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t United States Department of Agriculture <br />o MRCS <br />Na6ural Resources Conservation Service <br />102 Par Place <br />Montrose, CO 81401 <br />970-249-8407-OFFICE <br />david.dearstyne@co.usda.gov <br />3) Similar soils a1~e by definition two or more kinds of soils that can be separated using the tools <br />(soil taxonomy) of'soil survey, that for all intensive purposes would have no significant impact <br />of use and management for current or foreseeable future uses. If one examines the map unit 14, <br />Barx fine sandy loam, 1 to 3 percent slopes from the San Miguel Soil Survey (see attached), it <br />states "Bari and similar soils 85 percent". Now if you examine the two official soil series <br />descriptions for Barx and Darvey -the soil descn~bed in the Intermountain report (see attached <br />documents), these soils have really only one difference. One soil has a horizon that has evidence <br />of translocated clay (Bt) in the form clay illuviation and an increase in clay of at least 3 to 6 <br />percent from the overlying horizons (Bari) compared to a soil (Darvey) that does not exhibit this <br />clay increase. However, both of these soils have the same amount of clay for classification <br />purposes (fine-loa~rny) and the same amount of calcium carbonate (calcic). In other words, these <br />soils would be colasidered "similar soils" for the purpose of agriculture (present use). There are <br />no significant use or management differences for these two soils. <br />Another thing to point out is the fact that there isn't any particle-size analyses data on any of the <br />soil samples listed in the report from Intermountain. This would tend to indicate that texture was <br />probably estimate:d in the field by the "ribbon method". From over 20 years experience as a soil <br />scientist hand texturing tens of thousands of samples, and comparing some of these clay <br />estimates to laboratory run samples, an experienced soil scientist familiar with the area, can hope <br />for at best with h~r-d texturing, a clay estimate accuracy within 3 to 5 percent actual clay content <br />about 85% of the time. This accuracy is the margin of error between calling ahorizon a Bt - <br />argillic and a Bw - Iambic. <br />And last, if Intermountain conducted an order one soil survey as indicated, these two soils <br />(Bari and Darve:y) would, if distinguishable in the field, be separated for the intensity (order <br />one) of the survey conducted. These two soils still (even separated) have no significant <br />difference for agricultural purposes. <br />The only reason that Darvey was not included in the Prime Few thin the survey area1gIf 1 <br />Soil Survey is that the Darvey soil ward under the same slo p and not used for urban uses, it <br />Darvey had been identified and mappe Pei <br />also would have been identified as Prime Farmland (once again a similar soil to Barx). <br />David A. Dearstyne <br />Soil Scientist-Project Leader <br />USDA-MRCS <br />M Equal Opportunity Provider and Employer <br />