Laserfiche WebLink
United States Department of Agriculture <br />o NRCS <br />Natr+ral Resomcm Conservation Service <br />102 Per Place <br />Montrose, CO 81401 <br />870 - 249 -6407- OFFICE <br />davld.de8r8lWe@co.usd <br />• <br />3) Similar soils are by definition two or more kinds of sods 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 described in the Intermountain report (see attached <br />documents), these soils have really only one difference. One soil has a horizon that has evidence <br />o €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- loamy) and the same amount of calcium carbonate (calcic). In other words, these <br />soils would be considered "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 />sort samples listed in the report from Intermountain. This would tend to indicate that texture was <br />probably estimated 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 hand 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 a horizon a Bt — <br />argillic and a Bw — cambic. <br />And last, if Intermountain conducted an order one soil survey as indicated, these two soils <br />(Barx and Darvey) 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. Farmland list for the San Miguel <br />Soil Survey is that the Darvey soil was not identified and mapped within the survey area. If <br />Darvey had been identified and mapped under the same slope, and not used for urban uses, it <br />also would have been identified as Prime Farmland (once again a similar soil to Barx). <br />David A. Dearstync <br />Soil Scientist- Project 1eadcr <br />USDA -NRCS <br />• <br />M Equal Oppofumby PmvJder and En**Yer <br />Revised September 2010 (PR06) Attachment 2.04.9 -6 -6 <br />