RADIAC¸ ˜ AO GAMA E RESISTIVIDADE EL´ ETRICA EM SOLO COM APLICAC¸ ˜ AO DE CARBONATITO E FERTILIZANTES AGRNO DISTRITO FEDERAL

EMBRAPA (Empresa Brasileira de Pesquisa Agropecu´ aria) and Bras´olia University developed a research project about the viability of carbonatite rock as agricultural fertilizer. As an initial experiment, several mixtures of carbonatite, limestone, phosphorous and potassium compounds were added as fertilizers in an oxisol area (red-latosol, according with Brazilian System of Soil Classification), in Distrito Federal, central Brazil. The experiment area was divided in 56 plots (4 × 7m ) and each plot received a fertilizer mixture. The purpose of this work was to verify if the addition of fertilizer mixture to the soil modified its radiometric and resistivity propertiesandifitispossibletoidentifythischange. Gamma-rayandelectricalresistivitymeasurementswereobtainedinanexperimentalareaandinanaturalsavannah type vegetation area. The results showed that the fertilizer addition modified soil natural properties causing a small increase in K, U, Th levels and decreasing ten times electrical resistivity. A low contrast of radiation was observed between plots, and then it was not possible to differentiate the several treatments in base of gamma-ray measurements. Electrical resistivity was efficient to identify three groups of plots related to mixtures characteristics, respectively with phosphorous, potassium and limestone / carbonatite predominance.