Salt-tolerant Turfgrass Mixtures for Minnesota Roadsides

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1 Salt-tolerant Turfgrass Mixtures for Minnesota Roadsides Joshua Friell, Ph.D 26th Annual Transportation Research Conference St. Paul, MN 20 May, 2015

2 Roadside vegetation Safety Water quality Erosion prevention Cooling Aesthetics

3 Turfgrass on roadsides First interest in the 1930s following construction of US Numbered Hwy System and Autobahnen in Germany Turfgrasses were found to be especially well-adapted to roadsides and provided all of the necessary functions

4 Turfgrass on roadsides Minnesota Department of Transportation (MnDOT) specifies the use of mowed turfgrass wherever necessary to: keep desirable views open while maintaining consistency with turf types and care found along bordering land uses (MnDOT, 2011)

5 Extreme stresses Extreme temperature Drought & Compaction Disease Photo Courtesy Andrew Hollman

6 Extreme stresses

7 Extreme stresses

8 Extreme stresses Deicing Salt [primarily sodium chloride (NaCl)]

9 Road salt use in MN 317,514 metric tons yr -1 NaCl are applied in the Minneapolis-St. Paul Metro area (Sander et al., 2007) Applications are typically made as pre-wetted granular NaCl from rotary spreader Standard rates up to 45 kg lane -1 km -1 but are typically higher depending on local conditions (MN LRRB, 2012)

10 Road salt use in MN Saline soil Soil degradation Tissue desiccation Ion toxicity (Biesboer & Jacobsen, 1994; Kronzucker et al. 2013, Munns & Tester 2008) (Biesboer & Jacobsen, 1994)

11 2010 MNDOT specification

12 The problem It is likely that death of roadside turf is due to a combination of biotic and abiotic factors Salt is applied to roads in MN so likely plays a role

13 Two questions 1. Which cultivars of cool-season turfgrasses are salt tolerant and perform well on roadsides in Minnesota? 2. What mixture of turfgrass species is best for survival on Minnesota roadsides?

14 Research framework Phase I: Roadside Variety Trials Phase II: Controlled Variety Trials Phase III: Roadside Mixture Design

15 Phase I /II variety trials Objectives: 1. Evaluate improved cultivars of several species for use on roadsides where damage from sodium chloride has previously been shown to be a major factor in limiting the establishment and persistence of turfgrass 2. Evaluate relative salt tolerance of cool-season turfgrasses using nutrient solution culture in a controlled environment

16 Experimental design 2 Locations I-94, Albertville, MN Larpenteur Ave, Roseville, MN Randomized Complete Block 3 Replications 75 Cultivars in 14 Species

17 Trial Entries Species Entries Seeding Rate (lb-1000 ft -2 ) fine fescue (Festuca spp.) (HD,SLCR,STCR,SH,CH) 23 5 tall fescue (Festuca arundinacea Schreb.) 14 7 Kentucky bluegrass (Poa pratensis L.) perennial ryegrass (Lolium perenne L.) 16 8 tufted hairgrass (Deschampsia cespitosa (L.) P. Beauv.) 2 2 prairie junegrass (Koeleria macrantha (Ledeb.) Schult.) 2 3 creeping bentgrass (Agrostis stolonifera L.) 2 1 alkalaigrass (Puccinellia spp.) 4 4 Idaho bentgrass (Agrostis idahoensis Nash) 1 3

18 Data Collection & Analysis Fall 2010 Surface hardness (0.5 kg Clegg Hammer) Field capacity VWC Visual assessment of establishment 1-9 scale (Poor: 1-3; Fair: 4-6; Good: 7-9) Spring 2011 Visual assessment of survival 1-9 scale

19 Roselawn Cemetery, Roseville

20 Roselawn Blvd Survival 1 Data collected April 27, LSD= AK, alkaligrass BHD, blue hard fescue CH, chewings fescue HF, hard fescue TF, tall fescue SH, sheep fescue SLCRF, slender creeping red fescue STCRF, strong creeping red fescue

