Since the development of the first parkways in the early 20th century, mowed turfgrasses have been preferred vegetation for use on the shoulders and medians of limited access roadways in the United States (FHWA, 2003). In addition to their aesthetic qualities, these grasses prevent soil erosion, trap dust, and filter storm water while not posing a hazard to errant vehicles. However, the roadside is a hostile environment, and turfgrasses struggle to survive, particularly within 5 m of the pavement. The soil remaining in the highway right-of-way after construction is generally of poor quality, low in organic matter and microbial activity, and has impaired cation exchange capacity (Joshi et al., 2010; Muskett and Jones, 1981).
Heat reflected from the pavement and the constant wind from passing vehicles creates a droughty microclimate (Forman et al., 2003). The pavement is sloped to drain water to the vegetated shoulder or median, which is itself engineered to rapidly drain water into the swale leading either to storm drains or to ponds (NHI, 2009). In most states, in particular in regions with cold winters, salt (sodium chloride) is used to keep the pavement free of snow and ice. Heavy leaching, salt, and other chemicals from the pavement further degrade the soil. As a result, the first 5 m of the vegetated shoulder and median are often bare of vegetation or dominated by annual weeds such as crabgrass, which leave the soil vulnerable to erosion from heavy fall and spring rains.
Vehicle exhaust results in deposition of nitrogen (NOx and NH4) on the roadsides with deposition levels highest closer to the road (Truscott et al., 2005). In surveys along roadways in Scotland, Truscott et al. (2005) found that ruderal species such as turfgrasses were most abundant close to the road and abundance increased with the level of nitrogen deposition. This is also the area of highest salt deposition (Bryson and Barker, 2002; Hutchinson and Olson, 1967; Prior and Berthouex, 1967). Spencer et al. (1988) found interactions between salinity and nitrogen uptake in perennial ryegrass (Lolium perenne) suggesting that sodium chloride enhanced plant uptake of NOx. Bowman et al. (2006) found interactions in tall fescue (Festuca arundinacea Schreb.) showing that damage from sodium chloride was less severe when nitrogen levels were low than when plants were nitrogen-replete. However, both experiments used nitrogen levels sufficient to prevent stunting and chlorosis of the ryegrass, so the results may not apply to roadsides with infertile soil.
To improve the survival of perennial vegetation on the roadside, it is necessary to identify the specific factors limiting vegetation growth and then to either identify plants that can tolerate those factors or identify ways to ameliorate the stresses while still maintaining safety. This study was designed to evaluate the effects of improved cultivars, salt tolerance, and organic matter amendments on perennial grass survival along two highways in Rhode Island. It was initiated in response to widespread erosion and slope failure along limited access highways after two unusually snowy winters and extensive loss of perennial turf cover.
There has been a limited amount of published work on improving the survival of roadside grasses. In the 1960s and 1970s, researchers at the University of Rhode Island determined that low soil fertility and poor mowing practices were the major limiting factors for establishment and survival of roadside grasses (Wakefield et al., 1974, 1981). They recommended the use of red fescue (Festuca rubra L.), sheeps fescue (Festuca ovina L.), and ‘Exeter’ colonial bentgrass (Agrostis capillaris L.), all of which tolerate acidic, infertile soil, and seasonal drought. They also recommended the use of topsoil, annual fertilization, and a mowing height of 10 cm. Red fescue is still a major component of roadside seed mixes in Rhode Island and throughout New England (RIDOT, 2004) but fertilization was discontinued as being too labor-intensive and the use of wide flail mowers (2 to 3 m) on uneven ground inevitably resulted in scalping of vegetation and soil. At the same time, increased traffic levels and changes in deicing practices increased the salt deposition levels on roadsides.
