Erosion in the Palouse - Steep III (Solutions To Environmental and ...

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6Erosion in the Palouse:How Bad Is It?
7Frozen surface soilin early spring ishighly erosive.Since 1939, total erosion on Palousecropland has averaged 360 tons peracre—more than 9 tons per acre per year.Erosion rates on rangeland andforested areas average less than 1 tonper acre per year. On cropland, however,annual rates of 20 to 30 tons per acre arecommon and losses of 100 to 200 tonsfrequently occur on some steep slopes.Erosion has consistently been highestin the intermediate 15-to-18 inchprecipitation zone, averaging 20 tonsper acre per year. The rates are usuallyless in the low-precipitation zone of thewestern basin (13 tons per acre per year)and in the high-precipitation zone ofthe eastern basin (12 tons).Gully erosion accounts for only aminor part of soil erosion in the basin.Stream channel erosion accounts for lessthan 1 percent of total erosion in thebasin, but it is serious in the mountainforests, where it accounts for 50 percentof the total.The high erosion rates on croplandleave the land less productive. All theoriginal topsoil has been lost from 10percent of the cropland in the basin;one-fourth to three-fourths has beenlost from another 60 percent.Estimatedaverage annualsediment yield insource to streamsystem—PalouseRiver BasinSourceCroplandNoncropland*Stream channelsTotalSedimentproduced byerosion—tons17,471,0001,646,00021,00019,138,000Deliveryratio30%11%90%*Includes forest, rangeland, roads and other areas.SedimentYield—tons5,167,000184,00019,0005,370,000
Page 2 and 3: 2Erosion in the Palouse:A Summary o
Page 4 and 5: 4The LandCalled PalouseWestern port
Page 8 and 9: 8Effects of erosionThe millions of
Page 10 and 11: 10What CanConservation Do?Fall chis
Page 12 and 13: 12Stripcropping dividesa slope to r
Page 14 and 15: 14To reduceerosion...reducesummer f

Erosion in the Palouse - Steep III (Solutions To Environmental and ...

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