R2 = 0.98

R2 = 0.88

R2 = 0.64

R2 = 0.84

R2 = 0.29

R2 = N/A0

10

20

30

40

50

60

0 2 4 6 8 10 12 14 16Seed rate (lbs/1000 sqft)

Turf

cov

er (%

)

2 p/wk

4 p/wk

8 p/wk

12 p/wk

16 p/wk

20 p/wk

R2 = 0.85

R2 = 0.95

R2 = 0.97

R2 = 0.98

R2 = 0.97

R2 = 0.995

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60Seed rate (lbs/1000 sqft)

Tu

rf c

ove

r (%

)

2 p/wk

4 p/wk

8 p/wk

12 p/wk

16 p/wk

20 p/wk

R2 = 0.98

R2 = 0.98

R2 = 0.98

R2 = 0.98

R2 = 0.93

R2 = 0.96

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60Seed rate (lbs/1000 sqft)

Tu

rf c

ove

r (%

)

2 p/wk

4 p/wk

8 p/wk

12 p/wk

16 p/wk

20 p/wk

AbstractThis study was conducted at the Horticulture Research Farm in Ames Iowa. The species evaluated were Perennial ryegrass (Lolium perenne L.) (PR) and Kentucky bluegrass (Poa pratensis L.) (KB). First trial started in 3 September, 2003 and finished on 28 June, 2004. An identical trial started on 1 September, 2004 and concluded on 30 June, 2005. Football traffic simulation was applied weekly for 10 weeks immediately after seeding with a GA-SWC traffic simulator. Seeding rates were 4.9, 9.8, 14.7, 19.5, 24.4, 29.3 and 34.2 g∙m-2 for KB and 24.4, 48.9, 73.3, 97.7, 122.2, 146.6 and 171.0 g∙m-2 for PR. Seeding schedule treatments were single seeding (100% seed rate applied at beginning of trial) vs. multiple seeding (20% seed rate applied weekly over a 5 week period). Regression analysis on percent ground cover indicated that there is a significant positive effect of increased seed rates in both species and both seeding schedules at all evaluation dates. At the end of the traffic period and combined over seeding schedules and years, ground cover ranged from 1.3 to 2.6% and from 26.6 to 78.8% for KB and PR respectively. At the end of the recovery period, ground cover ranged from 55.0 to 75.6% and from 80.0 to 94.1% for KB and PR respectively.

MethodsTwo independent trials, one on Kentucky bluegrass KB (Poa pratensis L.) and the other on perennial ryegrass PR (Lolium perenne L.) were established on a Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll) soil with 4.0% organic matter at the Horticulture Research Farm in Ames, Iowa USA, on 3 Sep 2003 and repeated on 1 Sep 2004.•Each trial was composed of 7 seeding rates (1, 2, 3, 4, 5, 6 and 7 lbs/1000 ft2 for Kentucky bluegrass and 5, 10, 15, 20, 25, 30 and 35 lbs/1000 ft2 for perennial ryegrass) and 2 seeding schedules. Single seeding equaled 100% seed rate applied at beginning of trial. Multiple seeding equaled 20% seed rate applied weekly over a 5 week period. The experimental design was a randomized complete block with 4 replications.•Traffic stress was initiated immediately after the first seeding on 1 Sep in all plots. Traffic was applied weekly with a GA-SCW traffic simulator (Carrow et al., 2001) during a 10-week period. Twelve passes were made with the simulator every Friday for a total of 120 passes.•Turf cover was evaluated monthly; data are shown for the middle and end of the autumn traffic period and the beginning and end of the summer recovery period. The data were analyzed using PROC ANOVA of the SAS software, Version 8 of the SAS System for Windows (SAS Institute, 1999). Means were separated (α = 0.05) by Fischer’s protected LSD.

ConclusionsPerennial Ryegrass vs. Kentucky BluegrassQuestion: Is it a waste of resources to seed Kentucky bluegrass or perennial ryegrass during the autumn football season?Answer: Kentucky bluegrass fails to establish effective turf cover (less than 3%) from seed during the traffic period, however by the end of the following summer turf cover reached a respectable 68% (Table 1, Picture 1 and 2). The Kentucky bluegrass seed is not wasted since it contributes to turf cover by the following year, but during the autumn playing season there should be little expectation for this grass to contribute to turf cover. Perennial ryegrass provided up to 79% turf cover by the end of the traffic season and up to 94% turf cover by the end of the summer recovery period. Perennial ryegrass is far superior to Kentucky bluegrass in terms of providing turf cover from seed during the playing season and at the end of a recovery period (Table 1, Picture 1and 2).

Seed RateQuestion: High seeding rates are often used for athletic fields. How high should seeding rates go before there is no additional benefit from turf cover? Answer: The maximum seeding rate to provide a turf cover benefit could not be determined because the range of seeding rates tested (1-7 lbs/1000 ft2 for Kentucky bluegrass and 5-35 lbs/1000sqft for perennial ryegrass) was too low to produce sufficient R2 values that could reliably predict maximum turf cover (Figure 1). Current research (see below) using Kentucky bluegrass rates up to 15 lbs/1000 ft2. and perennial ryegrass rates up to 60 lbs/1000 ft2. have improved maximum seeding rate prediction for turf cover (R2 values between .85 to .95). Seeding rate plateaus were predicted at 45 lbs/1000 ft2 for Kentucky bluegrass and 200 lbs/1000 ft2 for perennial ryegrass. These rates are being investigated in field studies.

