Effectiveness of Sawdust and Rice Straw Mulch Strips to Control Runoff and Sediment Yield in Skid Trails

Mulches can be effective for reducing sediment loss and erosion from forest harvesting activities. This study evaluates the use of rice straw and sawdust as mulch covers for skid trails on clay loam soil. The treatments with three replications each included combinations of two levels of slope gradient (≤ 20% and > 20%), three types of mulch cover (bare soil, sawdust, and rice straw cover), three levels of mulching application schemes (1/3, 2/3, and 3/3 of the plot length), and two levels of surface cover rates (50% and 70%). Increasing levels of mulch cover had significantly lower runoff and sediment yields throughout the trails. The average runoff rates and sediment yield from the machine operating trails treated with sawdust cover (SC) (30.2 l and 2.7 g m-2) were lower than on trails covered with rice straw mulch (RSC) (36.8 l and 3.5 g m-2), which were, in turn, lower than on untreated bare soil (BS) trail sectors (48.80 l and 5.34 g m-2). Overall, mulching was more effective when applied over the entire plot length than over the 1/3 and 2/3 plots length strips, both in terms of runoff and sediment yield. Study Implications: We found that soil loss depended strongly on the slope gradient. Mulch cover had a significant improvement effect on the surface runoff and sediment yield, and mulching was more effective when applied over the entire plot length.