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the artificial alteration of the surfaces of slopes to control water erosion of soil in order to make possible better use of slopes for agricultural crops and forestation. Terracing has long been common in mountainous countries, such as Japan, India, Sri Lanka, Turkey, Greece, Italy, and countries of southern Africa. In the USSR it is practiced in the Caucasus, Moldavia, and the republics of Middle Asia. Fruit crops are planted at elevations of 2,000 to 3,000 m, vineyards somewhat lower, and citrus crops still lower.
Terraces are made in the form of small areas, ledges, ditches, and the like bounded by embankments. Terraces may be of the ridge, bench, trench, or ditch types. Ridge terraces are used when the grade is 0.02–0.12 by piling up ridges 25–40 cm high across the slope. The width of the terrace, which is the distance between ridges, is 18–50 cm. Terraces of this type are used in the cultivation of grapes and fruits. Trench terraces are used in the cultivation of tea and citrus fruits in areas where the grade is 0.09–0.18 or more and where the soil layer is thin. The subsoil layer removed from the trench is used to form the embankments, and the trenches are filled with the excavated soil and soil taken from adjacent areas. Ditch terraces are used in regions with slopes of 0.1–1 and a thin soil layer. The embankments are made in steps 2–2.5 m high from the soil removed from the ditches, which serve for collecting and carrying away runoff and for supplying moisture to the embankments. Ditch terraces are used for fruit crops and forestation.
Bench terraces are the most common; they are used in the cultivation of vegetables, fruits, and grapes in places where the grade is 0.12–0.25. The surface of such terraces is horizontal or with a grade of not more than 0.12. Bench terraces are also suitable for forestation. The width of bench terraces is at least 2.5–3 m. The retaining walls, or risers, of such terraces are sometimes reinforced with masonry. In some cases, sloped earthen banks are constructed and reinforced with a vegetative cover.
In terracing, runoff channels are constructed to regulate drainage. Mechanized working of the soil is possible if the benches are 4.5–5 m wide. In the case of terraces more than 6 m wide, two or more rows of apple or pear trees may be trained on espaliers—supports in the form of vertical, horizontal, or other surfaces to which the tree branches are fastened. Several methods are used in terracing: trenching, which is done with trench plows, bulldozing, which is done with a general-purpose bulldozer on very steep slopes, or plowing, which is done with ordinary tractor plows, gradually or rapidly.
REFERENCESDragavtsev, A. P. Gornoe plodovodstvo. Moscow, 1958.
Fedotov, V. S. Terrasirovanie sklonov pod sady i vinogradniki v Moldavii. Kishinev, 1961.
Dragavtsev, A. P., and G. V. Trusevich. Iuzhnoe plodovodstvo. Moscow, 1970.
E. V. KOLESNIKOV