Biesboer et al. (1998) evaluated the survival of 14 native and introduced grasses within 5 m of the pavement along urban roadsides in Minnesota. They concluded that high salt levels were responsible for poor establishment and survival of seedlings and that low nitrogen levels and poor soil structure reduced persistence of those species that successfully established. Only the highly salt-tolerant alkaligrass [Puccinellia distans (Jacq.) Parl.] was able to survive within 1 m of the pavement in their trials, and persistence of alkaligrass was attributed to the species’ heavy seed production even when mowed. Numerous studies have evaluated the salt tolerance of standard turfgrass species (reviewed in Marcum, 2009), and breeders are actively working to improve salt tolerance. However, most studies have been conducted under conditions of non-limiting moisture and fertility, which rarely occur on roadsides; often studies are conducted in the greenhouse. A number of researchers have evaluated grasses for use in low-input lawns with extremely limited moisture and low fertility (Dernoeden et al., 1998; Diesburg et al., 1997; McKernan et al., 2001; Mintenko et al., 2002). However, these studies have not exposed the grasses to the salt and other pollutants common on roadsides. Research in Texas, Connecticut, and Washington, DC, has shown that addition of composted organic matter to roadside soils improves establishment and persistence of perennial grasses by increasing soil fertility and water retention (Block, 2000; EPA, 1997). However, the incorporation of compost had no effect on perennial grass establishment in Iowa and Florida (Harrell, 2002; Richard et al., 2002). In Florida, the limiting factor for vegetation establishment was rainfall, whereas in Iowa, vegetation established effectively in unamended soil.
This study had two objectives. The first was to determine whether improved turfgrass cultivars selected for tolerance to either low-input or saline conditions were superior to common creeping red fescue under roadside conditions. Newer improved cultivars are generally not used on roadsides because seed is more expensive than for common types or old cultivars. The second objective was to determine whether amendment of existing roadside soil with organic matter would improve long-term persistence of perennial grasses. Incorporation of organic matter at planting is more feasible than yearly fertilization for highway departments, but there was concern that the increased organic matter would result in soil salinization and turf damage.
Biesboer, D.D., Neid, S. & Darveaux, B. 1998 Salt tolerance in short-statured native grasses University of Minnesota, St. Paul and Minnesota DOT St. Paul, MN
Bowman, D., Cramer, G. & Devitt, D. 2006 Effect of salinity and nitrogen status on nitrogen uptake by tall fescue turf J. Plant Nutr. 29 1481 1490
Brown, R.N. 2008 Salt tolerance of native grasses with potential for use on roadsides in New England 70 81 Stringer W.C. et al. Managing an ecosystem on the edge Clemson University Columbia, SC
Brown, R.N. 2010 Salt tolerance of some potential low-input turfgrass species ASA, CSSA, and SSSA 2010 International Annual Meetings, 31 Oct. to 4 Nov., Long Beach, CA. 6 Sept. 2011. <http://a-c-s.confex.com/crops/2010am/webprogram/Paper59309.html>. [abstr.].
Brown, R.N. & Sawyer, C.D. 2011 Plant species diversity of highway roadsides in southern New England Northeast Naturalist (in press).
Brown, S., Chaney, R.L., Hallfrisch, J.G. & Xue, Q. 2003 Effect of biosolids processing on lead bioavailability in an urban soil J. Environ. Qual. 32 100 108
Bryson, G.M. & Barker, A.V. 2002 Sodium accumulation in soils and plants along Massachusetts roadsides Commun. Soil Sci. Plant Anal. 33 67 78
Cowley, N., Thompson, D. & Henry, C. 1999 Nitrogen mineralization study: Biosolids, manures, composts Henry C., Sullivan D., Rynk R., Dorsey K. & Cogger C. 1999. Managing nitrogen from biosolids. WDOE Pub. No. 99-508. Univ of Washington Press Seattle, WA
Dernoeden, P.H., Fidanza, M.A. & Krouse, J.M. 1998 Low maintenance performance of five Festuca species in monostands and mixtures Crop Sci. 38 434 439
