Evaluation of Mulching Methods for Erosion Control on Newly Prepared and Seeded Highway Backslopes¹

Abstract

Evaluation of several mulching methods used by different highway departments showed that 2 tons of grain straw per acre provided adequate protection to newly prepared and seeded 2½:1 backslopes when subjected to l‐year frequency storms, 1.3 inches of rain in 30 minutes. However, when subjected to a 10‐year frequency storm, 2.7 inches in 60 minutes, two treatments stood out as superior. These were “whisker dams”, called the Florida method, which permitted 41% runoff and 10 tons per acre soil loss; and surface mulch, called the Cartersville method, which permitted 40% runoff and 11 tons per acre soil loss. In all cases where asphalt spray was a part of the treatment, the effectiveness of mulch was decreased when tested by the 10‐year frequency storm. Runoff and soil loss from mulch and mulch plus asphalt were 1.1. inches and 11 tons per acre and 1.3 inches and 32 tons per acre, respectively. Mulch mixed and mulch mixed plus asphalt were the same‐l.3 inches and 27 tons per acre‐indicating that the asphalt had no beneficial effect. The California method was a checkerboard arrangement of straw pressed into the surface. This treatment was inferior to the “whisker dams” because the staggered arrangement permitted more soil transport by over‐land flow. Runoff and soil loss for these two treatments were 1.2 inches and 44 tons per acre and 1.1 inches and 10 tons per acre, respectively. Bare, unprotected backslopes eroded at the rate of 97 tons per acre and permitted 62% runoff. Six months or more after planting, satisfactory stands had been established with all mulch treatments.

Forest Operations and Water Quality in the South

“…Estimated delivered sediment was less than observed sediment loss, and this reduction was attributed to the trapping of coarse sediments by downslope vegetation. The benefit of vegetation and obstructions in reducing sediment travel distances has been well documented in the literature (Barnett et al, 1967;Grace, 2000Grace, , 2002bSwift, 1985Swift, , 1986.…”

“…The majority of investigations of forest road effects primarily focus on soil erosion. Erosion rate studies have been conducted extensively throughout the southern states (Appelboom et al, 1998;Barnett et al, 1967;Blackburn et al, 1986;Beasley et al, 1986;Granillo, 1982, 1988;Grace, 2000Grace, , 2002aKochenderfer and Helvey, 1987;Swift, 1984aSwift, , 1984bSwift, , 1985Swift et al, 1993). However, few have related observed erosion rates to the quantity of sediment delivered to water systems or water quality.…”

Polyacrylamide in Agriculture and Environmental Land Management

“…Reduction of sediment from fiber mats, straw bales, and so on in welldesigned sites can be as high as 80-90% on a mass basis (Barnett et al, 1967;Benik et al, 2003a,b;Grace, 1999;Jennings and Jarrett, 1985). Nonetheless, Minton and Benedict (1999) noted that the turbidity from these best management practices (BMPs) often still range in value from hundreds to even thousands of nephelometric turbidity units (NTUs).…”

Effects of Soil and Water Conservation Measures on Groundwater Levels and Recharge

“…Adams [8] found that straw significantly increased the infiltration and movement of excess water in Temple, Texas. Increasing the soil cover with mulch decreased the runoff and soil loss and increased the apparent infiltration [8,9]. Vegetation also played a key role in the interactions between groundwater and surface-water systems, because of its direct and indirect influence on the recharge and the dependence of vegetation communities on groundwater [10].…”