THE STATE OF THE ART OF BRAZILIAN SOIL MAPPINGAND PROSPECTS FOR DIGITAL SOIL MAPPING

摘要

In this chapter, we shall discuss about the state of the art of the Brazilian soil survey and mapping, including a brief history of soil surveys in Brazil, a summary description of survey methods and techniques, mapping paradigms, as well as the present-day needs and current challenges. Digital soil mapping is viewed as an opportunity to recover the unaccomplished soil mapping program in Brazil. We also focus on several attempts to make a national soil database, starting at the beginning of the 1980s with SisSolos, followed by SigSolos, and lately, SigWeb "Iniciativa Solos br", available at http:/ / www.cnps.embrapa.br/soilsbr and the country's new challenges to improve soil mapping, as well as some insights into digital soil mapping. Traditional soil surveys in Brazil have covered almost the whole country; these soil surveys are mainly in small-scale mapping, except for the Amazon region, which is poorly provided with soil surveys. Four main governmental institutions, Brazilian Agricultural Research Corporation (EMBRAPA), Brazilian Institute of Geography and Statistics (IBGE), Agronomic Institute of Campinas (IAC) and Geological Survey of Brazil (CPRM), execute soil surveys at the national and state levels. Private consultants also perform soil surveys, particularly on larger scales, under private contracts. Consequently, there is much dispersed information about soil surveys, but at least the methods and procedures are kept reasonably uniform all over the country. The systematic, governmental-supported soil mapping of the entire country, as initially planned, has been cancelled for a long time, although the demand for soil survey information continues at the same or even higher levels in some regions. At present, complete soil mapping covers 17 states out of 26, and the Federal District, at scales ranging from 1:100,000 to 1:600,000, covers approximately 35% of Brazilian soil, as well as a full uniform cover at scales of 1:1,000,000 and 1:5,000,000. Extensive zones still lack complete soil information at suitable scales and survey levels, needed to face the current problems of use, management, conservation, prevention and recovery of agriculturally and nonagri-culturally degraded areas. Nowadays, soil surveys are made only on governmental de-mands, to support agroecological zonings and evaluation of environmental-impact projects, precision agriculture, degraded-area reclamation, planning of rural settlements and land-use planning, and are always linked to multidisciplinary activities. Soil and environmental data organisation, structuring and availability is imperative to perform digital soil mapping, which will certainly generate demands of quality databases as well as of the necessary tools for institutions involved in soil surveys in Brazil.