Single vs. Multiple Seeding ScheduleQuestion: Using the same total amount of seed applied during the autumn football season, is it better to seed all at once at the beginning of the football season or a little each week before each game? Answer: It doesn’t really matter (Table 1). Turf cover was very similar for both seeding schedules during the traffic and recovery period (Picture 1 and 2).

THE INFLUENCES OF SEEDING RATE AND TRAFFIC LEVEL ON TURFGRASS THE INFLUENCES OF SEEDING RATE AND TRAFFIC LEVEL ON TURFGRASS COVER WHEN TRAFFIC IS APPLIED DURING ESTABLISHMENTCOVER WHEN TRAFFIC IS APPLIED DURING ESTABLISHMENT

D. D. Minner*, F.J. Valverde, - Iowa State UniversityD. D. Minner*, F.J. Valverde, - Iowa State University dminner@iastate.edu fvalverd@iastate.edu

Picture 1. Kentucky bluegrass and perennial ryegrass turf cover on 17 Nov 2003 for 7 different seeding rates and 2 seeding schedules.

Current research 2004-06

R2 = 0.34

R2 = 0.20

R2 = 0.31

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8

Co

ve

r (%

)

R2 = 0.40

R2 = 0.66

R2 = 0.59

R2 = 0.720

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

1 0 0

0 10 20 30 40

Source Mid Traf End Traf Beg Rec End Rec Mid Traf End Traf Beg Rec End Rec

Seed Rate 0.0051 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001Year 0.0001 0.0001 0.0001 0.0043 0.0001 0.0001 0.0024 ns

Schedule 0.0001 0.0001 0.0224 0.0001 0.0001 0.0031 0.0001 nsBlock 0.0012 0.0001 0.0001 0.0001 ns 0.0001 ns ns

S. Rate * Year 0.0251 ns 0.0047 0.0455 ns ns ns nsS. Rate * Schedule 0.0251 0.0293 ns ns 0.0001 ns ns ns

Year * Schedule 0.0001 0.0001 0.0001 0.0002 0.0001 0.1418 0.0001 0.0001

Seed Rate lbs/M lbs/M1 0.69 1.25 2.81 55.00 5 13.00 26.56 38.13 80.002 0.81 1.56 4.44 64.38 10 20.63 37.50 51.56 84.383 1.25 2.06 5.75 66.88 15 28.13 50.63 62.19 88.444 1.19 1.94 6.31 65.00 20 37.44 59.38 68.75 89.385 1.31 2.31 8.88 67.50 25 44.94 67.38 82.81 92.506 1.31 2.38 9.00 72.81 30 46.81 75.00 85.31 94.067 1.31 2.56 10.94 75.63 35 48.25 78.75 79.38 93.44

lsd 0.40 0.47 1.48 3.93 lsd 5.10 6.60 10.30 2.93

Year2003 1.59 2.43 8.36 68.30 2003 37.05 61.59 71.25 89.552004 0.66 1.59 5.39 65.18 2004 31.29 51.32 62.50 88.21lsd 0.21 0.25 0.79 2.10 lsd 2.72 3.53 5.51 ns

Schedulesingle 1.59 2.34 6.41 64.55 single 45.80 59.18 73.13 89.11

multiple 0.66 1.68 7.34 68.93 multi 22.54 53.73 60.63 88.66lsd 0.21 0.25 0.79 2.10 lsd 2.72 3.53 5.51 ns

Mid Traf = middle of traffic period, 27 Oct 2003 and 28 Oct 2004.End Traf = end of traffic period, 17 Nov 2003 and 18 Nov 2004.Beg Rec = beginning of recovery period, 13 Apr 2003 and 2004.End Rec = end of recovery period, 9 Jun 2003 and 2004.

Pr > FKentucky bluegrass Perennial ryegrass

ResultsTable 1. Summary ANOVA and percent cover of Kentucky bluegrass and Perennial ryegrass for 7 seeding rates and 2 seeding schedules combined over 2003 and 2004.

Literature CitedCarrow, R.N. , R.R. Duncan, J.E. Worley and R.C. Shearman. 2001 Turfgrass traffic (soil compactation plus wear) simulator response of Paspalum vaginatum and Cynodon spp. P. 253-258. In K .Carey (ed.) Int. Turf Soc. Research J. vol. 9.

SAS Institute. 1999. The SAS system for windows, Version 8. SAS Institute Inc., Cary, NC.

Seed rate (lb/1000 ft2)

Figure 1. Turf cover of Kentucky bluegrass and perennial ryegrass taken in the middle (27 Oct) and end (17 Nov) of the autumn traffic period and at the beginning (13 Apr) and end (9 Jun) of the recovery period. Seven seeding rates were applied on 1 Sep 2003 and 3 Sep 2004.

Seeding rate studied in 2003-04 trial

Current research showing expanded levels of seeding rate and traffic. Picture taken at end of autumn traffic period 2004.

Picture 2. Kentucky bluegrass and perennial ryegrass turf cover on 1 Dec 2004 for 7 different seeding rates and 2 seeding schedules.

Kentucky bluegrass

Perennial ryegrass Tall fescue

IntroductionIn a turfgrass system under continuous traffic stress, overseeding is a common practice to improve turfgrass cover in worn out areas. Seeding at the upper range for a recommended species is often suggested. Many sports turf managers seed at rates that often exceed the recommended range by a factor of two and sometimes three. The upper range for seeding rates is not clearly understood when traffic is applied during the seed establishment period.The purpose of this research was to determine the optimum rates and schedules to overseed in a system under continuous traffic stress.

Perennial ryegrass

Kentucky bluegrass