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Implementation and Environmental Factors Correct installation of straw wattles is crucial to their effec- tiveness. They are labor intensive because they need to have good ground contact and anchoring. Wattles can be anchored to the ground by trenching and backfi]]ing or staking. An effective anchoring tech- nique is touse "U" shaped U8 in (3 mm) re-bar. Re-bar can hold wattles to the ground without trenching and is less likely to break than wood stakes in shallow soils. Straw wattles can work well on slopes greater than 40 percent but they are difficult to carry and hard to install on steep terrain. Spotting the wattles with heliwptera can solve some of this problem. Other Factors The ceat of straw wattle installation is about one half that of contour-felled loge. Tilling/Rionine Purpose. Tilling and ripping are mechanical soil treat- ments aimed at improving infiltration rates in ma- chine-compacted or water repellent soils. Both treat- mentsmay increase the amount ofmacropore apace in soils by physical breakup of dense or water repellent soils, and thus increase the amount of rainfall that infiltrates into the soil. Relative F.ffectlveness. Excellent-33% Good-33~io Fair- 33% Poor-0% (Replies = 3) Tilling and ripping was judged to be an "excellent" treatment for roads, firebreaks, and trails but less effective on hillslopes (table 16). These techniques may add roughness to the soil and promote infiltra- tion. They may be successful for site-specific circum- stances Like compacted or water repellent areas, but not economically feasible onlarge areas or safe to do on slopes greater than 30 to 45 percent. Size of the equipment and crawler tractor operator skill are also important effectiveness factors. Up- and down-hill tilling/ripping needs to be avoided because it can diminish the effectiveness of the treatment in reduc- ing soil erosion by promoting rilling in the furrows. According to some personnel, this type of treatment was the moat effective when done in combination with broadcast seeding. Others indicated that tIIling/rip- pingcan be successful accomplished at a high produc- tion rate on non-timbered areas without seeding. Implementation and Environmental Factors Shallow soils, rock outcrops, steep slopes, incised drainages, fine-textured soils, and high tree density create sig- nificant problems for tilling and ripping. These treat- ments work beat where there is a good soil depth, the soils are coarse textured, elopes are less than 30 percent, and woody vegetation density is low. This type of treatment has a high logistics support require- ment (fuel, transport carriers, access, and drainage crossing). Other Factors Since tilling and ripping are ground- diaturbingactivities, cultural clearances are required. Obtainingproper cultural clearances may significantly slow accomplishment of tilling/ripping projects. Contour Trenching and Terraces Purpose. Contour trenches are used to break up the elope surface, to slow runoffand allow infiltration, and to trap sediment. Rills are stopped by the trenches. Trenches or terraces are often used in conjunction with seeding. They can be constructed with machinery (deepertrenehes)orbyhand(generallyshallow).Width and depth vary with design storm, spacing, Boil type, and slope. Relative Effectrveness Excellent-67% Good-33% Fair- 0%Poor-0% {Replies = 3) Two o£the three interviewees who rated trenching considered its effectiveness "excellent;" the other thought it"good"(table 16).Trenchestrapsediment and interrupt water flow, slowing runoff velocity. They work beat on coarse granitic soils. When in- stalled with heavy equipment, trenches may result in considerable soil disturbance that can create problems. ImplementatlonandEnvironmentalFactors: Trenches must be built along the slope contour to workproperly; using baffles or soil mounds to divide the trench reduces the danger of excessive flow if they are not quite level. Digging trenches requires fairly deep soil, and slopes of less than 70 percent are best. Trenches are hard to construct in heavy, clay soils and are not recommended for areas prone to landslides. Hand crews can install trenches much faster than log ero- sion barriers (a similarly effective hillslope treat- ment), and crew skill is not quite as important to effective installation. Trenches have high visual im- pactwhen used in open areas (and thus maybe subject to controversy), but tend to disappear with time as they are filled with sediment and covered by vegeta- tion. On the other hand, more extreme (wide, deep) trenches installed several decades ago are still visible on the landscape in some areas. Geotextilea. Geowebbine Purpose: Matting is used to cover ground and control erosion in high risk areas where other methods will not work, such as extremely steep elopes, above roads or structures, or along stream banks. It is usually used in conjunction with seeding. Geotextilea come in dif- ferent grades with ultraviolet inhibitors that deter- mine how long they will last in the field. Relative Effectiveness No interviewees rated this treatment. 78 USDA Forest Service Gen. Tech. Rep. RMRS-GTRE3. 2000