21 MnROAD, Albertville

22 MnROAD survival 1 Data collected May 13, LSD= AK, alkaligrass TF, tall fescue HF, hard fescue SH, sheep fescue SLCRF, slender creeping red fescue CBG, creeping bentgrass

23 Phase I Conclusions Mean survival rating by site followed the same trend; however, good establishment of cultivars within sites was not a guarantee of survival the following spring Cultivars of fine fescues generally performed well across all sites Specifically, Shoreline slender creeping red fescue, Beacon hard fescue, Marco Polo sheep fescue did consistently well

24 Greenhouse evaluation Establishment Silica sand 12 wk establishment Fertilized 3x wk -1 Clipped 1x wk -1 to 5cm Nutrient Solution Culture 2 tubs 3 reps tub -1 2 experimental runs

25 Experimental design 4 salt exposure profiles Solution supplemented with 5 M NaCl 2 weeks at each level Ramp at 2 ds m -1 d -1

26 Data collection & analysis Digital image analysis

27 Data collection & analysis Digital image analysis 75.51%

28 14 ds m-1

29 Phase II Conclusions Significant differences exist between cultivars for tolerance to salinity in nutrient solution culture Cultivars of tall fescue performed best at the highest levels of salinity, followed closely by creeping red fescues and alkaligrass Despite breeding efforts, trends among species are more important than those between cultivars Indicated cultivars could be chosen from those performing well on roadsides

30 Two questions 1. Which cultivars of cool-season turfgrasses are salt tolerant and perform well on roadsides in Minnesota? 2. What mixture of turfgrass species is best for survival on Minnesota roadsides?

31 Phase III Roadside mixtures

32 Objectives 1. Evaluate the performance of several mixtures of turfgrass on roadsides in the presence of multiple stresses, in particular exposure to de-icing salt 2. Quantify the effect of individual species on the overall performance of turfgrass mixtures containing salt-tolerant cultivars for roadsides in Minnesota 3. Identify a suitable mixture of cool-season turfgrass species for Minnesota roadsides subject to stress from de-icing salts

33 Experimental approach One cultivar to represent each species Design 50 mixtures 5% x i 40% MnDOT mix included Fall 2011: 2 sites x 3 reps Larpenteur Ave (St. Paul) Hwy 14 (Centerville, MN)

34 Data collection & analysis Spring 2012 Spring 2013 Digital Images Visual assessment of weed cover (1-9 scale) Spring cm x 15.2 cm grid of 100 intersects Count those with living turf under them

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36 Results Mixture 5 40% SLCRF 40% SHF 20% TF Mixture 8 40% SLCRF 40% CBG 20% CHF Mixture 24 40% SLCRF 40% SHF 20% ALK

37 Results Mixture 17 40% HDF 40% KBG 7% SLCRF 7% CBG 7% TF Mixture 10 40% SHF 40% CBG 20% TF Mixture 5 40% SHF 40% SLCRF 20% TF

38 Mixture regression

39 Mixture regression

40 Phase IV conclusions & significance Quality characteristics of mixtures created using salt-tolerant cultivars were evaluated Mixtures containing large amounts of fine fescue species performed the best Specifically, a seed mixture containing 40% hard fescue, 40% sheep fescue, and 20% slender creeping red fescue has the best chance for survival on roadsides after two years

41 The big picture Results are currently being used to amend species proportions in MNDOT mixture specifications

42 The road ahead Comparisons in other locations will be useful in determining the extent to which our results may be generalized Current study evaluated seeded mixtures. Further evaluation of farm-grown sod establishment is needed Need to identify for best practices for establishment and maintenance

43 Acknowledgements Minnnesota Local Road Research Board Minnesota Department of Transportation UMN Turfgrass Research Group

44 Thank You!