same green. This is the lcatin where Black Layer mst frequently ccurs. Research was initiated in 1998 at the Hancck Turfgrass Research Center t investigate whether r nt altering the rtzne depth, decreasing it in high areas and increasing it in lw areas, will increase the water cntent near the sil surface in high areas and decrease the water cntent f the rtzne mix in lw areas. Materials and Methds In 1998, a 950 m 2 (10,000 ft2) research putting green was cnstructed at the Hancck Turfgrass Research Center at Michigan State University. The entire putting green is subdivided int 12 slping plts. The prfile f the green (frm Nrth t Suth) cnsists f a 2.3 m (8') lng flat prtin (teslpe Nrth), fllwed by a seven percent 5.3 m (17.3') lng slpe (backslpe Nrth) t the summit, fllwed by a mre gradual three percent 12.2 m (40') lng dwnward slpe (backs lpe Suth), fllwed by a final 4.5 m (14.7') lng flat prtin (teslpe Suth) (Figure 1). Barriers in the frm f particle bard dividing walls and PVC liners were placed alng the length f each plt t prevent lateral mvement f water between plts. Each plt received ne f three rtzne mixes; sand/peat, sand/sil, r straight sand. Three plts (ne f each rtzne type) have a rtzne mix with a unifrm 30 cm (12") depth (standard USGA type) and three have a rtzne mix depth varying frm 20 cm (8") at higher elevatins t 40 cm (16") at lwer elevatins (mdified USGA type). Drainage tiles were placed in trenches at strategic lcatins acrss the plts: at the extreme ends f each plt as well as at the end f each slpe, and in the middle f the backs lpe f the 3% slpe (Figure 1). The trenches were filled with gravel t cver the tiles and each tile was cnnected t a slid pipe that discharges at the lwer end f each slpe t a rain tipping bucket. A series f 120 Time Dmain Reflectmetry (TDR) prbes and cables were buried in the sil t measure sil misture in 10 cm (4") increments at several lcatins in every plt. The plts are arranged in a tw factr cmplete randmized split-blck design and are replicated twice. A Rainbird irrigatin system was installed t prvide unifrm irrigatin cverage fr the entire green. The green was seeded with creeping bentgrass (Agrstis palustris) cultivar 'L-93' in June f 1998. In 2000, data were cllected n sil misture, leaf surface temperature, turfgrass quality and clr, rt weights, and quantity f drainage water frm varius regins f the green. 16

Turfgrass quality, clr, and leaf surface temperatures were taken frm five lcatins per green (teslpe Nrth, backslpe Nrth, summit, backs lpe Suth, and teslpe Suth). Sil misture readings were cllected fr fur different 'dry dwn cycles' during the summer using a TRIME prtable TDR unit fr the 0 t 10 cm depth. A TDRI00 and a series f multiplexers were used t measure sil misture with the permanently installed prbes at depths f 10-20 cm, 20-30 cm and 30-40 cm. Sil misture measurements were taken in the Nrthfacing teslpe (TDR lcatin 1), summit (TDR lcatin 2), and at tw lcatins in the Suthfacing tes lpe (TDR lcatins 3 and 4) (Figure 1). Rt samples are in the prcess f being washed and weighed and results will be presented in future reprts. Thirty-six rain tipping buckets were installed at the suth end f the green t quantify the amunt f water draining frm three lcatins n the suth slpe f the green (Figure 1). Data frm the rain tipping buckets were cllected cntinuusly thrughut 2000. c Nrth a b TOR #2 e Suth TOR #1 TOR #3 TO #4 Drain tile lcatins 5 Figure 1. Crss sectin thrugh plts with variable rtzne depth and different lcatins fr measurements: (a) teslpe Nrth, (b) backs lpe nrth, (c) summit, (d) backs lpe Suth, (e) teslpe suth. 17

