The National Soil Erosion Research Laboratory

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Water Erosion Control Practices

Mulch, a type of protective covering which is in direct contact with the ground, provides more protection than canopy cover. It can vary from straw, to compost, to wood chips, or saw dust. Spread evenly onto the ground, mulch helps to reduce water evaporation, control weeds, and enrich the soil. It is also significant in protecting soil where vegetation has not had ample time to establish itself. By absorbing the destructive forces of raindrops and wind, mulch reduces erosion until the the seedlings mature enough to provide their own protective cover.

Terracing is a combination of contouring and land shaping in which earth embankments, or ridges, are designed to intercept runoff water and channel it to a specific outlet. Terraces reduce erosion by decreasing the steepness and length of the hillside slope and by preventing damage done by surface runoff.

There are basically two types of terraces:

  1. bench terraces
  2. broad base terraces

The bench terrace, perhaps one of the oldest forms of terraces, is used to reduce land slope. The broad base terrace, on the other hand, is used to control and retain surface water on sloping land.

Grassed Linings

Vegetated waterways are built to protect soil against the erosive forces of concentrated runoff from sloping lands. By collecting and concentrating overland flow, waterways absorb the destructive energy which causes channel erosion and gully formation..

Waterways can have cross sections in parabolic, trapezoidal, or triangular form, depending on the functional requirements. Several of these requirements are climate, channel capacity, and desired flow velocity.

Grass linings should be hardy, dense - growing perennials adapted to the geographical region and soil. The grass should be cut periodically, fertilized as needed, and not subjected to prolonged traffic by either livestock or vehicles.

Contouring entails performing all tillage and planting of crops on or near the same elevation or "contour." It is applicable on relatively short slopes up to about 8 percent steepness with fairly stable soils. By planting across the slope, rather than up and down a hill, the contour ridges slow or stop the downhill flow of water. Water is held in between these contours, thus reducing water erosion and increasing soil moisture. Contouring's impact on annual soil loss rates vary with slope steepness, but typically it's reduced about one half from up - and - down hill farming when the slope is between 4 and 7 percent.

Strip cropping is a very effective and inexpensive method for controlling soil erosion. Strip cropping is a combination of contouring and crop rotation in which alternate strips of row crops and soil conserving crops (sods) are grown on the same slope, perpendicular to the wind or water flow. When soil is detached from the row crops by the forces of wind or water, the dense soil conserving crops trap some of the soil particles and reduce wind translation and/or runoff.


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