Diesburg, K.L., Christians, N.E., Moore, R., Branham, B., Danneberger, T.K., Reicher, Z.J., Voigt, T., Minner, D.D. & Newman, R. 1997 Species for low-input sustainable turf in the U.S Upper Midwest. Agron. J. 89 690 694
Epstein, E., Taylor, J.M. & Chancy, R.L. 1976 Effects of sewage sludge and sludge compost applied to soil on some soil physical and chemical properties J. Environ. Qual. 5 422 426
Farfel, M.R., Orlova, A.O., Chaney, R.L., Lees, P.S.J., Rohde, C. & Ashley, P.J. 2005 Biosolids compost amendment for reducing soil lead hazards: A pilot study of Orgro® amendment and grass seeding in urban yards Sci. Total Environ. 340 81 95
Forman, R.T.T., Sperling, D., Bissonette, J.A., Clevenger, A.P., Cutshall, C.D., Dale, V.H., Fahrig, L., France, R., Goldman, C.R., Heanue, K., Jones, J.A., Swanson, F.J., Turrentine, T. & Winter, T.C. 2003 Road ecology: Science and solutions Island Press Washington, DC
Geremia Associates 2010 Industrial pretreatment program Annual Report (1 July 2009 to 30 June 2010). West Warwick Regional Wastewater Facility, Providence, RI
Grebus, M., Watson, M. & Hoitink, H. 1994 Biological, chemical and physical properties of composted yard trimmings as indicators of maturity and plant disease suppression Compost Sci. Util. 2 57 71
Haney, R., Brinton, W. & Evans, E. 2008 Estimating soil carbon, nitrogen, and phosphorus mineralization from short-term carbon dioxide respiration Commun. Soil Sci. Plant Anal. 39 2706 2720
Hargreaves, J.C., Adl, M.S. & Warman, P.R. 2008 A review of the use of composted municipal solid waste in agriculture Agric. Ecosyst. Environ. 123 1 14
Hutchinson, F.E. & Olson, B.E. 1967 The relationship of road salt applications to sodium and chloride ion levels in the soil bordering major highways Highw. Res. Rec. 193 1 7
Imperato, M., Adamo, P., Naimo, D., Arienzo, M., Stanzione, D. & Violante, P. 2003 Spatial distribution of heavy metals in urban soils of Naples City, Italy Environ. Pollut. 124 247 256
Joshi, S.R., Kumar, R., Saikia, P., Bhagobaty, R.K. & Thokhom, S. 2010 Impact of roadside pollution on microbial activities in sub-tropical forest soil of north east India Research Journal of Environmental Sciences 4 280 287
Krishnan, S. 2010 Physiology and genomics of salt tolerance in Lolium and Festuca Environmental Science, University of Rhode Island Kingston, RI
Marcum, K. 2009 Relative salinity tolerance of turfgrass species and cultivars 389 406 Pessarakli M. Handbook of turfgrass management and physiology CRC Press Taylor and Francis Group, Boca Raton, FL
McKernan, D., Ross, J. & Tompkins, D. 2001 Evaluation of grasses grown under low maintenance conditions Intl. Turfgrass Soc. Res. J. 9 25 32
Mintenko, A.S., Smith, S.R. & Cattani, D.J. 2002 Turfgrass evaluation of native grasses for the northern Great Plains region Crop Sci. 42 2018 2024
Richard, T., Persyn, R. & Glanville, T. 2002 Cover crop production and weed control on highway right-of-ways using composted organics American Society of Agricultural Engineers St. Joseph, MI ASAE Paper No. 022051.
Spencer, J.H., Scott, N.E., Portm, G.R. & Davison, A.W. 1988 Effects of roadside conditions on plants and insects. I: Atmospheric conditions J. Appl. Ecol. 25 699 707
Truscott, A.M., Palmer, S.C.F., McGowan, G.M., Cape, J.N. & Smart, S. 2005 Vegetation composition of roadside verges in Scotland: The effects of nitrogen deposition, disturbance and management Environ. Pollut. 136 109 118
Turer, D., Maynard, J. & Sansalone, J. 2001 Heavy metal contamination in soils of urban highways: Comparison between runoff and soil concentrations at Cincinnati, Ohio Water Air Soil Pollut. 132 293
Wakefield, R.C., Bell, R.S., Jagschitz, J.A., Clapham, A.J., Dore, A.T., Nielsen, A.P. & Laskey, B.C. 1974 Establishment of roadside vegetation in Rhode Island RI Agr. Exp. Sta. Bull. 416
Walter, I. & Cuevas, G. 1999 Chemical fractionation of heavy metals in a soil amended with repeated sewage sludge application Sci. Total Environ. 226 113 119
Yang, Y., He, Z., Stoffella, P.J., Graetz, D.A., Yang, X. & Banks, D.J. 2008 Leaching behavior of heavy metals in biosolids amended sandy soils Compost Sci. Util. 16 144 151