Results and Discussin Turfgrass quality, clr, and leaf surface temperatures There were n cnsistently significant differences bserved in quality, clr, r leaf surface temperatures amng the treatments in 2000. At several sampling times, there were lcatin x cnstructin type x rtzne mix interactins fr turf grass quality but analysis f the three way interactin revealed n imprtant differences amng the treatments. The abundant rainfall received thrughut the spring and summer f 2000 in East Lansing resulted in few differences in turfgrass quality and clr n the green. Sil Misture During the summer f 2000 there were five different 'dry dwn' cycles during which vlumetric sil misture measurements were taken using TDR prbes. Data were analyzed separately by depth fr the 0-10 and 10-20 cm depths. Since the 20-30 and 30-40 cm depths are nt present fr bth cnstructin methds at all lcatins n the green, statistical cmparisns f these depths was nt cnducted. The lcatin x cnstructin type and lcatin x rtzne mix interactin were significant thrughut the dry dwn cycles. Lcatin x Cnstructin Type Interactin 0-10 em depth At the 0-10 cm depth there was a significant lcatin x cnstructin type interactin at almst all measurement times. At the beginning f a dry dwn cycle n August 31, when the rtzne is near field capacity, the lcatin x cnstructin type interactin revealed that at TDR lcatins 1 and 3 the mdified USGA cnstructin type had lwer vlumetric sil misture cntent than the standard USGA cnstructin type (Table 1). There were n differences in vlumetric sil misture cntent between the cnstructin types at TDR lcatins 2 and 4. Furthermre, it was evident that there were n differences in vlumetric sil misture cntent amng TDR lcatins fr the mdified USGA cnstructin type. Hwever, fr the standard USGA cnstructin type the peak f the slpe, TDR lcatin 2, had significantly lwer sil misture cntent values than TDR lcatins 1 and 3. 18

Table 1. Vlumetric sil misture fr the lcatin x cnstructin type interactin at the 0-10 cm depth n August 31,2000. Cnstructin Type TDR Lcatin 1 2 3 4 Mdified USGA 17.5 Bta t 20.8 Aa 16.2 Ba 17.6 Aa Standard USGA 24.2 Aa 17.5 Ab 23.4 Aa 22.5 Aab t Means in a rw fllwed by the same capital letter are nt significantly different accrding t Fischer's prtected LSD (p=0.05) t Means in a clumn fllwed by the same small case letter are nt significantly accrding t Fischer's prtected LSD (p=0.05) different On September 3, 4 days after an irrigatin event, the lcatin x cnstructin type interactin was still significant fr vlumetric sil misture cntent. The mdified USGA cnstructin type had lwer vlumetric sil misture cntent values at TDR lcatins 1, 3, and 4 (Table 2). As n August 31, there were n differences in sil misture cntent amng the lcatins fr the mdified USGA cnstructin type, indicating that the mdified USGA cnstructin type had unifrm sil misture acrss the entire slpe f the green. Acrss the slpe f the standard USGA cnstructin type green, vlumetric sil misture cntent values were lwer at the peak f the slpe, TDR lcatin 2. Table 2. Vlumetric sil misture fr the lcatin x cnstructin type interactin at the 0-10 cm depth n Septmeber 3,2000. Cnstructin Type TDR Lcatin 1 2 3 4 Mdified USGA 14.1 Bta t 14.5 Aa 14.8 Ba 13.6 Ba Standard USGA 21.2 Aa 11.3 Ab 20.8 Aa 19.1 Aa t Means in a rw fllwed by the same capital letter are nt significantly different accrding t Fischer's prtected LSD (p=o.05) t Means in a clumn fllwed by the same small case letter are nt significantly accrding t Fischer's prtected LSD (p=o.05) different 19

Analysis f the lcatin x cnstructin type interactin at the 0-10 cm depth indicated that the mdified USGA cnstructin type had lwer vlumetric sil misture cntent than the standard USGA cnstructin type at TDR lcatins 1, 3, and 4. Althugh the differences were nt statistically significant at this time, vlumetric sil misture cntent was greater at the peak f the slpe, TDR lcatin 2, fr the mdified USGA cnstructin type. The results cnfirm ur initial hypthesis that altering the rtzne depth will decrease misture cntent in lwer regins and increase misture cntent n elevated areas f greens. Lcatin x Cnstructin Type Interactin 10-20 em depth Statistical analysis f vlumetric sil misture cntent fr the 10-20 cm depth revealed a significant lcatin x cnstructin type interactin. The lcatin x cnstructin type interactin results were similar t thse bserved fr the 0-10 cm depth. On August 31, day 1 f the dry dwn, the mdified USGA cnstructin type had lwer vlumetric sil misture cntent values than the standard USGA cnstructin type at TDR lcatins 1, 3, and 4 and higher vlumetric sil misture cntent values at TDR lcatin 2 (Table 3). In cntrast t the misture cntents at the 0-10 cm depth, fr the 10-20 cm depth there were n differences in misture cntent amng lcatins fr the standard USGA cnstructin type. Amng lcatins fr the mdified USGA cnstructin type, sil misture cntent was higher at TDR lcatin 2 than at the ther lcatins. On September 2, three days after an irrigatin event, the mdified USGA cnstructin type had lwer sil misture cntent at TDR lcatins 1 and 4 and was nt different frm the standard USGA cnstructin type at TDR lcatins 2 and 3 (Table 4)..Table 3. Vlumetric sil misture fr the lcatin x cnstructin type interactin at the 10-20 cm depth n August 31,2000. Cnstructin Type TDR Lcatin 1 2 3 4 Mdified USGA 17.0 Btb+ 23.2 Aa 17.3 Bb 16.4 Bb Standard USGA 22.7 Aa 17.8 Ba 21.7 Aa 22.3 Aa t Means in a rw fllwed by the same capital letter are nt significantly different accrding t Fischer's prtected LSD (p=0.05) + Means in a clumn fllwed by the same small case letter are nt significantly different accrding t Fischer's prtected LSD (p=0.05) 20

