2022 08 Drainage Report

How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, 'e general pattem of drainage: the kinds of crops and inds of bedrock, They observed and described many soil devoid of roots and other living organisms and has not been changed by biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAS are geographically associated land resour gical resources, and land uses (USDA, 2 ist of parts of one or more MLRA. and miscellaneous area area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform, By observing the soils and miscellaneous areas in the survey area and relating their position to specific. segments of the landform, a soll scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape, ‘Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soll map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries, Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to laxonomic classes (units). ‘Taxonomic classes are concepts. Each taxonomic

ls. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to laxonomic classes (units). ‘Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil Custom Soil Resource Report scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil 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 ut diminishes the usefulness or accuracy of the data, The del landforms and landform segments on the map provides suffici development of resource pians. If intensive use of small areas, investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. is dependent upon several factors, including scale of sign of map units, complexity of the landscape, number of measurements of it These measurements may ividual soil properties are made and recorded, fe field measurements, such as those for color, and laboratory measurements, such as those for and other components. Properties of each soil another across the landscape. typically vary from one p ‘Observations for map unit components are aggregated to develop ranges of characteristics for the components, The aggregated values are presented. Direct measurements do not exist for every properly presented for every map unit component. Values for some properties are estimated from combinations of other properties, While a soil survey is in

. Direct measurements do not exist for every properly 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. Soil scientisis interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils 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 fo meet local needs. Dala 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 experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over of time, but they are not predictable from year to year. For exam 's can predict with a fairly high degree of accuracy that a given soi hin certain depths in most years, but they cannot predi that a high water table will always be at a specific leve! in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and