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01/27/2010 16:98 FAX 970 295 5668 FSA/MRCS F.C. <br />How Soil Surveys Are Made <br />Soil suveps are made to provide oforrrnd'ion about the sails and miscefteous areas <br />in a specific area They include a description of the sods and miscellaneous areas and <br />their location on the landscape and tebies that show sod properties and Imitations <br />affecting various uses. Soil scientists observed the steepness, tenge and shape of <br />the slopes; the general pattern of drainage; the kinds of crops and native phut, and <br />the kinds of bedrock. They observed and descebed marry sod profiles. A sod profile is <br />the sequence of natural layers, or horizons. in a sod. The profile extends fnan the <br />surface down into the unoonsoddaled material in which the sail formed or from the <br />surface down to bedrock The unconsolidated maLeriai is devoid of rods and other <br />living organisms and has not been chgoVed by other biological activity. <br />Currently, soils are mapped aooor I g to the boundaries of am m lard resource areas <br />(MLRAs). KGAAs are geogapticapy associated kind resource units that share <br />common characteristics related to physiography, geology, climate. water resources. <br />soils, biological resource, arid land uses (USDA 2006). Sod survey areas typically <br />consist of paft of one or more N LRA <br />The soils and n nimus areas kr a survey area ooaur in an orderly patlem that is <br />related to the geology, b ndfi0rrms, reW cbvwkk and natural vin of the area. <br />Each kind of soill and misoellaneous area is associated with a particular kind of <br />landform or with a segment of the karrdform By observing the sow and miscellaneous <br />areas in the survey arena and relating Owl position to specific segmerds of the <br />landform.asodscientist develops a con cept,orrrhodek,ofhowtheymereforrrned.Thus, <br />during mapping, this model errabies the sod scientistlID prednd with a aonsidemble <br />degree of accuracy the kind of sit or niscellansous; area at a specific loon an the <br />landscape. <br />Commonly, individual sods on the ape merge into one another as their <br />characteristics gradually charge. To construct an accurate sod map, however, soil <br />scientists must determine the boundaries between the soils. They can observe only <br />a limited number of sod profiles- Nevedheiess. these obcerva ions. sWpiemented by <br />an understanding of the pe relationship, are sufficient to verify <br />predictions of the kinds of sal in an area and to detemnine the boundaries. <br />Soil scientids recorded the characteristics of the soil profiles that they studied. They <br />noted soil color, textue, size and shape of soil aggregates, kind and amount of rock <br />fragments, dnstrbution of plant rots, reaction, and o#w features that enable them to <br />identify soils. After describing the soils in the survey area and determining their <br />properties. the sod scientiM assigned the sails to t8xonomic dosses (units). <br />Taxonomic dosses are concepts. Each taxonomic otass has a set of soil <br />characteristics with precisely defined liimit& The classes are used as a basis for <br />comparison to dassiry Sods systematically- Sod taxonomy, the system of taxonomic <br />classification used in the United States, is based mainly on the kind and character of <br />soil properties and the arrangement of horizons vAd'win the profile. After the $oil <br />scientists classified and named the soft in the survey area, they compared the <br />Wvvo