Field evaluation of hydromulches for water quality and vegetation establishment.

Details

• Creators:
  McLaughlin, Richard A. ; Lee, Gina
• Corporate Creators:
  North Carolina State University. Soil Science Dept.
• Subject/TRT Terms:
  • Construction sites
  • Mulches
  • Grasses
  • Vegetation
  • Erosion control
  • Slopes
  • Straw
  • Runoff
  • Ground cover
• Publication/ Report Number:
  FHWA/NC/2010-15
• Resource Type:
  Tech Report
• Geographical Coverage:
  North Carolina
• Corporate Publisher:
  North Carolina. Dept. of Transportation
• NTL Classification:
  NTL-HIGHWAY/ROAD TRANSPORTATION-Soils and Geology ; NTL-ENERGY AND ENVIRONMENT-ENERGY AND ENVIRONMENT
• Abstract:
  Soil erosion and sediment pollution can be major problems in and around construction sites due to land disturbing activities that leave areas of ; unprotected soil during active construction. Establishing vegetation to control erosion can be difficult due to poor soil, steep slopes, and no ; irrigation. Our study was conducted on five construction sites in North Carolina to evaluate different mulch treatments on steep slopes for erosion ; control and vegetative establishment. Site 1 was located in the Coastal Plain region near Kinston, Site 2 was located in the mountain region near ; West Jefferson, and the remaining three were in the Piedmont near Raleigh. Of the five, two were 2:1 cut slopes and three were 2:1 fill slopes. ; On all sites the area was divided into 20 plots that were either 3 m wide and 6 m long (site 2) or 3 m wide and 9 m long (sites 1, 3 and 4). After ; seeding a grass mixture, erosion control treatments were applied in a randomized complete block design and included: 3,000 kg ha-1 ; wheat ; straw+tackifier (straw) and 3,000 kg ha-1 ; wheat straw+ tackifier with 22.4 kg ha-1 ; of granular, linear, anionic polyacrylamide (straw+PAM) were ; applied at all four sites; 3,900 kg ha-1 flexible growth medium (FGM) and 3,900 kg ha-1 stabilized mulch matrix (SMM) were applied at three ; sites; 3,900 kg ha-1 bonded fiber matrix (BFM), 2,800 kg ha-1 wood fiber/cellulosic blend (WCB) and 3,360 kg ha-1 wood fiber mulch (WFM) ; were applied at two sites. Runoff volumes, turbidity levels, eroded sediment and nutrient concentration data were collected after natural rain ; events, and grass growth and cover was evaluated once it reached a height of 4-5” (10-12 cm). At site 2, there were no differences between ; treatments most likely due to the combination of sandy soil texture (average 72% sand) and relatively light rainfall events that occurred there. At ; site 3, there was a trend of straw having higher runoff volume, turbidity, TSS and in general higher concentrations and amount of nutrient loss ; compared to all hydromulch treatments, and straw+PAM having higher losses than FGM. In contrast, at site 4 the straw treatment reduced runoff ; compared to FGM, WCB and WFM, while the only difference between treatments in reducing nutrient loss was between straw+PAM and WFM ; for total phosphorus (TP). The same trend of WFM and WCB ground covers producing higher turbidity, TSS and TSL compared to straw and ; straw+PAM was found on site 5. Addition of PAM did not have an effect on runoff volumes at any site, with turbidity reductions evident at two ; sites but only for individual storms and no significant reduction overall. Sites 2 and 4 had poor grass establishment with grass cover of <50%, ; while sites 3 and 5 had good grass establishment (67 and 85% cover, respectively). The reason for lower grass establishment under the ; hydromulches at some sites was explored further in a greenhouse study where our objective was to determine the effects of mulch type and rate ; on grass growth, resistance to penetration, and moisture holding capacity. The results suggest that straw may maintain sufficient soil moisture for ; plant growth for a longer period than hydromulch. Of the three grasses tested, tall fescue was inhibited by BFM but not FGM at recommend ; application rates or higher, while centipede and Bermuda grass had the same or higher growth as rates increased.
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• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/25866/dot_25866_DS1.pdf
• File Type:
  [PDF - 2.43 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:ee10b235ca2cbc9cc94d0ce77a28b60f2a5f114c42008eb4c8db7903ae00ab4b98ee56f353363de5dee801d00a9a3408c9e735fd6873f36e98413ed68d2ea238