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Water Erosion on Cropland, by Region and Year

Estimates presented here are based upon the latest information from the National Resources Inventory (NRI). The NRI is a longitudinal sample survey based upon scientific statistical principles and procedures. It is conducted by the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS), in cooperation with Iowa State University’s Center for Survey Statistics and Methodology. These results are based upon the 2007 NRI, which provides nationally consistent data for the 25-year period 1982–2007. Estimates here cover the contiguous 48 states. Separate estimates include Hawaii, Alaska, and the Caribbean.

Margins of error are reported for each NRI estimate and must be considered at all scales of analysis. The margin of error is used to construct the 95 percent confidence interval for the estimate. The lower bound of the interval is obtained by subtracting the margin of error from the estimate; the upper bound is obtained by adding the margin of error to the estimate. A 95 percent confidence interval means that in repeated samples from the same population, 95 percent of the time the true underlying population parameter will be contained within the lower and upper bounds of the interval.

Table 36. Water (Sheet & Rill) Erosion on Cropland, by Farm Production Region and Year, with Margins of Error
Region Year Million Tons per Year Tons per Acre per Year
Appalachian 1982 154.4
±5.7
6.8
±0.2
1987 138.7
±5.6
6.5
±0.2
1992 99.5
±3.4
5.1
±0.1
1997 79.6
±3.3
4.2
±0.2
2002 64.9
±2.8
3.4
±0.2
2007 58.0
±4.2
3.2
±0.2
Corn Belt 1982 604.2
±7.6
6.6
±0.1
1987 496.6
±7.6
5.5
±0.1
1992 391.3
±6.1
4.5
±0.1
1997 340.7
±5.0
3.9
±0.1
2002 353.3
±8.4
4.0
±0.1
2007 343.3
±10.0
3.9
±0.1
Delta States 1982 116.0
±4.6
5.3
±0.1
1987 98.2
±3.5
4.7
±0.1
1992 78.5
±2.9
4.1
±0.1
1997 70.4
±2.4
3.8
±0.1
2002 64.3
±3.4
3.6
±0.1
2007 60.4
±7.3
3.5
±0.4
Lake States 1982 123.3
±3.4
2.8
±0.1
1987 118.1
±3.5
2.8
±0.1
1992 99.5
±2.7
2.4
±0.1
1997 90.5
±2.2
2.2
±0.0
2002 92.5
±3.5
2.3
±0.1
2007 89.3
±5.1
2.3
±0.1
Mountain 1982 82.9
±4.0
1.9
±0.1
1987 75.5
±4.8
1.9
±0.1
1992 59.1
±3.5
1.6
±0.1
1997 54.3
±3.5
1.5
±0.1
2002 48.2
±3.8
1.4
±0.1
2007 44.4
±4.3
1.3
±0.1
Northeast 1982 60.8
±2.3
3.6
±0.1
1987 61.3
±2.2
3.8
±0.1
1992 50.1
±2.0
3.2
±0.1
1997 44.2
±1.8
2.9
±0.1
2002 41.0
±2.1
2.9
±0.1
2007 36.6
±2.4
2.7
±0.2
Northern Plains 1982 257.3
±6.5
2.8
±0.1
1987 240.6
±5.2
2.6
±0.0
1992 190.4
±5.0
2.2
±0.0
1997 170.4
±3.7
1.9
±0.0
2002 176.4
±7.3
2.0
±0.1
2007 170.7
±5.9
2.0
±0.1
Pacific 1982 68.5
±4.5
3.0
±0.2
1987 71.0
±5.4
3.3
±0.3
1992 48.0
±3.7
2.3
±0.2
1997 38.4
±2.6
1.9
±0.1
2002 35.8
±3.8
1.8
±0.2
2007 35.1
±5.8
1.8
±0.3
Southeast 1982 92.8
±3.2
5.1
±0.2
1987 77.2
±2.6
4.7
±0.2
1992 60.1
±3.0
4.2
±0.2
1997 53.2
±2.3
4.1
±0.2
2002 44.4
±2.7
3.6
±0.2
2007 38.0
±3.9
3.4
±0.3
Southern Plains 1982 116.3
±3.4
2.6
±0.1
1987 111.0
±3.2
2.6
±0.1
1992 103.0
±3.3
2.7
±0.1
1997 97.7
±3.2
2.6
±0.1
2002 90.4
±4.3
2.6
±0.1
2007 84.1
±4.2
2.6
±0.1
Notes:
• Cropland includes cultivated and non-cultivated cropland.

 

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