Table 4. Vlumetric sil misture fr the lcatin x cnstructin type interactin at the 10-20 cm depth n September 2,2000. Cnstructin Type TDR Lcatin 1 2 3 4 Mdified USGA 15.9 Bta t 20.3 Aa 16.6 Aa 15.7 Ba Standard USGA 21.1 Aa 16.5 Aa 20.4 Aa 21.0 Aa t Means in a rw fllwed by the same capital letter are nt significantly different accrding t Fischer's prtected LSD (p=0.05) t Means in a clumn fllwed by the same small case letter are nt significantly different accrding t Fischer's prtected LSD (p=0.05) Lcatin x Rtzne Mix Interactin The lcatin x rtzne mix interactin was als significant thrughut mst f the dry dwn cycles. Vlumetric sil misture cntent values are reprted fr the lcatin x rtzne mix interactin bserved n August 14 and 16, day 2 and 4 f a dry dwn cycle, respectively (Tables 5 and 6). The results indicate that the sand rtzne mix was drier than the sand/peat and sand/sil rtzne mixes at TDR lcatins 1, 2, and 3 n August 14 and at TDR lcatins 1 and 2 n August 16. There were n differences in vlumetric sil ~isture cntent amng lcatins fr the sand/peat and sand/sil rtzne mixes n bth dates. On bth August 14 and 16 within the sand rtzne mix plts, the lwest vlumetric sil misture cntent was at TDR lcatin 2. The results indicate that when vlumetric sil misture cntent is averaged acrss the cnstructin types, the sand/peat and sand/sil rtzne mixes d nt have differences in sil misture cntent acrss the slpe f the green while the sand rtzne mix is cnsistently drier at the peak f the slpe. 21

Table 5. Vlumetric sil misture fr the lcatin x rtzne mix interactin at the 0-10 cm depth n August 14,2000. TDR Lcatin Rtzne Mix 1 2 3 4 Sand 11.1 BCtb+ 7.05 Cc 16.6 Ab 15.2 Ab Sand/Peat 23.2 Aa 23.8 Aa 23.9 Aa 19.9 Aa Sand/Sil 21.4 Aa 17.8 Ab 20.2 Aa 18.4 Aab t Means in a rw fllwed by the same capital letter are nt significantly different accrding t Fischer's prtected LSD (p=0.05) + Means in a clumn fllwed by the same small case letter are nt significantly different accrding t Fischer's prtected LSD (p=0.05) Table 6. Vlumetric sil misture fr the lcatin x rtzne mix interactin at the 0-10 cm depth n August 16, 2000. TDR Lcatin Rtzne Mix 1 2 3 4 Sand 11.0 Atc+ 6.0Bc 14.5 Ab 13.6 Ab Sand/Peat 23.4 Aa 20.4 Aa 21.9 Aa 21.0 Aa Sand/Sil 19.2 Ab 16.4 Ab 17.1 Ab 16.0 Ab t Means in a rw fllwed by the same capital letter are nt significantly different accrding t Fischer's prtected LSD (p=0.05) +Means in a clumn fllwed by the same small case letter are nt significantly accrding t Fischer's prtected LSD (p=0.05) different Drainage Water The quantity f drainage water frm three different lcatins n the suth slpe f the green was cllected cntinuusly thrughut 2000. Water was cllected frm drain tiles lcated apprximately 2.3 m (8') suth f the peak f the slpe (drain tile #3), at the base f the suth backslpe (drain tile #4), and at the suth end f the suth teslpe (drain tile #5) (Figure 1). A ttal f 1.25 cm (0.5") f water was applied at 10:00 a.m. unifrmly acrss the entire green n September 3. N irrigatin had been applied fr the previus 4 days. The amunt f water 22

