Development of salt tolerant grasses for roadside use.

Details

• Creators:
  Brown, Rebecca Nelson ; Gorres, Joseph ; Sawyer, Carl
• Corporate Creators:
  University of Rhode Island
• Subject/TRT Terms:
  • Grasses
  • Roadside flora and fauna
  • Deicing chemicals
  • Sodium chloride
  • Environmental impacts
  • Soils
  • Grasses--Rhode Island
  • Grasses--Effect of salt on--Rhode Island
• Publication/ Report Number:
  FHWA-RIDOT-RTD-07-2A
• Resource Type:
  Tech Report
• Geographical Coverage:
  Rhode Island
• Edition:
  Final; 2007-2010.
• Corporate Publisher:
  Rhode Island. Dept. of Transportation
• Abstract:
  Roadsides in Rhode Island and elsewhere are planted to mowed turfgrass in order to prevent erosion, improve aesthetics, ; maintain visibility, and provide a safe means of stopping errant vehicles. However, there are a number of ways in which ; mowed turfgrass is failing to meet the expectations of highway managers and the traveling public. Regular mowing and turf ; maintenance is expensive. Use of non-native plants has resulted in problems with invasive species. Most importantly, the ; seeded turfgrasses are not surviving in the roadside environment and so are failing to prevent erosion. ; Solving this problem requires answering two questions: why are the seeded turfgrasses dying? And how can this be fixed ; given severe limitations on funding? The purpose of this study was to seek answers to the first question, and then generate ; possible solutions to the second. The initial hypothesis was that high levels of deicing salt were responsible for the damage. ; We proposed to test this hypothesis by establishing test plots of 21 grass varieties selected for tolerance to salt in the highsalt ; zone at two locations: I-95 North in Hopkinton, and I-295 North in Lincoln. The grass variety trial was combined with a ; test of two potential low-cost soil amendments: yard waste compost and biosolids. We also proposed to monitor salt ; deposition over two winters at six sites to determine how much salt the grass was being exposed to, and how long the salt ; persisted in the root zone. Persistence is important because the grass is more sensitive to salt damage when it is actively ; growing (April-October) than during the winter months. At the same time we proposed to survey the vegetation on ; established, mowed roadsides to determine which plant species were surviving, as these might be good candidates for ; inclusion in a modified seed mix. ; We found that salt tolerant grasses showed no improvement in survival over the grass varieties already in use, even though ; the salt tolerant grasses had shown significantly better survival in greenhouse salt screening trials. This suggested that the ; salt was not the primary cause of vegetation failure; the finding that the salt did not persist in the root zone at levels high ; enough to cause plant damage past early April further supported this hypothesis. Soil amendment, however, had a dramatic ; effect on turfgrass survival. Perennial vegetation cover on plots amended with biosolids remained above 50% throughout the ; two-year study, and beyond. ; At the beginning of this study it was assumed that most of the vegetation surviving on mowed roadsides was the turfgrasses ; seeded by RIDOT or weeds such as quack grass, sheep sorrel, and crab grass. However, in surveys of seven sites in mowed ; areas along limited access highways in Rhode Island we found a total of 80 plant species, approximately half of which are ; native to Rhode Island.. Our results suggest that the seed mix used by RIDOT is not persisting on the roadside, but that it is ; gradually being replaced by native or naturalized species. Reductions in mowing would further this process, as they would ; permit more of these naturally-occurring plants to mature seed, filling in gaps created by vehicles and other disturbances.
  More +
• Format:
  PDF
• Funding:
  SPR-231-2299
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/23797/dot_23797_DS1.pdf
• File Type:
  [PDF - 2.95 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:2b528e4a63b344129d539fab4b2b6a37aa6d2e087cf47b47f69900fa6a069cd76c4e35ee90e7bd6ab508a7c161673625d31e79c542a1381ec10c7a78aef3ef13