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U.S. DEPARTMENT OF AGRICULTURE PAGE 4 OF 4 <br /> NATURAL RESOURCES CONSERVATION SERVICE 01/18/00 <br /> • <br /> CONSTRUCTION MATERIALS <br /> Endnote -- CONSTRUCTION MATERIALS--ContinUed <br /> Topsoil is used to cover an area so that vegetation can be established and maintained. The upper 40 inches of a soil <br /> is evaluated for use as topsoil. Also evaluated is the reclamation potential of the borrow area. Plant growth is <br /> affected by toxic material and by such properties as soil reaction, available water capacity, and fertility. The ease <br /> of excavating, loading, and spreading is affected by rock fragments, slope, a water table, soil texture, and thickness <br /> of suitable material. Reclamation of the borrow area is affected by slope, a water table, rock fragments, bedrock, <br /> and toxic material. <br /> Soils rate "Good" have friable loamy material to a depth of at least 40 inches. They are free of stones and cobbles, <br /> have little or no gravel, and have slopes of less than 8 percent. They are low in content of soluble salts, are <br /> naturally fertile or respond well to fertilizer, and are not so wet that excavation is difficult. <br /> Soils rated 'Fair- are sandy soils, loamy soils that have a relatively high content of clay, soils that have only 20 <br /> to 40 inches of suitable material, soils that have an appreciable amount of gravel. stones, or soluble salts, or <br /> soils that have slopes of 8 to 15 percent. The soils are not so wet that excavation is difficult. <br /> Soils rate 'Poor' are very sandy or clayey, have less than 20 inches of suitable material, have a large amount of <br /> gravel, stones, or soluble salts, have slopes of more than 15 percent, or have a seasonal water table at or near the <br /> surface. The surface layer of most soils is generally preferred for topsoil because of it organic matter content. <br /> orIc matter greatly increases the absorption and retention of moisture and nutrients for plant growth. <br />