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Univ. of São Paulo, ESALQ-USP, CP 9, Piracicaba, SP, 13418-900, Brazil
* Corresponding author (mcooper{at}esalq.usp.br)
| ABSTRACT |
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| INTRODUCTION |
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To analyze global phenomena related to soil science we need comprehensive, consistent, georeferenced, and quantitative databases on national or continental scales. Some multi-country thematic specific databases are available such as HYPRES (Hydraulic Properties of European Soils, Wösten et al., 1999), WISE (World Inventory of Soil Emission Potentials, Batjes, 1996) and UNSODA (Unsaturated Soil Hydraulic Database, Nemes et al., 2001), but the type of information included in these databases is limited. Many countries already have soil electronic databases available such as the USA (USDA-National Resources Conservation Service, 2004), Canada (Agriculture and Agri-Food Canada, 2000), Australia (Commonwealth Scientific & Industrial Research OrganizationLand and Water, 2004), and FAO (Food and Agricultural Organization, 1993, 1995), but in most countries these data are not available. This is especially true in countries of the tropics. An attempt to solve this problem in Brazil was made through the Soil Information System (Sissolos) (EMBRAPA, 1984) started in the early 1980s but not completely established until now.
The usefulness of large-scale soil databases to assess important aspects related to tropical soil science is well described in Moraes et al. (1995) and Batjes and Dijkshoorn (1999) by calculating the C and N stocks of the Brazilian Amazon basin, that was based on the digitalization of 1162 and 618 soil profile data obtained from available bibliographic sources.
This manuscript describes the creation of a quantitative georeferenced soil database similar to that described in Moraes et al. (1995), but extending it to the total Brazilian territory and increasing comprehensiveness.
| DATABASE DESCRIPTION AND ORIGINS |
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The sequence used to show the data followed the Radam volumes, or that of the institution responsible for the regional soil surveys. This main table contains data from all of the soil profiles extracted from the abovementioned surveys. The profiles are numbered and georeferenced (latitude and longitude in geographic coordinates using decimal degrees with unspecified datum). Each profile contains data of the surface and the diagnostic subsurface horizons. The variables or soil attributes (Table 1) are listed according to a logical order that depends on the type of soil attribute (physical, chemical, or morphological).
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Some profiles, especially the more recent ones, had coordinates (latitude and longitude) in their description with no indication of datum. These coordinates were used in the database after examination of their inclusion within the coordinates of the respective mapping area. Most of the older profiles description had no coordinate indication. In some cases the profile number was indicated on the printed map and in others a general location description (e.g., distance from a city traveling along a specific road) was provided. In these cases, the location was identified on the printed map and coordinates were calculated using the map's georeferenced grid, or the profile's location was found on a digital road map. This procedure allowed the inclusion of several nongeoreferenced profiles as geocoded data in the final database.
Spatial Data Distribution and Intent
A total of 5255 profiles were originally included in the database, this corresponds to a total of 10528 horizons. After auditing 5086 profiles remained in the database. These were distributed over the whole of Brazil. This corresponds to data from 10034 horizons, where each horizon contains information on 31 soil variables (Table 1). Each profile and/or horizon is stored in the database linked to an identification key that contains the number of the Radam volume or code of the regional soil survey and the corresponding soil profile number. The soil profile number is the same as those found in the soil survey volumes so that crosschecking and/or correction can be done.
The uniformity of the data extracted from the soil surveys was quite low. In the Radam project, many regions of Brazil, mainly the regions concerning volumes 1 to 14, were mapped with very few sampling points (<100 per volume). The lowest sampling intensities are in volumes 1 to 6 where the number of profiles was <45. In the case of volumes 1 to 6, the sampling density was one profile for every 10000 km2 and for volumes 7 to 14, one profile for every 3800 km2. For volumes 14 to 33 where the mean number of soil profile per volume is 183, a sampling density of one profile for every 1370 km2 is found. The lack of uniformity in the Radam database can be explained by the changing financial and political situation during the 11-yr span of the project. The regional soil surveys, used to complement the database, also presented very low uniformity concerning the profile distribution. This can be partly explained by the different scales and sampling densities used in the different surveys. In these surveys, scales ranging from 1:10000 to 1:1000000 and sampling densities varying from one profile every 19 km2 to one profile every 2878 km2, were found.
One objective for assembling this database was to make available the most comprehensive soil profiles information as possible while using as sources only published data. In this way, information that was restricted to personal or public libraries is being made available through the Internet for noncommercial use. Several variables reflecting soil chemical, physical, mineralogical, morphological, and pedogenetic features were included, useful for a wide range of topics related to soil science. Of the 31 chosen variables (Table 1), six correspond to soil morphological attributes, eight correspond to soil physical attributes, and 16 correspond to soil chemical attributes. To these soil attributes, soil classification of each profile is also included, using the original terminology, completing the 31 variables contained in the database.
The database is useful to soil scientists, and other professionals working with agronomy, land-use planning, environmental management, soil process modeling or any other area in which basic soil data is necessary. Use of this database for noncommercial purpose is free, preserving the reference to its authorship. User-defined searches are allowed, as well as modifications to the structure or contents of all or part of the database. Importation into other database management systems and use with GIS or other interpolating systems is also possible. The database is available for free download at http://www.esalq.usp.br/gerd/ (verified 21 Dec. 2004).
| ACKNOWLEDGMENTS |
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Received for publication April 13, 2004.
| REFERENCES |
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