EROSION: IRRIGATION-INDUCED

Authors: Lehrsch, Gary; Sojka, Robert; Bjorneberg, David - Dave

Submitted to: Encyclopedia of Soils in the Environment
Publication Type: Book / Chapter
Publication Acceptance Date: 2/19/2004
Publication Date: 10/28/2004
Citation: Lehrsch, G.A., Bjorneberg, D.L., Sojka, R.E. 2005. Erosion: Irrigation-induced. In: Hillel, D., editor. Encyclopedia of Soils in the Environment. Oxford, U.K.: Elsevier Ltd. p. 456-463.

Interpretive Summary: Controlling erosion from highly productive irrigated lands is critical to sustain agricultural production in the years ahead. Reducing or managing runoff controls soil loss caused by sprinkler irrigation using center pivots or linear-move systems, and caused by surface irrigation using level basins, furrows, or borders. Erosion caused by sprinkler irrigation resembles that from rainfall, with many erosion control practices effective for both. Crop residues, left on the soil surface by conservation tillage, protect the soil from raindrop or sprinklerdrop impact and keep surface soil aggregates from fracturing, allow water to enter the soil, and reduce and slow runoff, thereby allowing entrained sediment to settle from the runoff. Erosion processes with surface irrigation are quite different from those with rainfall or sprinkler irrigation because water droplets do not strike the soil surface. Controlling erosion from surface irrigation is especially challenging because runoff must often occur and water flow and soil infiltration change. Irrigators should schedule irrigations to timely meet crop water demand and reduce inflow rates to furrows where and when possible. Furrows can be reoriented to reduce their slope and filter strips or settling basins can capture sediment in runoff. For both sprinkler and surface irrigation, off-site soil loss is often least where combinations of control practices are employed. For surface irrigation, polyacrylamide use is both economical and effective in controlling erosion from most furrow-irrigated production systems.

Technical Abstract: Controlling erosion on and soil loss from irrigated lands is critical to sustain agricultural production. Protecting and stabilizing the soil surface will minimize sediment detachment. Slowing or reducing overland flow will minimize sediment transport. Reducing or managing runoff is the key to controlling soil loss wherever sprinkler irrigation or surface irrigation is practiced. Erosion caused by sprinkler irrigation is similar to that caused by rainfall, with many erosion control practices effective for both. Techniques that protect the soil surface from raindrop or sprinklerdrop impact are effective in maintaining infiltration rates, reducing overland flow, and controlling both detachment and transport. Erosion processes with surface irrigation are quite different from those with rainfall, due to the absence of droplet kinetic energy input to the soil surface, and thus require different control strategies. Controlling erosion from surface irrigation is a challenge, due to the requirement for overland flow and runoff and to varying flow regimes and soil infiltration rates. For both sprinkler and surface irrigation, off-site soil loss is often least where combinations of control practices are employed. For surface irrigation, PAM use is not only economical but likely offers the most promise for effective erosion control for most furrow-irrigated production systems.