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