Evaluation of Mulching Methods for Erosion Control on Newly Prepared and Seeded Highway Backslopes
- A. P. Barnett,
- Ellis G. Diseker and
- E. C. Richardson
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 2 1/2:1 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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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