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United States Department of Agriculture

Agricultural Research Service

Title: Agricultural Tillage Systems: Water Erosion and Sedimentation

Authors
item Foster, George
item Dabney, Seth

Submitted to: Soil and Water Conservation Society
Publication Type: Popular Publication
Publication Acceptance Date: May 17, 1995
Publication Date: N/A

Interpretive Summary: Excessive erosion by raindrop impact and surface runoff is a process that can seriously degrade soil. Tillage systems such as no-till, reduced-till, ridge-till are methods preferred by farmers for controlling erosion. These systems are being widely adopted in response to federal legislation, but the systems have drawbacks in some situations. However, these drawbacks are being overcome with improved plant varieties, pesticides, and tillage and planting equipment. Residue is the single most important factor for erosion control. Other factors associated with a tillage system, such as roughness soil consolidation, amount of below ground biomass from residue and roots, and depth of incorporation of residue also affect erosion. The importance of these factors varies depending on soil and climate. For example, roughness is much more important where runoff rates are low, such as in the Northwestern Wheat and Range Region, than where runoff rates are high such as in the Southeastern US. Erosion varies greatly over the land- scape. Prescription farming techniques can vary operations of tillage systems to provide uniform erosion control over a field. Erosion prediction technology has been used for five decades as a tool in the development of conservation plans. This technology has limitations that have important implications for implementation of public policy. Foe example, how should uncertainties in soil loss estimates be treated because of an incomplete scientific understanding or because of practical limitations for estimating erosion as it varies over the landscape? It is important to ensure that farmers are not unfairly penalized by having to implement unnecessary erosion control practices while ensuring that the soil resource is protected over the long term.

Technical Abstract: Several factors associated with tillage systems including ground cover, surface roughness, amount of below ground plant biomass from buried residue and roots, depth of incorporation of plant material, and soil consolidation, affect soil erosion by raindrop impact and surface runoff. Supporting practices like contouring and grassed waterways are often used in conjunction with tillage systems to control erosion. The effectiveness of supporting practices is usually increased when used with conservation tillage systems like no-till, reduced-till, and ridge-till. Residue is the single important factor associated with tillage that affects erosion, but roughness can also have a major effect on reducing erosion where runoff rates are low. Erosion varies greatly over the landscape, and precision farming techniques can be used to vary implement operation to provide increased uniformity in erosion control over a field. Erosion prediction technology is a major tool that has long been used by conservationists to develop conservation plans. However, estimates from this technology involve considerable uncertainities because of incomplete scientific under- standing and lack of practical methods for considering the spatial varia- tion in erosion over the landscape. These uncertainties have implications in the implementation of public policy.

Last Modified: 10/24/2014
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