cllected frm the three drain tiles and the time ver which it was cllected are presented in Figures 2-4. Drain tile number three cllected the smallest amunt f water and nly fur f the rtzne mix/cnstructin type greens had any water cllected at this drain tile (Figure 2). All three f the mdified USGA cnstructin type greens had water draining frm drain tile number 3 and nly ne f the standard USGA cnstructin type greens, the USGA sand/peat rtzne mix, had water draining frm drain tile number 3. Drain tiles number 4 and 5 had larger amunts f water draining frm them and all greens had water draining frm these tiles (Figures 3 and 4). Fr drain tile number 4, all f the standard USGA cnstructin type greens had water draining frm the tile befre the mdified USGA cnstructin type greens (Figure 3). Fr drain tile number 5 the results are nt as clear (Figure 4). The time rder f water draining frm drain tile #5 is as fllws: standard USGA sand rtzne mix, mdified USGA sand rtzne mix, standard USGA sand/sil rtzne mix, standard USGA sand/peat rtzne mix, mdified USGA sand/sil rtzne mix, and finally the mdified USGA sand/peat rtzne mix. The percent f the ttal water cllected frm the suth slpe f the green that drained frm each individual drain tile is presented in Table 7. Drain tile number 3 had a maximum value f 8.5% f the ttal water cllected frm tiles 3, 4,. and 5. Fr the standard USGA cnstructin type, the highest percentage f water drained frm tile number 4. Fr the mdified USGA cnstructin type, the highest percentage f water drained frm tile number 5. Althugh preliminary in nature, these results seem t indicate that by altering the rtzne depth mre water is cllected ff the peak f the slpe and less drains t the lwer regins f the green. Further replicatin f irrigatin events in 200 1 and cmplete installatin f tipping buckets n the nrth side f the green will enable mre definitive cnclusins with respect t the amunts f water draining frm varius regins f a slped putting green. 600 500 ~ 400 (1)... c! 300...J E 200 - Irrigatin -+- Md-Sand --- Md-Sand/Sil -.- Md-Sand/Peat.USGA-Sand ~ USGA-Sand/Sil ~ USGA-Sand/Peat 100 ~~ ~ O;)~ ~~ ~~ ~ ~~ ~~ ~~ ~,,~ ~~ ~~ ~ ~~ ~~ ~~ ~~~~~~~~~~~~~~~~~ Time Figure 2. Amunt f water cllected frm drain tile number three after an irrigatin event n September 3. 23

8000... 7000 6000 Q) 5000 ns ~ 4000 -I E 3000 -+- Md-Sand -... Md-Sand/Sil '-if". Md-Sand/Peat ~USGA-Sand ~ USGA-Sand/Sil..- USGA-Sand/Peat 2000 1000 ~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~ Time Figure 3. Amunt f water cllected frm drain tile number fur after an irrigatin event n September 3. 8000 7000 6000...! 5000 ca!4000 ~ 3000 2000 1000 -+- Md-Sand --- Md-Sand/Sil '-;ih.'" Md-Sand/Peat -*- USGA-Sand... USGA-Sand/Sil -.-...- USGA-Sand/Peat ~~~~~~~~~~~.~~~~~~ ~~~~~~~~~~~~~~~~~ Time Figure 4. Amunt f water cllected frm drain tile number five after an irrigatin event n September 3. 24

Table 7. The percent f the ttal drainage water cllected frm the suth slpe f the green that drained frm each drain tile. Drain Tile Cnstructin Methd/Mix 3 4 5 Mdified Sand 1.79 t 36.3 61.9 Mdified Sand/Peat 8.53 22.6 68.9 Mdified Sand/Sil 0.26 36.3 63.4 USGA Sand 0.00 55.4 44.6 USGA SandlPeat 0.00 80.9 19.2 USGA Sand/Sil 3.34 63.5 33.2 t Percent f water cllected Cnclusins The results frm 2000 cnfirm ur initial hypthesis that altering the rtzne depth decreases sil misture cntent near the putting green surface in lwer regins f the green and increases sil misture cntent near the putting green surface in higher areas f greens. The cncern that was raised in the 1999 reprt that lwer misture cntent in the lwer regins f the green culd lead t greater susceptibility t drught stress still needs t be cnsidered. Analysis f rting depth in these areas shuld prvide valuable infrmatin t help determine the relevancy f this cncern. Future Directins fr 2001 Research will cntinue t investigate sil misture cntent using TDR prbes thrughut the entire seasn f 2001. Rain tipping buckets will be installed n the nrth side f the green s an entire balance f water applied t the green will be able t be accunted fr thrugh the drainage water. A sil gas analyzer has been acquired this fall and will be used in 2001 t measure gas cncentratin at different lcatins and depths in the green. Acknwledgements This research is currently supprted by grants frm the United States Glf Assciatin, Glf Curse Superintendents Assciatin f America, and the O.J. Ner Turfgrass Fundatin. We are als grateful fr supprt frm the Michigan Turfgrass Fundatin, TriTurflnc., Rainbird, and Bruce Mathews frm Design3. 25