2012-03-30_REVISION - M1987013 (3)

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Custom Sod Resource Report individual soils with similar sods in the same taxonomic Bass in other areas so that they could confirm data and assemble additional data based on expenence and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into Iandforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of sod components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such tandfom►s and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned. onsite investigation is needed to define and locate the sods and miscellaneous areas. Sal scientists make many field observations in the process of producing a sal map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the sod scientist. Observations are made to test and refine the sod- landscape model and predictions and to verify the classification of the soils at specific locations. Once the sod - Landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, sift, clay, salt, and other components_ Properties of each sal typically vary from one point to another across the landscape_ Observations for map unit components are aggregated to develop ranges of charactenstics for the components The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Sod scientists interpret the data from these analyses and tests as well as the field-observed charactenstics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the sods are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot expenments on the same kinds of soil. Predictions about sal behavior are based not only on sal properties but also on such variables as climate and biological activity. Sat conditions are predictable over long penods of time, but they are not predictable from year to year. For example, sod scientists can predict with a fairly high degree of accuracy that a given sod will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the sal on a specific date After sal scientists located and identified the significant natural bodies of sal in the survey area, they drew the boundaries of these bodies on aerial photographs and identified each as a specific map knit. Aenal photographs show trees, buildings, fields, roads, and nvers, all of which help in locating boundaries accurately. 6