Performance of grass barriers and filter strips under interrill and concentrated flow

Area of Science:

• Agricultural Engineering
• Environmental Science
• Soil Science

Background:

• Vegetative filter strips (FS) and grass barriers are used to reduce sediment and nutrient runoff.
• Their effectiveness can be influenced by varying runoff flow conditions, such as interrill and concentrated flow.

Purpose of the Study:

• To assess the performance of fescue filter strips (FS) alone and switchgrass barriers above fescue filter strips (B-FS).
• To compare their effectiveness in reducing runoff, sediment, nitrogen (N), and phosphorus (P) loss under interrill and concentrated flow conditions.

Main Methods:

• Evaluated fescue filter strips (FS) and switchgrass barriers above fescue filter strips (B-FS) under interrill and concentrated flow on Mexico silt loam.
• Monitored runoff and sediment at multiple distances below the sediment source area.
• Simulated larger sediment source areas with supplemental runoff.

Main Results:

• Filter strips (FS) reduced sediment by 80% under interrill flow and 72% under concentrated flow at 0.7 m.
• When combined with barriers (B-FS), runoff was reduced by 34%, sediment by 99%, and nutrients by 70% at 8 m.
• Barriers above filter strips (B-FS) were equally effective under both flow types at 8 m, outperforming filter strips alone (FS) under concentrated flow.

Conclusions:

• Grass barriers combined with filter strips offer an effective solution for reducing sediment and nutrient loss, particularly in areas prone to concentrated flows.
• This combined approach presents a viable alternative to using filter strips alone, enhancing overall runoff management effectiveness.