Erosion Control Systems
Erosion Control Systems may be a single or group of practices that prevent detachment and interrupt the transport of soil by rainfall, runoff, melting snow or ice, and irrigation water. Since phosphorus is often attached to sediment particles, Erosion Control Systems serve to decrease phosphorus delivery from agricultural areas.
Erosion control practices are available to reduce runoff and the amount of soil particles and attached phosphorus from leaving a location. Keeping soil particles and nutrients on site can enhance soil properties and maintain productivity.
How Does This Practice Work?
An Erosion Control System is a combination of practices and structures that reduce soil loss and sediment transport. The USDA-NRCS has identified several Conservation Practice Standards to control soil erosion on agricultural areas.
Conservation Cover results from the establishment and maintenance of permanent vegetative cover. A planned sequence of crops grown on the same ground over a rotation cycle is Conservation Crop Rotation. Crops associated with these rotations include high-residue producing crops in rotation with low-residue producing crops. Increased vegetative cover protects the soil surface from raindrop impact and minimizes soil detachment. Cover Crops include grasses, legumes, and forbs that provide seasonal cover and other conservation benefits.
Contour Buffer Strips are narrow strips of permanent, herbaceous vegetative cover established around the hill slope, and alternated down the slope with wider cropped strips that are farmed on the contour. Suspended sediment is removed as overland flow approaches and enters the Contour Buffer Strips. Contour Buffer Strips, which can be positioned at a variety of locations within a landscape, also increase infiltration.
Aligning ridges, furrows, and oriented roughness formed by tillage, planting, and other operations at a grade near the contour to alter the velocity or the direction of water flow is Contour Farming. Spacing and height of ridges impact the effectiveness at reducing erosion, as runoff accumulates in furrows and allows sediment to deposit. A Field Border is a strip of permanent vegetation established at the edge or around the perimeter of a field.
A Filter Strip is an area of herbaceous vegetation that removes contaminants from overland flow. A shaped or graded channel that is established with suitable vegetation to convey surface water at a non-erosive velocity using a broad and shallow cross section to a stable outlet is a Grassed Waterway. Grassed Waterways capture nutrients transported in runoff and serve to prevent ephemeral gully erosion.
No Till, Residue and Tillage Management, limits disturbance to the soil and manages the amount, orientation, and distribution of crop and plant residue on the surface year around. Reduced Till, Residue and Tillage Management, manages the amount, orientation, and distribution of crop and other plant residue on the soil surface year-round while limiting soil disturbing activities used to grow and harvest crops in systems where the soil surface is tilled prior to planting.
Growing planned rotations of erosion-resistant and erosion-susceptible crops or fallow in a systematic arrangement of strips across a field is Strip-cropping. The most effective Strip-cropping systems include Conservation Cover that alternates with grain and row crops.
A Terrace is an earth embankment or a combination ridge and channel, constructed across the field slope. Runoff travels at relatively low velocities along the gentle grades used in Terraces, reducing erosion and retaining soil particles in the field. Therefore, the amount of sediment in surface water leaving Terraced fields is decreased. Runoff from Terraces can be conveyed using Grassed Waterways, thus preventing erosion. Permanent strips of stiff, dense vegetation established along the general contour of slopes or across concentrated flow areas are Vegetative Barriers.
Where This Practice Applies and Its Limitations
All land managers should consider erosion control as a key component for all land management decisions. Rainfall characteristics, soil factors, topography, climate, and land use all influence soil loss. A variety of erosion control practices could be used on a particular landscape. More than one erosion control practice may be necessary for protection on areas with high soil loss potential. Each Erosion Control System should be personalized towards those practices that in combination will meet site-specific conditions.
Erosion Control Systems have been successfully used to reduce soil loss and sediment transport for decades. A combination of erosion control practices may be implemented to effectively control erosion from agricultural lands and sediment delivery to sensitive areas. One of the most effective means of reducing erosion is to maintain a vegetative or residue cover on the soil surface through No Till or Reduced Till in conjunction with Cover Crops. Residue serves to protect the soil surface by adsorbing and dissipating raindrop energy, which significantly reduces soil detachment. Cover Crops provide seasonal protection to the soil surface during early spring months. Substantial reductions in erosion can result from small amounts of residue cover.
Cost of Implementing the Practice
Conservation Crop Rotation, Contour Farming, and Strip-cropping are erosion control practices that can be easily implemented using existing farm equipment. Adopting No till or Reduced Till, Residue and Tillage Management may require the purchase of specialized equipment suitable for use under high residue conditions. The establishment of Conservation Cover, Contour Buffer Strips, Field Borders, Filter Strips, and Grassed Waterways can remove degraded cropland areas from production.
Cost-share may be available for the establishment of many of these erosion control practices. By reducing excessive erosion and conserving water and nutrients, erosion control measures can also enhance profitability.
Operation and Maintenance
When Contour Farming is used, the effectiveness of ridges in trapping runoff and reducing soil loss decreases as slope gradient becomes greater. To prevent runoff from large precipitation events from over-topping ridges, a small slope gradient along the row is desirable.
To improve erosion control under Strip-cropping conditions, the strips are usually planted using Contour Farming in a rotation that shifts crops annually from one strip to the next. Strip widths are dictated by farm implement requirements.
With the increased availability of herbicides, the use of tillage for weed control under Reduced Till, Residue and Tillage Management has diminished. When tillage is performed, crop residues are maintained by using special implements that cause only minimal soil disturbance. To maintain sufficient residue cover for erosion control, No Till, Residue and Tillage Management is used before planting for some row crops such as soybeans. On Terraced fields, Contour Farming is included as an erosion control practice, since crop rows are usually planted parallel to the Terrace. Sediment accumulating in the Terrace channel should be periodically removed and placed on the Terrace bank.
Sedimentation may occur along the upslope portion of Contour Buffer Strips. Accumulated sediment must be removed to prevent flow channelization, one of the most common problems impacting Contour Buffer Strip performance.
To prevent failure, a Grassed Waterway should not be used as a road, stock trail, or pasture, especially during wet conditions. Care should also be taken when farm machinery crosses the waterway to avoid compaction. The waterway should be managed to stimulate new growth and control weeds, and an annual application of fertilizer is recommended.
To obtain information on the Conservation Practice Standards identified in this article, contact your USDA-NRCS State Office or visit the Field Office Technical Guide online at https://www.nrcs.usda.gov/ and type FOTG in the search field.
For Further Information
Contact your local Conservation District, Cooperative Extension Service office, or USDA-NRCS for assistance. To find your local USDA Service Center, visit https://www.nrcs.usda.gov/contact/find-a-service-center.
|John E. Gilley
Editing and Design
NC State University
University of Tennessee
Gilley, J. and K. Wacha. 2023. Erosion Control System. SERA17 Phosphorus Conservation Practices Fact Sheets. https://sera17.wordpress.ncsu.edu/erosion-control-systems/