Soil Conservation

Mechanical Methods

One simple mechanical soil conservation technique involves placing logs behind field stumps, a method that is often used when a field is newly cleared from forest. Another simple means of erosion control involves placing logs or rocks across small gullies or streambeds to trap [Page 2577]sediments and create workable farm plots. These “check dams” also help harvest rainwater in arid regions or in regions with highly seasonal rainfall patterns.

Terraces: (A) bench and (B) platform (tree)

Source: Author.

Terraces involve modifying a sloping surface to reduce the flow of water over the surface, to provide a deeper soil in areas where soils are otherwise too thin for crop production, or to encourage water infiltration. Terraces can take many forms, which include sloping terraces, bench terraces, step terraces, and platform terraces (see terrace photos). Terraces, especially bench terraces, generally involve moving large amounts of materials, and thus, they are only recommended when conditions favor their use over other less labor- and time-intensive methods of soil conservation.

Other mechanical conservation systems involve less initial time and labor inputs than terraces, but they are effective only under the right conditions. One widely used technique is the construction of narrow ridges along the contour. In the United States, this technique is referred to as contour plowing, but Guatemalan farmers construct similar features, called surcos, by hand using a short-handled, broad-bladed hoe called an azadón (see contour ridges photo).

Ditches can also be constructed to divert water off fields or to collect sediments and encourage infiltration of runoff water. Diversion ditches and storm water drains are designed to divert runoff from field surfaces into open surface drains or grass-lined waterways at field edges. Infiltration ditches trap runoff and allow entrained sediment to settle out, as runoff water infiltrates into the soil rather than running downslope.

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