Evaluation of native grass sod for stabilization of steep slopes

Abstract

The purpose of this investigation was to evaluate the ability of native grass sod to establish on several different steep slope environments. Specific objectives were to (i) measure plant growth characteristics on slopes with native grass sod treatments compared to other plant establishment methods, (ii) compare runoff, sediment yield, and infiltration rates on slopes with native grass sod to other plant establishment methods for a peak 10 year 24 hour storm event, (iii) model sediment yield on native grass sodded slopes compared to other plant establishment methods using RUSLE version 2.0, and (iv) evaluate the economic cost of using native sod compared to other plant establishment methods. The sites selected were a highway fill site with a 40 % slope, a ski slope with a 35 % slope, and abandoned mine waste with a 70 % slope. Treatments included native grass sod, redtop sod, broadcast seed, broadcast seed with a straw blanket installed in 2003 and 2001, and broadcast seed with hydromulch. During the 2003 growing season, mean perennial grass production of native grass sod was significantly greater (14 to 190 fold) than the other treatments on all three sites. Mean basal and canopy cover were significantly greater for native grass sod than the other treatments during both the 2003 and 2004 growing seasons on all three sites. In 2004, mean perennial grass production of native grass sod was significantly greater (7 fold) than the other treatments on the highway fill site. On the mine waste site in 2004, mean perennial grass production of native grass sod was significantly greater (6 fold) than the broadcast seed with the straw blanket installed in 2003. When a peak 10 year 24 hour precipitation event was applied on the highway fill site, native grass sod and the broadcast seed with the straw blanket treatments had significantly less runoff and sediment loss than the broadcast seed with hydromulch treatment. RUSLE2 estimated sediment loss for native sod (4929 kg/ha/yr) to be four to five times less than the other treatments. A cost analysis indicated that native sod would cost two to eight times more than the other treatments. However, native sod provided complete and immediate erosion control where the other treatments could not.