Soil Conservation Assessing the National Resources Inventory, Volume 1 (1986) / Chapter Skim
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1. Scope and Content of the 1982 NRI
1. Scope and Content of the 1982 NRI
Pages 1-18
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The product of this project is the 1982 National Resources Inventory (NRI) : a computerized natural resource data base covering all nonfedera1 land in the United States.
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of 1982 NRI data suggests that land converted to crop use between 1979 and 1982 generally produced lower yields and eroded at rates higher than average for all cropland in 1982. With some cautions and exceptions, erosion rates reported for major land uses in the inventories can be compared to indicate changes from 1977 to 1982.
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Data on sheet and rid erosion from the 1977 NRI have been used to investigate the relationship between soil erosion and crop yields across broad geographic areas. Some studies have been made possible by the capability to link NRI data via computer with detailed soil information contained in the computerized SCS soil survey file, Soils-5.
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level, could help determine how much of this apparent increase is attributable solely to definitional changes. (MLRAs consist of geographically associated land resource units; groupings by patterns of soil, climate, water resources, land use; and type of farming.
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Some of this land was reciassifiecl as rural in 1982 as a result of more accurate expansion factors and other improved inventory procedures app! fed retrospectively to the 1 977 survey resu Its.
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Information on erosion and conservation practices contained in the NFIs suggests the potential value of focusing new conservation programs and policies on particular lands. A proposed soil conservation reserve, for example, would offer land rental payments to farmers who voluntarily retire erosion-prone land currently in cultivation.
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And Use and Soil Erosion Rates The acreage in each of eight major uses of nonfederal land is reported in Table 1-3. Of the total of 1.498 billion acres of nonfederal land in 1982, TABLE 1-3 Use of Nonfederal Rural Land, 1982a Land Use Rural land Cropland Pastureland Rangeland Forestland Minor land cover/usesb Acres (millions)
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Table 1-4 illustrates the substantial differences in erosion rates reported for each use. Cropland has the highest average rates of sheet, rill, and wind erosion.
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To the extent that erosion contributes to offsite damages such as water pollution from runoff, for example, soil loss tolerance values in the future might reflect the on-farm and off-farm consequences of erosion.
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Credit: U.S. Department of Agriculture, Soil Conservation Service.
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Where wind erosion is additive, total average soil loss may exceed these estimated tolerance levels. However, the interrelationship of wind and water erosion is uncertain.
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had sheet and rill erosion rates below the average assigned tolerance level for all cropland. This 75 percent of cropland contributed only 30 percent of the total soil eroded (see Table 1-7~.
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14 au En o rig cn cr: a; ._ ._ Q o 3 o C)
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Conservation tillage is the dominant conservation practice; it is applied to 49 percent of row crop acreage and 24 percent of total cropland acreage. Other traditional cropland conservation practices occupy a relatively small share of the row crop acreage and the total cropland.
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Credit: U.S. [Department of Agriculture, Soil Conservation Service.
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Conservation practices are described in detail in Chapter 5.
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