Effects of Mulch Type and Polyacrylamide On Runoff and Vegetation Establishment On Steep Slopes.

Soil erosion and sediment pollution can be a big problem in and around construction sites due to high erosion rates during active construction. Establishing vegetation to control erosion can be difficult due to poor soil, steep slopes, and no irrigation. Our study evaluated erosion control and vegetation establishment on 2:1 slopes at three road construction sites. The first site was located in the Mountain region near West Jefferson, NC with sandy loam-loamy sand subsoil. The two other sites were located in the Piedmont, with a fill slope near Garner and a cut slope near Apex, NC, respectively, with a variety of subsoil textures. Treatments were: 2268 kg ha^-1 wheat straw (S); 2268 kg ha^-1 wheat straw with 22.4 kg ha^-1 of granular, linear, anionic polyacrylamide (SP); five types of hydromulches: 3900 kg ha^-1 flexible growth medium (FGM); 3900 kg ha^-1 bonded fiber (BFM); 3900 kg ha^-1 stabilized mulch matrix (SMM), 2800 kg ha^-1 70/30 wood paper bland (WCM) and 2240 kg ha^-1 wood fiber hydromulch (WM). The plots were arranged in a randomized, complete block design. Runoff volumes, turbidity levels, and total suspended solid (TSS) data were collected after rain events, and grass growth and cover were evaluated once it reached a height of 10-12 cm. On the first site there were no differences among the treatments in runoff water quality or vegetation establishment. On the Garner site, hydromulch treatments reduced overall runoff volume compared to straw alone, the FGM treatment significantly reduced overall turbidity compared to straw alone, and all treatments reduced TSS compared to straw. However, the straw cover resulted in the best grass growth compared to hydromulch, probably due to better moisture holding between storms. On the Apex site, WM and WCM treatments increased overall runoff volume, turbidity or TSS compared to straw alone.